Accuracy and Efficiency Assessment of Harmonic Balance Method for Unsteady Flow in Multi-Stage Turbomachinery
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https://doi.org/10.1007/s11630-020-1201-x
Article ID: 1003-2169(2019)00-0000-00
Accuracy and Efficiency Assessment of Harmonic Balance Method for Unsteady Flow in Multi-Stage Turbomachinery ZHANG Zhen1, 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: With the relative movement of neighboring blade rows, flows in multi-stage turbomachinery are unsteady and periodic in time at the design condition. As an alternative to the widely used time domain time marching method, the harmonic balance (HB) method has been successfully applied to simulate the essentially unsteady flow of multi-stage turbomachinery. By modelling various number of harmonics, the accuracy of this method could be adjusted at different level of computational cost. In this article, accuracy of the harmonic balance method is not only validated against the time domain time marching method, as in most previous works on this topic, but also against the data from an experiment campaign of a two-stage high-pressure turbine where strong tip leakage flow exists. Efficiency of this method is also assessed in detail by adjusting the number of harmonics and comparing with time domain time marching solution results. Results show that the harmonic balance method is a flexible tool with adjustable accuracy for fast-turnaround unsteady flow simulation of multi-stage turbomachinery. Results from this work can provide a guidance in applying the harmonic balance method with balance between accuracy and computational cost.
Keywords: multi-stage turbomachinery, unsteady flow, harmonic balance, accuracy, efficiency
1. Introduction With the relative movement of neighboring blade rows, flows in multi-stage turbomachinery are essentially unsteady. While the steady mixing-plane model has been very popular for multi-stage turbomachinery, as pointed out by Denton [1], the error caused by neglecting the unsteady effects would accumulate with the number of blade rows, leading to inaccurate performance predictions and sometimes completely wrong flow details. Therefore, fully unsteady simulations are preferred for more accurate flow prediction of multi-stage
Received: Mar 23, 2019
AE: KAN Xiaoxu
turbomachinery [2,3]. However, the time domain time marching unsteady simulation could be expensive for simulating turbomachinery flows, where the transient state is long. For example, time domain time marching unsteady flow simulation of the transonic compressor stage 35 of NASA carried out by Gopinath [4] was marched for 4.5 rotor periods and the flow did not fully turned into periodic state. With the periodically passing blades of the neighboring row, unsteady flows in multi-stage turbomachinery are periodic in time at the design condition. In the past thr
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