Numerical Simulation Of Working Process In SI Engine And Vcr Technology Based On LabVIEW

The power performance, fuel economy and exhaust emissions of engine is directly related to its working process, and the research on the working process is one of the main methods of engine research.Through the simulation we can have a profound knowledge of the variation law of parameters in the working process and the effect degree of some influencing factors such as the structure parameters and operating conditions on the working process of engine. Combined with experiment, we can get a better understanding of engine's performance.This subject is conducted as a part of the analysis software of engine's working process which is being developed by Cars and Engines Laboratory of Southwest Jiaotong University. This paper mainly writes a working process simulation program of good universality with LabVIEW, the program can take simulation calculation of SI engine's working process. The indicator diagram and main performance indexes with this program are calculated, and then the effect of some main influencing factors which influences the engine's performance are analyzed, and some rules are sought to offer guidance to engine's design, improvement and application. The calculated indicator diagram can also be provided for other companions to calculate engine's emission.Firstly, this paper simulates the working process of one gasoline engine, calculates its indicator diagram and main performance indexes, which are compared with the reference data to prove the program's validity. After proving the correctness of the program, some results had been analyzed as the parameter changed. Then this paper discusses the influence of some main influencing factors such as compression ratio and ignition advanced angle on performance of the engine and gives some improvement measure. Secondly, this paper conducts an expansive performance research on a CNG engine which is modified by gasoline engine, and studies how to solve the problems such as the performance decline while burning CNG in the engine. Finally, this paper studies the influence of compression ratio on engine's performance, introduces the variable compression ratio technology, and then discusses its advantages and how to realize the compression ratio which changes with the condition of the engine in order to obtain the biggest potential capacity.Through the analysis, we draw a conclusion that this simulation program has good feasibility and universality, and it also has the capability to simulate and forecast the common engine's working process.