直喷式柴油机燃烧数值计算研究

以KIVA-3为计算平台,对4气门直喷式柴油机的早喷燃烧、预喷燃烧和传统燃烧三种燃烧方式工作过程进行了模拟计算,得以下结论:早喷燃烧方式因喷到缸壁的油量较多,受进气涡流影响较少,同时利用喷射效应改善缸内氧气分布,因此早喷燃烧比较完全。预喷燃烧方式仍以扩散燃烧为主,预喷油燃烧改变了主喷初期油注周围的组分分布与温度分布,从而改变主喷燃油的燃烧历程。进气涡流造成的缸内流场不均匀性是影响传统燃烧方式燃烧不完全的主要因素之一。

NUMERICAL SIMULATION OF COMBUSTION PROCESS IN DI DIESEL ENGINE

The combustion processes of early injection, two stage split fuel injection and traditional mode in the model 135 four-valve DI diesel engine were simulated using KIVA-3 computational platform. Results indicate: the combustion completeness of early injection mode is relatively best, because more quantity of oil was injected onto cylinder wall. The combustion was less affected by the intake turbulence and makes use of the fuel injection effect to improve the oxygen distribution in the cylinder. In two stage split fuel injection, the combustion mode of the pilot or main injection is mainly diffusion combustion, the pilot combustion changes the oxygen and temperature distribution around the main spray at the initial stages of injection, so that the combustion process of the main spray would be changed. The anisotropy due to intake turbulence is one of the main factors of affecting the combustion completeness of traditional combustion mode.