Three-dimensional flow investigation of a high-pressure turbine with rotor tip desensitization based on Winglet geometry

Abstract

© 2022, The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering.The tip clearance is the gap between the rotor blade row and its casing. In this region, a leakage flow on the rotor blade tip is induced by pressure differences from rotor blade pressure side to suction side, resulting in a loss in the turbomachine efficiency and drop in performance. High pressure turbines (HPT) operate in the limit of the energy transfer process with low-aspect ratio blades and high-pressure loading. The tip clearance loss is significant when compared with other loss sources. To minimize the performance drop, different desensitization techniques were tested for turbulent flow in steady state. First, the HPT developed by NASA in the Energy Efficient Engine (E3) program was studied with its original configuration of rotor tip, also called flat-tip. Then, the winglet was implemented on rotor tip geometry, for both suction and pressure sides. Numerical simulations using the computational fluid dynamics were performed, and the results are compared with experimental data for both cases. The results show that in general, for the same HPT pressure ratio, the use of winglet on the rotor tip pressure side achieved the best results showing an increase in efficiency of 1.025 % for 3.7 of pressure ratio. Even the winglet on the rotor tip suction side presented an efficiency increase of 0.625 % for 3.7 of pressure ratio compared with flat-tip rotor configuration. Overall, both winglet configurations obtained results better than the common rotor blade flat-tip geometry, for the same pressure ratio operational condition.

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