Cycle Uniformity Research Of Compression Ignition Engine

In this thesis, researches are mainly concentrating on analyzing several key variableparameters in engine to study their effects on diesel engine’s operation stability and cycleuniformity changing. The variable parameters include advance angle of injection,compression ratio and other parameters in diesel engine, besides, selecting different dieselengine rotate speed and load operation conditions.During the project, selected the partial load speed character and maximum torquerotate speed load character as the research operation conditions, took different advanceangle of injection, compression ratio and fuel delivery per cycle as variables to analysisthe variation in combustion process, the cycle uniformity in operation and workingstability fluctuation. Among the variables, the effect of advance angle of injection wasbased on analysis of the indicator diagram gained from diesel engine bench experiments,the effects of other parameters were studied by simulations in software.By analyzing and comparison between experimental and simulation results, theoperation conditions of the diesel engine is stable and it also has good cycle uniformityperformance. For effect of each parameter, if advance angle of injection is too small, thepost combustion is severe and this phenomenon becomes more obvious with rotate speedincreases, the effect to cycle fluctuation is not obvious. By increasing compression ratio isan effective way to improve dynamic and economic performance of engine but thismethod will increase maximum pressure in cylinder which is harmful to operation stability.The change of fuel delivery per cycle would cause an obvious influence to performance ofdiesel engine; on the basis that when the parameters are not varying, rotate speed hasrelative high influence on combustion cycle uniformity and low speed, intermediate speedand high speed have different effects on cycle fluctuation rate, under low speed high loadcondition the combustion is not stable and cycle fluctuation rate will increase; when therotate speed remain the same and change the load has little influence on combustion cycleuniformity in diesel engine.