Free surface-pressurized flow in ceiling-sloping tailrace tunnel of hydropower plant: simulation by VOF model

2007 ◽  
Vol 45 (1) ◽  
pp. 88-99 ◽  
Author(s):  
Yongguang Cheng ◽  
Jinping Li ◽  
Jiandong Yang
Keyword(s):  
Free Surface ◽  
Hydropower Plant ◽  
Vof Model ◽  
Tailrace Tunnel ◽  
Plant Simulation

Stability Analysis of Hydropower Stations With Complex Flow Patterns in the Tailrace Tunnel

2013 ◽  
Author(s):  
Jianxu Zhou ◽  
Fulin Cai ◽  
Ming Hu
Keyword(s):  
Free Surface ◽  
Stability Analysis ◽  
Flow Patterns ◽  
Normal Operation ◽  
Complex Flow ◽  
Diversion Tunnel ◽  
Implicit Model ◽  
Special Cases ◽  
Tailrace Tunnel ◽  
Hydropower Stations

For some special tailrace tunnels in the hydropower stations, including the changing top-altitude tailrace tunnel and the tailrace tunnel with downstream reused flat-ceiling diversion tunnel, during normal operation and hydraulic transients, the flow patterns inside are relatively complex mainly including the free-surface pressurized flow and partial free flow if the tail water level is lower than the top elevation of tunnel’s outlet. These complex flow patterns have obvious effect on system’s stability, and can not be simulated accurately by the traditional models. Therefore, a characteristic implicit model is introduced to simulate these complex flow patterns for further stability analysis. In some special cases, the characteristic implicit model also fails to completely simulate the mixed free-surface pressurized flow in the flat-ceiling tailrace tunnel. A new method is presented based on both experimental research and numerical simulation, and then, system’s stability is analyzed by compared with traditional ordinary boundary condition. The results indicate that, with different simulation models for the complex water flow in the tailrace tunnel, system’s dynamic characteristic can be actually revealed with the consideration of the effect of complex flow patterns in the tailrace tunnel on system’s stability and regulation performance.

Benchmark Studies Using Virtual Model Basin for Resistance and Diffraction: A RANS CFD Approach

2008 ◽  
Author(s):  
Balasubramanyam Sasanapuri
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Diffraction Problem ◽  
Turbulence Models ◽  
General Purpose ◽  
Virtual Model ◽  
Ansys Fluent ◽  
Vof Model ◽  
Flow Features ◽  
Surface Combatant

Virtual Model Basin (VMB) developed based on RANS CFD Approach along with VOF model to simulate free-surface has been used to perform benchmark studies and the results are presented in this paper. The VMB based on general purpose CFD solver ANSYS FLUENT has been used to simulate resistance and diffraction problems for a Navy surface combatant hull and the results are validated against experimental data. The resistance simulations are done to assess two turbulence models and best among the two is used to solve the diffraction problem. The validation results suggest that the VMB approach reproduces the flow features, forces and moments accurately.

scholarly journals Free surface profile and inception point as characteristics of aerated flow over stepped spillway: Numerical study

2019 ◽  
Vol 42 (1) ◽  
pp. 42-48
Author(s):  
Chakib Bentalha ◽  
Mohammed Habi
Keyword(s):  
Free Surface ◽  
Kinetic Energy ◽  
Water Depth ◽  
Numerical Study ◽  
Surface Profile ◽  
Air Entrainment ◽  
Stepped Spillway ◽  
Ansys Fluent ◽  
Vof Model ◽  
Inception Point

Abstract Stepped spillway is hydraulic structure designed to dissipate the excess in kinetic energy at the downstream of dams and can reduce the size of stilling basin at the toe of the spillway or chute. The flow on a stepped spillway is characterised by the large aeration that can prevent or reduce the cavitation damage. The air entrainment starts where the boundary layer attains the free surface of flow; this point is called “point of inception”. Within this work the inception point is determined by using software Ansys Fluent where the volume of fluid (VOF) model is used as a tool to track the free surface thereby the turbulence closure is derived in the k − ε turbulence standard model. This research aims to find new formulas for describe the variation of water depth at step edge and the positions of the inception point, at the same time the contour map of velocity, turbulent kinetic energy and strain rate are presented. The found numerical results agree well with experimental results like the values of computed and measured water depth at the inception point and the numerical and experimental inception point locations. Also, the dimensionless water depth profile obtained by numerical method agrees well with that of measurement. This study confirmed that the Ansys Fluent is a robust software for simulating air entrainment and exploring more characteristics of flow over stepped spillways.

