Simulation Research of Natural Gas Injection Timing on Combustion Process in a Diesel Engine Fueled with Pilot-ignited Directly-injected Natural Gas

The numerical model of diesel engine fueled with pilot-ignited directly-injected natural gas is built, and the influence of natural gas injection timing on the combustion process is studied using CFD software. And obtained the following conclusions, as the delay of natural gas injection timing, the maximum of the mean pressure and mean temperature decrease gradually and the timings for the maximum value increase. With every delay of 5 degrees CA of the injection, the mean pressure reduces by about 16%.As the delay of injection timing, the delay of the timing of the high temperature and the range decrease for the high temperature region, and this is beneficial for the emission of NO, but not conducive to the emission of HC, CO and PM