Experimental Investigation on Effect of EGR on Combustion Noise in Transient Conditions of DI-Diesel Engine

By means of introduction of an appropriate exhaust gas recirculation(EGR) system in the engine and measuring the parameters affecting combustion noise before and after EGR implement,the effect of EGR on combustion noise under transient conditions of DI diesel engine was examined.The results show that combustion noise under transient conditions may be reduced by EGR,engine noise in transient conditions is reduced more than 1dB for most load range and the power output is not obviously affected.It is deduced from thorough analysis of the test data that appropriate EGR ratio makes the pressure rise rate and the pressure high-frequency oscillation magnitude under transient condition reduce,leading to combustion noise being lowered.