An active perceivable device–oriented modeling framework for hydropower plant simulation

Energy ◽  
2018 ◽  
Vol 165 ◽  
pp. 1009-1023 ◽  
Author(s):  
Binqiao Zhang ◽  
Xiaohui Yuan ◽  
Yanbin Yuan ◽  
Xu Wang
Keyword(s):  
Hydropower Plant ◽  
Modeling Framework ◽  
Plant Simulation

scholarly journals A Review of the Hydraulic Transient and Dynamic Behavior of Hydropower Plants with Sloping Ceiling Tailrace Tunnels

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3220 ◽  
Author(s):  
Guo
Keyword(s):  
Free Surface ◽  
Dynamic Behavior ◽  
Thermal Power ◽  
Future Research ◽  
Efficient Operation ◽  
Dynamic Behaviors ◽  
Hydraulic Transient ◽  
Hydro Turbine ◽  
Hydropower Plants ◽  
Tailrace Tunnel

The sloping ceiling tailrace tunnel is a novel tailrace tunnel system for hydropower plants. The design, operation, and maintenance of hydropower plants with sloping ceiling tailrace tunnels are based on the calculation and analysis of hydraulic transients and dynamic behavior. Research achievements have provided guidance and a basis for the safe, stable, and efficient operation of hydropower plants with sloping ceiling tailrace tunnels. Based on research achievements, sloping ceiling tailrace tunnels have been applied to more and more hydropower plants. This review paper gives a systematic literature investigation on the hydraulic transient and dynamic behaviors of hydropower plants with sloping ceiling tailrace tunnels. First, the appearance and development of sloping ceiling tailrace tunnels are stated. Key issues in the hydraulic transient and dynamic behaviors of hydropower plants with sloping ceiling tailrace tunnels are illuminated. Then, research achievements on six issues (i.e., the working principles of sloping ceiling tailrace tunnels, the shape design of sloping ceiling tailrace tunnels, the free surface pressurized flow characteristics in sloping ceiling tailrace tunnels, numerical simulations of transient processes for hydro-turbine governing systems with sloping ceiling tailrace tunnels, the stability of hydro-turbine governing systems with sloping ceiling tailrace tunnels, and the transient process control of hydro-turbine governing systems with sloping ceiling tailrace tunnels) are elaborated. Finally, future research trends are presented. In future research, fluid–solid coupling of the tunnel wall and free surface pressurized flow in sloping ceiling tailrace tunnels is worth studying. For hydropower plants with sloping ceiling tailrace tunnels, a combined operating scheme with thermal power and wind power should be explored.

CFD Simulation of the Whole Pump Station Inlet Flow Field

2008 ◽  
Author(s):  
Zhou Daqing ◽  
Zheng Yuan ◽  
Xinfeng Ge
Keyword(s):  
Free Surface ◽  
Flow Field ◽  
Hydraulic Structure ◽  
Geometric Model ◽  
Surface Model ◽  
Inlet Flow ◽  
Pump Station ◽  
Vof Model ◽  
Hypothesis Model ◽  
Pump Stations

Wu-Hao-Gou pump station is one of many pump stations being going to build in order to meet the increasing need of water supply in the Shanghai city. Owing to limited building site, large discharge and multi water outlet direction, the design and arrangement of hydraulic structure become more difficult than usual pump station. In the paper, CFD method is used to simulate the whole inlet flow field and improve hydraulic performance of the pump station. Firstly, the whole hydraulic structure geometric model, combined by Penstock, transition passage, diversion channel, fore bay, suction bay and suction pipe, is built and subdivided with unstructured mesh. Secondly, inlet flow field of the original pump station scheme is simulated and analyzed with the SIMPLEC algorithm, the realizable k-ε turbulence model and the symmetric boundary hypothesis on the free surface. Thirdly, the better scheme is calculated with the same numerical method after taking some effective measurements. Lastly, the better scheme is simulated with the VOF model, as well as the numerical results are compared with the above symmetric boundary hypothesis model to reveal the fact that the main flow character is similar but some flow details differ between the two free surface model. Then, the physical model experiment will be performed to verify the better scheme in the next step.

