Study On Flow And Heat Transfer Characteristic And Optimization Design Of Microchannel

The improvement of the performance of aircraft and the development of aeronautical technology have increased the thermal load,the aircraft fuel cooling system is facing a severe challenge.As a key component,the fuel heat exchanger needs to be more compact and efficient.Compared with conventional heat transfer technology,microchannel heat transfer technology has the outstanding advantages of high efficiency,compacte structure and high heat transfer efficiency,and has been widely used in many industrial fields.This paper will take aircraft fuel heat exchanger as the application to analyze the flow and heat transfer characteristics of the microchannel,and optimize the structure design of the channel type and flow maldistribution of the microchannel.The thermal environment of aircraft fuel heat exchanger was analyzed,and a physical property replacement model of aviation kerosene RP-3 was constructed.The numerical calculation method applicable to the microchannel and several evaluation indexes used to evaluate the performance of flow heat transfer were established.The field synergy theory was used to evaluate the efficiency of heat transfer and the cost of pressure.Based on the orthogonal design of Taguchi method and the SNR loss function analysis,the influences of operating conditions(Inlet temperature,inlet velocity,Wall temperature)and structural factors(channel type)on the eight heat transfer and pressure evaluation indexes,their contribution degrees and optimal combinations were obtained.Since RP-3 thermal-physical property model is greatly affected by temperature and different evaluation indexes have different influence rules,the appropriate evaluation index should be selected considering the Prandtl number change of working medium.With different wave channel corrugated angle,different amplitude frequency sine channels,open and disturbed fin set of interupted sin channel and bidirectional variable angle fin of louvered channel were analyzed,the field synergy principle was used to evaluate the heat transfer and pressure performance.Parametric modeling was carried out for the improved head with direct entrance and side entrance at the microchannel.Flow unevenness and shunting pressure drop were taken as optimization objectives.The multi-objective optimization method of header structure is established,which can provide reference for multiple operating conditions and header structure optimization application.