考虑两相流沸腾传热的气缸盖温度场仿真研究

Simulation Study on Cylinder Head Temperature Field with Consideration of Two-Phase Flow Boiling Heat Transfer

以ANSYS Workbench为仿真计算平台,考虑冷却水流动与沸腾传热的影响,在计算流体动力学模块CFX中,采用气液两相流沸腾传热和单相流不考虑沸腾传热的计算方法,对柴油机气缸盖与冷却水腔所组成的流固耦合传热系统进行整场求解,得到了标定工况下气缸盖温度场分布,结果表明:与单相流不考虑沸腾传热的计算结果相比,两相流沸腾传热能够有效降低气缸盖火力面鼻梁区和排气道侧的最高温度。最后采用Design Exploration模块,以冷却水腔进口温度和进口速度为输入参数,对气缸盖火力面排气门鼻梁区温度进行响应分析,结果表明:气缸盖火力面排气门鼻梁区温度随着进口温度的升高而升高,随着进口速度的增加而降低,当速度增大到一定值时温度随着进口速度的增加而增高;其中冷却水进口速度和温度分别为4.876m/s和353.31K时,可分别使火力面排气门鼻梁区的温度值达到最小。

Taking ANSYS Workbench as simulation platform and considering effects of cooling water flow and boiling heat transfer,a mesh model for fluid-solid coupled heat transfer system consisting of cylinder head and cooling water jacket was built up based on the computational fluid dynamics module CFX. Two methods , the gas-liquid two-phase flow boiling heat transfer and single-phase flow （without considering boiling heat transfer ） were used to resolve together the fluid-solid coupled heat transfer system consisting of cylinder head and cooling water jacket, the cylinder head temperature field distribution under rated power condition was obtained. Results show that compared with the single-phase flow without considering boiling heat transfer, the highest temperatures in the head exhaust valve bridge zone and exhaust port side were effectively reduced using the two-phase flow boiling heat transfer method. Finally, using the Design Exploration module and taking cooling water jacket inlet temperature and velocity as the input parameters, the head exhaust valve bridge zone temperature response were analyzed. Simulation results show that the head exhaust valve bridge zone temperature increases with the inlet temperature rising and decreases with the inlet velocity increasing,but as the inlet velocity reaches a certain value the temperature increases with the inlet velocity increasing conversely. While at cooling water inlet temperature of 353. 31K and velocity of 4. 876 m/s,the exhaust valve bridge zone temperature is minimal.