Investigation On The Effects Of Combustion Chamber And CNG Injection Timing Of CNG Engine

Recently, environmental improvement and energy issues have become more and more important which attract the concerns of the worldwide. Natural gas is a good alternative fuel to solve these problems because of its plentiful resources and clean burning characteristics. As the increase of market demand for heavy-duty CNG (Compressed Natural Gas) engine in China, it is necessary to have an in-depth study on CNG engine. To improve the performance of CNG engine, it is necessary to ameliorate the in-cylinder combustion process. To meet the stricter emission rule in the future, just investigating the effects of some aggregate factors on macroscopical performance of engine is not enough, and in-depth investigating the law of each effect factor on CNG engine combustion process is imperative under the situation. With the development of computer and computation science, more researchers are engaged in computational simulation of engine combustion process including: air intake process simulation, combustion simulation, the formation of pollution simulation and so on. There are many advantages of numerical simulation by using computational fluid dynamic (CFD) software such as low cost, short period and can show some information which can't be provided by testing. The distributing of concentration, velocity, pressure and temperature in the computational area can be got by computational simulation in detail.To find out how the two factors effect on the combustion progress and emission progress, the test and numerical simulation about the different combustion chambers and different CNG injection timing on CA6SE1-21N engine were investigated in this dissertation. The effect of the two factors on the performation was profoundly discussed. The intake progress,compress progress and combustion progress were simulated with the commercial CFD software STAR-CD. Characteristics of the engine in-cylinder velocity field, turbulent kinetic energy field, mixture concentration field, temperature field and NOx concentration field were emphaticly investigated.Characteristics of the engine in-cylinder velocity field, turbulent kinetic energy field, mixture concentration field and temperature field were...