Impact of Internal Crossflow on Flow Topology Inside and Outside of Film-Cooling Holes With Varying Inclination and Supply Flow Angles: 3D Velocity Data From Magnetic Resonance Velocimetry

Abstract Crossflow on both sides of film-cooling holes with engine-representative length-to-diameter ratios significantly impacts flow topology and cooling effectiveness in gas turbine airfoils. This experimental study investigates the three-dimensional flow characteristics of film-cooling holes, focusing on the influence of inlet conditions on flow behavior within and outside of the holes. The primary objectives are to (1) deepen the understanding of flow sensitivity to inlet and geometric parameters and (2) characterize a high-quality dataset for validating computational fluid dynamics (CFD) models. Two experimental setups were examined: a single inclined hole with a length-to-diameter ratio (L/D) of 6, varying supply flow angles (0 deg, 90 deg, and 180 deg), and hole inclination angles (30 deg and 60 deg); and a row of five 15 deg inclined holes with an L/D ratio of 18. Magnetic resonance velocimetry (MRV) was used to capture three-dimensional velocity data upstream, inside, and downstream of the holes, supplemented by Reynolds stress and temperature measurements for the case with five holes. The high-resolution MRV data reveal detailed flow structures, including vortex formation, flow separation within the cooling holes, and turbulent mixing in the external flow. A comprehensive dataset of this kind can provide a robust benchmark for validating CFD simulations and advancing the design of film-cooling systems in gas turbines.