Reserch On Air Side Flow And Heat Trasfer Character Of Vehiclecooling Systems

Set up the wind tunnel test system and study the heat transfer and friction characterics for five type vehicle heat exchangers outside fin, fit the j and f factors correlations for these type fins; combining the methods of theoretical analysis and experimental research, the author analyzes the heat transfer and friction performance of the cooling package and vehicle cooling systems. The thesis includes the following topics:(1) Heat transfer and friction performance experimental study for vehicle heat exchanger outside finsUsing the wind tunnel test system, finished the heat transfer and friction performance test for 5 types fin using in air side of vehicle heat exchangers. It is 67 fin samples with different geometry parameters, which includ the fin height, fin pitch, fin length and fin thickness, etc, al.(2) Performance analysis and the j and f factors correlation fittingCompare and analyze the thermal-hydraulic performance of five types fin with different geometry parameters under the same condition. Using nonlinear regression analysis and F significance test method, get the j and f factors correlations for different type fins. The comparison results of predict data and test show these correlations can predict the 90% test data within the±12%. The comparison of predict data and those of other correlations or data in paper has been done, and this comparison give the direction of using these correlation during the heat exchanger design.(3) Parametric study on the performance of the finUsing the Taguchi method study the effect of the control factors on the overall enhaned heat transfer performance; these control factors include the main geometry parameters for all kinds of fin. And analysis the characterics of the different levels for the control factors effect on the heat transfer and pressure drop.(4) Overall enhanced heat transfer performance comparison for finsUsing all kind of methods evaluate the overall heat transfer performance for different type fins under the same condition. These methods include the factors of area goodness, heat transfer vs. fan power of heat transfer area, VG-I criteria, etc.(5) Numerical simulation and analysis of enhanced heat transfer mechanism for wavy finThe heat transfer and friction performance of wavy fin are gotten using the 3D numerical simulation, and compare with test data. The comparison results shows : Re=1000~5000, the mean deviations of j and f factor are 9.2% and 7.8%; Calculate and compare the thermal-hydraulic performance of wavy fin for different geometry parameters; The enhanced heat transfer mechanism of wavy fin is explained in view of field synergy principle.(6) Simulation model of vehicle cooling systemsSet up the heat transfer and pressure drop performance calculation models for the different type vehicle heat exchangers, using the lumped parameter model or distribution parameter model; Set up the 1D and 3D combine simulation model for cooling package, the simulation results are compared with wind tunnel test; make the cooling system of vehicle simulation, study and analyze the heat transfer and friction performance of cooling systems under different working conditions.