hydraulic turbines
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2021 ◽  
Vol 68 (12) ◽  
pp. 906-915
Author(s):  
S. Fialová ◽  
F. Pochylý ◽  
A. V. Volkov ◽  
A. V. Ryzhenkov ◽  
A. A. Druzhinin

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6669
Author(s):  
Alfredo Guardo ◽  
Alfred Fontanals ◽  
Mònica Egusquiza ◽  
Carme Valero ◽  
Eduard Egusquiza

Runner and distributor blockages in hydraulic turbines occur due to the ingestion of external bodies such as rocks or logs. These obstructions can change the amplitude and uniformity of the pressure pulsations in the machine, creating large unbalanced forces that can lead to reduced efficiency, increased vibration and mechanical damage. In this paper, the effects of obstructions caused by ingested bodies in the runner and the distributor of a pump turbine on its internal pressure pulsation were investigated by means of computational fluid dynamics. A numerical model of an unobstructed pump turbine is presented and validated against experimental data. Several cases of runner or distributor blockage were studied, and their RSI pressure pulsations were recorded and analyzed at different locations. The results obtained allow us to characterize the effect of these blockages on the machine’s RSI, which can be helpful for the correct diagnosis of these types of damage.


Author(s):  
Melissa Fortin ◽  
Bernd Nennemann ◽  
Claire Deschênes ◽  
Sébastien Houde

Abstract For hydraulic turbines, no-load is considered a homogeneous family of operating conditions although the literature exposes a wide variety of flow structures depending on many factors. A better understanding of the flow structures developed during NL operation is necessary since they generate pressure fluctuations in the turbine causing significant fatigue damage and reducing the life expectancy of the machines. Hydraulic turbines at model scale show that behavioral trends can be identified for no-load conditions. This paper presents a classification of no-load operating conditions following the swirl level at the runner outlet. The main tendencies linking the cavitation level to the runner speed and the discharge for operating points along no-load curves of different turbines are also detailed. To study the no-load conditions, data from 26 Francis turbines, measured between 2007 and 2020 at the laboratory of Andritz Hydro Canada Inc., are analyzed. This study demonstrates that no-load operating conditions exhibit flow features very similar to those at regular operation with similar runner outlet swirl. The runner acceleration or deceleration with cavitation is related to the flow topology at the runner outlet.


Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1883
Author(s):  
Philippe Martineau Rousseau ◽  
Azzeddine Soulaïmani ◽  
Michel Sabourin

Due to the large number of aging hydraulic turbines in North America, rehabilitation is a growing market as these turbines have low efficiency compared to modern ones. Computational Fluid Dynamics identifies components with poor hydraulic performance. The models often used in industry are based on individually analyzing the sub-components of a turbine instead of full turbine simulations due to computational and time limitations. An industrial case has shown that such analyses may lead to underestimating the efficiency increases by modifying the stay vane. The unsteady full turbine simulation proposes to simulate all components simultaneously to assess this efficiency augmentation due to stay vane rehabilitation. The developed simulation methodology is used to evaluate the efficiency increase and the flow of two rehabilitated turbines with stay vane modifications. Comparison with model tests shows the accuracy of the simulations. However, the methodology used shows imprecision in predicting the efficiency increase compared to model tests. Further works should consider the use of more complex flow modeling methods to measure the efficiency increase by the stay vane modifications.


2021 ◽  
Vol 1955 (1) ◽  
pp. 012090
Author(s):  
Cheng Liu ◽  
XinYi Su ◽  
Jialing Wu ◽  
Qun Zhou ◽  
Tao Li ◽  
...  

2021 ◽  
Vol 774 (1) ◽  
pp. 012114
Author(s):  
B Nennemann ◽  
M Melot ◽  
C Monette ◽  
M Gauthier ◽  
S Afara ◽  
...  

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