轿车发动机舱内流动与散热特性数值研究

Simulation on Vehicle Underhood Thermal Management System

将整车热管理系统作了模型简化,对发动机舱内的流动特性进行了数值模拟,给出了流经冷凝器的质量流率和ETA值与车速和风扇转速的关系.在此基础上,分别对考虑与不考虑辐射时各种工况下发动机舱的散热特性进行分析.数值结果表明:怠速工况下发动机舱的热环境问题主要是前端空气再循环降低了车辆空调系统和冷却系统的散热效率;满载爬坡工况发动机舱的热环境情况最为恶劣;高速工况时,即使关闭风扇也能保证发动机舱良好的热环境状况.

The objective of this work is to analysis the underhood airflow and heat transfer characteristics by simulating the whole vehicle thermal management system.The underhood airflow characteristics of the same vehicle operation condition by Star-CD code and the Fluent code were obtained and compared,the results are not any noticeable differences.The underhood airflow characteristics of the different vehicle operation conditions were obtained and the results showed the ETA decreases and the mass flux increase as the increase of the vehicle speed.Moreover,the underhood heat transfer characteristics of different vehicle operation conditions were also simulated and analyzed,the results show the existence of the front-end air re-circulation should be noted especially at vehicle idle condition,there are the most temperature distribution at vehicle uphill condition with full load and the fans can be shut off at high speed from the point of view of the underhood thermal environment.