Probably, it is worth talking in more detail about the exhaust systems of internal combustion engines in general, in order to learn how to separate "flies from cutlets" in this not easy-to-understand area. Not simple from the point of view of the physical processes occurring in the muffler after the engine has already completed the next working cycle, and, it would seem, has done its job.
Further we will talk about model two-stroke engines, but all the reasoning is true for four-stroke engines, and for engines of "non-model" cubic capacity.
Let me remind you that not every exhaust tract of an internal combustion engine, even built according to a resonant scheme, can increase the power or torque of the engine, as well as reduce its noise level. By and large, these are two mutually exclusive requirements, and the task of the designer exhaust system usually comes down to finding a compromise between the noise of the internal combustion engine, and its power in a particular mode of operation.
This is due to several factors. Let us consider an "ideal" engine, in which the internal energy losses due to the sliding friction of the nodes are equal to zero. Also, we will not take into account losses in rolling bearings and losses that are inevitable during the flow of internal gas-dynamic processes(suction and purge). As a result, all the energy released during combustion fuel mixture, will be spent on:
1) useful work of the propeller of the model (propeller, wheel, etc. We will not consider the efficiency of these units, this is a separate topic).
2) losses arising during another cyclic phase of the process ICE operation- exhaust.
Exhaust losses are worth considering in more detail. Let me emphasize that we are not talking about the "working stroke" cycle (we agreed that the engine "inside itself" is ideal), but about the losses due to "pushing" the combustion products of the fuel mixture from the engine into the atmosphere. They are determined mainly by the dynamic resistance of the exhaust tract- everything that connects to the motor crankcase. From the inlet to the outlet of the "muffler". Hopefully, there is no need to convince anyone that the lower the resistance of the channels through which the gases "leave" the engine, the less effort will have to be spent on this, and the faster the process of "gas separation" will take place.
Obviously, it is the ICE exhaust phase that is the main one in the process of noise generation (let's forget about the noise that occurs during the intake and combustion of fuel in the cylinder, as well as mechanical noise from the operation of the mechanism - an ideal ICE simply cannot have mechanical noise). It is logical to assume that in this approximation, the overall efficiency of the internal combustion engine will be determined by the ratio between useful work and exhaust losses. Accordingly, reducing exhaust losses will increase engine efficiency.
Where is the exhaust energy spent? Naturally, it is converted into acoustic vibrations. the environment(atmosphere), i.e. into the noise (of course, there is a heating of the surrounding space, but we will keep silent about this for now). The place of occurrence of this noise is the cut of the engine exhaust window, where an abrupt expansion of the exhaust gases occurs, which initiates acoustic waves. The physics of this process is very simple: at the moment of opening the exhaust window in a small volume of the cylinder there is a large portion of compressed gaseous residues of fuel combustion products, which expands rapidly and abruptly when entering the surrounding space, while a gas-dynamic shock occurs, provoking subsequent damping acoustic vibrations in the air (remember the pop when you uncork a bottle of champagne). To reduce this cotton, it is sufficient to increase the time for the outflow of compressed gases from the cylinder (bottle), limiting the section of the exhaust window (smoothly opening the plug). But this method of noise reduction is not acceptable for real engine, in which, as we know, the power directly depends on the revolutions, therefore - on the speed of all the processes taking place.
You can reduce the exhaust noise in another way: do not limit the sectional area of the exhaust window and the expiration time exhaust gases, but to limit the rate of their expansion already in the atmosphere. And such a method was found.
Back in the 30s of the last century, sports motorcycles and cars began to be equipped with a kind of conical exhaust pipes with a small opening angle. These mufflers are called "megaphones". They slightly reduced the level of exhaust noise of the internal combustion engine, and in some cases allowed, also slightly, to increase the engine power by improving the cleaning of the cylinder from the remains of exhaust gases due to the inertia of the gas column moving inside the conical exhaust pipe.
Calculations and practical experiments have shown that the optimal opening angle of the megaphone is close to 12-15 degrees. In principle, if you make a megaphone with such an opening angle of a very long length, it will be quite effective at damping the engine noise, almost without reducing its power, but in practice such designs are not feasible due to obvious design flaws and limitations.
Another way to reduce ICE noise is to minimize the pulsation of exhaust gases at the outlet of the exhaust system. For this purpose, the exhaust is not made directly into the atmosphere, but into an intermediate receiver of sufficient volume (ideally, at least 20 times the working volume of the cylinder), followed by the release of gases through a relatively small hole, the area of which may be several times smaller than the area of the exhaust window. Such systems smooth out the pulsating nature of the movement of the gas mixture at the exit from the engine, turning it into a nearly uniformly progressive movement at the exit of the muffler.
Let me remind you that at the moment we are talking about muffling systems that do not increase the gas-dynamic resistance to exhaust gases. Therefore, I will not touch upon all sorts of tricks such as metal grids inside the jamming chamber, perforated baffles and pipes, which, of course, help reduce engine noise, but at the expense of its power.
The next step in the development of silencers were systems consisting of various combinations of the above-described noise suppression methods. I will say right away that for the most part they are far from ideal, tk. to one degree or another increase the gas-dynamic resistance of the exhaust tract, which definitely leads to a decrease in the engine power transmitted to the propeller.
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UDC 621.436
INFLUENCE OF AERODYNAMIC RESISTANCE OF INLET AND EXHAUST SYSTEMS OF AUTOMOTIVE ENGINES ON GAS EXCHANGE PROCESSES
L.V. Plotnikov, B.P. Zhilkin, Yu.M. Brodov, N.I. Grigoriev
The paper presents the results of an experimental study of the effect of aerodynamic resistance of intake and exhaust systems piston engines on gas exchange processes. The experiments were carried out on full-scale models of a single-cylinder internal combustion engine. The setup and experimental technique are described. The dependences of the change in the instantaneous speed and pressure of the flow in the gas-air paths of the engine on the angle of rotation are presented. crankshaft... The data was obtained at different drag coefficients of the intake and exhaust systems and different crankshaft speeds. Based on the data obtained, conclusions were drawn about the dynamic features of the gas exchange processes in the engine at different conditions... It is shown that the use of a noise damper smoothes flow pulsations and changes the flow characteristics.
Key words: piston engine, gas exchange processes, process dynamics, flow velocity and pressure pulsations, noise muffler.
Introduction
To intake and exhaust systems of piston engines internal combustion a number of requirements are imposed, among which the main ones are the maximum reduction in aerodynamic noise and the minimum aerodynamic resistance. Both of these indicators are determined in the relationship between the design of the filter element, intake and exhaust mufflers, catalytic converters, the presence of pressurization (compressor and / or turbocharger), as well as the configuration of the intake and exhaust pipelines and the nature of the flow in them. At the same time, there is practically no data on the influence of additional elements of the intake and exhaust systems (filters, mufflers, turbochargers) on the gas dynamics of the flow in them.
This article presents the results of a study of the influence of the aerodynamic resistance of the intake and exhaust systems on the gas exchange processes in relation to a piston engine with a dimension of 8.2 / 7.1.
Experimental setup
and data collection system
Studies of the effect of aerodynamic resistance of gas-air systems on the processes of gas exchange in piston internal combustion engines were carried out on a full-scale model of a single-cylinder 8.2 / 7.1 engine driven into rotation asynchronous motor, the frequency of rotation of the crankshaft of which was regulated in the range of n = 600-3000 min1 with an accuracy of ± 0.1%. The experimental setup is described in more detail in.
In fig. 1 and 2 show configurations and geometric dimensions inlet and outlet tracts of the experimental setup, as well as the location of the sensors for measuring instantaneous
values average speed and air flow pressure.
To measure the instantaneous values of the pressure in the flow (static) in the channel px, a WIKA pressure sensor £ -10 was used, the response rate of which is less than 1 ms. The maximum relative root-mean-square error of pressure measurement was ± 0.25%.
To determine the instantaneous average air flow velocity wх over the channel cross-section, constant-temperature hot-wire anemometers of an original design were used, the sensitive element of which was a nichrome thread with a diameter of 5 μm and a length of 5 mm. The maximum relative root-mean-square error in measuring the speed wх was ± 2.9%.
The measurement of the crankshaft rotational speed was carried out using a tachometer counter consisting of a toothed disk attached to the crankshaft and an inductive sensor. The sensor generated a voltage pulse with a frequency proportional to the shaft rotation speed. These impulses were used to record the rotation frequency, determine the position of the crankshaft (angle φ) and the moment the piston passed the TDC and BDC.
Signals from all sensors were fed to an analog-to-digital converter and transferred to a personal computer for further processing.
Before the experiments, static and dynamic calibration of the measuring system as a whole was carried out, which showed the speed required to study the dynamics of gas-dynamic processes in the intake and exhaust systems of piston engines. The total rms error of experiments on the effect of the aerodynamic drag of gas-air ICE systems on gas exchange processes was ± 3.4%.
