Experimental Study of Pressure Fluctuations of a Pump-Turbine in Transient Period

2012 ◽  
Vol 516-517 ◽  
pp. 896-899
Author(s):  
Yue Kun Sun ◽  
Zhi Gang Zuo ◽  
Shu Hong Liu ◽  
Jin Tao Liu ◽  
Yu Lin Wu
Keyword(s):  
Experimental Study ◽  
Turbine Unit ◽  
Pressure Fluctuations ◽  
Power Station ◽  
Operating Period ◽  
Pump Turbine ◽  
Guide Vanes ◽  
Transient Period ◽  
Rotor Stator Interaction ◽  
Pump Storage Power

Pressure fluctuations strongly affect the performance stability of the Pump-turbine unit. According to previous research, pressure fluctuations observed between runner and guide vanes (vaneless area) have the large amplitudes and complicated sources. This article analyzed this type of pressure fluctuations in transient operating period, by carrying out observations in a pump-storage power station. Amplitudes and frequencies were analyzed to show the characteristics of pressure fluctuations caused by rotor-stator interaction, vibration and vortex.

scholarly journals Distribution of Pressure Fluctuations in a Prototype Pump Turbine at Pump Mode

2014 ◽  
Vol 6 ◽  
pp. 923937 ◽  
Author(s):  
Yuekun Sun ◽  
Zhigang Zuo ◽  
Shuhong Liu ◽  
Jintao Liu ◽  
Yulin Wu
Keyword(s):  
Mass Flow ◽  
Pressure Fluctuations ◽  
Dominant Frequency ◽  
Pump Mode ◽  
Pump Turbine ◽  
Guide Vanes ◽  
Path Direction ◽  
Mass Flow Rates ◽  
Operating Points ◽  
Spiral Casing

Pressure fluctuations are very important characteristics in pump turbine's operation. Many researches have focused on the characteristics (amplitude and frequencies) of pressure fluctuations at specific locations, but little researches mentioned the distribution of pressure fluctuations in a pump turbine. In this paper, 3D numerical simulations using SSTk − ω turbulence model were carried out to predict the pressure fluctuations distribution in a prototype pump turbine at pump mode. Three operating points with different mass flow rates and different guide vanes’ openings were simulated. The numerical results show how pressure fluctuations at blade passing frequency (BPF) and its harmonics vary along the whole flow path direction, as well as along the circumferential direction. BPF is the first dominant frequency in vaneless space. Pressure fluctuation component at this frequency rapidly decays towards upstream (to draft tube) and downstream (to spiral casing). In contrast, pressure fluctuations component at 3BPF spreads to upstream and downstream with almost constant amplitude. Amplitude and frequencies of pressure fluctuations also vary along different circumferential locations in vaneless space. When the mass flow and guide vanes’ opening are different, the distribution of pressure fluctuations along the two directions is different basically.

Experimental Evidence of Rotating Stall in a Pump-Turbine at Off-Design Conditions in Generating Mode

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Vlad Hasmatuchi ◽  
Mohamed Farhat ◽  
Steven Roth ◽  
Francisco Botero ◽  
François Avellan
Keyword(s):  
High Speed ◽  
Pressure Fluctuations ◽  
Frequency Component ◽  
Rotating Stall ◽  
Image Processing Technique ◽  
Scale Model ◽  
Pump Turbine ◽  
Guide Vanes ◽  
Radial Pump ◽  
Generating Mode

