TY - JOUR

T1 - Three-dimensional simulation of full load instability in Francis turbines

AU - Chirkov, Denis V.

AU - Cherny, Sergey G.

AU - Shcherbakov, Pavel K.

AU - Skorospelov, Vladimir A.

AU - Zakharov, Alexander V.

PY - 2019/9/3

Y1 - 2019/9/3

N2 - Full load instability is one of the most dangerous unsteady flow phenomena, and practically restricts the zone of stable operation of the whole hydraulic power plant. This paper presents a mathematical model and a numerical method for simulation of full load instability and the resulting pressure pulsations in Francis turbines. The model consists of one-dimensional hydro-acoustic equations for a long penstock domain, and three-dimensional Reynolds averaged Navier–Stokes equations of “liquid-vapour” flow for the turbine domain. Series of computations of a high head hydraulic power plant are carried out. Investigated are the sensitivities to time step and mesh size refinements as well as the effect of turbulence model. Thoma number and operating point dependencies of the computed amplitude and frequency of pressure pulsations are compared to measurements and to the predictions of the fully one-dimensional model of the power plant. The amplitude of the computed pressure and power oscillations agree well with the available experimental data, showing the potential of the presented approach to investigate and predict high load pulsations in hydraulic power plants.

AB - Full load instability is one of the most dangerous unsteady flow phenomena, and practically restricts the zone of stable operation of the whole hydraulic power plant. This paper presents a mathematical model and a numerical method for simulation of full load instability and the resulting pressure pulsations in Francis turbines. The model consists of one-dimensional hydro-acoustic equations for a long penstock domain, and three-dimensional Reynolds averaged Navier–Stokes equations of “liquid-vapour” flow for the turbine domain. Series of computations of a high head hydraulic power plant are carried out. Investigated are the sensitivities to time step and mesh size refinements as well as the effect of turbulence model. Thoma number and operating point dependencies of the computed amplitude and frequency of pressure pulsations are compared to measurements and to the predictions of the fully one-dimensional model of the power plant. The amplitude of the computed pressure and power oscillations agree well with the available experimental data, showing the potential of the presented approach to investigate and predict high load pulsations in hydraulic power plants.

KW - Cavitation

KW - flow instabilities

KW - Francis turbine

KW - numerical simulation

KW - three-dimensional models

KW - water pipelines

KW - NUMERICAL-SIMULATION

KW - FLOW

UR - http://www.scopus.com/inward/record.url?scp=85052337205&partnerID=8YFLogxK

U2 - 10.1080/00221686.2018.1494047

DO - 10.1080/00221686.2018.1494047

M3 - Article

AN - SCOPUS:85052337205

VL - 57

SP - 623

EP - 634

JO - Journal of Hydraulic Research/De Recherches Hydrauliques

JF - Journal of Hydraulic Research/De Recherches Hydrauliques

SN - 0022-1686

IS - 5

ER -