Rice. 1. Configuration and geometrical dimensions of the inlet tract of the experimental setup: 1 - cylinder head; 2 - inlet pipe; 3 - measuring tube; 4 - hot-wire anemometer sensors for measuring the air flow velocity; 5 - pressure sensors
Rice. 2. Configuration and geometrical dimensions of the exhaust tract of the experimental setup: 1 - cylinder head; 2 - working area - exhaust pipe; 3 - pressure sensors; 4 - hot-wire anemometer sensors
The influence of additional elements on the gas dynamics of the intake and exhaust processes was studied at various drag coefficients of the systems. The resistances were created using various intake and exhaust filters. So, as one of them, a standard car air filter with a resistance coefficient of 7.5 was used. A fabric filter with a resistance coefficient of 32 was chosen as another filter element. The resistance coefficient was determined experimentally by means of static blowing under laboratory conditions. Studies were also conducted without filters.
Influence of aerodynamic drag on the intake process
In fig. 3 and 4 show the dependences of the air flow rate and pressure рх in the intake duct.
le from the angle of rotation of the crankshaft ф at different speeds and when using different intake filters.
It was found that in both cases (with and without a muffler) the pulsations of pressure and air flow rate are most pronounced at high crankshaft rotation frequencies. At the same time, in the intake duct with a silencer, the values maximum speed the air flow, as expected, is less than in the duct without it. Most
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Rice. 3. Dependence of the air speed wх in the intake channel on the angle of rotation of the crankshaft φ at different speeds of rotation of the crankshaft and different filter elements: a - n = 1500 min-1; b - 3000 min-1. 1 - without filter; 2 - standard air filter; 3 - fabric filter
Rice. 4. Dependence of the pressure px in the intake channel on the angle of rotation of the crankshaft φ at different speeds of rotation of the crankshaft and different filter elements: a - n = 1500 min-1; b - 3000 min-1. 1 - without filter; 2 - standard air filter; 3 - fabric filter
this was clearly manifested at high speeds of the crankshaft.
After closing the inlet valve, the pressure and air flow rate in the channel under all conditions do not become zero, but some fluctuations are observed (see Fig. 3 and 4), which is also typical for the exhaust process (see below). In this case, the installation of an intake silencer leads to a decrease in pressure pulsations and air flow rate under all conditions both during the intake process and after the intake valve is closed.
Influence of aerodynamic
resistance to the release process
In fig. 5 and 6 show the dependences of the air flow rate wx and the pressure px in the exhaust channel on the angle of rotation of the crankshaft φ at its different speeds and when using different exhaust filters.
The studies were carried out for various speeds of the crankshaft (from 600 to 3000 min1) at various excess pressures at the outlet (from 0.5 to 2.0 bar) without and if equipped with a silencer.
It was found that in both cases (with and without a muffler) the pulsations of the air flow rate were most clearly manifested at low crankshaft rotation frequencies. At the same time, in the exhaust duct with a silencer, the values of the maximum air flow rate remain at
approximately the same as without it. After closing exhaust valve the air flow velocity in the channel under all conditions does not become equal to zero, but some velocity fluctuations are observed (see Fig. 5), which is also typical for the intake process (see above). At the same time, the installation of a silencer at the outlet leads to a significant increase in the pulsations of the air flow rate under all conditions (especially at pb = 2.0 bar) both during the exhaust process and after the closing of the exhaust valve.
It should be noted the opposite effect of aerodynamic resistance on the characteristics of the intake process into the internal combustion engine, where, when using air filter pulsating effects during the intake and after the closing of the intake valve were present, but they decayed clearly faster than without it. At the same time, the presence of a filter in the intake system led to a decrease in the maximum air flow rate and a weakening of the dynamics of the process, which is in good agreement with the previously obtained results in work.
An increase in the aerodynamic drag of the exhaust system leads to a slight increase in the maximum pressures during the exhaust process, as well as to a shift in the peaks beyond TDC. At the same time, it can be noted that the installation of an exhaust silencer leads to a decrease in air flow pressure pulsations under all conditions both during the exhaust process and after the exhaust valve is closed.
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Rice. 5. Dependence of the air speed wх in the exhaust channel on the angle of rotation of the crankshaft φ at different speeds of rotation of the crankshaft and different filter elements: a - n = 1500 min-1; b - 3000 min-1. 1 - without filter; 2 - standard air filter; 3 - fabric filter
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Rice. 6. Dependence of the pressure px in the exhaust channel on the angle of rotation of the crankshaft φ at different speeds of rotation of the crankshaft and different filter elements: a - n = 1500 min-1; b - 3000 min-1. 1 - without filter; 2 - standard air filter; 3 - fabric filter
Based on the processing of the dependences of the change in the flow rate for a single cycle, the relative change in the volumetric air flow Q through the exhaust channel was calculated when the muffler was placed. It was found that at low excess pressures at the outlet (0.1 MPa), the flow rate Q in the exhaust system with a silencer is less than in the system without it. Moreover, if at a crankshaft speed of 600 min-1 this difference was approximately 1.5% (which lies within the error), then at n = 3000 min4 this difference reached 23%. It is shown that for a high overpressure equal to 0.2 MPa, the opposite tendency was observed. The volumetric air flow through the exhaust duct with the muffler was greater than in the system without it. At the same time, at low speeds of rotation of the crankshaft, this excess was 20%, and at n = 3000 min1, only 5%. According to the authors, this effect can be explained by some smoothing of the pulsations of the air flow rate in the exhaust system in the presence of a noise muffler.
Conclusion
The study showed that the intake process in a piston internal combustion engine is significantly influenced by the aerodynamic resistance of the intake tract:
An increase in the resistance of the filter element smoothes the dynamics of the filling process, but at the same time reduces the air flow rate, which accordingly reduces the filling ratio;
The effect of the filter increases with an increase in the crankshaft speed;
The threshold value of the filter resistance coefficient (approximately 50-55) was set, after which its value does not affect the flow rate.
At the same time, it was shown that the aerodynamic resistance of the exhaust system also significantly affects the gas-dynamic and flow characteristics of the exhaust process:
An increase in the hydraulic resistance of the exhaust system in a piston internal combustion engine leads to an increase in the pulsations of the air flow rate in the exhaust channel;
At low excess pressures at the outlet in a system with a silencer, a decrease in the volumetric flow through the exhaust channel is observed, while at high pf, on the contrary, it increases compared to an exhaust system without a silencer.
Thus, the results obtained can be used in engineering practice in order to optimally select the characteristics of the intake and exhaust noise mufflers, which can have a positive effect.
a significant effect on the cylinder filling with a fresh charge (filling ratio) and the quality of cleaning the engine cylinder from exhaust gases (residual gas ratio) at certain speed modes of operation of piston internal combustion engines.
Literature
1. Draganov, B.Kh. Design of inlet and outlet channels of internal combustion engines / B.Kh. Draganov, M.G. Kruglov, V.S. Obukhova. - Kiev: Vischa school. Head publishing house, 1987.-175 p.
2. Internal combustion engines. In 3 kn. Book. 1: Theory of work processes: textbook. / V.N. Lu-kanin, K.A. Morozov, A.S. Khachiyan and others; ed. V.N. Lukanin. - M .: Higher. shk., 1995 .-- 368 p.
3. Sharoglazov, B.A. Internal combustion engines: theory, modeling and calculation of processes: textbook. on the course "Theory of work processes and modeling of processes in internal combustion engines" / B.A. Sharoglazov, M.F. Farafontov, V.V. Klementyev; ed. honored active Science of the Russian Federation B.A. Sharoglazova. - Chelyabinsk: SUSU, 2010.-382 p.
4. Modern approaches to the creation of diesel engines for passenger cars and small cars
Zovikov / A.D. Blinov, P.A. Golubev, Yu.E. Dragan and others; ed. V.S. Paponov and A.M. Mineeva. - M .: Research Center "Engineer", 2000. - 332 p.
5. Experimental study of gas-dynamic processes in the intake system of a piston internal combustion engine. Zhilkin, L.V. Plotnikov, S.A. Korzh, I.D. Larionov // Dvigatelestroyeniye. - 2009. -No. 1. - S. 24-27.
6. On the change in the gas dynamics of the release process in piston internal combustion engines when installing a muffler / LV. Plotnikov, B.P. Zhilkin, A.V. Krestovskikh, D.L. Padalyak // Bulletin of the Academy of Military Sciences. -2011. - No. 2. - S. 267-270.
7. Pat. 81338 RU, IPC G01 P5 / 12. Thermoanemometer of constant temperature / S.N. Plokhov, L.V. Plotnikov, B.P. Zhilkin. - No. 2008135775/22; declared 09/03/2008; publ. 10.03.2009, Bul. No. 7.
