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.

Experimental and Numerical Analysis of Pressure Pulsation in Francis Turbine

2008 ◽  
Author(s):  
Yexiang Xiao ◽  
Zhengwei Wang ◽  
Zongguo Yan ◽  
Yongyao Luo ◽  
Ruofu Xiao ◽  
...  
Keyword(s):  
Unsteady Flow ◽  
Flow Pattern ◽  
Pressure Fluctuation ◽  
Pressure Pulsation ◽  
Draft Tube ◽  
Flow Distribution ◽  
Internal Flow ◽  
Operating Conditions ◽  
Francis Turbine ◽  
Spiral Case

The pressure fluctuation taking place at the whole passage of a prototype Francis hydraulic turbine is studied by carrying out both experimental and numerical simulation. Unsteady wall pressure measurements at six different typical operating conditions are performs to thoroughly investigate pressure fields in the spiral case and straight draft tube dynamically. 3-D unsteady turbulent simulations are performed and compared to the experimental data. The computed flow domain includes the spiral case, stay vanes, guide vanes, rotating runner and the draft tube. The characteristic of unsteady flow and the pressure pulsation as well as their relationships are discussed in this paper, which also analyzed the correlation between the unsteady flow pattern and the pressure fluctuation at different parts of the turbine. In order to optimize the internal flow distribution in Francis turbines at partial loads, this paper presents some preliminary methods to control the unsteady flow pattern.

Numerical Analysis of Blade Channel Vortex in Francis Turbine at Part Load of Middle-Low Head

2009 ◽  
Author(s):  
Yexiang Xiao ◽  
Zhengwei Wang ◽  
Jin Zhang ◽  
Guangjie Peng ◽  
Dingyou Liu ◽  
...  
Keyword(s):  
Unsteady Flow ◽  
Guide Vane ◽  
Flow Behavior ◽  
Operating Conditions ◽  
Francis Turbine ◽  
Flow Passage ◽  
Part Load ◽  
Eddy Characteristics ◽  
Low Head ◽  
Dominant Frequencies

The unsteady flow behavior and pressure fluctuations in the runner of a Francis turbine were predicted numerically for the middle-low head at three small guide vane openings. The unsteady Reynolds-averaged Navier-Stokes equations with the k–ω based SST turbulence model were solved to model the unsteady flow within the entire flow passage. The eddy characteristics inside the runner passage were discussed for various operating conditions, the shape of the blade channel vortex illustrate by the instantaneous iso-surfaces of the vorticity was similar with the experimental observation. This study investigates the characteristics of the unsteady flow dominant frequencies at different monitored points of the runner by spectrum analysis. At small guide vane opening conditions, the pulse in the runner flow passage are due to the rotor-stator interference between the runner and the guide vanes, the blade channel vortex in the runner blade passage. And the dominant frequencies of blade channel vortex were a low frequency. The unsteady flow behavior of blade channel vortex in the runner was classified numerically at part load of middle-low head.

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

Experimental and numerical analysis to identify the performance limiting mechanisms in solid-state lithium cells under pulse operating conditions

2019 ◽  
Vol 21 (41) ◽  
pp. 22740-22755 ◽  
Author(s):  
Mei-Chin Pang ◽  
Yucang Hao ◽  
Monica Marinescu ◽  
Huizhi Wang ◽  
Mu Chen ◽  
...  
Keyword(s):  
Solid State ◽  
Numerical Analysis ◽  
Energy Density ◽  
Lithium Ion Batteries ◽  
Lithium Batteries ◽  
Safety Concern ◽  
Lithium Ion ◽  
Thermal Runaway ◽  
Operating Conditions ◽  
Lithium Cells

Solid-state lithium batteries could reduce the safety concern due to thermal runaway while improving the gravimetric and volumetric energy density beyond the existing practical limits of lithium-ion batteries.

scholarly journals A Simplified Francis Turbine for Micro Hydro Application: Design and Numerical Analysis

2021 ◽  
Vol 627 ◽  
pp. 012018
Author(s):  
Dadi Ram Dahal ◽  
Hari Prasad Neopane ◽  
Biraj Singh Thapa ◽  
Nikshan Paudel ◽  
Sailesh Chitrakar ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Francis Turbine ◽  
Application Design

Numerical simulation and experimental performance research of cylindrical vane pump

2021 ◽  
pp. 095440622110200
Author(s):  
Yiqi Cheng ◽  
Xinhua Wang ◽  
Waheed Ur Rehman ◽  
Tao Sun ◽  
Hasan Shahzad ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Rotational Velocity ◽  
Geometric Theory ◽  
Mechanical Efficiency ◽  
Operating Conditions ◽  
Experimental Results ◽  
Field Analysis ◽  
Total Efficiency ◽  
Three Dimensional Model ◽  
Vane Pump

This study presents a novel cylindrical vane pump based on the traditional working principle. The efficiency of the cylindrical vane pump was verified by experimental validation and numerical analysis. Numerical analysis, such as kinematics analysis, was performed in Pro/Mechanism and unsteady flow-field analysis was performed using ANSYS FLUENT. The stator surface equations were derived using the geometric theory of the applied spatial triangulation function. A three-dimensional model of the cylindrical vane pump was established with the help of MATLAB and Pro/E. The kinematic analysis helped in developing kinematic equations for cylindrical vane pumps and proved the effectiveness of the structural design. The maximum inaccuracy error of the computational fluid dynamics (CFD) model was 5.7% compared with the experimental results, and the CFD results show that the structure of the pump was reasonable. An experimental test bench was developed, and the results were in excellent agreement with the numerical results of CFD. The experimental results show that the cylindrical vane pump satisfied the three-element design of a positive-displacement pump and the trend of changes in efficiency was the same for all types of efficiency under different operating conditions. Furthermore, the volumetric efficiency presented a nonlinear positive correlation with increased rotational velocity, the mechanical efficiency showed a nonlinear negative correlation, and the total efficiency first increased and then decreased. When the rotational velocity was 1.33[Formula: see text] and the discharge pressure was 0.68[Formula: see text], the total efficiency reached its maximum value.

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