An experimental investigation of the rotating stall in reduced scale model of a low specific speed radial pump-turbine at runaway and turbine brake conditions in generating mode is achieved. Measurements of wall pressure in the stator are performed along with high-speed flow visualizations in the vaneless gap with the help of air bubbles injection. When starting from the best efficiency point (BEP) and increasing the impeller speed, a significant increase of the pressure fluctuations is observed mainly in the wicket gates channels. The spectral analysis shows a rise of a low frequency component (about 70% of the impeller rotational frequency) at runaway, which further increases as the zero discharge condition is approached. Analysis of the instantaneous pressure peripheral distribution in the vaneless gap reveals one stall cell rotating with the impeller at sub-synchronous speed. High-speed movies reveal a quite uniform flow pattern in the guide vanes channels at the normal operating range, whereas at runaway the flow is highly disturbed by the rotating stall passage. The situation is even more critical at very low positive discharge, where backflow and vortices in the guide vanes channels develop during the stall cell passage. A specific image processing technique is applied to reconstruct the rotating stall evolution in the entire guide vanes circumference for a low positive discharge operating point. The findings of this study suggest that one stall cell rotates with the impeller at sub-synchronous velocity in the vaneless gap between the impeller and the guide vanes. It is the result of rotating flow separations developed in several consecutive impeller channels which lead to their blockage.

scholarly journals On the Rotor Stator Interaction Effects of Low Specific Speed Francis Turbines

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Einar Agnalt ◽  
Igor Iliev ◽  
Bjørn W. Solemslie ◽  
Ole G. Dahlhaug
Keyword(s):  
Guide Vane ◽  
Pressure Fluctuations ◽  
Angular Position ◽  
Pressure Sensors ◽  
Pump Turbine ◽  
Blade Loading ◽  
Loading Case ◽  
Rotor Stator Interaction ◽  
Low Specific Speed ◽  
Specific Speed

The rotor stator interaction in a low specific speed Francis model turbine and a pump-turbine is analyzed utilizing pressure sensors in the vaneless space and in the guide vane cascade. The measurements are analyzed relative to the runner angular position by utilizing an absolute encoder mounted on the shaft end. From the literature, the pressure in the analyzed area is known to be a combination of two effects: the rotating runner pressure and the throttling of the guide vane channels. The measured pressure is fitted to a mathematical pressure model to separate the two effects for two different runners. One turbine with 15+15 splitter blades and full-length blades and one pump-turbine with six blades are investigated. The blade loading on the two runners is different, giving different input for the pressure model. The main findings show that the pressure fluctuations in the guide vane cascade are mainly controlled by throttling for the low blade loading case and the rotating runner pressure for the higher blade loading case.

scholarly journals The Influence of Flow Rates on Pressure Fluctuation in the Pump Mode of Pump-Turbine with Splitter Blades

2020 ◽  
Vol 10 (19) ◽  
pp. 6752
Author(s):  
Ping Huang ◽  
Yajing Xiao ◽  
Jinfeng Zhang ◽  
Haikun Cai ◽  
Haiqin Song
Keyword(s):  
Pressure Fluctuation ◽  
Draft Tube ◽  
Guide Vane ◽  
Pump Mode ◽  
Pump Turbine ◽  
Flow Rates ◽  
Guide Vanes ◽  
Rotor Stator Interaction ◽  
Computational Fluid Dynamics Cfd ◽  
The Stability

This paper takes a pump-turbine as the research subject and, based on the Computational Fluid Dynamics (CFD) numerical method and combined with test data, investigates the pressure fluctuation characteristics in the pump mode and analyzes the pressure fluctuation characteristics at 0.75 Qd, 1.0 Qd and 1.25 Qd when the guide vane opening is 17.5°. The results showed that the protruding frequencies of pressure fluctuation in the bladeless region were mainly 5 fn, 10 fn and 20 fn, and the main frequencies in the runner area and near the outlet wall of the draft tube were 16 fn and 5 fn, respectively. At different heights for the guide vanes, the pressure fluctuation in the bladeless region had significant differences, and the pressure fluctuation near the bottom ring was the most intense. The amplitude of the rotor–stator interaction frequency continuously attenuates from the bladeless region to the outlet of the stay vanes, and the amplitude attenuation of each frequency is mainly concentrated in the area of the guide vanes. In this paper, the influence of different flow rates on the pressure fluctuation in the pump mode is analyzed, which provides a theoretical reference for the stability and further study of pump-turbines.

scholarly journals Analysis of Rotor-Stator Interaction of a Pump-Turbine with Splitter Blades in a Pump Mode

