| New challenge of isolator research have to faced, along with the development of scramjettechnology, such as how to link a rectangular inlet to a circular combustion and how the isolatorperformance changing with rough surface and heat exchanging. This paper just wants to deal withthese tasks, using theoretical analysis, numerical simulation and wind tunnel test.This paper consists of two parts:Firstly, a method for designing a rectangular-to-circular isolator was proposed. Parametricinvestigation of the isolator was done, and then the performance of three hypersonic inlets, with arectangular isolator, a rectangular-to-circular isolator and a curved rectangular-to-circular isolator,were compared. The results indicated the variance of section corners and length-to-height ratios, notsection itself, play an important role on the characterizations of shock-train structures. The bilinearitydesign method given by this paper shows better performance than a rectangular isolator and UGtransition one. The results of the comparison between three inlets show that using a transformingisolator can increase the maximum pressure ratio.Secondly, the effects of surface roughness, temperature and heat exchange on isolatorperformance were investigated, especially shock train structures and the shock-sustaining capabilityof an isolator under asymmetric incoming flow with rough surface by experimental method. And thenheat effect on isolator performance was investigated numerically. It is indicated that surfaceroughness which can significantly reduce the effects of asymmetric incoming flow, such as makingwall pressure rising smoothly and shock train structures symmetric, shorting distance between shocksand the maximum back pressure by8.7%, plays an important role in defining isolator performance.Adding total temperature or heat to a supersonic flow may increase boundary layer thickness andtherefore decrease the maximum back pressure, but the absorption of heat from flow just reversed. |
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