Numerical Study On Heat Transfer And Flow Characteristics Of The Heat Exchanger Used On Electric Locomotive Main Transformer

With the strengthening of comprehensive national strength and the rapid developmentof railway transportation, the mileage of railway transport and the quantities of electriclocomotive are rising year by year. Especially in recent10years, domestic electriclocomotive has made considerable progress, meanwhile, the cooler of traction transformershave developed from the structure and the performance, and put forward higherrequirements.With the help of CFD numeral simulation, a numeral research is done on the heat tran-sfer and resistance characteristics of the wave fin on air side and off-set strip fin on liquidside. Then the heat transfer factor j and friction factor f under different parameter ratio canbe calculated. j/f is defined as the comprehensive performance of the finned sur-face.Heat transfer factor and friction factor under fin’s different structural parameters areobtained by simulation calculation. The above data as the original data, the writerestablished the nonlinear regression analysis model of heat transfer factors "j" andresistance factor "f" with multivariate nonlinear regression method. In the process of return,by using the method of universal global optimization in the "1stOpt" software whichcriterion is nonlinear least squares method, it will obtained fin’s regression parametersthrough iterative calculation and then established a method of no initial model’s datamodeling.Thus, he mathematical model of automatic looking for hidden in the data hasimplemented and parameters of the initial value is no need., The validity of the model hasproved based on residual value. It turned out that the analytical model which made by thewriter can ensure the calculation accuracy. Meanwhile, it can overcome the low efficiencyof the simulation calculation.According to the research on heat transfer factors and friction factor of the offset stripfin and wavy fin, we develop a design and optimization software about these two types offin using C++programming language,the software is manly divided into3parts, calculationof friction factor and the heat transfer factor, using conjugate gradient method to search forthe best fin structure, result showing. This software is used to improve the work efficiencyand provide technical support on fin structure optimization for better heat transferperformance.