Simulation Calculation And Experimental Study On Combustion Noise Control With Pilot Injection

Combustion noise of diesel engine plays a most important role in whole noise of diesel engine. Based on the research of reducing combustion noise, pilot injection is an effective measure to control it. Especially for a diesel engine with high pressure common rail electronic-control direct injection system, it enables a higher injection pressure and meanwhile excellent controllable performance, which can achieve accurate control to the pilot mjection.The diesel combustion noise had been simulated by the GT-SUITE software in this paper. The mathematic model was established based on the parameters of 6106 type diesel, the influence of parameters like the speed, the load, the injection pressure etc on the maximum pressure rise rate and the heat release rate was studied computationally with different injection strategies of single injection, and the superiority of pilot injection over single injection in decreasing combustion noise was also compared. Simulation calculation results showed that the injection timing was a most important factor in effecting combustion noise, and the influence of injection pressure on combustion noise was comparatively smaller. In different conditions, the maximum pressure rise rate reduced basically according to the retarding of main injection timing, which was consistent with the injection timing in single injection.The performance test had been operated in a test rig with a 6106 type DI diesel engine based on the results of simulation calculation, the noise signal, the specific fuel consumption and the emissions were studied experimentally by high pressure common rail electronic-control system and other test equipments. It was indicated from the results of test, the speed had biggish effect on the combustion noise no matter with single injection or pilot injection, but the reduced noise quantity by pilot injection was unconspicuous by changing speed; Contrarily, the load had little effect on the combustion noise no matter with single injection or pilot injection, but the reduced noise quantity by pilot injection was obvious by changing load. Taking one with another, the reduced noise quantity by pilot injection exceeded that by changing pilot injection strategyBased on the results of simulation calculation and experiment, the variables of pilot injection were optimized. During optimizing with the purpose of decreasing combustion noise, the influence on the emissions and the specific fuel consumption were also considered. It could be concluded that pilot injection enabled the improvement in combustion noise of diesel...