MULTIGRID COMPUTATIONS OF UNSTEADY ROTOR-STATER INTERACTION USING THENAVIER-STOKES EQUATIONS

A Navier-Stokes time-accurate solver has been extended to the analysis of unsteady rotor-stator interaction. In the proposed method a fully- implicit time discretization is used to remove stability limitations. A four-stage Runge-Kutta scheme is used in conjunction with several ac celerating techniques typical of steady-state solvers, instead of trad itional time-expensive factorizations. Those accelerating strategies i nclude local rime stepping, residual smoothing, and multigrid. Direct interpolation of the conservative variables is used to handle the inte rfaces between blade rows. Two-dimensional viscous calculations of uns teady rotor-stator interaction in a modern gas turbine stage are prese nted to check for the capability of the procedure.