Aerodynamic losses for squealer tip with different winglets

Abstract

Aerodynamic loss measurements and flow visualizations have been conducted for a squealer tip with different winglets. The present results for seven winglets indicate that winglet coverage along the pressure side has a negative effect in the loss reduction, whereas winglet coverage along the suction side has a positive effect. Winglet coverage along both sides performs better than that along the pressure side but worse than that along the suction side. The upstream half of the suction-side winglet plays a crucial role in the loss reduction. Thus, this portion needs to be included in the winglet for better aerodynamic performance. The pressure-side winglet brings additional flow disturbances similar to the ones existing over the plane tip back to the tip gap flow over the squealer tip. For the suction-side winglet, however, the tip gap flow is separated from the casing in a wide range between the leading edge and mid-chord.