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Evaluation of gap influence on the dynamic response behavior of pump-turbine runner

Lingyan He (College of Water Resources and Civil Engineering, China Agricultural University, Beijing, China and Beijing Engineering Research Center of Safety and Energy Saving Technology for Water Supply Network System, Beijing, China)
Lingjiu Zhou (College of Water Resources and Civil Engineering, China Agricultural University, Beijing, China and Beijing Engineering Research Center of Safety and Energy Saving Technology for Water Supply Network System, Beijing, China)
Soo-Hwang Ahn (Department of Energy and Power Engineering, Tsinghua University, Beijing, China)
Zhengwei Wang (Department of Energy and Power Engineering, Tsinghua University, Beijing, China)
Yusuke Nakahara (Hydroelectric Power Engineering Department, Toshiba Energy Systems and Solutions Corporation, Kawasaki, Japan)
Sadao Kurosawa (Hydraulic Machinery Group, Rotating Machine Technology R&D Department, Power and Industrial Systems, Toshiba Corporation, Yokohama, Japan)

Engineering Computations

ISSN: 0264-4401

Article publication date: 25 January 2019

Issue publication date: 7 March 2019

248

Abstract

Purpose

The gaps between runner and nearby structures play an important role in the dynamic response of runner, especially for pump-turbines. This paper aims to evaluate the gap influence on the added mass and dynamic stress of pump-turbine runner and provide an improved method to predict the resonance of runner.

Design/methodology/approach

Acoustic-structural coupling method was used to evaluate the added mass factors of a reduced scale pump-turbine with different axial and radial gap size between runner and nearby rigid walls. Improved one-way fluid-structural interaction (FSI) simulation was used to calculate the dynamic stress of the runner, which takes into account fluid added mass effect. The time-dependent hydraulic forces on the runner surfaces that were obtained from unsteady CFD simulation were transferred to the runner structure as a boundary condition, by using mesh-matching algorithm at the FSI surfaces.

Findings

The results show that the added mass factors increase as the gap size decreases. The axial gaps have greater influence on the added mass factors for the in-phase (IP) modes than the counter-phase (CP) and crown-dominant (CD) modes, while the CP and CD modes are very sensitive to the radial gaps. The largest added mass factor is observed in (2 + 4)ND-CP mode (resonance mode). The results reveal that the transient structural dynamic stress analysis, with the consideration of gaps and fluid added mass, can accurately predict the resonance phenomenon. Resonance curve of the pump-turbine has been obtained which agrees well with the test result. The gap fluid has great influence on the resonance condition, while for non-resonance operating points, the effect of gaps on the dynamic stress amplitude is quite small.

Originality/value

This paper provides an accurate method to analyze the dynamic response during runner design stage for safety assessment. The resonance curve prediction has more significance than previous methods which predict the resonance of runner by modal or harmonic analysis.

Keywords

Acknowledgements

The work was supported by National Natural Science Foundation of China (No. 51479200) and Toshiba Corporation – Tsinghua University cooperate project.

Citation

He, L., Zhou, L., Ahn, S.-H., Wang, Z., Nakahara, Y. and Kurosawa, S. (2019), "Evaluation of gap influence on the dynamic response behavior of pump-turbine runner", Engineering Computations, Vol. 36 No. 2, pp. 491-508. https://doi.org/10.1108/EC-04-2018-0169

Publisher

:

Emerald Publishing Limited

Copyright © 2019, Emerald Publishing Limited

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