Effects of the Casing-blade Relative Motion on the Blade Tip Aerothermal Performance in a High-pressure Gas Turbine

Base on the standard k-ω turbulent model,numerical method for solving three dimensional Reynolds Averaged Navier-Stokes(RANS)was adopted to study the aerothermal characteristics of the turbine blade with casing relative motion.Experimental data were used to verify the effectiveness of the numerical method and turbulent model.The effect of blade tip clearance,geometry and relative motion on blade tip aerothermal characteristics were analyzed.The numerical results show that for the flat tip,relative motion can effectively suppress tip leakage and reduce leakage vortex size at rotating blade-static casing(BRCS)and static bladerotating casing(BSCR)conditions.A high level of heat transfer region can be observed near the leading edge at the conditions of rotating bladerotating casing(BRCS)and static bladestatic casing(BSCR).The blade tip heat transfer coefficient expands with the increase of tip clearance at different relative motion modes.At the brcs and bscs,the axial average heat transfer trend is the closest when the tip clearance is 1.5％H.The scraping vortex generated by relative motion at brcr and bscs inhib-its the development of leakage flow for squealer tip because of its sealing effect.High level of heat transfer region is also concentrated in the leading edge at brcr and bscs.The size of scraping vortex weakens with the increase of cavity depth.The distribution trend of the average heat transfer coefficient is similar in the two cases of relative static and relative motion,except for the case of 2.5％H cavity depth.