Numerical Investigation on the Flow Mechanism of Multi-Peak Frequency Feature of Rotating Instability
- PDF / 4,435,445 Bytes
- 14 Pages / 595.22 x 842 pts (A4) Page_size
- 28 Downloads / 198 Views
https://doi.org/10.1007/s11630-020-1349-4
Article ID: 1003-2169(2020)00-0000-00
Numerical Investigation on the Flow Mechanism of Multi-Peak Frequency Feature of Rotating Instability WANG Hao1*, WU Yadong2*, YUE Shaoyuan1, WANG Yan’gang1 1. School of Power and Energy, Northwestern Polytechnical University, Xi’an 710072, China 2. School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China © Science Press, Institute of Engineering Thermophysics, CAS and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract: In this paper, the rotating instability (RI) in an axial compressor has been investigated numerically in order to examine the capability of URANS method to simulate its typical characteristics of RI broadband humps with multi-peak frequencies (MPFs) and further to uncover the underlying flow mechanism. A full-annulus modeling solution has been adopted to fully capture the wide range of different length-scale flow disturbances that circumferentially propagating around the compressor rotor. During the transient computing process, long-term monitoring up to 50 revolutions has been carried out to achieve a fine frequency resolution, and that would be essential for resolving the MPFs with small frequency interval. It is shown that the MPFs feature of RI has been successfully captured by the full-annulus URANS approach, and also its frequency range and spectral feature agree well with the experimental results. Further, with a circumferential mode decomposition on the MPFs characteristics of RI, it has been found that the MPFs result from the interaction between long- and short-scale flow disturbances which circumferentially propagate around the compressor rotor near the clearance region. Detailed examination on the numerical three dimensional flow field indicates that the short-scale disturbance is induced by the unsteady oscillation of tip clearance vortexes with inter-passage phase delay. The long-scale disturbance is caused by the mistuning of the wave number of the short-scale disturbance and the blade number within the whole annulus.
Keywords: axial compressor, rotating instability, multiple frequency peaks, URANS, tip leakage vortex
1. Introduction Stall and surge are the most severe aerodynamic problems in compressors, causing steep fall of the performance. On the characteristic curve of compressors, stall and surge line defines the boundary of stable operating range. Several to hundreds of rotor’s revolutions before stall, stall inception appears as modal type or spike type waves [1]. Stepping back further from Received: Jun 20, 2019 AE: DU Juan
the stall inception process, but still in the operating range near the stall boundary, pre-stall disturbances can be detected in compressor flow field which are usually seen as the indicator for stall warning [2]. To achieve a deeper physical insight of pre-stall disturbances is important for understanding stalling mechanism, setting up theories for describing and predicting stalling flow [3, 4] and exploiting more effective w
Data Loading...
