内冷油腔振荡冷却仿真方法研究

为了得出一种较为通用的活塞内冷油腔仿真分析方法,采用数值仿真研究方法,从湍流模型、多相流模型、压力速度耦合算法以及油腔几何模型进行油腔CFD仿真分析方法的研究。通过对比分析仿真所得的平均机油填充率、机油分布、壁面平均换热系数和换热系数分布,得出在进行活塞油腔CFD模拟时,标准k-ε湍流模型可以更为经济地进行流动传热计算。可保证计算模拟精度的多相流模型CLSVOF计算结果周期间变化更小,计算结果稳定。活塞油腔瞬态仿真计算时,压力速度耦合算法PISO计算得出的流动换热结果精度更高,收敛速度和达到计算稳定的速度更快,模拟所得流动传热情况更接近实际。全油腔模型模拟效果相对于简化模型效果更好。通过对油腔各壁面区域换热系数随曲轴转角变化的分析得出:振荡过程极大增强了顶面和底面的换热,油腔内壁面中顶部壁面周期平均换热系数最大;底部壁面换热系数变化趋势与顶部壁面变化趋势基本相反,这是由机油分布以及振荡规律决定的;由于侧部壁面未收到机油强烈的冲击,换热系数随曲轴转角变化相对较平缓。

Simulation Method for Oscillation Cooling of Internal Cooling Oil Cavity

In order to obtain a more general simulation method for the inner cooling oil cavity of the piston,numerical simulation research method is used to study the oil cavity CFD simulation analysis method from turbulence model,multiphase flow model,pressure velocity coupling algorithm and oil cavity geometry model.By comparing and analyzing the average oil filling rate,oil distribution,wall average heat transfer coefficient and heat transfer coefficient distribution,it is concluded that the standard k-εturbulence model can be used to calculate the flow heat transfer more economically when performing CFD simulation of piston oil chamber.The multi-phase flow model CLSVOF which can guarantee the calculation accuracy can be changed less periodically,and the calculation result is stable.In the transient simulation calculation of piston oil cavity,the flow velocity heat transfer result calculated by the pressure velocity coupling algorithm PISO is more accurate,convergence speed and speed of calculation stability are faster,and the simulated flow heat transfer is closer to reality;the simulation effect of the full oil cavity model is better than the simplified model.Through the analysis of the heat transfer coefficient of each wall surface of the oil chamber with the change of the crank angle,it is concluded that the oscillation process greatly enhances the heat exchange between the top surface and the bottom surface.The average heat transfer coefficient of the top wall surface in the inner wall surface of the oil chamber is the largest;the change trend of heat transfer coefficient of the bottom wall surface is basically opposite to the change trend of the top wall.This is determined by the oil distribution and the oscillation law.Since the side wall surface does not receive strong impact of the oil,the heat transfer coefficient changes relatively gently with the crank angle.