The use of resonant exhaust pipes on engine models of all classes can dramatically improve the sporting performance of the competition. However, the geometric parameters of pipes are determined, as a rule, by trial and error, since until now there is no clear understanding and clear interpretation of the processes occurring in these gas-dynamic devices. And in the few sources of information on this matter, contradictory conclusions are given that have an arbitrary interpretation.
For a detailed study of the processes in the tuned exhaust pipes, a special installation was created. It consists of a stand for starting engines, a motor-pipe adapter with fittings for sampling static and dynamic pressure, two piezoelectric sensors, a C1-99 dual-beam oscilloscope, a camera, a resonant exhaust pipe from an R-15 engine with a "telescope" and a homemade pipe with blackening surface and additional thermal insulation.
The pressure in the pipes in the exhaust area was determined as follows: the motor was brought to resonant speed (26000 rpm), the data from the piezoelectric sensors connected to the pressure take-off fittings were displayed on an oscilloscope, the sweep frequency of which was synchronized with the engine speed, and the oscillogram was recorded on photographic film.
After developing the film in a contrast developer, the image was transferred onto tracing paper to the scale of the oscilloscope screen. The results for a pipe from an R-15 engine are shown in Figure 1 and for a homemade pipe with blackening and additional thermal insulation - in Figure 2.
On the graphs:
R dyn - dynamic pressure, P st - static pressure. OBO - opening the exhaust window, BDC - bottom dead center, ZVO - closing the exhaust window.
Analysis of the curves reveals the pressure distribution at the inlet of the resonance tube as a function of the crankshaft rotation phase. An increase in dynamic pressure from the moment the exhaust window with a 5 mm diameter of the outlet pipe is opened occurs for R-15 up to approximately 80 °. And its minimum is in the range of 50 ° - 60 ° from the bottom dead center at maximum blowdown. The pressure increase in the reflected wave (from the minimum) at the moment of closing the exhaust window is about 20% of the maximum value of P. The delay in the action of the reflected wave of exhaust gases is from 80 to 90 °. Static pressure is characterized by an increase in the range of 22 ° from the "plateau" on the graph up to 62 ° from the moment the exhaust port is opened, with a minimum located at 3 ° from the moment of the bottom dead center. Obviously, in the case of using a similar exhaust pipe, purge oscillations occur at 3 °… 20 ° after the bottom dead center, and by no means at 30 ° after the exhaust window is opened, as was previously thought.
The research data for the DIY pipe differs from the R-15 data. The rise in dynamic pressure to 65 ° from the moment the exhaust port is opened is accompanied by a minimum located at 66 ° after the bottom dead center. In this case, the increase in the pressure of the reflected wave from the minimum is about 23%. The delay in the action of the exhaust gases is less, which is probably associated with an increase in temperature in the thermally insulated system, and is about 54 °. Variations in blowdown are noted at 10 ° after bottom dead center.
Comparing the graphs, it can be seen that the static pressure in the heat-insulated pipe at the moment of closing the exhaust window is less than in R-15. However, the dynamic pressure has a maximum reflected wave of 54 ° after closing the exhaust window, and in the R-15 this maximum is shifted by as much as 90 “! The differences are related to the difference in the diameters of the exhaust pipes: on the R-15, as already indicated, the diameter is 5 mm, and on the thermally insulated one - 6.5 mm. In addition, due to the more perfect geometry of the R-15 pipe, it has a higher static pressure recovery factor.
The efficiency of the resonant exhaust pipe largely depends on the geometric parameters of the pipe itself, the section of the engine exhaust pipe, temperature and valve timing.
The use of counter-deflectors and the selection of the temperature regime of the resonant exhaust pipe will allow the maximum pressure of the reflected exhaust gas wave to be shifted to the moment of closing the exhaust window and thus sharply increase the efficiency of its action.
1This article discusses the issues of assessing the effect of the resonator on the filling of the engine. As an example, a resonator is proposed - equal in volume to the volume of the engine cylinder. The geometry of the intake tract, together with the resonator, was imported into the FlowVision software. Mathematical modeling was carried out taking into account all the properties of the moving gas. To estimate the flow through the inlet system, to estimate the flow rate in the system and the relative air pressure in the valve slot, computer simulations were carried out, which showed the effectiveness of using the additional tank. The changes in flow through the valve slot, flow rate, pressure and flow density were evaluated for the standard, retrofit and intake systems with a receiver. At the same time, the mass of the incoming air increases, the flow rate decreases and the density of the air entering the cylinder increases, which has a favorable effect on the output indicators of the internal combustion engine.
intake tract
resonator
filling the cylinder
math modeling
modernized channel.
1. Zholobov LA, Dydykin AM Mathematical modeling of gas exchange processes of internal combustion engines: Monograph. N.N .: NGSKhA, 2007.
2. Dydykin AM, Zholobov LA Gas-dynamic research of internal combustion engines by methods of numerical modeling // Tractors and agricultural machines. 2008. No. 4. S. 29-31.
3. Pritsker D. M., Turyan V. A. Aeromechanics. M .: Oborongiz, 1960.
4. Khailov, MA, Calculation equation of pressure fluctuations in the suction pipeline of an internal combustion engine, Tr. CIAM. 1984. No. 152. P.64.
5. Sonkin, VI, Study of air flow through the valve slot, Tr. US. 1974. Issue 149. S.21-38.
6. Samarskiy AA, Popov Yu. P. Difference methods for solving problems of gas dynamics. Moscow: Nauka, 1980. P.352.
7. Ore BP Applied non-stationary gas dynamics: Textbook. Ufa: Ufa Aviation Institute, 1988. P.184.
8. Malivanov MV, Khmelev RN On the issue of development of mathematical and software for calculating gas-dynamic processes in an internal combustion engine: Proceedings of the IX International Scientific and Practical Conference. Vladimir, 2003.S. 213-216.
The amount of engine torque is proportional to the incoming air mass, referred to the speed. Increasing the filling of the cylinder of a gasoline internal combustion engine by modernizing the intake tract will lead to an increase in the pressure of the intake end, improved mixture formation, an increase in the technical and economic performance of the engine and a decrease in the toxicity of exhaust gases.
The main requirements for the intake tract are to ensure minimum intake resistance and uniform distribution of the combustible mixture over the engine cylinders.
Minimum inlet resistance can be achieved by eliminating roughness of the inner walls of pipelines, as well as abrupt changes in flow direction and elimination of sudden narrowings and expansions of the path.
Various types of pressurization provide a significant influence on the filling of the cylinder. The simplest type of boost is to use the dynamics of the incoming air. The large volume of the receiver partly creates resonance effects in a certain range of speeds, which lead to improved filling. However, they have, as a consequence, dynamic disadvantages, for example, deviations in the composition of the mixture when the load changes rapidly. An almost perfect torque flow is ensured by a changeover of the intake manifold, in which, for example, depending on engine load, speed and throttle position, variations are possible:
Pulse tube lengths;
Switching between pulsation pipes of different lengths or diameters;
- selective shutdown of a separate pipe of one cylinder in the presence of a large number of them;
- switching the volume of the receiver.
With resonant pressurization, groups of cylinders with the same flash interval are connected by short pipes to resonant receivers, which are connected through resonance pipes to the atmosphere or to a collecting receiver acting as a Hölmholtz resonator. It is a spherical vessel with an open neck. The air in the throat is an oscillating mass, and the volume of air in the vessel plays the role of an elastic element. Of course, such a division is valid only approximately, since some part of the air in the cavity has inertial resistance. However, with a sufficiently large value of the ratio of the hole area to the cavity cross-sectional area, the accuracy of this approximation is quite satisfactory. The main part of the kinetic energy of vibrations is concentrated in the throat of the resonator, where the vibrational velocity of air particles is greatest.
The intake resonator is installed between the throttle valve and the cylinder. It begins to act when the throttle is closed enough so that its hydraulic resistance becomes comparable to the resistance of the resonator channel. When the piston moves down, the combustible mixture enters the engine cylinder not only from under the throttle, but also from the container. With a decrease in rarefaction, the resonator begins to suck the combustible mixture into itself. A part, and quite a large one, of the reverse ejection will also go here.
The article analyzes the flow movement in the inlet channel of a 4-stroke gasoline internal combustion engine at a nominal crankshaft speed using the example of a VAZ-2108 engine at a crankshaft speed n = 5600 min-1.
This research problem was solved mathematically using a software package for modeling gas-hydraulic processes. Modeling was carried out using the FlowVision software package. For this purpose, geometry was obtained and imported (geometry refers to the internal volumes of the engine - intake and exhaust pipes, over-piston volume of the cylinder) using various standard file formats. This allows you to use CAD SolidWorks to create a computational domain.
The area of calculation is understood as the volume in which the equations of the mathematical model are defined, and the boundary of the volume, on which the boundary conditions are defined, then save the resulting geometry in a format supported by FlowVision and use it when creating a new design case.
