Experimental investigation of the mass flow gain factor in a draft tube with cavitation vortex rope

C. Landry, Arthur Tristan Favrel, A. Müller, K. Yamamoto, S. Alligné, F. Avellan

Research output: Contribution to journalConference article

Abstract

At off-design operating operations, cavitating flow is often observed in hydraulic machines. The presence of a cavitation vortex rope may induce draft tube surge and electrical power swings at part load and full load operations. The stability analysis of these operating conditions requires a numerical pipe model taking into account the complexity of the two-phase flow. Among the hydroacoustic parameters describing the cavitating draft tube flow in the numerical model, the mass flow gain factor, representing the mass excitation source expressed as the rate of change of the cavitation volume as a function of the discharge, remains difficult to model. This paper presents a quasi-static method to estimate the mass flow gain factor in the draft tube for a given cavitation vortex rope volume in the case of a reduced scale physical model of a ν = 0.27 Francis turbine. The methodology is based on an experimental identification of the natural frequency of the test rig hydraulic system for different Thoma numbers. With the identification of the natural frequency, it is possible to model the wave speed, the cavitation compliance and the volume of the cavitation vortex rope. By applying this new methodology for different discharge values, it becomes possible to identify the mass flow gain factor and improve the accuracy of the system stability analysis.

Original languageEnglish
Article number012022
JournalJournal of Physics: Conference Series
Volume813
Issue number1
DOIs
Publication statusPublished - 2017 Apr 4
Externally publishedYes
EventHYdropower Plants PERformance and FlexiBle Operation Towards Lean Integration of New Renewable Energies Symposium, HYPERBOLE 2017 - Porto, Portugal
Duration: 2017 Feb 22017 Feb 3

Fingerprint

draft
mass flow
cavitation flow
vortices
tubes
resonant frequencies
methodology
hydraulic equipment
systems stability
underwater acoustics
turbines
two phase flow
hydraulics
estimates
excitation

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Experimental investigation of the mass flow gain factor in a draft tube with cavitation vortex rope. / Landry, C.; Favrel, Arthur Tristan; Müller, A.; Yamamoto, K.; Alligné, S.; Avellan, F.

In: Journal of Physics: Conference Series, Vol. 813, No. 1, 012022, 04.04.2017.

Research output: Contribution to journalConference article

@article{fd1634e0741b46e7bab95656105798fd,
title = "Experimental investigation of the mass flow gain factor in a draft tube with cavitation vortex rope",
abstract = "At off-design operating operations, cavitating flow is often observed in hydraulic machines. The presence of a cavitation vortex rope may induce draft tube surge and electrical power swings at part load and full load operations. The stability analysis of these operating conditions requires a numerical pipe model taking into account the complexity of the two-phase flow. Among the hydroacoustic parameters describing the cavitating draft tube flow in the numerical model, the mass flow gain factor, representing the mass excitation source expressed as the rate of change of the cavitation volume as a function of the discharge, remains difficult to model. This paper presents a quasi-static method to estimate the mass flow gain factor in the draft tube for a given cavitation vortex rope volume in the case of a reduced scale physical model of a ν = 0.27 Francis turbine. The methodology is based on an experimental identification of the natural frequency of the test rig hydraulic system for different Thoma numbers. With the identification of the natural frequency, it is possible to model the wave speed, the cavitation compliance and the volume of the cavitation vortex rope. By applying this new methodology for different discharge values, it becomes possible to identify the mass flow gain factor and improve the accuracy of the system stability analysis.",
author = "C. Landry and Favrel, {Arthur Tristan} and A. M{\"u}ller and K. Yamamoto and S. Allign{\'e} and F. Avellan",
year = "2017",
month = "4",
day = "4",
doi = "10.1088/1742-6596/813/1/012022",
language = "English",
volume = "813",
journal = "Journal of Physics: Conference Series",
issn = "1742-6588",
publisher = "IOP Publishing Ltd.",
number = "1",

}

TY - JOUR

T1 - Experimental investigation of the mass flow gain factor in a draft tube with cavitation vortex rope

AU - Landry, C.

AU - Favrel, Arthur Tristan

AU - Müller, A.

AU - Yamamoto, K.

AU - Alligné, S.

AU - Avellan, F.

PY - 2017/4/4

Y1 - 2017/4/4

N2 - At off-design operating operations, cavitating flow is often observed in hydraulic machines. The presence of a cavitation vortex rope may induce draft tube surge and electrical power swings at part load and full load operations. The stability analysis of these operating conditions requires a numerical pipe model taking into account the complexity of the two-phase flow. Among the hydroacoustic parameters describing the cavitating draft tube flow in the numerical model, the mass flow gain factor, representing the mass excitation source expressed as the rate of change of the cavitation volume as a function of the discharge, remains difficult to model. This paper presents a quasi-static method to estimate the mass flow gain factor in the draft tube for a given cavitation vortex rope volume in the case of a reduced scale physical model of a ν = 0.27 Francis turbine. The methodology is based on an experimental identification of the natural frequency of the test rig hydraulic system for different Thoma numbers. With the identification of the natural frequency, it is possible to model the wave speed, the cavitation compliance and the volume of the cavitation vortex rope. By applying this new methodology for different discharge values, it becomes possible to identify the mass flow gain factor and improve the accuracy of the system stability analysis.

AB - At off-design operating operations, cavitating flow is often observed in hydraulic machines. The presence of a cavitation vortex rope may induce draft tube surge and electrical power swings at part load and full load operations. The stability analysis of these operating conditions requires a numerical pipe model taking into account the complexity of the two-phase flow. Among the hydroacoustic parameters describing the cavitating draft tube flow in the numerical model, the mass flow gain factor, representing the mass excitation source expressed as the rate of change of the cavitation volume as a function of the discharge, remains difficult to model. This paper presents a quasi-static method to estimate the mass flow gain factor in the draft tube for a given cavitation vortex rope volume in the case of a reduced scale physical model of a ν = 0.27 Francis turbine. The methodology is based on an experimental identification of the natural frequency of the test rig hydraulic system for different Thoma numbers. With the identification of the natural frequency, it is possible to model the wave speed, the cavitation compliance and the volume of the cavitation vortex rope. By applying this new methodology for different discharge values, it becomes possible to identify the mass flow gain factor and improve the accuracy of the system stability analysis.

UR - http://www.scopus.com/inward/record.url?scp=85017437201&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85017437201&partnerID=8YFLogxK

U2 - 10.1088/1742-6596/813/1/012022

DO - 10.1088/1742-6596/813/1/012022

M3 - Conference article

VL - 813

JO - Journal of Physics: Conference Series

JF - Journal of Physics: Conference Series

SN - 1742-6588

IS - 1

M1 - 012022

ER -