The Inverse Design Of Axial Turbomachinery Airfoil

A growing harsh desire is essential in blade aerodynamic performance of modern compressor and turbine. There are two methods in turbomachine blade design, direct method and inverse method. The characteristic of direct method is simple ,easy to implement but costing time and strongly dependent on the experiences. The advantage of the inverse method is less dependent on the experiences and less time. In this paper, we developed an inverse design method program based on solving N-S equations, then apply it to 2D design cases. The main work of this paper includes:The self-developed direct method program was improved, and the inverse method program was complied based on the virtual velocity. The direct method is based on solving N-S equations. The inviscid flow flux was discretized by high order accuracy Chakravathy-Osher TVD scheme and the viscous flow flux were discretized by central difference scheme. The 4th Runge-Kutta time stepping scheme was used. To accelerate the convergence, local time stepping and residual smoothing were used. Then this thesis compared the direct method program with commercial software to validate the accuracy. The inverse method was based on iterate and correct. The prescribed design quantities were either the pressure distributions on the blade surface or the pressure loading and its thickness distribution. It was assumed there is a virtual velocity on the blade surface. The blade geometry was modified by the difference between the temporary pressure and the target pressure. The inverse design method was validated by the returning tests of the thicker blade and thinner blade. The solution show the effectiveness of the inverse method. Then this inverse design method was applied to the design of turbine and compressor cascade. Two methods was specified to improve the performance of the turbine cascade: the distributions of target pressure and the distributions of the target pressure loading. The result show the pressure gradient was decreased and the flow loss was reduced while keep the whole airfoil loading unchanged. The distributions of target pressure was specified when apply this inverse method to the compressor airfoil which shock wave exist. The shock wave was eliminated and the total pressure coefficient was reduced by 6.36% through the inverse design. The performance of the airfoil was improved.The commercial software has a richer general physical model and more turbulence model than the self-developed program. In order to make the inverse program a wider range of application, a inverse design platform was built based on the CFD software. The ANSYS-CFX. NUMECA AutoGrid5 and the profile modification program Inv was integrated with software Isight. The platform used Numeca-AutoGrid5 as the mesh generator, take the ANSYS-CFX as solver, and modified the profile with the virtual velocity. The implementation was validated by the returning tests of the thicker compressor profile, the solution was in good agreement with the target in blade profile and indicated the robustness of the platform. Finally,the 2D inverse design platform was used to redesign the turbine and compressor profiles to improve the aerodynamic performance and reduce the total pressure loss.