In this task, the ASCII format, binary, in the stl extension, the StereoLithographyformat type with an angular tolerance of 4.0 degrees and a deviation of 0.025 meters was used to improve the accuracy of the obtained simulation results.
After obtaining a three-dimensional model of the computational domain, a mathematical model is set (a set of laws for changing the physical parameters of a gas for a given problem).
In this case, an essentially subsonic gas flow is assumed at low Reynolds numbers, which is described by a turbulent flow model of a fully compressible gas using the standard k-e turbulence model. This mathematical model is described by a system consisting of seven equations: two Navier - Stokes equations, equations of continuity, energy, ideal gas state, mass transfer, and equations for the kinetic energy of turbulent pulsations.
(2)
Energy equation (total enthalpy)
Ideal gas equation of state:
Turbulent components are related to other variables through the value of turbulent viscosity, which is calculated in accordance with the standard k-ε turbulence model.
Equations for k and ε
turbulent viscosity:
constants, parameters and sources:
(9)
(10)
σk = 1; σε = 1.3; Cμ = 0.09; Cε1 = 1.44; Сε2 = 1.92
The working medium in the intake process is air, in this case considered as an ideal gas. The initial values of the parameters are set for the entire computational domain: temperature, concentration, pressure and velocity. For pressure and temperature, the initial parameters are equal to the reference ones. The speed inside the computational domain in the X, Y, Z directions is zero. Variables temperature and pressure in FlowVision are represented by relative values, the absolute values of which are calculated by the formula:
fa = f + fref, (11)
where fa is the absolute value of the variable, f is the calculated relative value of the variable, fref is the reference value.
Boundary conditions are set for each of the design surfaces. Boundary conditions should be understood as a set of equations and laws typical for surfaces of computational geometry. Boundary conditions are necessary to determine the interaction between the computational domain and the mathematical model. The page specifies a specific type of boundary condition for each surface. The type of boundary condition is set on the inlet windows of the inlet channel - free entrance. The rest of the elements - the wall-boundary, which does not pass and does not transmit the design parameters further than the computational domain. In addition to all of the above boundary conditions, it is necessary to take into account the boundary conditions on the moving elements included in the selected mathematical model.
Moving parts include the inlet and outlet valves and the piston. At the boundaries of the moving elements, we define the type of the boundary condition wall.
For each of the moving bodies, a law of motion is set. The change in piston speed is determined by the formula. To determine the laws of valve movement, the valve lift curves were taken through 0.50 with an accuracy of 0.001 mm. Then the speed and acceleration of the valve movement were calculated. The received data is converted into dynamic libraries (time - speed).
The next stage in the modeling process is the generation of the computational grid. FlowVision uses a locally adaptive computational grid. First, an initial computational mesh is created, and then the criteria for mesh refinement are specified, according to which FlowVision breaks the cells of the initial mesh to the desired degree. The adaptation is made both in terms of the volume of the flow path of the channels and along the walls of the cylinder. Adaptations with additional refinement of the computational mesh are created in places with the maximum possible speed. In terms of volume, grinding was carried out to level 2 in the combustion chamber and to level 5 in the valve slots; along the cylinder walls, adaptation was made to level 1. This is necessary to increase the time integration step for the implicit calculation method. This is due to the fact that the time step is defined as the ratio of the cell size to the maximum speed in it.
Before starting the calculation of the created variant, it is necessary to set the parameters of numerical simulation. In this case, the time for continuing the calculation is set equal to one full cycle of the internal combustion engine operation - 7200 sc.c., the number of iterations and the frequency of saving the data of the calculation option. Certain calculation steps are saved for subsequent processing. The time step and options for the calculation process are set. This task requires setting a time step - a choice method: an implicit scheme with a maximum step of 5e-004s, an explicit CFL number - 1. This means that the time step is determined by the program itself, depending on the convergence of the pressure equations.
In the postprocessor, the parameters of visualization of the obtained results of interest to us are configured and set. Modeling allows you to obtain the required visualization layers after the completion of the main calculation, based on the calculation stages saved with a certain frequency. In addition, the postprocessor allows you to transfer the obtained numerical values of the parameters of the process under study in the form of an information file to external editors of spreadsheets and obtain the time dependence of such parameters as speed, flow rate, pressure, etc.
Figure 1 shows the installation of the receiver on the inlet of the internal combustion engine. The volume of the receiver is equal to the volume of one cylinder of the engine. The receiver is installed as close to the inlet as possible.
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Rice. 1. The computational area modernized with the receiver in CADSolidWorks |
The natural frequency of the Helmholtz resonator is:
(12)
where F is the frequency, Hz; C0 - speed of sound in air (340 m / s); S is the section of the hole, m2; L - pipe length, m; V is the resonator volume, m3.
For our example, we have the following values:
d = 0.032 m, S = 0.00080384 m2, V = 0.000422267 m3, L = 0.04 m.
After calculating F = 374 Hz, which corresponds to the crankshaft rotation frequency n = 5600 min-1.
After setting the created version for calculation and after setting the parameters of numerical modeling, the following data were obtained: flow rate, speed, density, pressure, temperature of the gas flow in the inlet channel of the internal combustion engine by the angle of rotation of the crankshaft.
From the presented graph (Fig. 2) according to the flow rate in the valve slot it can be seen that the modernized channel with the receiver has the maximum flow rate characteristic. The flow rate is 200 g / sec higher. The increase is observed throughout 60 gp.c.
From the moment the inlet valve is opened (348 g.p.c.), the flow velocity (Fig. 3) begins to increase from 0 to 170 m / s (at the modernized inlet channel 210 m / s, with the receiver -190 m / s) in the interval up to 440-450 g.p.c. In the channel with the receiver, the speed value is higher than in the standard one by about 20 m / s, starting from 430-440 g.c.v. The numerical value of the speed in the channel with the receiver is much smoother than that of the modernized intake channel, during the opening of the intake valve. Further, a significant decrease in the flow rate is observed, up to the closing of the intake valve.
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Rice. 2. Gas flow rate in the valve slot for standard, modernized and receiver channels at n = 5600 min-1: 1 - standard, 2 - modernized, 3 - modernized with receiver |
Rice. 3. The rate of flow in the valve slot for channels of standard, modernized and with a receiver at n = 5600 min-1: 1 - standard, 2 - modernized, 3 - modernized with a receiver |
From the graphs of the relative pressure (Fig. 4) (atmospheric pressure is taken as zero, P = 101000 Pa) it follows that the pressure value in the modernized channel is higher than in the standard one by 20 kPa at 460-480 g.c.v. (associated with a large value of the flow rate). Starting from 520 g.p.c., the pressure value is equalized, which cannot be said about the channel with the receiver. The pressure value is higher than the standard one by 25 kPa, starting from 420-440 g.p.c. until the intake valve is closed.
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Rice. 4. Flow pressure in a standard, modernized and channel with a receiver at n = 5600 min-1 (1 - standard channel, 2 - modernized channel, 3 - modernized channel with a receiver) |
Rice. 5. Flux density in the standard, upgraded and channel with a receiver at n = 5600 min-1 (1 - standard channel, 2 - upgraded channel, 3 - upgraded channel with receiver) |
The flow density in the area of the valve slot is shown in Fig. 5.
In a modernized channel with a receiver, the density value is lower by 0.2 kg / m3 starting from 440 g.c.v. compared to the standard channel. This is due to high pressures and gas flow rates.
From the analysis of the graphs, the following conclusion can be drawn: the channel of an improved shape provides a better filling of the cylinder with a fresh charge due to a decrease in the hydraulic resistance of the inlet channel. With an increase in the speed of the piston at the moment of opening the intake valve, the shape of the channel does not significantly affect the speed, density and pressure inside the intake channel, this is explained by the fact that during this period the indicators of the intake process mainly depend on the speed of the piston and the flow area of the valve slot ( in this calculation, only the shape of the intake channel is changed), but everything changes dramatically at the time of the deceleration of the piston movement. The charge in a standard channel is less inert and more "stretches" along the length of the channel, which together gives a lower filling of the cylinder at the moment of the piston movement speed decrease. Until the valve is closed, the process proceeds under the denominator of the already obtained flow rate (the piston gives the initial velocity to the flow of the overvalve volume, when the piston speed decreases, the inertial component of the gas flow plays a significant role in filling, due to a decrease in the resistance to flow), the modernized channel hinders the passage of the charge much less. This is confirmed by higher rates of speed and pressure.
In the intake duct with the receiver, due to additional charging of the charge and resonance phenomena, a much larger mass of the gas mixture enters the cylinder of the internal combustion engine, which ensures higher technical performance of the internal combustion engine. The increase in pressure at the end of the intake will have a significant impact on the increase in the technical, economic and environmental performance of the internal combustion engine.
