Multi-Dimensional Simulation Of Optimization Of Combustion System Parameters In A Highly Intensified Diesel Engine

The increasingly rigid power and economic performance indicators of diesel engine make it imperative to design a high-efficiency diesel engine to meet the strict emission regulations. However, it is intractable to organize the combustion process in a highly intensified diesel engine cylinder for its high engine speed and high injection pressure. Investigations of CFD simulation of optimization of the combustion system parameters on a highly intensified diesel engine are important and valuable to improve the overall performance of the highly intensified diesel engine.In this thesis, profited from the CFD software FIRE, the mathematics models for simulation of in-cylinder process are introduced for researching the combustion and emission of the highly intensified diesel engine. According to the experiment date of combustion pressure in the cylinder and heat release profile, the EBU multi-dimensional combustion model parameter A and WAVE droplet breakup model parameter C2 are adjusted and the performance of the highly intensified diesel engine was predicted. Furthermore, the combustion system parameters are optimized.To the beginning, the effect of swirl rate, nozzle diameter, spray timing, spray angle and chamber configuration on combustion and overall performance of the engine are studied based on single parameter rotatory method. Then the effects of seven combustion system parameters and the interaction effect of three pair of different combustion system parameters to the emission, indicated power, fuel consumption of the highly intensified diesel engine are investigated and analyzed based on the Orthogonal Experiment Method. The individual influence coefficient to the NOx and soot emission, indicate power, fuel consumption and overall performance of different combustion system parameters are obtained. And the optimized combustion systems to different evaluation objectives of the engine are acquired. At last, based on the optimized diesel chamber configuration through Orthogonal Experiment Method, swirl rate, nozzle diameter, spray timing, spray angle are further optimized based on the Genetic Algorithm Method, and a further optimized result are obtained.