发动机冷却系统数值模拟分析及优化研究

Numerical simulation analysis and optimization of engine cooling system

为了给发动机冷却系统性能评估及优化提供理论指导,本文以某四缸发动机为研究对象,采用CFD方法对其冷却系统进行数值模拟分析及优化,结果表明:油水交换器及散热器流阻的CFD仿真值与实验值误差小于10%,说明搭建的冷却系统性能仿真模型是可靠的;缸体水套排气侧上部区域冷却液流速较低,缸头水套上鼻梁区冷却液流速低于1.5 m/s且分布不均匀。为提升冷却系统散热性能和水套内部流动均匀性,对水泵性能、管路直径及水套结构进行了优化,优化后冷却系统在发动机转速10000 r/min时流量提升至90 L/min,水套流动均匀性提升,缸体水套排气侧区及缸头水套鼻梁区冷却液流速均满足1.5 m/s的冷却液流速设计要求。

In order to provide theoretical guidance for the performance evaluation and optimization of engine cooling system,a four cylinder engine is selected as the research object,the CFD method is used to analyze and optimize its cooling system.The error between the CFD simulation value and the experimental value of the flow resistance of oil-water heat exchanger and radiator is less than 10%,which shows that the performance simulation model of the cooling system is reliable.The coolant velocity in the upper area of the exhaust side of the cylinder block water jacket is low,and the coolant velocity in the upper nose bridge area of the cylinder head water jacket is less than 1.5 m/s and the velocity distribution is uneven.In order to improve cooling performance of the cooling system and the internal coolant velocity uniformity of the water jacket,the performance of the water pump,the diameter of the pipeline and the structure of the water jacket are optimized.After optimization,the flow rate of the cooling system is increased to 90 L/min at the engine speed of 10000 r/min,and the coolant velocity uniformity of the water jacket is improved.The coolant velocity in the exhaust side area of the cylinder block water jacket and the nose area of the cylinder head water jacket meet the coolant velocity design requirements of 1.5 m/s.