Journal ArticleDOI
Runner cone optimization to reduce vortex rope-induced pressure fluctuations in a Francis turbine
TLDR
In this paper, two new types of runner cones (i.e., abnormally shaped and long straight cones) were proposed to optimize the pressure distribution in the draft tube, and unsteady numerical simulations were performed to determine their mechanism of action.Abstract:
Pressure fluctuations induced by a vortex rope are the major causes of hydraulic turbine vibration in partial load operating conditions. Hence, an effective control strategy should be adopted to improve rotating characteristics of the vortex rope and reduce the corresponding pressure fluctuation. In this study, two new types of runner cones (i.e., abnormally shaped and long straight cones) were proposed to optimize the pressure distribution in the draft tube, and unsteady numerical simulations were performed to determine their mechanism of action. Numerical results were validated using flow observation and pressure fluctuation experiments. Detailed analyses were conducted to understand the effects of the helical vortex rope operating conditions. The results indicated that pressure fluctuations in the draft tube at partial load operation result primarily from low frequency fluctuations induced by the rotation of the helical vortex rope, whose amplitudes are related to the rotating radius of the helical vortex rope. Both runner cone types could effectively reduce the pressure-fluctuation amplitude. The long straight type could reduce the amplitude of low-frequency fluctuation induced by vortex rope to a maximum of 74.08% and the abnormal-shape type to 38.31%. Thus, the effective optimization of the runner cone can potentially reduce pressure-fluctuation amplitudes. Our research findings were applied to a real hydraulic plant in China.read more
Citations
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Journal ArticleDOI
Comparative Analysis of Strength and Modal Characteristics of a Full Tubular Pump and an Axial Flow Pump Impellers Based on Fluid-Structure Interaction
TL;DR: In this paper, the structural properties of full tubular and axial-flow pump impellers were investigated using fluid-structure interaction (FSI) to determine the structural mechanical characteristics of the pump impeller, which showed that as the flow rate increases, the total deformation and equivalent stress are significantly reduced.
Journal ArticleDOI
Influence of Upstream Disturbances on the Vortex Structure of Francis Turbine Based on the Criteria of Identification of Various Vortexes
Tao Guo,Lihui Xu,Wenquan Wang +2 more
TL;DR: In this paper, the authors conduct a simulation that adopts sliding grid technology and the large-eddy simulation (LES) method based on the wall-adapting local eddy viscosity (WALE) model.
Journal ArticleDOI
The Effect of J-Groove on Vortex Suppression and Energy Dissipation in a Draft Tube of Francis Turbine
TL;DR: In this article , the authors used numerical simulation to study the effect of the J-groove on vortex suppression and energy dissipation in the draft tube of the HLA551-LJ-43 turbine.
Journal ArticleDOI
Evolution mechanism of water column separation in pump turbine: Model experiment and occurrence criterion
TL;DR: In this paper , the authors used a model pumped storage power station platform with two units to perform water column separation and found that the pressure in the inlet section of the draft tube below the vaporization pressure that lasts for several seconds is a sufficient and necessary condition for water column separations.
Journal ArticleDOI
Influence of Solid–Liquid Two-Phase Flow on Cavitation of Tubular Turbine Blades Under Combined Conditions
TL;DR: The influence of sediment media on the blade pressure and cavitation of a tubular turbine was investigated in this paper , where the Zwart-Geber-Belamri cavitation model and the shear stress transport k-w turbulence model were applied to numerically simulate and experimentally validate the full flow path of the turbine under combined conditions for sediment particle sizes of 0.01 and 0.05 mm.
References
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Journal ArticleDOI
Numerical investigation on radial impeller induced vortex rope in draft tube under partial load conditions
TL;DR: In this article, the vortex rope phenomena appearing in a draft tube under partial load operations were investigated using a homogeneous equilibrium vapor-liquid two-phase model and a blending SST turbulence model, and the former takes account of the weak compressibility of mixed media.
Journal ArticleDOI
Investigation on reversible pump turbine flow structures and associated pressure field characteristics under different guide vane openings
Maxime Binama,Wen-Tao Su,Wen-Tao Su,Weihua Cai,Feng-Chen Li,Xianzhu Wei,Alex Muhirwa,Ruzhi Gong,David Wafula Wekesa +8 more
TL;DR: In this paper, the authors investigated the onset and development mechanism of RPT unsteady flow structures as well as the evolutional characteristics of associated pressure pulsations throughout the RPT complete flow passage, under off-design conditions for three GVOs namely 17, 21 and 25 mm.
Journal ArticleDOI
Investigation of flow pattern downstream of spiral grooved runner cone in pump-turbine
TL;DR: In this paper, a new runner cone with spiral grooves on the surface was developed to mitigate the amplitude of pressure fluctuation simultaneously, and the effect was confirmed by model tests.
Journal ArticleDOI
Experimental and numerical investigation of unsteady behavior of cavitating vortices in draft tube of low specific speed Francis turbine
Y Tamura,Kiyohito Tani,N Okamoto +2 more
TL;DR: In this article, the authors investigated the interaction between the flow pattern at runner outlet and the unsteady behavior of cavitating vortices in the draft tube with experimental and numerical approaches.