矩形通道内超临界RP-3非对称加热的传热研究

Study on heat transfer of supercritical RP-3 in rectangular channel by asymmetric heating

为了优化航空发动机的设计,本文采用Realizable k-ε湍流模型对航空煤油RP-3在矩形通道内的流动换热过程进行了研究,重点分析了非对称加热对换热的作用机理。基于通道截面密度、比热容及二次流的分布态势,通过类气膜温度梯度和强二次流的演变,进一步阐释了非对称加热时换热恶化的产生原因。结果表明:再生冷却通道上壁加热时的换热效果要强于底壁加热。一方面是因为热流密度再分配原理,更重要的是浮升力和类膜态效应的影响。浮升力引起强二次流,致使流场和温度场出现畸变,类气膜厚度周向不均,隔绝了受热壁面与核心冷流体的交流,对应的传热恶化加剧。据此提出的换热关联式误差区间位于±20%内,适用于矩形通道内航空煤油的换热研究。

To optimize aircraft engine design,the Realizable k-εturbulence model was employed to investigate the flow and heat transfer processes of aviation kerosene RP-3 in a rectangular channel.The mechanisms were analyzed by which asymmetric heating to affect heat transfer.Analyzing the effects of asymmetrical heating on flow and heat transfer mechanisms were specifically focused.Based on the distribution of the density,specific heat capacity and secondary flow in channel cross-section,the cause of heat transfer deterioration during asymmetric heating was further explained through the evolution of gas-like film temperature gradient and intense secondary flow.The results indicate that the heat transfer effect of top wall heating in the regenerative cooling channel is better than that of the bottom wall heating.On the one hand,because of the principle of heat flux redistribution,what is more significant is the influence of buoyancy and gas-like film effect.Buoyancy induces strong secondary flows,causing distortions in the flow and temperature fields.This results in an uneven circumferential thickness of the film-like layer,isolating the heated wall from the core cold fluid and exacerbating heat transfer deterioration.The proposed heat transfer correlation has an error margin within±20%,making it suitable for heat transfer studies of aviation kerosene in rectangular channels.