通用小型汽油机冷却系统的CFD分析和试验研究

CFD analysis and experiment research of non-road gasoline engine cooling system

以170F汽油机冷却系统为研究对象,建立了其冷却空气流场三维分析模型,使用CFD软件Fluent为工具,计算得出该机型冷却系统的压力场和速度场;同时进行了整机冷却试验,分析了其冷却空气流量及流速分布状况;对原机存在的问题给出了改进的优化方案,通过对导风罩改进,合理分配气缸盖和气缸体部分的冷却风量,对气缸盖的冷却风道优化来强化燃烧室顶部的冷却,使整机冷却空气的流场合理,有利于减少气缸盖热应力和热负荷,减少进气道对进气量的加热量。整机试验表明改进后汽油机性能得到了改善,工作温度合理,提高了汽油机整机的可靠性。

Taking 170F gasoline spark-ignition engine as object, this paper establishes the 3D model of 170F cooling system .With the con- clusion of pressure field and velocity field of the engine cooling system reached via the CFD software of Fluent and experiment research of this engine cooling system, this paper analyzes the distribution of flow rate and velocity of the cooling air. Several improvement projects are proposed, such as improving wind scooper to optimize the ration of flow capacity between cylinder head and cylinder block, optimizing the structure of cooling air channel in cylinder head to intensify the wall heat transfer over combustion chamber. By improving the structure of cooling system, the cooling air is properly allocated to different part of the engine, which is good for reducing heat stress and heat load, be- s,ides good for reducing heating intake charge. Through experiment on the engine, it is proved that the engine work performance is improved, working temperature is reasonable and the engine work reliability is increased.