EFFICIENT APPROACH FOR ANALYSIS OF UNSTEADY VISCOUS FLOWS IN TURBOMACHINES

A nonlinear harmonic methodology has been developed to calculate unste ady viscous flows through turbomachinery blades. Flow variables are de composed into time-averaged variables and unsteady perturbations, resu lting in the time-averaged equations with extra nonlinear stress terms depending on the unsteady perturbations. An efficient evaluation of a n unsteady flowfield is obtained by solving the first-order harmonic e quations. The nonlinear interactions between the time-averaged flowfie ld and the unsteady perturbations were included by a strong coupling a pproach. The basic computational methodology was applied to the two-di mensional Navier-Stokes equations, and the method was validated agains t several test cases. Computational results show that this method is m uch more efficient than the nonlinear time-marching methods while stil l modeling dominant nonlinear effects.