A novel blade force approach to two-dimensional meanline simulation of transonic compressor rotating stall

Abstract

The equations of an inviscid blade force component for modeling the flow turning through real blade rows are analytically combined with Euler equations in the meanline annulus of a complete compressor. This combination gives rise to a modified set of unsteady 2D flow equations with specific convective flux and source terms that explicitly depend on the geometry of the blade camberline. At the leading and trailing edges of each bladed region, the new set of equations is coupled to standard Euler equations in unbladed regions by means of boundary conditions that allow modeling of a leading edge shock. The numerical flux difference splitting scheme for time integration of the governing equations includes a consistent, upwind formulation of the delay model for correction of empirical input on loss and deviation at each (either stalled or unstalled) circumferential grid station. The steady 1D solution of the new equations provides the numerical compressor map in normal operation. Several stall configurations can then be obtained by artificially perturbing a near-stall solution assumed as unstable with respect to some well-known stall criteria. The method predicts experimental stalled performance of a transonic rotor with accuracy higher than 4%. The predicted stall inception transients and stall propagation speed are also in line with previous experience.