Research On Inverse Method For Compressor Blade Design

Turbomachine blade design methods are commonly comprised direct method and inverse method.In direct method, first the designer choose an initial blade which aerodynamic performance is close tothe design requirements, then obtain the performance by CFD technology or through experiments, if itdoes not meet the requirements, then a blade modification is needed. The designers will modify bladeprofiles according to design experiences or through the optimization methods repeatedly until the newblade meet the requirements. Simpleness and easy to implement but time costing is the characteristicof direct method. In inverse design processes, designer obtain some aerodynamic parameters throughstudying the design requirements, then use these aerodynamic parameters as the input information ofinverse design, then obtain the blade profile directly through relationship between aerodynamicparameters and the physical characteristics. Therefore, the advantage of the inverse method is itdesigning efficient, and less dependent on the designers’ experiences. Based on the research of VonKarman Institute for Fluid Dynamics, the inverse method is researched in this paper. The mainresearch work of this paper includes:(1) Construct the inviscid inverse design process for blade design. Two key technologies of thisinverse method--the permeable boundary and modify technique–are detailed discussed in the paper.The permeable boundary is realized base on the program NAPA which is a self-developed CFDprogram, and realized the blade modify module to realize the inverse design program.(2) Inverse design is validated in three kinds of pipeline flow and cascade flow:1) pipeline withno flow turning, such as bump flow, laval nozzle;2) pipeline which flow in it turning and expanding;3) double circular arc profile cascade. Validate the inverse method in the case of subsonic flow and theflow with shock in transonic.(3) Improve the permeable boundary, made it can be used in the case that exist big differencebetween the target flow and the initial flow in flow structure. And validate this improving in case ofthe eliminating channel shock in cascade flow.(4) Construct the viscous inverse design process, and research the method to extend the inviscidinverse method to viscous flow. Validate the viscous inverse method in double circular arc blade in thesubsonic flow case. Improve the inviscid target pressure distribution prediction method in viscousinverse process, so it can be used in the shock-existence cascade flow.(5) Choose a fan which designed by NASA Lewis Research Center, apply this inverse method to redesign a profile of the fan rotor blade in middle section. The result profile, at the same inflowconditions, flow loss is reduced, besides the blade load is increasing. Calculating indicate the newprofile, at the free stream Mach number1.02, the blade load compared with the initial profileincreased by2.2%, the pressure coefficient increased by9.4%, and the total pressure loss is reducedby1.47%.