Turbines experience pressure losses from various sources, one of which is the tip leakage flow in the rotor blades. This is one of the main factors responsible for the decrease in turbine efficiency. This leakage is caused by pressure differences between the blade pressure and suction sides. High-pressure turbines with low aspect ratios and high-pressure loading face critical tip clearance losses, impacting turbine performance. One way to reduce tip leakage flow is to apply the desensitization technique to modify the rotor blade tip geometry. This study aims to apply the desensitization technique to the Energy-Efficient Engine developed by NASA. Different Winglet geometries with varying extensions along the blade tip chord (A—100%, B—80%, and C—60%), three types of Squealers with different rim dimensions and cavity heights (Squealer A and B), and the same rim thickness and cavity height of Squealer A with a decreased trailing edge region down to 1% (Squealer C) were numerically tested. Additionally, the study simulates blending Winglet A with Squealer A (Squealer–Winglet A), Squealer A with Winglet B (Squealer–Winglet B), and Winglet A with Squealer B (Squealer–Winglet C). Numerical simulations are conducted and compared with experimental data. Comparing the various geometries at the design-point pressure ratio, the Winglet A configuration demonstrates an increase of 0.30% in efficiency, Squealer C an increase of 0.20%, and for cases involving all Squealer–Winglet models, no improvement was obtained. For 80% N at the design-point pressure ratio, Winglet B demonstrates an increase of 1.47% in efficiency, Squealer C an increase of 1.43%, and Squealer–Winglet A an increase of 1.43%. These are interesting results in the case of the engine operating at cruise condition, in which the rotational speed is around 80% N.
Bontempo et al. (Mon,) studied this question.