Abstract

An aerodynamic inverse shape design method is implemented into ANSYS-CFX using a User Defined Function. The implementation is validated first; the method is then assessed on a subsonic axial compressor stage and a turbine stage. The design method is based on specifying a target pressure distribution over the blade suction surface (or a target pressure loading) and a blade thickness distribution as the design variables. The blade wall moves with a fictitious velocity, which is derived from a balance of design and target momentum fluxes, in order to reach a blade shape that would produce the prescribed target pressure distribution. The wall movement obtained from the design method is computed in a User Defined Function through the CFX Expression Language; it is then communicated to ANSYS-CFX at each time step. In ANSYS-CFX, a cell-centered finite volume formulation is used for space discretization. The time accurate Reynolds-Averaged-Navier-Stokes (URANS) equations are written in an arbitrary Lagrangian-Eulerian (ALE) form so as to account for the wall and mesh movement. The k- turbulence model is used for both compressor and turbine stages. Once the UDF is validated, ANSYS-CFX is used to redesign the E/CO-3 axial compressor stage and the E/TU-3 axial turbine stage so as to improve the stage aerodynamic performance.