Unsteady winglet-cavity tip on leakage flow in a high-pressure turbine stage of low-aspect ratio

作者：Zhou, Zhihua; Chen, Shaowen^*; Wang, Songtao

来源：Proceedings of the Institution of Mechanical Engineers - Part C: Journal of Mechanical Engineering Science , 2018, 232(20): 3708-3721.

DOI：10.1177/0954406217741517

• Unsteady flow
• winglet-cavity tip
• tip leakage flow
• low-aspect ratio
• high-pressure turbine

In an unshrouded high-pressure turbine, the upstream vane wake, vane-blade interaction and blade tip leakage flow indicate complex and unsteady flow characteristics. Considering a high-pressure turbine stage of low-aspect ratio, the effects of the flat tip, cavity tip and winglet-cavity tip on the unsteady flow characteristics are investigated by numerical simulation. The exit Mach number and Reynolds number based on the chord of vane are 0.9 and 5.5 x 10(5), respectively. The pressure ratio of stage is 2.4. The time-resolved results indicate that the winglet-cavity tip scheme has smaller time variation of the total performance parameters and obtains a smaller tip leakage mass flow and a higher turbine stage efficient than the other cases. The vane-rotor interaction affects the pressure distribution at the region of blade leading edge remarkably and leads to a large time variation of tip leakage mass flow at the front of blade tip. The unsteady aerodynamic performance is analyzed with entropy-increase distribution at stage outlet and the vane-rotor interaction is discussed by the entropy-increase phase-time and phase-phase diagrams at blade outlet. Compared with the flat tip and cavity tip, the upper passage vortex loss is reduced obviously by the winglet-cavity tip. Thus, it is evaluated that the improvement of turbine stage coefficient with winglet-cavity tip results from the reduction of the upper passage vortex loss.

• 出版日期2018-10
• 单位哈尔滨工业大学