柴油机喷嘴内空穴流动可视化试验与数值模拟

柴油机喷雾特性除了与气缸内气流运动有关外,也与喷嘴内空穴流动有密切的关系.设计了比例放大多孔喷嘴内空穴流动和喷雾的可视化试验装置,进行了不同燃油喷射压力下喷嘴内空穴现象和喷雾的可视化试验,对所建喷嘴内空穴流动的三维数值计算模型进行了试验验证.采用试验和数值模拟相结合的方法分析了喷嘴内部流动从单相湍流流动发展为空穴流动、超空穴流动的流动特性,得出了喷嘴流量系数与喷射压力及空穴参数之间的关系以及喷嘴内出现空穴现象的临界条件.

Visualization Experiment and Numerical Simulation for Cavitating Flow in a Diesel Injector Nozzle

A visualization unit with a proportion of the multi-hole injector nozzle for cavitating flow was developed, and by means of high-speed video camera, the pictures of the cavitating flow in a large-scale transparent nozzle were taken under various injection pressures. A three-dimensional grid model of the injector nozzles was established, and the three-dimensional numerical simulation of cavitating flow in nozzle holes of a multi-hole injector combined with these pictures from experiment was utilized to analyze flow characteristics of single-phase flow to supercavitation flow. The relationship between injection pressure, non-dimensional cavitation parameters and the discharge coefficient, as well as the critical conditions when the cavitation appeared was pointed out clearly.