It has been confirmed that the polytropic efficiency and pressure ratio increase due to reduction in the tip clearance overentire operating range. In case of blade type A at design condition, efficiency and total pressure ratio increased by 0.6% point and 0.79% point compared to predictions using the un-deformed condition. In case of blade type B at design condition, efficiency and total pressure ratio increased by 0.96% point and 1.24% point compared to un deformed condition.The predictions indicated that the differences between deformed and un-deformed impellers are mainly caused by the tip clearance variation.