Reviewers:
Gots Alexander Nikolaevich, Doctor of Technical Sciences, Professor of the Department of Heat Engines and Power Plants, Vladimir State University of the Ministry of Education and Science, Vladimir.
Aleksey Removich Kulchitskiy, Doctor of Technical Sciences, Professor, Deputy Chief Designer of VMTZ LLC, Vladimir.
Bibliographic reference
Zholobov L. A., Suvorov E. A., Vasiliev I. S. INFLUENCE OF ADDITIONAL CAPACITY IN THE INLET SYSTEM ON FILLING THE ICE // Modern problems of science and education. - 2013. - No. 1 .;URL: http://science-education.ru/ru/article/view?id=8270 (date of access: 11/25/2019). We bring to your attention the journals published by the "Academy of Natural Sciences"
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1 As a manuscript Mashkur Mahmud A. MATHEMATICAL MODEL OF GAS DYNAMICS AND HEAT EXCHANGE IN INLET AND EXHAUST SYSTEMS OF ICE Specialty "Heat engines" Abstract of the thesis for the degree of candidate of technical sciences St. Petersburg 2005
2 General characteristics of the work The relevance of the dissertation In modern conditions of the accelerated pace of development of engine building, as well as the dominant tendencies of intensification of the work process, provided that its efficiency is increased, more and more attention is paid to reducing the time for creating, fine-tuning and modifying existing types of engines. The main factor that significantly reduces both time and material costs in this task is the use of modern computers. However, their use can be effective only if the created mathematical models are adequate to the real processes that determine the functioning of the internal combustion engine. Particularly acute at this stage in the development of modern engine building is the problem of heat stress in the parts of the cylinder-piston group (CPG) and the cylinder head, which is inextricably linked with an increase in the aggregate power. The processes of instantaneous local convective heat transfer between the working fluid and the walls of gas-air channels (GWC) still remain insufficiently studied and are one of the bottlenecks in the theory of internal combustion engines. In this regard, the creation of reliable, experimentally substantiated theoretical and computational methods for studying local convective heat transfer in a GWC, which make it possible to obtain reliable estimates of the temperature and heat stress state of internal combustion engine parts, is an urgent problem. Its solution will make it possible to make a reasonable choice of design and technological solutions, improve the scientific and technical level of design, make it possible to shorten the engine development cycle and obtain an economic effect by reducing the cost and costs of experimental fine-tuning of engines. Purpose and objectives of the research The main purpose of the dissertation is to solve a set of theoretical, experimental and methodological problems, 1
3 related to the creation of new weft mathematical models and methods for calculating the local convective heat transfer in the GVK engine. In accordance with the set goal of the work, the following main tasks were solved, which largely determined the methodological sequence of the work: 1. Conducting a theoretical analysis of the unsteady flow in the GWC and assessing the possibilities of using the boundary layer theory in determining the parameters of local convective heat transfer in engines; 2. Development of an algorithm and numerical implementation on a computer of the problem of the inviscid flow of a working fluid in the elements of the intake-exhaust system of a multi-cylinder engine in a non-stationary setting to determine the speeds, temperature and pressure used as boundary conditions for further solving the problem of gas dynamics and heat transfer in the cavities of the main engine room. 3. Creation of a new method for calculating the fields of instantaneous velocities of the flow around the working body of the GWC in a three-dimensional setting; 4. Development of a mathematical model of local convective heat transfer in the GVK using the foundations of the theory of the boundary layer. 5. Checking the adequacy of mathematical models of local heat transfer in the GVK by comparing experimental and calculated data. The implementation of this set of tasks allows the achievement of the main goal of the work - the creation of an engineering method for calculating the local parameters of convective heat transfer in the GVK of a gasoline engine. The relevance of the problem is determined by the fact that the solution of the set tasks will make it possible to make a reasonable choice of design and technological solutions at the engine design stage, increase the scientific and technical level of design, reduce the engine development cycle and obtain an economic effect by reducing the cost and costs of experimental fine-tuning of the product. 2
4 The scientific novelty of the thesis is that: 1. For the first time, a mathematical model was used that rationally combines the one-dimensional representation of gas-dynamic processes in the intake and exhaust systems of the engine with a three-dimensional representation of the gas flow in the GVK to calculate the parameters of local heat transfer. 2. Developed methodological foundations for designing and fine-tuning a gasoline engine by modernizing and refining methods for calculating local thermal loads and thermal state of cylinder head elements. 3. New calculated and experimental data on the spatial gas flows in the intake and exhaust channels of the engine and the three-dimensional distribution of temperatures in the body of the cylinder head of a gasoline engine have been obtained. The reliability of the results is ensured by the use of proven methods of computational analysis and experimental studies, general systems of equations reflecting the fundamental laws of conservation of energy, mass, momentum with appropriate initial and boundary conditions, modern numerical methods for the implementation of mathematical complex in an experimental study, as well as a satisfactory agreement between the results of modeling and experiment. The practical value of the results obtained lies in the fact that an algorithm and a program for calculating a closed working cycle of a gasoline engine with a one-dimensional representation of gas-dynamic processes in the intake and exhaust systems of the engine, as well as an algorithm and a program for calculating the parameters of heat transfer in the GVK of the cylinder head of a gasoline engine in a three-dimensional setting, have been developed, recommended for implementation. The results of theoretical research, confirmed by 3
5 experiment, can significantly reduce the cost of designing and fine-tuning engines. Approbation of the work results. The main provisions of the dissertation work were reported at scientific seminars of the Department of Internal combustion of SPbSPU in the city, at the XXXI and XXXIII Science Weeks of the SPbSPU (2002 and 2004). Publications Based on the materials of the dissertation, 6 publications have been published. Structure and scope of work The dissertation work consists of an introduction, fifth chapters, conclusion and a list of references from 129 titles. It contains 189 pages, including: 124 pages of the main text, 41 figures, 14 tables, 6 photographs. The content of the work The introduction substantiates the relevance of the topic of the dissertation, defines the goal and objectives of the research, formulates the scientific novelty and practical significance of the work. The general characteristics of the work are given. The first chapter contains an analysis of the main works on theoretical and experimental studies of the process of gas dynamics and heat transfer in an internal combustion engine. Research tasks are set. A review of the design forms of the exhaust and inlet channels in the cylinder head and an analysis of the methods and results of experimental and theoretical calculations of both stationary and non-stationary gas flows in the gas-air ducts of internal combustion engines is carried out. The presently existing approaches to the calculation and modeling of thermo- and gas-dynamic processes, as well as the intensity of heat transfer in the GWC, are considered. It is concluded that most of them have a limited area of application and do not provide a complete picture of the distribution of heat transfer parameters over the surfaces of the GWC. First of all, this is due to the fact that the solution of the problem of the motion of the working fluid in the GWC is carried out in a simplified one-dimensional or two-dimensional 4
6 statement, which is inapplicable in the case of GVK of complex shape. In addition, it was noted that for calculating convective heat transfer, in most cases, empirical or semi-empirical formulas are used, which also does not allow obtaining the required accuracy of the solution in the general case. These issues were most fully considered earlier in the works of Bravin V.V., Isakov Yu.N., Grishin Yu.A., Kruglov M.G., Kostin A.K., Kavtaradze R.Z., Ovsyannikov M.K. , Petrichenko R.M., Petrichenko M.R., Rosenblita G.B., Stradomsky M.V., Chainova N.D., Shabanova A.Yu., Zaitseva A.B., Mundshtukova D.A., Unru P.P., Shekhovtsova A.F., Voshni G, Heywood J., Benson RS, Garg RD, Woollatt D., Chapman M., Novak JM, Stein RA, Daneshyar H., Horlock JH, Winterbone DE, Kastner LJ , Williams TJ, White BJ, Ferguson CR The analysis of the existing problems and methods of studying gas dynamics and heat transfer in the GWC made it possible to formulate the main goal of the study as the creation of a method for determining the parameters of the gas flow in the GWC in a three-dimensional formulation with the subsequent calculation of local heat transfer in the GWC of the cylinder heads of high-speed internal combustion tasks of reducing the thermal stress of cylinder heads and valves. In connection with the above, the following tasks have been set in the work: - To create a new method of one-dimensional-three-dimensional modeling of heat transfer in the exhaust and intake systems of the engine, taking into account the complex three-dimensional gas flow in them in order to obtain initial information for setting the boundary conditions of heat transfer when calculating the problems of heat stress of piston cylinder heads ICE; - Develop a methodology for setting the boundary conditions at the inlet and outlet of the gas-air channel based on the solution of a one-dimensional non-stationary model of the working cycle of a multi-cylinder engine; - Check the reliability of the methodology using test calculations and comparison of the results obtained with the experimental data and calculations using the methods previously known in engine building; 5
