Numerical investigation was performed to simulate the sensitivity of turbine performance to blade tip clearance variation for four different tips including flat tip and other three tips: cavity tip

flat tip with injection and cavity tip with injection; passive

active and compound clearance control methods were used respectively by solving Reynolds-averaged Navier-Stokes equations in conjunction with a standard k-ω two-equation turbulence model. The influences on the clearance flow structure and losses caused by tip clearance variation were analyzed. In addition

the variation of the turbine performance which changes by the different clearances was investigated. Furthermore

the sensitivities of the efficiency-gains caused by different clearance control methods to changes in incidence angles were assessed. Results show that

with different clearance control methods

the growth rate of the strength of tip leakage vortex slows down

especially for the compound clearance control method. This leads to the results that the compound clearance control method presents the lowest sensitivity of turbine performance to clearance variation. In addition

only the leakage flows over the front part of the blade are sensitive to incidence angle variation

which causes the best adaptability of cavity tip to incidence angle variation.