Multi-field Coupling Analysis And Structural Optimization Of Automotive Radiators

The radiator is an important part of an automobile engine cooling system, its thermal performance directly affects the engine power, reliability and economy. In this dissertation, a new type radiator was researched using CFD method and coupled heat transfer theory, on the basis of summarizing the problems that model simplification, lack of multi-field coupling analysis and low variability of tube structure exist in the research of radiator. The main research works are as follow:Firstly, the physical fields involved in the process of radiator are analyzed, and the coupling of temperature field, flow field and pressure is determined, according to the evaluation index of radiator performance.Secondly, the waist tubes which aspect ratio are 5 and 10 are proposed on the basis of flat heat tube, according to the theory of fluid mechanics on the flow state influenced by the flow channel. The simulation results show that the waist heat tube has better thermal performance than the flat tube, and the waist tube which aspect ratio is 5 has higher overall performance than the other two heat tubes.Thirdly, the waist tube radiator containing heat fin is established, on the basic of waist tube. The heat transfer characteristics and flow resistance characteristics under different working conditions are obtained by simulation, and then the sample of waist tube radiator is made and the wind tunnel test is carried out. The comparison between simulation results and test results reveals that the two are in good agreement, which verifies the reliability of the method and model. By comparing the wind tunnel test results of different tube radiators, it is found that the performance of waist tube radiator is better than that of the circular tube, elliptical tube and flat tube radiator.Finally, the multi-parameter optimization of heat fin is carried out. According to orthogonal experiment rules, 9 models with different parameters of fin are established, the influence laws of different parameters on the radiator performance are summarized, and a group of multi-parameter of fin is obtained that has a better overall performance.The research results of this dissertation can provide a reference for the structure improvement of radiator and the matching of the tube with fin. It is beneficial to promote the design and development of the new radiator.