气道喷水对点燃式发动机燃烧及排放性能的影响OA

For a direct-injection gasoline engine equipped with a centrally located high-pressure fuel injector,the experimental study was conducted on the effect of the airway water injection on the combustion and emissions performance of spark-ignition gasoline engines.By adjusting the water injection quantity and ignition timing,the study investigated the differences in combustion characteristics and emissions under different water-to-fuel ratios(W/F).The results indicate that under constant ignition timing,the combustion phase delays significantly and the average effective pressure decreases with the increasing of W/F.Advancing the ignition timing can advance the combustion phase,suppress the tendency of knocking combustion,and further increase the engine load.Under different load conditions,the influence of W/F on the combustion process varies.At medium to high loads,an increase in W/F can shift the overall combustion process forward,significantly improving the combustion stability and reducing the fuel consumption.For instance,comparing W/F=0.3 with W/F=0,the fuel consumption can be reduced to be approximately 10%.However,at low loads,the excessively high W/F can deteriorate the combustion stability and increase the fuel consumption.Simultaneously,as W/F increases,the combustion temperature decreases,leading to a decrease in NOx emissions.However,the combustion efficiency decreases,and hydrocarbon emissions worsen.