某型二冲程航空活塞发动机缸头热负荷研究

Research on Thermal Load of a Certain Type of Two-Stroke Aviation Piston Engine Cylinder Head

某型二冲程航空活塞发动机缸头的冷却形式为风冷,影响缸头热负荷的主要因素包括缸头外部冷却空气流速、缸头燃烧室内燃气温度。以某型二冲程航空活塞发动机缸头为对象,研究缸头在极限工况下的热负荷,分析缸头温度场分布特点,为缸头的散热片结构优化设计提供参考依据。以缸内燃气瞬时温度和缸内燃气瞬时传热系数为基础,利用经验公式计算了缸内燃气与缸头内壁的换热边界条件以及缸头外部与冷却空气的换热边界条件。利用有限元数值仿真分析软件对某型二冲程航空活塞发动机缸头热负荷进行了仿真计算,获得缸头的温度场分布。通过对发动机进行地面台架试验测取了缸头在该工况下的特征点温度,试验测量值与仿真值对比,可见仿真结果与试验的误差小于5%,满足工程需要。

The cooling mode of a certain type of two-stroke aviation piston engine cylinder head is air cooling.The main factors influencing the cylinder head thermal load include:the flow rate of external cooling air of the cylinder head;and the gas temperature of the combustion chamber of the cylinder head.Taking the cylinder head of a certain type of two-stroke aviation piston engine as the research object,the thermal load of the cylinder head under the extreme working conditions was studied.The distribution characteristics of the temperature field of the cylinder head were analyzed to provide reference for the optimization design of the heat sink structure of the cylinder head.Based on the instantaneous temperature of the gas in the cylinder and the instantaneous heat transfer coefficient of the gas in the cylinder,the heat transfer boundary conditions between the gas in the cylinder and the inner wall of the cylinder head,and the boundary conditions of the heat exchange between the cylinder head and the cooling air were calculated using an empirical formula.The finite element simulation software was used to simulate the cylinder head thermal load of a two-stroke aviation piston engine,and the temperature field distribution of the cylinder head was obtained.Through the ground bench test of the engine,the temperature of the characteristic point of the cylinder head under this working condition was measured.The comparison between the experimental measurement value and the simulation value is less than5%,which meets the engineering needs.