7 - Check and refine the methodology by performing a computational and experimental study of the thermal state of the engine cylinder heads and comparing the experimental and calculated data on the temperature distribution in the part. The second chapter is devoted to the development of a mathematical model of a closed working cycle of a multi-cylinder internal combustion engine. To implement the scheme of one-dimensional calculation of the working process of a multi-cylinder engine, a well-known method of characteristics was chosen, which guarantees a high convergence rate and stability of the calculation process. The gas-air system of the engine is described as an aerodynamically interconnected set of individual cylinder elements, sections of inlet and outlet channels and pipes, manifolds, mufflers, neutralizers and pipes. The processes of aerodynamics in the intake-exhaust systems are described using the equations of one-dimensional gas dynamics of an inviscid compressible gas: Continuity equation: ρ u ρ u + ρ + u + ρ t x x F df dx = 0; F 2 = π 4 D; (1) Equation of motion: u t u + u x 1 p 4 f + + ρ x D 2 u 2 u u = 0; f τ = w; (2) 2 0.5ρu Energy conservation equation: p p + u a t x 2 ρ x + 4 f D u 2 (k 1) ρ q u = 0 2 u u; 2 kp a = ρ, (3) where a is the speed of sound; ρ-gas density; u is the flow velocity along the x axis; t- time; p-pressure; f is the coefficient of linear losses; D-diameter C of the pipeline; k = P is the ratio of specific heat capacities. C V 6
8 The boundary conditions are set (based on the basic equations: continuity, energy conservation and the ratio of density and sound speed in the non-entropic nature of the flow) conditions on the valve slots in the cylinders, as well as the conditions at the inlet and outlet from the engine. The mathematical model of a closed engine operating cycle includes design ratios that describe the processes in the engine cylinders and parts of the intake and exhaust systems. The thermodynamic process in the cylinder is described using a technique developed at SPbSPU. The program provides the ability to determine the instantaneous parameters of the gas flow in the cylinders and in the intake and exhaust systems for different engine designs. The general aspects of using one-dimensional mathematical models by the method of characteristics (closed working fluid) are considered and some results of calculating the change in the parameters of the gas flow in the cylinders and in the intake and exhaust systems of single and multi-cylinder engines are shown. The results obtained make it possible to assess the degree of perfection of the organization of the intake-exhaust systems of the engine, the optimal valve timing, the possibility of gas-dynamic adjustment of the working process, the uniformity of operation of individual cylinders, etc. The pressures, temperatures and rates of gas flows at the inlet and outlet to the gas-air channels of the cylinder head, determined using this technique, are used in subsequent calculations of heat transfer processes in these cavities as boundary conditions. The third chapter is devoted to the description of a new numerical method that makes it possible to calculate the boundary conditions of the thermal state from the side of gas-air channels. The main stages of the calculation are: one-dimensional analysis of the unsteady gas exchange process in the sections of the intake and exhaust system by the method of characteristics (second chapter), three-dimensional calculation of the quasi-stationary flow in the intake and 7
9 outlet channels by the finite element method FEM, calculation of local heat transfer coefficients of the working fluid. The results of the execution of the first stage of the closed-loop program are used as boundary conditions in the subsequent stages. To describe the gas-dynamic processes in the channel, a simplified quasi-stationary scheme of an inviscid gas flow (the system of Euler equations) with a variable domain shape was chosen due to the need to take into account the valve motion: r V = 0 rr 1 (V) V = p the volume of the valve, a fragment of the guide sleeve makes 8 ρ necessary. (4) Instantaneous, cross-section-averaged gas velocities at the inlet and outlet cross sections were set as the boundary conditions. These speeds, as well as temperatures and pressures in the channels, were set based on the results of calculating the working process of a multi-cylinder engine. To calculate the gas dynamics problem, the FEM finite element method was chosen, which provides high accuracy of modeling in combination with acceptable costs for the implementation of the calculation. The computational FEM algorithm for solving this problem is based on minimizing the variational functional obtained by transforming the Euler equations using the Bubnov-Galerkin method: (llllllmm) k UU Φ x + VU Φ y + WU Φ z + p ψ x Φ) llllllmmk (UV Φ x + VV Φ y + WV Φ z + p ψ y) Φ) llllllmmk (UW Φ x + VW Φ y + WW Φ z + p ψ z) Φ) llllllm (U Φ x + V Φ y + W Φ z ) ψ dxdydz = 0.dxdydz = 0, dxdydz = 0, dxdydz = 0, (5)
10 using a volumetric model of the computational domain. Examples of calculated models of the inlet and outlet channels of the VAZ-2108 engine are shown in Fig. 1.-b- -a Fig. 1. Models (a) inlet and (b) exhaust channels of a VAZ engine To calculate heat transfer in the GVK, a volumetric two-zone model was chosen, the main assumption of which is the division of the volume into regions of an inviscid core and a boundary layer. To simplify, the solution of gas dynamics problems is carried out in a quasi-stationary setting, that is, without taking into account the compressibility of the working fluid. The analysis of the calculation error showed the possibility of such an assumption, except for a short period of time immediately after the opening of the valve slot, which does not exceed 5-7% of the total time of the gas exchange cycle. The process of heat exchange in the GVK with open and closed valves has a different physical nature (forced and free convection, respectively), therefore, they are described using two different methods. With the valves closed, the technique proposed by MSTU is used, which takes into account two processes of thermal loading of the head in this section of the working cycle due to free convection itself and due to forced convection due to residual oscillations of the column 9
11 gas in the channel under the influence of pressure variability in the manifolds of a multi-cylinder engine. When the valves are open, the heat exchange process obeys the laws of forced convection, initiated by the organized movement of the working fluid during the gas exchange cycle. Calculation of heat transfer in this case involves a two-stage solution to the problem of analyzing the local instantaneous structure of the gas flow in the channel and calculating the intensity of heat transfer through the boundary layer formed on the walls of the channel. The calculation of the processes of convective heat transfer in the GWC was based on the model of heat transfer in the flow around a flat wall, taking into account either the laminar or turbulent structure of the boundary layer. The criterion dependences of heat transfer were refined based on the results of comparing the calculation and experimental data. The final form of these dependences is shown below: For a turbulent boundary layer: 0.8 x Re 0 Nu = Pr (6) x For a laminar boundary layer: Nu Nu xx αxx = λ (m, pr) = Φ Re tx Kτ, (7) where: α x local heat transfer coefficient; Nu x, Re x local values of the Nusselt and Reynolds numbers, respectively; Pr Prandtl number at a given time; m characteristic of the flow gradient; Ф (m, Pr) is a function depending on the flow gradient index m and the Prandtl number of the working medium Pr; K τ = Re d - correction factor. The instantaneous values of heat fluxes at the design points of the heat-receiving surface were averaged per cycle, taking into account the valve closing period. ten
12 The fourth chapter is devoted to the description of the experimental study of the temperature state of the cylinder head of a gasoline engine. An experimental study was carried out with the aim of checking and refining the theoretical methodology. The task of the experiment was to obtain the distribution of stationary temperatures in the body of the cylinder head and to compare the calculation results with the obtained data. Experimental work was carried out at the Department of Internal Combustion Engines of St. To measure the stationary temperature distribution in the head, 6 chromel-copel thermocouples installed along the GVK surfaces were used. The measurements were carried out both in terms of speed and load characteristics at various constant crankshaft rotation frequencies. As a result of the experiment, the readings of the thermocouples were obtained, taken during the operation of the engine according to the speed and load characteristics. Thus, the studies carried out show what are the real values of temperatures in the parts of the cylinder head of the internal combustion engine. More attention is paid in the chapter to the processing of the experimental results and the estimation of errors. The fifth chapter provides data from a computational study, which was carried out in order to test the mathematical model of heat transfer in the GVK by comparing the calculated data with the results of the experiment. In fig. 2 shows the results of modeling the velocity field in the inlet and outlet channels of the VAZ-2108 engine by the finite element method. The data obtained fully confirm the impossibility of solving this problem in any formulation other than three-dimensional, 11
