Optimization Design Of High Load Compressor Blade Based On Curvature Control

With the increasing improvement of aero-engine performance,compressor stages are required to operate with high loadings and efficiencies.Blade geometry is critical to the development of compressors.Meanwhile,continuous surface curvature distribution is also one of the key factors to blade aerodynamic performance.The discontinuous curvature can cause a kick in Mach number and pressure distribution along the blade surface.In this paper,the optimization designs of 2D airfoil and 3D blade based on curvature control are realized to explore the effect of curvature continuity.The 2D airfoils are described with a thickness distribution and camber line splines.The camber line adopts three parametric methods respectively:(1)simple Bezier curve;(2)polynomial curve;(3)curvature of camber line controlled by 3rd Non-uniform B-spline.Numerical simulations of totally three cases with different 2D airfoil design schemes are carried out.The influences of different parameterized curves on the aerodynamic performance of the blade are analyzed.Then the parametric method called curvature-controlled stacking-line method(CCSLM)is performed by changing the magnitude of the sweep or lean.A 4th Bezier-spline is adopted to define the curvature of spanwise stacking line directly ensuring surface smoothness.Then the redesign cascades are created by sectional profiles stacked along the radial stacking lines which are obtained by twice integrating the Bezier-spline.And the influence of different design parameters on the aerodynamic performance of blade at 0-degree incidence angle is studied.Finally,an optimization platform is applied to find the optimal blade which can improve the aerodynamic performance.The results show that the camber line of different parametric curves has a certain influence on the isentropic Mach number distribution and variation of loss against attack angles.Based on the 2D airfoil parametric method,the composite swept-curved blade controlled by curvature has significant effects on the end wall flow vortex as well as radial loading distribution.The reduction of total pressure loss and secondary flow is also observed and the aerodynamic performance is well improved compared with the original cascade.In addition,the proposed approach CCSLM can minimize the number of design variables in the optimization process,and the optimization speed can be improved without affecting the design space.A single objective optimization is performed using Kriging model and GA to optimize total pressure loss and the optimized geometry is obtained which can simultaneously improve the performance at design condition and offdesign condition.