基于简化机理的四冲程点燃式活塞发动机爆震燃烧数值模型

Detonating combustion has become one of the key issues limiting engine performance. Therefore, it is of great significance to construct detonation combustion numerical model of four-stroke ignition piston engine to explore detonation combustion mechanism. Based on the three-component substitution model of RP-3 aviation kerosene consisting of 73.0% (mass fraction) n-dodecane, 14.7% 1, 3, 5-trimethyl-cyclohexane and 12.3% n-propylbenzene proposed by Sichuan University, presented the idea of simplifying first and then merging, and applying the direct relation graph method (DRG), direct relation graph method considering error passing (DRGEP) and computational singular perturbation (CSP) mechanism simplification methods to finally construct a simplified mechanism of RP-3 aviation kerosene containing 127 substances and 360 steps. By comparing results of the ignition delay period prediction with those of the detailed mechanism, it is found that when the initial temperature is between 900K and 1200K, the error of the ignition delay period prediction results of the simplified mechanism and the detailed mechanism is within 30%, which verified the effectiveness of the simplified mechanism. On this basis, based on the CONVERGE platform, the detonation combustion numerical calculation model of the four-stroke ignition piston engine was constructed and checked by using the G equation coupled chemical reaction dynamics mechanism. Finally, the detonation combustion process of the four-stroke ignition piston engine was simulated. The results show that the detonation combustion numerical calculation model constructed by the RP-3 aviation kerosene simplification mechanism coupled with three-dimensional numerical calculation can effectively simulate the self-ignition phenomenon of the mixture gas in the detonation combustion process of the four-stroke ignition piston engine, and reflect the variation characteristics of average parameters in cylinder during detonation combustion, and describe the evolution of pressure and temperature and spatial distribution of intermediate materials in cylinder.