Tip Leakage Losses for the Squealer Tip Winglets Designed on the Basis of Flow Visualization

Aerodynamic performances of a squealer tip equipped with three different winglets, which are designed on the basis of flow visualization for the squealer tip without winglet, have been tested experimentally in a cascade wind tunnel. The results show that all three winglets installed on the squealer tip reduce aerodynamic loss by more than 20% in comparison with the simple flat tip loss. This loss reduction is attributed to the decrease of tip leakage mass flow rate resulting from the wide leakage flow separation from the casing within the tip gap. Among the three tested winglets, the winglet having its coverage only along the suction side with no coverage along the upstream separation area performs best in the loss reduction. Its loss reduction is about 25% of the simple flat tip loss and about 12% of the simple squealer tip loss.