Experimental Study on the High Relative Casing Motion Effect on Turbine Blade Tip Aerodynamic Characteristics

Abstract The high-speed relative motion between the casing and turbine blade tip significantly complicates the flow field distribution near the blade tip and greatly increases the difficulty of flow field measurement. In this paper, based on a novel high-speed disk rotor experimental rig, first-of-its-kind aerodynamic experimental results near the squealer near-tip region under high-speed relative casing motion conditions are presented. The outlet total pressure loss distribution, outlet flow angle, and near-tip blade loading are measured and compared with those under stationary conditions. Additionally, Reynolds-Averaged Navier–Strokes computational fluid dynamics simulations are employed to validate the results, and the aerodynamic effects near the blade tip under high-speed relative casing conditions are thoroughly discussed. These results reveal the significant influence of high-speed relative casing motion on the flow field near the blade tip, showcasing a concentration of Over-Tip-Leakage flow, enhancement of passage flow, changes in the flow field within the cavity, and interactions between vortices, among a series of findings.