NUMERICAL-SIMULATION OF TURBINE BLADE BOUNDARY-LAYER AND HEAT-TRANSFER AND ASSESSMENT OF TURBULENCE MODELS

The boundary layer development and convective heat transfer on transon ic turbine nozzle vanes are investigated using a compressible Navier-S tokes code with three low-Reynolds-number k-epsilon models. The mean-f low and turbulence transport equations are integrated by a four-stage Runge-Kutta scheme. Numerical predictions are compared with the experi mental data acquired at Allison Engine Company. An assessment of the p erformance of various turbulence models is carried out. The two modes of transition bypass transition and separation-induced transition, are studied comparatively. Effects of blade surface pressure gradients, f ree-stream turbulence level, and Reynolds number on the blade boundary layer development, particularly transition onset, are examined. Predi ctions from a parabolic boundary layer code are included for compariso n with those from the elliptic Navier-Stokes code. The present study i ndicates that the turbine external heat transfer under real engine con ditions, can be predicted well by the Navier-Stokes procedure with the low-Reynolds-number k-epsilon models employed.