| Radiator is the core component of automobile cooling system,which provides the engine with a suitable temperature working environment.In order to meet the development trend of energy saving and emission reduction,high efficiency and lightweight radiator design has become the main research direction.In the radiator fin structure,louver fin is recognized as the typical representative of heat transfer enhancement in the field of automotive radiator,which has the advantages of high efficiency and compact structure.In this paper,the structure of louver fin is optimized by numerical simulation.LBM algorithm based on double distribution function model is used to simulate the traditional rectangular louver fin.Comparing the simulation results with the experimental fitting formula,it is found that the average relative error of heat transfer factor is 6.53%,the average relative error of flow factor is 5.72%,and all the relative errors are less than 10%,which verifies the feasibility and rationality of LBM applied to the numerical simulation of louver fin.On this basis,a stepped louver fin is proposed by dividing the louvers of the traditional rectangular louver fin equally and placing them horizontally in a stepped shape.The following conclusions can be drawn from the numerical simulation analysis:(1)Numerical simulation of 3-layer,4-layer and 5-layer stepped louver fins shows that the heat transfer performance and comprehensive performance of 3-layer and 4-layer stepped louver fins are not as good as those of traditional rectangular louver fins,only the flow performance is improved.The performance of the 5-layer stepped louver fins is just the opposite.Compared with the traditional rectangular louver fin,the average heat transfer performance is increased by 18.00%,the average flow performance is decreased by 10.17%,and the average comprehensive performance is increased by 14.27%.The 5-layer stepped louver fins were used as the original model to optimize the structure.(2)Adjusting the step spacing is 0.15 ～0.25.It is found that with the increase of step spacing,the heat transfer and comprehensive performance of the stepped louver fins will be increased and the flow performance will be decreased.(3)Adjusting the angle of louver and fin is 19°～31°.It is found that the comprehensive performance is the largest at 24.05°.Compared with the original model of 27°,the average heat transfer performance is increased by 14.67%,the average flow performance is decreased by9.81%,and the average comprehensive performance is increased by 11.39%.(4)Adjusting the step width-thickness ratio is 1.57～3.52.It is found that with the decrease of the step width-thickness ratio,the heat transfer performance of the stepped louver fins increases slightly,the flow performance decreases greatly,and the comprehensive performance basically remains unchanged with the maximum change percentage of 2.02%. |
