The Research Of Design Method On Shorter Length And Larger Curvature Inter-stage Duct

At present, birotor structure is the mainstream of the aeroengine.The duct can be found inareo-engines compressors as inter-stage components,which transmit the flow from the high-pressurecompressor to the low-pressure compressor.The high-pressure compressor is usually at the largerradius and has lower speed.While the low-pressure compressor is at the smaller radius and has higherspeed.This change in radius gives them their characteristic “S” shape. In the shortest possible axiallength makes high and low pressure compressor smooth transmit, which not only reduce the weighttransition and related peripheral components, but also makes the rotor length of high and low pressurecompressors shortened.Thus it reduces the intensity of the load of the engine rotor system, and enginereliability is guaranteed. This paper do the research on the flow field characteristics of the duct,whichhas large streamline curvature and strong adverse pressure gradient.First, this paper uses two experimental examples to make sure the numerical methods appliedwere corrected.And it indicate that k-w SST turbulence model suit the imulation study of a largeexpansion duct. A method for the parameterization of an compressor S-shape duct is presented. Theduct geometry is expressed as a function of the axial position of the inflection point..The methodallows the design rapid and accurate.Meanwhile the method ia applied to the design of a compressduct to explore the design principle.The results show that the total pressure loss comes mainly fromthe upper and lower wall boundary layer,and the loss come from the lower wall is more than theupper wall.;The area variation in an increase-decrease sequence along the duct,generates a meanpressure gradient,and improve the performance of the duct..This paper also do the research on the flows in strutted annular S-ducts. It was found that“0.35-0.65” duct with the struts, the total pressure loss is significantly increased by the total pressurerecovery coefficient is reduced to99.1%and99.5%. The total pressure loss sources in addition to thehub, the case end wall boundary layer losses, comes from secondary flow losses caused by the struts.Meanwhile the range from the position of maximum thickness to the trailing edge of the strut,thecombination of strut diffusion and duct diffusion caused by the curvature is so high that a cornerseparation occur in the flow between the strut and the hub wall. Meanwhile influenced by the radialpressure gradient,the low-energy fluid move away from the hub end wall, toward to the case endwall.Finally, this paper also do the research on the mounting position t of the struts.When the distance from the leading edge of the struts to the inlet of the ducts is0.1L, the duct performance isbetter.While choose0.15L and0.2L two positions, the performance has declined, but the gap betweenthe two programs is not too large. Also we get some results from the research on the sweep angle.When the sweep angle θ is00, the inter-stage duct has the highest performance, and when250, thetotal pressure recovery coefficient is relatively low.