Effect of Unsteady Secondary Vortices on Performance of a 1.5-Stage High-Pressure Turbine
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https://doi.org/10.1007/s11630-020-1371-6
Article ID: 1003-2169(2020)00-0000-00
Effect of Unsteady Secondary Vortices on Performance of a 1.5-Stage HighPressure Turbine WANG Qingsong1, MA Can2, SU Xinrong1*, YUAN Xin1 1. Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Tsinghua University, Beijing 100084, China 2. Science and Technology on Thermal Energy and Power Laboratory, Wuhan 430205, China © Science Press, Institute of Engineering Thermophysics, CAS and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract: In modern high-load high-pressure turbine, the secondary flow in the blade channel is very strong and occupies a large spanwise region. Although high-quality experimental data at the stage interfaces have been obtained in previous research, the influence of the clocking position on the secondary flow patterns is not fully understood. This paper investigates the clocking effect in a 1.5-stage high-pressure turbine and focuses on the variations of secondary flow patterns and their effect on the turbine performance. The detailed flow fields of various clocking positions were obtained by carrying out unsteady flow simulations using an in-house code. Among the four clocking positions in this work, the highest entropy generation was observed when the wakes from stator 1 hit the leading edges of stator 2, which is opposite to the well-known conclusion for the turbine with high-aspect-ratio blades. Detailed flow analysis showed that the wakes and the near tip secondary vortices from stator 1 showed different traces when entering the stator 2 channel and the secondary vortices clearly have a more important influence in determining the performance. The different behaviors of the secondary vortices explained the performance variations due to the clocking effect.
Keywords: clocking effect, secondary vortices, entropy generation, unsteady flow
1. Introduction In multi-stage axial turbines, the relative positions of successive stator or rotor blade rows have an impact on the efficiency of the machine, which is known as the clocking effect. The machine efficiency can be improved by taking advantage of the clocking effect. Huang et al. [1] compared the influence of clocking effects for two axial gaps and eight clocking positions for each gap on the compressor by experiment and numerical simulation. For the turbine with high-aspect-ratio blades, a common conclusion is that a positive effect on the Received: Aug 11, 2019
AE: KAN Xiaoxu
adiabatic efficiency is achieved if the wakes of the upstream blade rows are aligned with the leading edges of the same type of downstream blades [2–6]. For blades with low aspect ratio of high-pressure turbine, however, the role of wakes is weakened since strong secondary flow exists in the blade channels which occupy a large portion of the span [5, 6]. Schennach et al. [7] studied the clocking effect in a 1.5-stage transonic high-pressure turbine using the experimental data obtained by the Laser Doppler Velocimetry. Their results show tha
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