Investigation of pressure surface film cooling of the turbine vane considering the strong swirl characteristics at the combustor exit

Strong swirling flow is a critical feature that requires explicit consideration in aero-engine combustor-turbine integrated design, which fundamentally limits the applicability of conventional turbine vane cooling design criteria established under uniform inflow assumptions. For turbine vane pressure surfaces that require critical thermal protection, research on film cooling characteristics and their configuration optimization under combustor exit swirling flow conditions remains insufficient. This study systematically evaluates and validates the enhancement and development potential of fan-shaped holes on vane pressure surface film cooling effectiveness (η) under varying swirl numbers (SN) and blowing ratios (M), using steady-state pressure-sensitive paint (PSP) techniques combined with numerical simulations. Based on in-depth analyses, a novel film hole layout with locally compounded angles is further proposed. The results demonstrate that strong swirling inflow (SN=0.5) creates radial pressure gradients on the pressure surface, radially deflecting film trajectories while deteriorating streamwise coverage and increasing distribution non-uniformity. Increasing M partially mitigates the adverse effects of swirling inflow. At SN=0.5, fan-shaped holes enhance pressure surface cooling performance relative to cylindrical holes, achieving up to 9.27% higher area-averaged film cooling effectiveness (η_sur-ave), albeit with increased coolant outflow sensitivity to external flows. Based on the pressure surface pressure distribution, the novel film hole configuration imparts counteracting coolant momentum against the radial pressure gradient, which enlarges the film coverage area and improves its distribution uniformity. Consequently, the optimized design effectively mitigates swirl-induced film deflection at higher blowing ratios, achieving a maximum η_sur-ave enhancement of 40.7 %. Therefore, the proposed design serves as a reference for turbine vane cooling design incorporating strong combustor-exit swirl conditions.