| OPOC diesel engine is a kind of two stroke engine which has the advantages of compact structure,good balance and high efficiency.In this paper,the left cylinder of OPOC diesel engine is taken as the research object,and the modeling and numerical simulation are carried out by using the three-dimensional modeling software Pro/E and the numerical analysis software AVL-FIRE.Through the analysis of different parameters of turbulent kinetic energy and the equivalence ratio in the cylinder combustion pressure,heat release rate,the average temperature and the NO and soot emission results,summed up the injection timing and injection and EGR curve effect on performance and emissions of combustion in OPOC diesel engine,to provide a reference for the development and promotion of OPOC diesel oil machine.Firstly,the working principle of OPOC diesel engine,and the special structure of the moving parts down combustion cycle analysis and formula;establishing the finite element model of the combustion chamber of OPOC diesel engine by using PRO/E software,and import the FIRE software to create dynamic mesh model.Secondly,in the finite element model,the influence of injection timing and exhaust recirculation on the performance of diesel engine is calculated and analyzed.The research shows that the rate of EGR decreases with the increase of peak pressure in cylinder combustion and the crank angle corresponding to the peak after the shift,the EGR rate is relatively large when the cylinder combustion pressure,with the rate of EGR is more sensitive to the change;advance angle increases with the maximum cylinder pressure,need to select the appropriate timing of comfort the parts of the engine bearing capacity as well as car considerations.Increase the peak cylinder average temperature and partial combustion temperature will increase as the EGR ratio decreased;the peak temperature increases with the increase of advance angle,without considering the OPOC diesel engine cylinder head,piston thermal load sharing a lot,consideration should be given to the life of the piston.With the increase of EGR value,the peak value of instantaneous heat release rate decreases,and the phase shift of the peak value decreases.EGR rate increases fuel consumption,increase fuel consumption in advance angle.The exhaust gas recirculation technology has a significant effect on the reduction of NOx and soot emissions.Engine development is to consider the full range of power,economy and emission performance,select the best program.Finally,using the finite element model to explore the influence of four kinds of fuel injection rate-shape on the performance of diesel engine.The results showed that the fuel injection law curve triangle cylinder maximum pressure peak value of the outbreak,but the pressure rises too fast,taking into account the engine working flat retardancy,rectangle fuel injection rate-shape is more appropriate;curves of different injection rate,cylinder mixture formation rate,initial rectangular cylinder mixing rate curve,the late trapezoidal injection the curves of oil and gas mixed combustion more good;large amount of heat release curve of rectangular mixed fuel injection law of pre injection,because the initial maximum injection quantity curve of rectangular,trapezoidal curve injection rule,the diffusion stage of combustion heat quantity,the final temperature of the cylinder average temperature tends to be the same;triangle injection rule generation of NO and the large amount of production of soot small,but the lowest content of NO wedge injection law of mass fraction of soot is high,because the mixing rate is slow and incomplete combustion made. |
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