Mathematics ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1465 ◽  
Author(s):  
Haiqin Song ◽  
Jinfeng Zhang ◽  
Ping Huang ◽  
Haikun Cai ◽  
Puyu Cao ◽  
...  
Keyword(s):  
Radial Force ◽  
Stable Operation ◽  
Power Station ◽  
Pump Turbine ◽  
Main Frequency ◽  
Pulsation Amplitude ◽  
Depth Analysis ◽  
Rotor Stator Interaction ◽  
Guide Blade ◽  
Pumped Storage

The pump-turbine is the core component of a pumped storage power station. This paper considers an in-depth analysis of the rotor-stator interaction characteristics under computational fluid dynamics (CFD) and experimental measurements of pump-turbine with splitter blades used in a domestic pumped storage power station. The results show that as the guide blade opening increases, the rotor-stator interaction of the pump-turbine intensifies and the magnitude of the runner radial force and its pulsation amplitude as well as the magnitude of the guide blade water moment and its pulsation amplitude also increase. In addition, when the opening degree increases from 9.8° to 17.5°, the influence on the main frequency is mainly reflected in the phase change. While the opening degree increases from 17.5° to 24.8°, the influence on the main frequency is mainly reflected in the amplitude change. Moreover, the amplitude of 5fn at opening 9.8° and opening 24.8° is greater than the optimal opening 17.5°, indicating that deviation from the optimal opening will aggravate the difference of rotor-stator interaction between splitter blades and guide blades. In the paper, the influence of guide blade openings on the rotor-stator interaction between the splitter guide blade is studied, which provides a theoretical reference for the stable operation of the pump-turbine.

Mechanism and influence factors of hydraulic fluctuations in a pump-turbine

2021 ◽  
pp. 095765092110285
Author(s):  
Xiaolong Fu ◽  
Deyou Li ◽  
Hongjie Wang ◽  
Guanghui Zhang ◽  
Xianzhu Wei
Keyword(s):  
Guide Vane ◽  
Three Dimensional ◽  
Influence Factors ◽  
Simulation Method ◽  
Power Station ◽  
Pump Turbine ◽  
Available Energy ◽  
Exciting Forces ◽  
Pump Storage Power ◽  
Pumped Storage

Pumped-storage power technology is currently the only available energy storage technology in the grid net, and its reliability is receiving attention increasingly. However, when a pump-turbine unit undergoes runaway transitions, hydraulic fluctuations intensively affect the reliable operation of a pumped-storage power station. To reduce hydraulic fluctuations, this study investigated the formation mechanism of hydraulic fluctuations and explored its influence factors. In this study, a developed one-dimensional and three-dimensional (1 D-3D) coupling simulation method was adopted. Transient runaway transitions of a pump-turbine with three different inertias (0.5 J, 1 J, and 2.0 J) at three different guide vane openings (21°, 15°, and 12°, respectively) were simulated and compared. The results suggest that, at smaller guide vane openings (15° and 12°), water hammer owing to the increase in rotational speed is the primary unstable issue compared to the pulsation of radial hydraulic exciting forces on the runner. However, at a larger guide vane opening (21°), the latter owing to the back-flow near the runner inlet is the primary unstable issue. Moreover, it is found that a sufficiently large inertia improves the hydraulic fluctuations of the pump-storage power station, particularly in reducing the pulsation of radial hydraulic exciting loads on the runner. The findings of this study provide a valuable reference for determining suitable rotor inertia.

Experimental study of the pressure fluctuations in a pump turbine at large partial flow conditions

2012 ◽  
Vol 25 (6) ◽  
pp. 1205-1209 ◽  
Author(s):  
Hongjuan Ran ◽  
Xianwu Luo ◽  
Lei Zhu ◽  
Yao Zhang ◽  
Xin Wang ◽  
...  
Keyword(s):  
Experimental Study ◽  
Pressure Fluctuations ◽  
Flow Conditions ◽  
Pump Turbine
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