scholarly journals A Study of the Location of the Entrance of a Fishway in a Regulated River with CFD and ADCP

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Anders G. Andersson ◽  
Dan-Erik Lindberg ◽  
Elianne M. Lindmark ◽  
Kjell Leonardsson ◽  
Patrik Andreasson ◽  
...  
Keyword(s):  
Acoustic Doppler Current Profiler ◽  
Field Measurements ◽  
Fish Passage ◽  
Hydropower Plant ◽  
Regulated River ◽  
Unstable Flow ◽  
River Bed ◽  
Current Profiler ◽  
Tailrace Tunnel ◽  
Made In

Simulation-driven design with computational fluid dynamics has been used to evaluate the flow downstream of a hydropower plant with regards to upstream migrating fish. Field measurements with an Acoustic Doppler Current Profiler were performed, and the measurements were used to validate the simulations. The measurements indicate a more unstable flow than the simulations, and the tailrace jet from the turbines is stronger in the simulations. A fishway entrance was included in the simulations, and the subsequent attraction water was evaluated for two positions and two angles of the entrance at different turbine discharges. Results show that both positions are viable and that a position where the flow from the fishway does not have to compete with the flow from the power plant will generate superior attraction water. Simulations were also performed for further downstream where the flow from the turbines meets the old river bed which is the current fish passage for upstream migrating fish. A modification of the old river bed was made in the model as one scenario to generate better attraction water. This considerably increases the attraction water although it cannot compete with the flow from the tailrace tunnel.

Coordinated Hydropower Plant Simulation for Multireservoir Systems

2014 ◽  
Vol 140 (2) ◽  
pp. 216-227 ◽  
Author(s):  
Jesus M. Latorre ◽  
Santiago Cerisola ◽  
Andres Ramos ◽  
Alejandro Perea ◽  
Rafael Bellido
Keyword(s):  
Hydropower Plant ◽  
Plant Simulation

scholarly journals Photogrammetry for Free Surface Flow Velocity Measurement: From Laboratory to Field Measurements

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1675
Author(s):  
Hang Trieu ◽  
Per Bergström ◽  
Mikael Sjödahl ◽  
J. Gunnar I. Hellström ◽  
Patrik Andreasson ◽  
...  
Keyword(s):  
Free Surface ◽  
Particle Tracking ◽  
Field Measurements ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Hydropower Plant ◽  
Surface Velocity ◽  
Camera System ◽  
Particle Tracking Method ◽  
Calibration Methods

This study describes a multi-camera photogrammetric approach to measure the 3D velocity of free surface flow. The properties of the camera system and particle tracking velocimetry (PTV) algorithm were first investigated in a measurement of a laboratory open channel flow to prepare for field measurements. The in situ camera calibration methods corresponding to the two measurement situations were applied to mitigate the instability of the camera mechanism and camera geometry. There are two photogrammetry-based PTV algorithms presented in this study regarding different types of surface particles employed on the water flow. While the first algorithm uses the particle tracking method applied for individual particles, the second algorithm is based on correlation-based particle clustering tracking applied for clusters of small size particles. In the laboratory, reference data are provided by particle image velocimetry (PIV) and laser Doppler velocimetry (LDV). The differences in velocities measured by photogrammetry and PIV, photogrammetry and LDV are 0.1% and 3.6%, respectively. At a natural river, the change of discharges between two measurement times is found to be 15%, and the corresponding value reported regarding mass flow through a nearby hydropower plant is 20%. The outcomes reveal that the method can provide a reliable estimation of 3D surface velocity with sufficient accuracy.

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