Influence of Key Structural Parameters of Combustion Chamber on the Performance of Diesel Engine

The structural parameters of combustion chamber have great impacts on the process of air-fuel mixing, combustion, and emissions of diesel engine. The dynamic characteristics and emission performances could be improved by means of optimizing the parameters of the combustion chamber. In this paper, the key structure of a diesel engine combustion chamber is parameterized, and the influence of individual structural parameter on dynamic characteristics and emissions of the engine is simulated and analyzed by computational fluid dynamics (CFD) software AVL-FIRE. The results show that under constant compression ratio, the in-cylinder peak pressure decreases with increasing inclination angle of the combustion chamber (a), while the height (T-m) and bowl radius (R) have little influence on the in-cylinder peak pressure. With increasing a, NO emissions decrease, and soot emissions first increase and then decrease. With increasing R, both NO and soot emissions decrease first and then increase. Therefore, the combustion chamber parameters could be optimized by comprehensive consideration of cylinder pressure, NO and soot emissions.