Vane-blade interaction in a transonic turbine. I - Aerodynamics

Results of a computational investigation of the effects of blade row interaction on the aerodynamics of a transonic turbine stage are presented. The predictions are obtained using a two-dimensional unsteady Navier-Stokes code based on an explicit Runge-Kutta algorithm and an overlapping O-H grid system. This code simulates the flow in time-accurate fashion using nonreflective stage inflow and outflow boundary conditions and phase-lagging procedures for modeling arbitrary airfoil counts in the vane and blade rows. The O-H grid provides high spatial resolution of the high gradient regions near the airfoil surfaces and allows for arbitrary placement of stage inflow and outflow boundaries. Unsteady and time-averaged airfoil surface pressure predictions are compared with those from an older version of the code based on the explicit hopscotch algorithm and an O-grid system, and experimental data obtained in a short-duration shock tunnel facility.