scholarly journals Experimental investigation and numerical simulation of flow in the draft tube elbow of a Francis turbine over its entire operating range

2019 ◽  
Vol 240 ◽  
pp. 072009
Author(s):  
M Sakamoto ◽  
A Müller ◽  
L Andolfatto ◽  
T Hashii ◽  
K Yamaishi ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Experimental Investigation ◽  
Draft Tube ◽  
Francis Turbine ◽  
Operating Range

Influence of the velocity field at the inlet of a Francis turbine draft tube on performance over an operating range

2012 ◽  
Vol 15 (3) ◽  
pp. 032008 ◽  
Author(s):  
R Susan-Resiga ◽  
S Muntean ◽  
T Ciocan ◽  
E Joubarne ◽  
P Leroy ◽  
...  
Keyword(s):  
Velocity Field ◽  
Draft Tube ◽  
Francis Turbine ◽  
Operating Range

Analysis of CFD for the Vortex Rope in the Draft Tube Urged by the Long and Short Blades Runner

2011 ◽  
Vol 105-107 ◽  
pp. 52-55
Author(s):  
Si Qing Zhang ◽  
Chang Zhen Li ◽  
Li Xiang Zhang ◽  
Xiao Xu Zhang
Keyword(s):  
Numerical Simulation ◽  
Flow Pattern ◽  
Mixed Model ◽  
Draft Tube ◽  
Operating Conditions ◽  
Francis Turbine ◽  
Vortex Rope ◽  
Operation Stability ◽  
Rng Turbulence Model ◽  
Blade Model

The RNG turbulence model is used to carry out the 3D steady turbulent calculation on the runner and draft tube of the Francis turbine. And the prototype of the Francis turbine is HLA351. Under 8 typical operating conditions, numerical simulation on how the runner outlet urge the vortex rope in draft tube are accomplished in this paper, and the calculation models are long blade model and mixed blade model. The results show that the runner outlet of the mixed model can lead the vortex rope location to the downstream relatively, reduce the circumfluence and cushion area and the probability of the second-vortex. What’s more, the flow pattern in mixed model is superior to the long model and that benefits the operation stability and economy of the unit.

Investigation on Combined Air and Water Injection in Francis Turbine Draft Tube to Reduce Vortex Rope Effects

2018 ◽  
Vol 141 (5) ◽  
Author(s):  
Moona Mohammadi ◽  
Ebrahim Hajidavalloo ◽  
Morteza Behbahani-Nejad
Keyword(s):  
Flow Rate ◽  
Draft Tube ◽  
Water Injection ◽  
Total Loss ◽  
Design Flow ◽  
Air Injection ◽  
Francis Turbine ◽  
Two Phase ◽  
Operating Range ◽  
Two Fluids

In this paper, the effect of water, air, and their combined injection from two different injection points is studied in order to reduce vorticity effects in a draft tube of prototype turbine working at three operating points. The flow from spiral case to the end of draft tube is simulated using the shear stress transport k–ω turbulence and two-phase models. Using an appropriate validation method, acceptable results were obtained under the noninjection condition. To determine suitable number of points and inlet flow rate for air injection as well as the appropriate nozzle diameter for air and water injection, a new method which considers the ratio of total loss to the pressure recovery factor is used, in addition to using the traditional method which calculates the total loss in the draft tube. Comparing results of the three types of injections shows air injection in the operating range greater than 70% of turbine design flow rate, is much more effective than water injection or the combination of air and water injection. However, in the operating range below 70%, either water or air injections are not suitable, but combination of these two fluids can improve system performance.

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