13 because the valve stem has a significant impact on the results in the critical area of the cylinder head. In fig. 3-4 show examples of the results of calculating the intensities of heat transfer in the inlet and outlet channels. Studies have shown, in particular, a substantially non-uniform character of heat transfer both along the generatrix of the channel and along the azimuthal coordinate, which is obviously explained by the substantially non-uniform structure of the gas-air flow in the channel. The resulting fields of heat transfer coefficients were used for further calculations of the temperature state of the cylinder head. The boundary conditions for heat transfer along the surfaces of the combustion chamber and cooling cavities were set using the techniques developed at SPbSPU. The calculation of the temperature fields in the cylinder head was carried out for steady-state modes of engine operation with a crankshaft speed from 2500 to 5600 rpm according to the external speed and load characteristics. As a design diagram of the cylinder head of a VAZ engine, a head section related to the first cylinder was selected. When modeling the thermal state, the finite element method in a three-dimensional formulation was used. The complete picture of thermal fields for the computational model is shown in Fig. 5. The results of the computational study are presented in the form of temperature changes in the body of the cylinder head in the places where the thermocouples are installed. Comparison of the calculated and experimental data showed their satisfactory convergence, the calculation error did not exceed 3 4%. 12
14 Outlet duct, ϕ = 190 Inlet duct, ϕ = 380 ϕ = 190 ϕ = 380 Fig.2. The velocity fields of the working fluid in the exhaust and inlet channels of the VAZ-2108 engine (n = 5600) α (W / m2 K) α (W / m2 K), 0 0.2 0.4 0.6 0.8 1 , 0 S -b- 0 0.0 0.2 0.4 0.6 0.8 1.0 S -a Fig. 3. Curves of changes in the intensity of heat exchange on the outer surfaces -a Outlet duct -b- Inlet duct. 13
15 α (W / m2 K) at the beginning of the intake duct in the middle of the intake duct at the end of the intake duct section-1 α (W / m2 K) at the beginning of the exhaust duct in the middle of the exhaust duct at the end of the exhaust duct section b- Inlet duct - Exhaust duct Fig. 4. Curves of changes in the intensity of heat transfer depending on the angle of rotation of the crankshaft. -a -b- Fig. 5. General view of the finite element model of the cylinder head (a) and the calculated temperature fields (n = 5600 rpm) (b). fourteen
16 Conclusions on the work. Based on the results of the work carried out, the following main conclusions can be drawn: 1. A new one-dimensional-three-dimensional model for calculating complex spatial processes of the flow of the working fluid and heat transfer in the channels of the cylinder head of an arbitrary piston ICE has been proposed and implemented, which differs in greater accuracy and complete versatility in comparison with the previously proposed methods results. 2. New data on the features of gas dynamics and heat transfer in gas-air channels have been obtained, confirming the complex spatially non-uniform nature of the processes, which practically excludes the possibility of modeling in one-dimensional and two-dimensional versions of the problem statement. 3. The necessity of setting the boundary conditions for calculating the problem of gas dynamics of inlet and outlet channels based on the solution of the problem of unsteady gas flow in pipelines and channels of a multi-cylinder engine was confirmed. The possibility of considering these processes in a one-dimensional setting is proved. A method for calculating these processes based on the method of characteristics is proposed and implemented. 4. The conducted experimental study made it possible to refine the developed calculation methods and confirmed their accuracy and reliability. Comparison of the calculated and measured temperatures in the part showed the maximum error of the results, not exceeding 4%. 5. The proposed computational and experimental technique can be recommended for implementation at the enterprises of the engine-building industry when designing new and fine-tuning existing four-stroke piston internal combustion engines. 15
17 The following works have been published on the topic of the dissertation: 1. Shabanov A.Yu., Mashkur M.A. Development of a model of one-dimensional gas dynamics in the intake and exhaust systems of internal combustion engines // Dep. in VINITI: N1777-B2003 dated, 14 p. 2. Shabanov A.Yu., Zaitsev A.B., Mashkur M.A. Finite-element method for calculating the boundary conditions of thermal loading of the cylinder head of a piston engine // Dep. in VINITI: N1827-B2004 dated, 17 p. 3. Shabanov A.Yu., Mahmud Mashkur A. Computational and experimental study of the temperature state of the engine cylinder head // Dvigatelestroyeniye: Scientific and technical collection dedicated to the 100th anniversary of the birth of Professor N.Kh. Dyachenko // Otv. ed. L. E. Magidovich. SPb .: Publishing house of the Polytechnic University, with Shabanov A.Yu., Zaitsev A.B., Mashkur M.A. A new method for calculating the boundary conditions for thermal loading of the cylinder head of a piston engine // Dvigatelestroyeniye, N5 2004, 12 p. 5. Shabanov A.Yu., Mahmud Mashkur A. Application of the finite element method in determining the boundary conditions of the thermal state of the cylinder head // XXXIII Science Week SPbSPU: Proceedings of the interuniversity scientific conference. SPb .: Publishing house of the Polytechnic University, 2004, with Mashkur Makhmud A., Shabanov A.Yu. Application of the method of characteristics to the study of gas parameters in gas-air channels of an internal combustion engine. XXXI Science Week SPbSPU. Part II. Materials of the interuniversity scientific conference. SPb .: Publishing house of SPbSPU, 2003, p.
18 The work was carried out at the State Educational Institution of Higher Professional Education "St. Petersburg State Polytechnic University", at the Department of Internal Combustion Engines. Scientific adviser - Candidate of Technical Sciences, Associate Professor Shabanov Alexander Yurievich Official opponents - Doctor of Technical Sciences, Professor Erofeev Valentin Leonidovich Candidate of Technical Sciences, Associate Professor Kuznetsov Dmitry Borisovich Leading organization - State Unitary Enterprise "TsNIDI" State educational institution of higher professional education "St. Petersburg State Polytechnic University" at the address:, St. Petersburg, st. Polytechnicheskaya 29, Main building, room .. The thesis can be found in the fundamental library of the State Educational Institution "SPbSPU". Abstract sent in 2005 Scientific Secretary of the Dissertation Council, Doctor of Technical Sciences, Associate Professor B. Khrustalev
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UDC 621.43.016 A.V. Trinev, Cand. tech. Sciences, A.G. Kosulin, Cand. tech. Sciences, A.N. Avramenko, engineer USE OF LOCAL AIR COOLING VALVE ASSEMBLY FOR FORCE AUTOMATIC TRACTOR DIESELS
HEAT RELEASE COEFFICIENT OF EXHAUST MANIFOLD OF ICE Sukhonos RF, Master student of ZNTU Supervisor Mazin V. А. tech. Sciences, Assoc. ZNTU With the spread of combined internal combustion engines, it becomes important to study
SOME SCIENTIFIC AND METHODOLOGICAL DIRECTIONS OF EMPLOYEES OF THE DPO SYSTEM IN ALTGTU CALCULATION AND EXPERIMENTAL METHOD FOR DETERMINING THE CONSUMPTION COEFFICIENT OF THE PURGE WINDOWS OF A TWO-STROKE ENGINE WITH A CRANK
STATE SPACE AGENCY OF UKRAINE STATE ENTERPRISE "DESIGN BUREAU" YUZHNOE " M.K. YANGEL "As a manuscript Sergey Shevchenko UDC 621.646.45 IMPROVEMENT OF THE PNEUMATIC SYSTEM
ANNOTATION of the discipline (training course) M2.DV4 Local heat exchange in the internal combustion engine (code and name of the discipline (training course))
THERMAL CONDUCTIVITY IN A NON-STATIONARY PROCESS Let us consider the calculation of the temperature field and heat fluxes in the process of thermal conductivity using the example of heating or cooling of solids, since in solids
REVIEW of the official opponent on the dissertation work of Ivan Nikolaevich Moskalenko "IMPROVEMENT OF METHODS FOR PROFILING THE SIDE SURFACE OF PISTON INTERNAL COMBUSTION ENGINES" presented
UDC 621.43.013 E.P. Voropaev, engineer MODELING THE EXTERNAL SPEED CHARACTERISTICS OF A SUZUKI GSX-R750 SPORT BIKE ENGINE Introduction The use of three-dimensional gas-dynamic models in the design of piston
94 Engineering and technology UDC 6.436 P.V. Dvorkin St. Petersburg State Transport University DETERMINATION OF THE HEAT RELEASE COEFFICIENT IN THE WALLS OF THE COMBUSTION CHAMBER Currently, there is no single
REVIEW of the official opponent on the dissertation work of Ilya Ivanovich Chichilanov, performed on the topic "Improving the methods and means of diagnosing diesel engines" for the degree
UDC 60.93.6: 6.43 E.A.Kochetkov, A.S. Kurylev
Laboratory work 4 STUDY OF HEAT TRANSFER WITH FREE MOVEMENT OF AIR Task 1. Carry out thermal measurements to determine the heat transfer coefficient of a horizontal (vertical) pipe
UDC 612.43.013 Working processes in the internal combustion engine А.А. Khandrimailov, engineer, V.G. Solodov, Dr. Sciences STRUCTURE OF AIR CHARGE FLOW IN A DIESEL CYLINDER ON INLET AND COMPRESSION STATUS Introduction Process of volumetric film
UDC 53.56 ANALYSIS OF EQUATIONS FOR LAMINARY BOUNDARY LAYER Dokt. tech. Sciences, prof. ESMAN R.I.Belarusian National Technical University When transporting liquid energy carriers in channels and pipelines
I APPROVE: d u I / - gt l. eorector for scientific work and A * ^ 1 doctor of biological quarrels M.G. Baryshev ^., - * c ^ x \ "l, 2015 REVIEW OF THE LEADING ORGANIZATION on the dissertation work of Elena Pavlovna Yartseva
HEAT TRANSFER Lecture plan: 1. Heat transfer in the free motion of a liquid in a large volume. Heat transfer during free movement of liquid in a confined space 3. Forced movement of liquid (gas).
