内燃机活塞内冷油腔稳态综合传热预测模型

摘要

Using the dimensionless correlation, a prediction model of the convection heat transfer coefficient in the oil cooling gallery of the piston was established after taking account of the effects of several factors, such as oil cooling gallery structure, physical property of two-phase flow and local flow characteristics, on the heat transfer coefficient and analyzing the flow characteristics in the cooling gallery under different piston diameters and engine speeds.The results show that the natural logarithm of the product of the Reynolds number and Prandtl number increases with the increase of engine speed.Under the same engine speed, the natural logarithm of the product of the Reynolds number and Prandtl number increases with the increase of piston diameter.Through comparing the numerical simulation results and templug test results of the piston head, it is concluded that the prediction model can predict the heat transfer coefficient of the oil cooling gallery effectively and hence provides a theoretical basis for the design of the oil cooling gallery.%利用量纲为1的基础关联式, 考虑活塞内冷油腔结构、两相流的物理特性和局部流动特性对传热系数的影响, 分析不同缸径活塞在不同发动机转速时内冷油腔内流体的流动特性, 建立对流换热系数的预测模型.结果表明:雷诺数和普朗特数乘积的自然对数值随发动机转速的增加而增大;在发动机转速相同时, 随着内燃机活塞缸径的增加, 内冷油腔内流体的雷诺数和普朗特数乘积的自然对数值随之增大.通过对比数值模拟和硬度塞试验测试结果可知, 对流换热系数预测模型可有效预测内冷油腔的传热系数, 能为内冷油腔的设计提供一定的理论依据.