Experimental study of turbine blade tip heat transfer with high-speed relative casing motion

The relative casing motion can significantly influence the HP turbine blade tip aerothermal performance. The existing experimental facilities either can not achieve high rotating speeds, or have difficulties to gain full optical access to the tip region. In this study, spatially resolved squealer tip heat transfer data were obtained from Infrared thermal measurement by using a novel high-speed disk rotor rig which can mimic the high-speed casing relative motion close to actual operating turbines. The Mach number and Reynolds number were also engine realistic. Distributions of tip heat transfer coefficient at a relative casing speed of 140 m/s were compared with results at stationary condition. Distinctly different thermal performance with the effect of casing motion were observed both experimentally and numerically. With closely coupled RANS CFD analysis, the flow physics behind are further discussed. The key finding in the present study highlights the importance of relative casing motion for tip aerothermal management.