TY - JOUR

T1 - Oscillation of Cavitating Vortices in Draft Tubes of a Simplified Model Turbine and a Model Pump–Turbine

AU - Skripkin, Sergey

AU - Zuo, Zhigang

AU - Tsoy, Mikhail

AU - Kuibin, Pavel

AU - Liu, Shuhong

N1 - Funding Information: Funding: The study of the simplified turbine (ST) and development of an analytical approach were supported by a grant from the Russian Science Foundation (project no. 21-79-10080), the study of the pump–turbine (PT) was supported by the National Natural Science Foundation of China (no. 52076120 and no. 52079066), the open Fund of State Key Laboratory of Eco-hydraulics in Northwest Arid Region (no. 2018KFKT-10), the State Key Laboratory of Hydroscience and Engineering (2019-KY-04, sklhse-2019-E-02 and sklhse-2020-E-03), and the Creative Seed Fund of Shanxi Research Institute for Clean Energy, Tsinghua University. Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

PY - 2022/4/1

Y1 - 2022/4/1

N2 - The self-oscillation of the cavitating vortices is one of the dangerous phenomena of hydraulic turbine operation near full-load conditions. This work is an attempt to generalize data and expand insight on the phenomenon of self-excited oscillations by comparing the experimental results obtained on a simplified turbine and scaled-down pump–turbine models. In both cases, a series of high-speed imaging was carried out, which made it possible to study these phenomena with high temporal resolution. The high-speed imaging data was subjected to additional processing such as binarization, cropping, and scaling. For a simplified turbine model, the volume of the vapor cavity was calculated based on the assumption of the axial symmetry of the cavity, after which fast Fourier transform (FFT) analysis was carried out. A proper orthogonal decomposition (POD) analysis was also performed to examine individual modes in the original digital imaging data. For the pump–turbine, visualization data on the cavitation cavity oscillations were supplemented by pressure measurements in the draft tube cone to determine the frequency characteristics. Based on obtained experimental data, an improved one-dimensional model describing the oscillations of the cavitation cavity arising behind the hydraulic turbine runner is proposed.

AB - The self-oscillation of the cavitating vortices is one of the dangerous phenomena of hydraulic turbine operation near full-load conditions. This work is an attempt to generalize data and expand insight on the phenomenon of self-excited oscillations by comparing the experimental results obtained on a simplified turbine and scaled-down pump–turbine models. In both cases, a series of high-speed imaging was carried out, which made it possible to study these phenomena with high temporal resolution. The high-speed imaging data was subjected to additional processing such as binarization, cropping, and scaling. For a simplified turbine model, the volume of the vapor cavity was calculated based on the assumption of the axial symmetry of the cavity, after which fast Fourier transform (FFT) analysis was carried out. A proper orthogonal decomposition (POD) analysis was also performed to examine individual modes in the original digital imaging data. For the pump–turbine, visualization data on the cavitation cavity oscillations were supplemented by pressure measurements in the draft tube cone to determine the frequency characteristics. Based on obtained experimental data, an improved one-dimensional model describing the oscillations of the cavitation cavity arising behind the hydraulic turbine runner is proposed.

KW - cavitating vortices

KW - high-speed visualization

KW - proper orthogonal decomposition (POD)

KW - pump–turbine

KW - turbine

UR - http://www.scopus.com/inward/record.url?scp=85129123377&partnerID=8YFLogxK

U2 - 10.3390/en15082965

DO - 10.3390/en15082965

M3 - Article

AN - SCOPUS:85129123377

VL - 15

JO - Energies

JF - Energies

SN - 1996-1073

IS - 8

M1 - 2965

ER -