| With the oil energy crisis and increasingly stringent emissions regulations, various countries are actively looking for alternative fuels. Natural gas as a clean fuel, which has abundant reserves, is the first choice of alternative fuel for vehicle engine. Reasonable selection of the ignition timing, air fuel ratio and combustion chamber structure on the gas engine will have a very important influence on the economy, power and emission characteristics. In this research, through theoretical analysis, numerical simulation and experimental study of the combination of means, a natural as engine's combustion process was studied.Firstly, the nature gas engine has been on test, including the total power test, and performance test when change the ignition timing and air-fuel ratio at the conditions of maximum torque and calibration,getting the performance parameters of cylinder pressure indicator diagram and heat release rate, analyzing the influence of ignition timing and air-fuel ratio on the performance of power, economy and emissions, and get the better ignition timing and air-fuel ratio values under the condition of maximum torque conditions and calibration conditions. Then this nature gas engine's cylinder flow and combustion process were analyzed by the three-dimensional numerical simulation. At last, the shape of the combustion chamber has been optimized design, by comparing the performance and emissions of nature gas engines with three different combustion chambers, providing a reference of further improvement of the engine performance's optimization. |
