Mechanism of low frequency high amplitude pressure fluctuation in a pump-turbine during the load rejection process. Issue 2 (4th March 2021)

• Record Type: Journal Article
• Authors: Fu, Xiaolong; Zuo, Zhigang; Chang, Hong; Li, Deyou; Wang, Hongjie; Wei, Xianzhu
• Is Part Of: Journal of hydraulic research. Volume 59:Issue 2(2021)
• Page Start: 280
• Page End: 297
• Publication Date: 2021-03-04
• Subjects: Load rejection process -- low frequency pressure fluctuation -- numerical simulation -- pump-turbine; Hydraulics -- Research -- Periodicals; Hydraulic engineering -- Periodicals; Hydraulic engineering; Electronic journals; Periodicals; 621.2
• DOI: 10.1080/00221686.2020.1780488
• Languages: English
• ISSNs: 0022-1686

Abstract

ABSTRACT: Owing to the complexity of the load rejection process, the accompanied complex low frequency pressure fluctuations and their sources have not been determined. Herein, the load rejection transient process of a pump-turbine was simulated with a three-dimensional (3-D) large eddy simulation method and a dynamic mesh technology. The simulation results were validated against the experimental data. Through the joint time-frequency analysis of simulated pressure, the complex low frequency pressure fluctuation components were captured, which are generally lower than the rated rotational frequency of the runner. A comprehensive formation mechanism of these complex low frequency pressure fluctuation components was attributed to three transient hydraulic phenomena and their interactions: the water hammer in the pump-turbine, local reverse flow near the runner inlet, and 3-D blocking water ring in the vaneless space. These findings facilitate the elucidation and elimination of complex low frequency high amplitude pressure fluctuations during the load rejection transient process.