Meridional flow calculation using advanced CFD techniques

Abstract

Working experience on traditional Meridional Flow Solvers has revealed difficulties concerning both convergence and accuracy of the solution. These difficulties have been observed for instance in certain industrial applications where steep gradients of flow and/or geometrical quantities are present. Transonic flow conditions can cause extra difficulties. All these difficulties may be circumvented when advanced CFD techniques are utilized. A computational tool, suitable for the solution of the Meridional Through Flow equations for Turbomachinery applications is presented. Assuming that the flow is compressible and inviscid the governing equations are obtained using a streamfunction formulation for the pitch-averaged flow equations. Viscous corrections have been incorporated in the inviscid model in terms of flow angle deviation and total pressure losses. Governing equations, are discretized using body fitted finite difference schemes. An artificial density upwinding scheme assures convergence in the transonic region. Particular attention has been paid to the numerical integration procedure which is based on a preconditioned gradient method (GMRES). Calculation results for low and high-speed turbomachines are presented and discussed.