Detailed experimental investigations of the flows in the cascades of conventional straight blades and positively curved ones

both with 2.3% tip clearance

were carried out in a low speed wind tunnel.The measuring planes were arranged as 4 before

11 in 4 after the cascades and 1 in the middle of the tip clearance.Flows inside the clearance were searched in great detail with a micro five-hole pitot tube of 1mm head size and another of 5 mm head size in the passage.The quite detailed information about the tip leakage flows and the flows in the cascades has been obtained

such as flow vectors

pressure and loss distributions throughout the clearance and in the passage.In comparison with the conventional straight blades

positive blade curving decreases the flow vectors within the tip clearance and also reduces the strength of the leakage vortex.As a result

the mass flux crossing the tip clearance decreased

the interaction between leakage vortex and passage vortex in the curved cascade also decreased.Thereby

the total flow losses downstream of the curved blade have been cut down by 8%.