Prediction Of Direct Injection Diesel Engine's Performance And Its Parameters Optimization

This paper is about the performance research of ZS1125 direct injection diesel engine, the simulation of diesel engine working process is chiefly dealt with the computer. The results of simulation and experiment are analyzed and compared with each other. The main research work includes:(1) According to the diesel engine working process calculation principle and the calculation theory of the software AVL BOOST, the working model is built up and some necessary parameters are estimated. On the base of the working model, the full load characteristics at 1600r/min, 2000r/min and 2200r/min are respectively simulated, and the speed characteristics are also simulated. The simulated values are contrasted with the tested values at the same operating condition. The results show the correspondence of the calculated values with tested values. So it is proved that the working model is right, and on the basis, the influences of the compression ratio and fuel injection advance angle on the diesel engine's combustion performance are studied.(2) Energy resource and environment protection are two important problems that diesel engine is faced with. So in this paper the constrained optimization is studied in order to decrease fuel consumption within the limitation of the regulation on exhaust emission and power output. A new calculation method for optimizing diesel engine performance, called nonlinear regression-mess method, is put forward. In this paper, 25 groups of simulated values are calculated from the diesel engine working model, specific fuel consumption, peak pressure, rate of pressure rise, NOX and peak temperature are fitted into explicit function about compression ratio and fuel injection advance angle. The best compression ratio and fuel injection advance angle are calculated through mess optimization calculation program of language C. On the basis, optimization simulation of inlet and exhaust timing has been carried with the diesel engine working model to increase diesel engine's volumetric efficient. The performance has been predicted for ZS1125 direct injection diesel engine under this optimum.(3) According to the optimization calculated results, the structural parameters of ZS1125 direct injection diesel engine are changed, and the experiments are carried out. The comparison of the diesel engine performance before and after optimization shows that the diesel engine's specific fuel consumption ,exhaust temperature and smoke decreased, which reached research goal.