This paper proposes to investigate the capacity of numerical simulation to estimate wall heat fluxes in a highly loaded turbine guide vane (with both structured and unstructured flow solvers). Different numerical approaches are assessed, from steady-state methods based on the Reynolds Averaged Navier-Stokes (RANS) equations to more sophisticated methods such as the Large Eddy Simulation (LES) technique. As expected steady flow simulations fail to predict the wall heat transfer, mainly because unsteady flows and laminar-to turbulent transition are not taken into account. The results underline the role of the vortex shedding, mainly through the emission of acoustic waves that interact with the suction side boundary layer. Only the LES (partially) succeeds to estimate wall heat fluxes since this method considerably improves the level of physical description (including boundary layer transition). However, the LES still requires validation and developments for such complex flows. This study also points out the dependency of results to the freestream turbulence intensity, which is a difficult parameter to manage with LES. Structured and unstructured flow solvers predict a different behaviour of the boundary layer (natural or by-passed transition), depending on the external turbulence intensity.
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