On the effects of inlet swirl on adiabatic film cooling effectiveness and net heat flux reduction of a heavily film-cooled vane

A linear cascade of high-pressure vanes equipped with a realistic film-cooling configuration has been studied. The aim is to provide an accurate analysis of a heavily cooled high-pressure vane subjected to aggressive inlet swirl. The analyzed vane is characterized by the presence of multiple rows of fan-shaped holes along pressure and suction side while the leading edge is protected by a showerhead system. Numerical simulations have been performed on hybrid unstructured grids using a steady approach with the commercial code ANSYS Fluent®. The transitional kT-kL-ω model by Walters and Cokljat has been selected as turbulence closure. A realistic computational domain that mimic a combustor/vane count of 1:2 has been used. The classical analysis approach with uniform inlet flow has been compared with an approach that takes into account inlet swirl motion considering two clocking positions of such velocity distortion. This latter have been obtained through a non-reacting swirl generator experimented during the EU-funded TATEF2 Project and representative of modern aeroengines. Results highlight the importance of considering realistic boundary conditions for cooling system analysis and quantify the effects of swirl in affecting external heat transfer. Nomenclature C chord [m] HTC heat transfer coefficient [W/m2K] k kinetic energy [m2/s2] L length scale [m] NHFR net heat flux reduction [-] p pressure [Pa] q heat flux [W/m2] s curvilinear abscissa [m] T temperature [K] Tu turbulence level [-] average ~ spanwise average ̂ pitch-wise average Subscripts 0 stagnation quantity ax axial aw adiabatic wall c referred to coolant exit referred at cooling holes exit in inlet L laminar m referred to mainstream max maximum min minimum rec recovery T turbulent un referred to uncooled geometry w wall Greek symbols η adiabatic effectiveness [-] φ overall film effectiveness [-] ω specific dissipation rate [s-1] Abbreviations BR Blowing Ratio DR Density Ratio GCI Grid Convergence Index HPV High-Pressure Vane LE Leading Edge TE Trailing Edge