摘要
为研究柴油机活塞环形油腔周向振荡冷却特性,在非惯性坐标系下应用流体体积函数(VOF)多相流模型,对活塞环形油腔振荡冷却进行了瞬态换热研究,得到了环形油腔周向壁面平均换热系数的变化规律,发现壁面平均换热系数的振荡幅度最大的并不是入口冲击的周向10°区域,而是周向20°区域.一个周期内油腔周向区域的壁面平均换热系数整体呈类"对数"减小的趋势,在周向10°~30°区域急剧减小,而后随着远离入口段,其值呈现先增大后减小的变化规律.最后通过两种方法计算活塞温度场并进行对比,发现使用18周向区域的壁面平均换热系数所计算的活塞温度场的顶部温度波动更大,更符合实际情况.
The VOF multiphase flow model was used to study the oscillatory cooling of the piston oil cavity in the non-inertial coordinate system.It is found that the maximum amplitude of the wall heat transfer coefficient appears not on the circumferential 10 degree region of the entrance but on the circumferential 20 degree region.The average heat transfer coefficient of the circumference area shows a tendency to decrease with a alike logarithmic step in one cycle.The wall heat transfer coefficient in the circumferential area of 10 degrees to 30 degrees is sharply reduced,and then the value increases first and then decreases with the distance away from the entrance section.The temperature oscillatory on the piston top calculated by the heat transfer coefficient of 18 zones in the circumference is larger but more realistic.
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