Simulation And Optimization On Matching Of Turbocharger And Electronically Controlled CNG Engine

The power capability of the spark ignition engine fueled with natural gas which was refit from a diesel would decline, even when lean burn used, the situation would be worse. Therefore, the turbocharging technology was need to improve the power capability of the natural gas engine. And then, it was to be very important to match the natural gas engine with turbochargers.The thesis based on software GT-POWER is applied for establishing the calculation model of turbocharged and electronically controlled CNG engine, the predictions can accord with the experiment results accurately. On the basis of model, the study of the matching of the engine and the turbocharger on four representative work conditions was on in terms of GT-POWER's method step by step. And then, the combination operating curve of the turbocharger and the engine is established, and external characteristics and maximum torque's characteristics of the engine are analyzed, Simulation results showed that the engine and the supercharger match better.In this paper, the parameters of the main structure of intake/exhaust system, combustion system, pressurization system and the opration parameters of the CNG engine model were varied and simulations were runed. Effects of different parameters on the engine turbocharging as well as the power, economy capability of the engine were analyzed, and then the law of the effects was summarized. And then, relative effects of different parameters' relative varying on the engine turbocharging were investigated, the rusults were that the main structure parameters such as the compression ratio, the diameter of the waster gate, the diameter of the intake pipe, the opration parameters of the CNG engine such as the intake and exhaust cam timing angle, the air-to-fuel ratio were the main factors. And then volumetric efficiency of the CNG engine was chosen as RLT quantity to be optimized, The main structure parameters of the CNG engine: the compression ratio, the diameter of the waster gate, the diameter of the intake pipe and the opration parameters of the CNG engine: the intake and exhaust cam timing angle, the air-to-fuel ratio were chosen as independent variable, the simulations in optimizer were run.