Improvement of suction-side film cooling effectiveness in a low-solidity turbine vane via a targeted subregional injection strategy

Low-solidity turbine vanes enable weight reduction in modern aero-engines. However, the associated increase in aerodynamic loading amplifies secondary flows and degrades the film cooling performance. This paper presents a combined experimental and numerical investigation into the suction-side film cooling performance of a low-solidity vane, employing Pressure-Sensitive Paint (PSP) and Reynolds-Averaged Navier–Stokes (RANS) simulations. Results indicate that intensified cross-passage pressure gradients induce a pronounced radial lift-off of the passage vortex (PV), sweeping the coolant from the shroud towards the hub. This enhanced secondary flow promotes shear mixing and coolant dilution, leading to insufficient coolant coverage in the near-shroud region. To mitigate this adverse interaction, a targeted subregional injection strategy is proposed. Instead of a uniform arrangement, this strategy targets the passage vortex-affected region by introducing additional film cooling holes. Results demonstrate that this strategy improves film coverage by replenishing coolant in the vortex-affected region and redistributing the flow to suppress upstream jet lift-off. Compared to the baseline, the modified configuration improves area-averaged film cooling effectiveness by approximately 30% over MFR = 5.0%–13.0%, while maintaining aerodynamic performance.