Please use this identifier to cite or link to this item: https://hdl.handle.net/2440/126818
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Type: Journal article
Title: Mechanism of fast transition of pressure pulsations in the vaneless space of a model pump-turbine during runaway
Author: Zhang, X.
Zeng, W.
Cheng, Y.
Yang, Z.
Chen, Q.
Yang, J.
Citation: Journal of Fluids Engineering, 2019; 141(12):121104-1-121104-13
Publisher: American Society of Mechanical Engineers
Issue Date: 2019
ISSN: 0098-2202
1528-901X
Statement of
Responsibility: 
Xiaoxi Zhang, Wei Zeng, Yongguang Cheng, Zhiyan Yang, Qiuhua Chen, Jiandong Yang
Abstract: The pressure pulsations in the vaneless space of pump-turbines are extremely intense and always experience rapid time variations during transient scenarios, causing structural vibrations and even more serious accidents. In this study, the mechanism behind the rapid time variations of the vaneless space pressure pulsations in a model pump-turbine during runaway was analyzed through three-dimensional (3D) numerical simulations. These results show that the high-frequency pressure pulsation components originating from rotor–stator interactions (RSI) are dominant during the whole process. These components fluctuate significantly in frequency when the working point goes through the S-shaped region of the characteristic curve, with the amplitudes increasing. Meanwhile, some low-frequency pulsations are also enhanced and become obvious. These features can be attributed to the transitions of the inter blade vortex structures (IBVSs) to the forward flow vortex structures (FFVSs) and the back flow vortex structures (BFVSs) at the impeller entrance, when the pump-turbine operates in the region with S-shaped characteristics. The FFVSs mainly cause decreases in frequency and introduce low-frequency pulsations, while the BFVSs are responsible for the unstable fluctuations. These findings contribute to the understanding of how transient flow patterns evolve and may provide new ideas about avoiding severe pressure pulsations caused by rotating stalls in the pump-turbine during transient scenarios.
Rights: Copyright © 2019 by ASME
DOI: 10.1115/1.4044068
Appears in Collections:Aurora harvest 8
Civil and Environmental Engineering publications

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