Comparison of predicted and experimental Nusselt number for a film cooled rotating blade

The predictions from a three-dimensional (3-D) Navier-Stokes code have been compared to the Nusselt number data obtained on a film-cooled, rotating turbine blade. The blade chosen is the ACE rotor with five rows containing 93 film-cooling holes covering the entire span. This is the only film-cooled rotating blade on which experimental heat transfer data are available for the present comparison. Over 2.25 million grid points are used to compute the flow over the blade. Usually, in a film cooling computation on a stationary blade, the computational domain is just one spanwise pitch of the film-cooling holes, with periodic boundary conditions in the span direction. However, for a rotating blade, the computational domain consists of the entire blade span from hub to tip, as well as the tip clearance region. As far as the authors know, the present work is the first comparison of the prediction of surface heat transfer using a 3-D Navier-Stokes code with film injection and the measured heat flux on a fully film-cooled rotating transonic turbine blade. A reasonably good comparison with the measured data is obtained on the suction surface, particularly near the hub section. On the pressure surface, however, the comparison between the data and the prediction is poor. A potential reason for the discrepancy on the pressure surface could be the presence of unsteady effects caused by stator-rotor interaction in the experiments, which are not modeled in the present numerical computations. (C) 1997 by Elsevier Science Inc.