Using shrouded blades with fins is a common method to reduce the leakage mass flow rate through the clearance between rotor and stator. A variety of methods have been developed improving the discharge behaviour of this sealing application. The leakage mass flow rate and its interaction with the main flow resulting in mixing losses and deviations in turning is also an important issue and has to be taken into consideration. The objective of this paper is to present a method aiming at reduction of tip-leakage mass flow rate and its high angular momentum by means of passive tip-injection. The results include analytical study followed by CFD calculations for compressible flow in a rotational frame of reference as well as experimental data. An uncooled low pressure air turbine with shrouded blades is considered for the CFD and the measurements. Three passive tip-injection configurations are investigated numerically out of which one configuration is also examined experimentally in the framework of this study.

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