基于Fluent的柴油机冷却环道流动特性分析

 为缓解柴油机活塞的过热问题，对冷却环道内的气液两相流动状态及传热特性进行了研究。根据计算流体力学方法确立柴油机冷却环道流动的湍流模型和相界面模型。采用有限元方法，建立冷却环道两相流仿真模型，针对柴油机不同的转速、油压和油温条件分别进行仿真计算，得出油液的体积率和平均换热系数随曲轴转角的变化规律。通过发动机喷流试验台的验证可知，冷却环道内两相流动状态的实验与仿真结果具有良好的匹配性。研究结果表明：喷油压力对油液体积率和平均换热系数的影响非常小；油体积率和平均换热系数的变化趋势不存在一致性；冷却环道的换热能力主要由油液黏度和振荡强度决定。

Flow Characteristic Analysis of Diesel Engine Cooling Ring Based on Fluent

In order to alleviate the overheating problem of diesel piston, the gas-liquid two-phase flow and heat transfer characteristics in the cooling ring were studied. According to the computational fluid dynamics (CFD) method, the turbulence model and the phase interface model of the cooling ring flow in diesel engine are established. The simulation model of two-phase flow in cooling ring is established by finite element method. The simulation calculation is carried out for different rotational speed, oil pressure and oil temperature conditions of diesel engine, and the variation rule of oil volume ratio and average heat transfer coefficient with crankshaft rotation angle is obtained. The validation of the engine jet test bench shows that the experimental and simulation results of the two-phase flow in the cooling ring have a good match. The results show that the influence of injection pressure on the oil volume ration and average heat transfer coefficient is very small. The variation trend of oil volume ratio and average heat transfer coefficient is not consistent necessarily. The heat transfer capacity of cooling ring is mainly determined by the oil viscosity and oscillation intensity.