Effect of Combustion Chamber on Combustion And Emission for Diesel Engines
Three kinds of combustion chamber shapes were optimized and designed to reduce the compression ratio(CR),increase the diameter of the orifice,increase the depth of the pit and enhance the flow in the cylinder,which is conducive to forming a more uniform mixture gas in the cylinder.and the combustion chamber selection testing of two-stage supercharged diesel engine is carried out coupling with EGR.The experimental results show that:Under low load condition,compared with the original engine,SF1,SF2 and SF3 have a longer ignition de-lay,but their instantaneous heat release rate and maximum heat release rate are higher,and their combustion du-ration is relatively short,CA50 is closer to TDC,so that heat transfer loss is lower,which can improve brake specific fuel consumption(BSFC).High load conditions,the combustion temperature,maximum explosion pres-sure and pressure rise rate of the two-stage supercharged diesel engine can be reduced by reducing the combustion chamber compression ratio(16.8 and 16.2),and the maximum pressure in the cylinder can be controlled within the range of 160 bar to meet the diesel engine strength design requirements.Low speed high load and middle speed low-load conditions,SF1 and SF4 can significantly improve the trade-off relationship between NOx,smoke and BFS.Considering the emission and fuel economy of several operating conditions,SF1 has the best overall performance.
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