LECTURE 13 CALCULATION EQUATIONS IN THE PROCESS OF HEAT EXCHANGE Determination of heat transfer coefficients in processes without changing the aggregate state of the heat carrier Heat exchange processes without changing the aggregate
REFERENCE of the official opponent to the thesis of Svetlana Olegovna Nekrasova "Development of a generalized methodology for designing an engine with an external heat supply with a pulsating tube", presented for defense
15.1.2. CONVECTIVE HEAT RELEASE DURING FORCED MOTION OF A FLUID IN PIPES AND CHANNELS In this case, the dimensionless heat transfer coefficient Nusselt criterion (number) depends on the Grashof criterion (at
REVIEW of the official opponent of Tsydypov Baldandorzho Dashievich on the dissertation work of Maria Zhalsanovna Dabaeva
RUSSIAN FEDERATION (19) RU (11) (51) IPC F02B 27/04 (2006.01) F01N 13/08 (2010.01) 169 115 (13) U1 RU 1 6 9 1 1 5 U 1 FEDERAL SERVICE FOR INTELLECTUAL PROPERTY (12) USEFUL MODEL DESCRIPTION
MODULE. CONVECTIVE HEAT EXCHANGE IN SINGLE-PHASE MEDIA Specialty 300 "Technical Physics" Lecture 10. Similarity and modeling of convective heat transfer processes Modeling of convective heat transfer processes
UDC 673 RV KOLOMIETS (Ukraine, Dnepropetrovsk, Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Academy of Sciences of Ukraine) CONVECTIVE HEAT EXCHANGE IN AIRFONT DRYER Problem statement
Review of the official opponent on the dissertation work of Podryga Victoria Olegovna "Multiscale numerical modeling of gas flows in the channels of technical microsystems"
REVIEW of the official opponent for the thesis of Sergey Viktorovich Alyukov "Scientific foundations of inertial continuously variable transmissions of increased load capacity", presented for the degree
Ministry of Education and Science of the Russian Federation State educational institution of higher professional education SAMARA STATE AEROSPACE UNIVERSITY named after academician
REVIEW of the official opponent Pavlenko Alexander Nikolaevich on the thesis of Maxim Olegovich Bakanov "Study of the dynamics of the pore formation process during heat treatment of foam glass batch", presented
D "spbpu a" "rotega o" "a IIIII I L 1 !! ^ .1899 ... G MINOBRNAUKI RUSSIA federal state autonomous educational institution of higher education" St.
REVIEW of the official opponent on the thesis of Dmitry Igorevich LEPESHKIN on the topic "Improving diesel performance under operating conditions by increasing the stability of the fuel equipment" presented
Review of the official opponent on the dissertation work of Kobyakova Yulia Vyacheslavovna on the topic: "Qualitative analysis of the creep of nonwovens at the stage of organizing their production in order to increase competitiveness,
The tests were carried out on a motor stand with a VAZ-21126 injection engine. The engine was installed on a MS-VSETIN brake test bench equipped with instrumentation to control
Electronic journal "Technical acoustics" http://webceter.ru/~eeaa/ejta/ 004, 5 Pskov Polytechnic Institute Russia, 80680, Pskov, st. L. Tolstoy, 4, e-mail: [email protected] About the speed of sound
Review of the official opponent on the dissertation work of Egorova Marina Avinirovna on the topic: "Development of methods for modeling, forecasting and assessing the operational properties of polymer textile ropes
In the space of speeds. This work is actually aimed at creating an industrial package for calculating rarefied gas flows based on solving the kinetic equation with a model collision integral.
BASICS OF THE THEORY OF HEAT EXCHANGE Lecture 5 Plan of the lecture: 1. General concepts of the theory of convective heat transfer. Heat transfer with free movement of liquid in a large volume 3. Heat transfer with free movement of liquid
AN UNEXPECTED METHOD FOR SOLVING CONJUGATED PROBLEMS OF A LAMINAR BOUNDARY LAYER ON A PLATE Lesson plan: 1 Purpose of work Differential equations of the thermal boundary layer 3 Description of the problem to be solved 4 Solution method
Methodology for calculating the temperature state of the warheads of the elements of rocket and space technology during their ground operation # 09, September 2014 Kopytov VS, Puchkov VM UDC: 621.396 Russia, MSTU im.
Stresses and the actual operation of foundations at low-cycle loads, taking into account the history of loading. In accordance with this, the topic of research is relevant. Assessment of the structure and content of work B
REVIEW of the official opponent of Doctor of Technical Sciences, Professor Pavlov Pavel Ivanovich on the dissertation work of Alexei Nikolaevich Kuznetsov on the topic: "Development of an active noise reduction system in
1 Ministry of Education and Science of the Russian Federation Federal State Budgetary Educational Institution of Higher Professional Education "Vladimir State University
To the dissertation council D 212.186.03 FSBEI HE "Penza State University" Scientific secretary, Doctor of Technical Sciences, Professor Voyachek I.I. 440026, Penza, st. Krasnaya, 40 REVIEW OF OFFICIAL OPPONENT Semenov
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CONTROL AND MEASURING MATERIALS for the discipline "Power units" Questions for test 1. What is the engine intended for, and what types of engines are installed on domestic cars? 2. Classification
D.V. Grinev (Ph.D.), M.A. Donchenko (Ph.D., Associate Professor), A.N. Ivanov (graduate student), A.L. Perminov (postgraduate student) DEVELOPMENT OF A METHOD FOR CALCULATION AND DESIGN OF ROTARY-VANE MOTORS WITH EXTERNAL SUPPLY
Three-dimensional modeling of the working process in a rotary-piston aircraft engine AA Zelentsov, VP Minin TsIAM them. P.I. Baranova Dept. 306 "Aircraft piston engines" 2018 Purpose of work Rotary piston
NON-ISOTHERMAL MODEL OF GAS TRANSPORTATION Trofimov AS, Kutsev VA, Kocharyan EV g Krasnodar When describing the processes of pumping natural gas along the main gas pipeline, as a rule, the problems of hydraulics and heat transfer are considered separately
UDC 6438 METHOD FOR CALCULATING THE INTENSITY OF GAS FLOW TURBULENCE AT THE OUTPUT OF THE COMBUSTION CHAMBER OF A GAS TURBINE ENGINE 007
DETONATION OF GAS MIXTURE IN ROUGH PIPES AND SLITS V.N. S. I. OKHITIN I. A. KLIMACHKOV PEREVALOV Moscow State Technical University. N.E. Bauman Moscow Russia Gas-dynamic parameters
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Lecture. Diffusion boundary layer. Equations of the theory of a boundary layer in the presence of mass transfer The concept of a boundary layer considered in Sections 7. and 9. (for hydrodynamic and thermal boundary layers
AN EXPRESS METHOD FOR SOLVING THE EQUATIONS OF THE LAMINAR BOUNDARY LAYER ON A PLATE Laboratory work 1, Lesson plan: 1. Purpose of the work. Methods for solving the equations of the boundary layer (methodological material) 3. Differential
UDC 621.436 ND Chaynov, LL Myagkov, NS Malastovsky METHOD OF CALCULATING THE MATCHED TEMPERATURE FIELDS OF A CYLINDER COVER WITH VALVES A method for calculating the matched fields of a cylinder head is proposed
# 8, August 6 UDC 533655: 5357 Analytical formulas for calculating heat fluxes on blunt bodies of small elongation Volkov MN, student Russia, 55, Moscow, MSTU named after NE Bauman, Aerospace faculty,
Review of the official opponent on the dissertation of Samoilov Denis Yurievich "Information-measuring and control system for stimulating oil production and determining the water cut of well production",
Federal Agency for Education State Educational Institution of Higher Professional Education Pacific State University Thermal tension of internal combustion engine parts Methodical
Review of the official opponent of Doctor of Technical Sciences, Professor Labudin Boris Vasilyevich on the dissertation work of Xu Yun on the topic: "Increasing the bearing capacity of joints of elements of wooden structures
Review of the official opponent of Lvov Yuri Nikolaevich on the thesis of Olga Sergeevna MELNIKOVA "Diagnostics of the main insulation of power oil-filled electric power transformers according to statistical
UDC 536.4 Gorbunov A.D. Dr. Tech. Sci., prof., DSTU DETERMINATION OF THE HEAT RELEASE COEFFICIENT AT TURBULENT FLOW IN PIPES AND CHANNELS BY ANALYTICAL METHOD Analytical calculation of the heat transfer coefficient
