Multi-parameters Optimization Matching Study Of Diesel Engine Combustion Chamber And Fuel Injection System

In order to satisfy China V emission regulations of mobile vehicle, and to realize the improvement of fuel economy. The paper makes simulation calculation of diesel engine combustion chamber and fuel injection system parameters by means of numerical simulation, concluding the influence law of various parameters on the engine performance. By analysising the influence law of these parameters on engine power, fuel economy and emissions, making PM limit of China V emission regulations of mobile vehicle as the constaint conditions, then making the reduce of the brake specific fuel consumption as the goal of optimization. Adopting the internal purification technology by improving combustion process, then through the exhaust aftertreatment reduce the NOX emission, the combustion chamber and injection system parameters was optimized and matched, and a series of methods for low-carbon economy diesel engine has been put forward.In this paper, a supercharged diesel engine simulation model was established using the engine performance simulation software Diesel-RK, and through a comparison of the simulation results and experimental results the accuracy of the model was verified. Combustion chamber geometric parameters such as the opening diameter, double lip diameter and depth of the pit has been calculated, the influence of various parameters on the engine performance also has been explored, and through the analysising of heat release rate, fuel distribution and the visualization of spray development characteristics, the deep mechanism of the effects of various parameters has been concluded. Optimizing the structural parameters of combustion chamber at the maximum power point of rated speed, then the best combustion chamber was obtained. Though the comprasion and analysis of the heat release of original model and optimized model, it is found that optimized model’s better peformace of the engine due to its fast burning speed, short combustion duration, highheat utilization efficiency and small expansion losses. Through the simulation calculation of fuel injector structure, the best hole number and diameter are 6×0.23 mm, spray cone angle is 74°. The results of multiple injecion strategy optimization are:main injection timing is 12°CA BTDC, the fuel mass of pilot injection is 2mg,the injection interval between pilot injection and main injection is 6°CA.The final optimized model increase 5.58 kW power relative to the original model, and reduce the brake specific fuel consumption by 3.35g/kW.h, PM emissions by 0.01706g/kW.h, on the basis of meet the performance and emissions, oil-saving effect is obvious.