Numerical Simulation Of Coupled Heat Transfer For Automotive Louvered Fin Radiator And Its Optimization

As a key component of automotive cooling system, the cooling capacity of radiator is directly related to the performance of engine. From this, the radiator structure design with high heat transfer efficiency is very important. In view of the high heat transfer efficiency and the compact structure of louvered fin, in order to realize the optimization design of the radiator structure this paper selected coupled heat transfer mechanism for louvered fin radiator as study object.Firstly, the three-dimensional numerical model of a common rectangular louvered fin is established, and then the method for calculating the coupled heat transfer in a radiator is studied. By comparing the numerical results with experimental results and empirical correlation results, the effectiveness of the proposed model and the calculation method is verified. Based on this, a type of oblique needle shaped louvered fin is put forward. For different working conditions and different structure parameters, the heat transfer performance of oblique needle shaped louvered fin is compared and analyzed, and the optimal design method of oblique angle and the number of louver fins on both sides of reversing area is studied. Finally, the fitting correlation between j and f is obtained by regression analysis, and the values of ? and L_p are optimized on the basis of the comprehensive heat transfer factor j/f1/3 .The main conclusions are as follows:(1) The performances of oblique needle shaped louvered fin and rectangular louvered fin heat transfer are compared, and the results show that with ReL_p being in the range of 400?1200, the friction factor f of oblique needle shaped louver fin is 20.7% lower than that of rectangular louvered fin, and the heat transfer factor j is 11.2% higher than that of ordinary rectangular louvered fin;(2) With the other structural parameters unchanged, it is discovered that the larger the louvered fin angle and the fin thickness, the greater the heat transfer coefficient and the pressure drop. Meanwhile, the heat transfer coefficient and the pressure drop increase with head wind speed;(3) When the ratio of louver pitch to fin pitch L_p/Fp varies within 0.6?1.7, it is found that only in the range of 0.9 to 1.1, can the effective and efficient flow of oblique needle shaped blind happen. The heat transfer coefficient has its largest value with L_p/Fp=1.52;(4) For four kinds of oblique angle deviation, the best overall heat transfer performance is obtained when oblique angle of needle is symmetrical relative to arrangement mode in both sides of commutation area, and the pressure drop at this time can be up to 15.4% in comparison with the other three forms;(5) The integrated performance of oblique needle shaped blind is best when the oblique angle a is in the range of 10° to 15°. In consideration of processing difficulty and economical efficiency, the recommended value of needle angle is about 15°;(6) By virute of optimal design, it is found that the heat transfer performance is best when louver fin angle is 28.9° and L_p is 0.902 mm. The heat transfer performance becomes worse with increasing L_p.