An experimental and numerical study of endwall heat transfer in a turbine blade cascade including tangential heat conduction analysis

This paper presents an experimental and numerical investigation of heat transfer in the endwall region of a large scale turbine cascade. The steady-state liquid crystal technique has been used to provide the map of the heat transfer coefficient. Numerical solutions have been obtained by using a commercial CFD software and different turbulent models. In the presence of two- and three-dimensional flows with significant spatial variations of the heat transfer coefficient, tangential heat conduction could lead to error in the heat transfer coefficient determination, since local heat fluxes at the wall-to-fluid interface tend to differ from point to point and surface temperatures to be smoothed out, thus making the uniform heat-flux boundary condition difficult to be perfectly achieved. For this reason, numerical simulations including the effect of tangential heat conduction inside the endwall have been performed in order to investigate the influence of wall heat conduction on the convective heat transfer coefficient determined during a nominal iso-flux heat transfer experiment and to interpret possible differences between numerical and experimental heat transfer results.