Three-Dimensional Combustion Modeling And Experimental Investigation In LPG Engine

As the voice of environmental protection and saving energy becoming more and more intensively, gas-vehicle receives the unprecedented recognition because of its less emission and more economical. The research and utilization of LPG-vehicle develop quickly. The purpose of this study is to develop a three-dimensional numerical calculation model for spark-ignited premixed-charge LPG single fuel engine, which includes chemical kinetics submodel, ignition submodel, turbulent combustion submodel and emissions submodel. The conclusions obtained from this study provide a principle guide for optimum design of combustion system and to obtain satisfying characteristics in emission, performance and economy of LPG engine upon suitable structure and operating parameters, such as compression ratio, valve timing and spark timing.With effective work in chemical kinetics mechanism, turbulent combustion, estimation of the initial and boundary conditions and the combination of the complex chemistry solver technology from the CHEMKIN Collection and the flow solver technology of STAR-CD, the success of the three-dimensional numerical calculation is first obtained in spark-ignited premixed-charge LPG single fuel engine.Main characteristic and innovative points:1. The sensitivity analysis is first to applied in the reaction mechanism reduction of LPG combustion under premixed lean burn, that is, finding a reduced mechanism that only relates the principal component and skeletal mechanism but can produces similar predictions of detailed mechanism. Subsequently the reduced mechanism is used for three-dimensional numerical calculation in the flow solver technology of STAR-CD.2. Different from the one-step irreversible reaction, a multi-step reaction combined time scale model is developed to the solve combustion-turbulence interaction firstly. Both accurate initial and boundary conditions is assured with a suitable residual gas fraction mode and unstructed dynamic calculation mesh guarantee good agreement between modeling and experimental results.3. A multizone p-pdf is applied to calculate the instantaneous rate of NO_x with high turbulent conditions in the LPG engine.4. Construct an experimental spark-ignited premixed-charge LPG single fuel engine with Universal wide range Exhaust Gas Oxygen sensor.