scholarly journals Investigation of a High Head Francis Turbine at Runaway Operating Conditions

Energies ◽  
2016 ◽  
Vol 9 (3) ◽  
pp. 149 ◽  
Author(s):  
Chirag Trivedi ◽  
Michel Cervantes ◽  
B. Gandhi
Keyword(s):  
Operating Conditions ◽  
Francis Turbine ◽  
High Head

Numerical analysis of unsteady flow under high‐head operating conditions in Francis turbine

2010 ◽  
Vol 27 (3) ◽  
pp. 365-386 ◽  
Author(s):  
Xiao Yexiang ◽  
Wang Zhengwei ◽  
Yan Zongguo ◽  
Li Mingan ◽  
Xiao Ming ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Unsteady Flow ◽  
Operating Conditions ◽  
Francis Turbine ◽  
High Head

Impact of Different Operating Conditions on the Dynamic Excitation of a High Head Francis Turbine

2016 ◽  
Author(s):  
Markus Eichhorn ◽  
Eduard Doujak
Keyword(s):  
Fatigue Analysis ◽  
Operating Conditions ◽  
Francis Turbine ◽  
Fluid Structure Interactions ◽  
Cfd Simulations ◽  
Dynamic Excitation ◽  
Hydropower Plants ◽  
Rotor Stator Interaction ◽  
High Head ◽  
Strain Gauge Measurements

Fatigue analysis becomes more important in the design phase of Francis turbine runners due to the changing requirements on hydropower plants, affected by the increasing amount of volatile energy sources. Francis turbines are operated more often and over longer periods of time at off-design conditions to provide regulating power to the electric grid. The lifetime of a Francis runner depends mainly on the dynamic excitation induced by unsteady pressure pulsations like the rotor-stator interaction or draft tube vortex ropes. An approach using one-way coupled fluid-structure interactions has been developed and is now extended using unsteady CFD simulations as well as harmonic and transient FEM computations. The results are compared to strain gauge measurements on the according high head Francis turbine to validate the overall procedure. The investigations should be further used to perform a fatigue analysis and to examine the applicability for lifetime investigations on Francis machines with different specific speeds.

Experimental and Numerical Studies for a High Head Francis Turbine at Several Operating Points

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Chirag Trivedi ◽  
Michel J. Cervantes ◽  
B. K. Gandhi ◽  
Ole G. Dahlhaug
Keyword(s):  
Power Generation ◽  
Entire Range ◽  
Pressure Sensors ◽  
Operating Conditions ◽  
Francis Turbine ◽  
Head Model ◽  
Numerical Studies ◽  
Pressure Time ◽  
Advection Schemes ◽  
High Head

Experimental and numerical studies on a high head model Francis turbine were carried out over the entire range of turbine operation. A complete Hill diagram was constructed and pressure-time measurements were performed at several operating conditions over the entire range of power generation by installing pressure sensors in the rotating and stationary domains of the turbine. Unsteady numerical simulations were performed at five operating conditions using two turbulent models, shear stress transport (SST) k-ω and standard k-ε and two advection schemes, high resolution and second order upwind. There was a very small difference (0.85%) between the experimental and numerical hydraulic efficiencies at the best efficiency point (BEP); the maximum difference (14%) between the experimental and numerical efficiencies was found at lower discharge turbine operation. Investigation of both the numerical and experimental pressure-time signals showed that the complex interaction between the rotor and stator caused an output torque oscillation over a particular power generation range. The pressure oscillations that developed due to guide vanes and runner blades interaction propagate up to the trailing edge of the blades. Fourier analysis of the signals revealed the presence of a vortex rope in the draft tube during turbine operation away from the BEP.

The Strength Analysis of Francis Turbine Runner Based on the Fluid-Solid Coupling

2014 ◽  
Vol 709 ◽  
pp. 41-45
Author(s):  
Kan Kan ◽  
Yuan Zheng ◽  
Xin Zhang ◽  
Bin Sun ◽  
Hui Wen Liu
Keyword(s):  
Water Pressure ◽  
Eastern China ◽  
Static Stress ◽  
Operating Conditions ◽  
Francis Turbine ◽  
Strength Analysis ◽  
Maximum Deformation ◽  
The North ◽  
North Eastern ◽  
Turbine Runner

This paper does unidirectional fluid-solid coupling calculation on the runner strength under three designed head loading conditions of a certain Francis turbine in the north-eastern China. The water pressure on the blade in the flow fields of different operating conditions is calculated by means of CFD software CFX. With the help of ansys workbench, the water pressure is loaded to the blade as structural load to conclude the static stress distribution and deformation of the runner under different operating conditions. The results show that the maximum static stress increases with the rise of the flow and appears near the influent side of the blade connected to the runner crown; the maximum deformation increases with the rise of the flow and appears on the band. The results provides effective basis for the structural design and safe operation of the Francis turbine.

scholarly journals Dynamics of the Blade Channel of an Inducer Under Cavitation-Induced Instabilities

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Angelo Pasini ◽  
Ruzbeh Hadavandi ◽  
Dario Valentini ◽  
Giovanni Pace ◽  
Luca d'Agostino
Keyword(s):  
Experimental Data ◽  
Spectral Analysis ◽  
Main Flow ◽  
Operating Conditions ◽  
Flow Instabilities ◽  
Mean Flow ◽  
Flow Oscillations ◽  
Rotating Frames ◽  
The Mean ◽  
High Head

A high-head three-bladed inducer has been equipped with pressure taps on the hub along the blade channels with the aim of more closely investigating the dynamics of cavitation-induced instabilities developing in the impeller flow. Spectral analysis of the pressure signals obtained from two sets of transducers mounted both in the stationary and rotating frames has allowed to characterize the nature, intensity, and interactions of the main flow instabilities detected in the experiments: subsynchronous rotating cavitation (RC), cavitation surge (CS), and a high-order axial surge oscillation. A dynamic model of the unsteady flow in the blade channels has been developed based on experimental data and on suitable descriptions of the mean flow and the oscillations of the cavitating volume. The model has been used for estimating at the inducer operating conditions of interest the intensity of the flow oscillations associated with the occurrence of the CS mode generated by RC in the inducer inlet.

scholarly journals Manipulation of the swirling flow instability in hydraulic turbine diffuser by different methods of water injection

2018 ◽  
Vol 180 ◽  
pp. 02090 ◽  
Author(s):  
Pavel Rudolf ◽  
Jiří Litera ◽  
Germán Alejandro Ibarra Bolanos ◽  
David Štefan
Keyword(s):  
Swirling Flow ◽  
Flow Instability ◽  
Draft Tube ◽  
Water Injection ◽  
Hydraulic Turbine ◽  
Operating Conditions ◽  
Francis Turbine ◽  
Necessary Condition ◽  
Vortex Rope ◽  
Wide Range

Vortex rope, which induces substantial pressure pulsations, arises in the draft tube (diffuser) of Francis turbine for off-design operating conditions. Present paper focuses on mitigation of those pulsations using active water jet injection control. Several modifications of the original Susan-Resiga’s idea were proposed. All modifications are driven by manipulation of the shear layer region, which is believed to play important role in swirling flow instability. While some of the methods provide results close to the original one, none of them works in such a wide range. Series of numerical experiments support the idea that the necessary condition for vortex rope pulsation mitigation is increasing the fluid momentum along the draft tube axis.

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