Pressure pulsation in small opening operating mode of pump turbine’s turbine mode

Liao, Weili; Lei, Xu; Zhao, Yaping; Ruan, Hui; Li, Z H

doi:10.1088/1755-1315/163/1/012051

Cited by 4 publications

(6 citation statements)

References 1 publication

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Section: Unsteady Pressure Characteristics Of the Inter-blade Vortex mentioning

confidence: 71%

“…This result can be interpreted to indicate that unsteady pressure characteristics were induced by the development and revolution of the vortex rope. Liao et al [12] and Kirschner et al [14] observed similar unsteady pressure characteristics in the low-frequency region due to a vortex rope by numerical analysis. In order to indicate the unsteady pressure characteristics along the flow direction in the draft tube, Figure 21 compares the unsteady pressures that occurred with GVAs of 21.5°, 12.5°, and 7°, at the measuring points of p1 through p4 at the location L1 indicated in Figure 4.…”

Section: Unsteady Pressure Characteristics Of the Inter-blade Vortex mentioning

confidence: 71%

“…Yan et al [11] conducted unsteady state incompressible analyses on a reduced-scale radial pump-turbine model in turbine mode at off-design conditions to predict the amplitude of the normal forces on the impeller. Liao et al [12] investigated pressure pulsations in the small-opening operation mode of a pump-turbine, with and without consideration of the weak compressibility of water, to observe the internal flow and pressure characteristics in the runner passages and draft tube.…”

Section: Introductionmentioning

confidence: 99%

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Inter-Blade Vortex and Vortex Rope Characteristics of a Pump-Turbine in Turbine Mode under Low Flow Rate Conditions

Kim

Suh

Choi

et al. 2019

Water

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Pump-turbines are often used to provide a stable power supply with a constant frequency in response to intermittent renewable energy resources. However, existing pumped-storage power stations often operate under off-design conditions because of the increasing amounts of inconsistent renewable resources that have been added to the grid. Under off-design low flow rate conditions, inter-blade vortex and vortex rope phenomena usually develop in the runner and draft tube passages, respectively, in turbine mode. These vortices cause complicated flow patterns and pressure fluctuations that destabilize the operation of the pump-turbine system. Therefore, this study investigates the influence of correlation between the inter-blade vortex and vortex rope phenomena under low flow rate conditions. Three-dimensional steady- and unsteady-state Reynolds-averaged Navier–Stokes equations were calculated with a two-phase flow analysis using a shear stress transport as the turbulence model. The inter-blade vortices in the runner passages were captured well at the low flow rate conditions, and the vortex rope was found to develop within a specific range of low flow rates. These vortex regions showed a blockage effect and complicated flow characteristics with backflow in the passages. Moreover, higher unsteady pressure characteristics occurred at locations where the vortices were especially pronounced.

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Section: Unsteady Pressure Characteristics Of the Inter-blade Vortex mentioning

confidence: 71%

Section: Unsteady Pressure Characteristics Of the Inter-blade Vortex mentioning

confidence: 71%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Inter-Blade Vortex and Vortex Rope Characteristics of a Pump-Turbine in Turbine Mode under Low Flow Rate Conditions

Kim

Suh

Choi

et al. 2019

Water

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“…As an illustration, Svarstadand and Nielsen [12] measured the pressure pulsation variation in reversible pump turbines, both in the laboratory and in the field, when transitioning from the pump to turbine conditions and found that the highest-pressure pulsation amplitude occurred at the back pump condition. Liao et al [13] investigated the low compressibility of water and simulated the steady and unsteady internal flow under turbine conditions and found that under the condition of a small blade opening, large pressure fluctuations were observed in both the bladeless zone and the draft tube [14]. Through these studies, we can conclude that the pressure fluctuation in the vaneless area and in the draft tube is the highest.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Flow and Runner Dynamic Response Characteristics under Pump Conditions of Variable-Speed Pump Turbine

Shang

Cao

Wang

et al. 2023

JMSE

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Pumped storage power stations can ensure the safe operation of the grid, as well as utilize clean energy sources to establish a low-carbon, safe, and efficient energy system. As pump turbines, the core components of pumped storage power plants, become more and more popular, the technical requirements for hydraulic design begin to improve year by year. However, when the unit operates far beyond the optimal range, the variable-speed pump turbine can overcome the shortcomings of the fixed-speed unit and solve the problem of unstable operation under partial load. The pressure pulsation of the unit in the pump condition is investigated by numerical simulation, analyzing the hydraulic thrust, and studying the dynamic response characteristics of the runner at a maximum speed of 456.5 rpm. Comparing the pressure pulsation amplitude of various components in the entire flow passage, the highest values of pressure pulsation were found in the runner and vaneless space. The axial hydraulic thrust has a fluctuation range between 174t and 198t and 0t to 40t for radial force. As per the structural analysis, it has been observed that the runner demonstrates uneven patterns in both its axial and radial deformations, with deformation mainly concentrated in radial displacement and stress distribution mainly concentrated on the blades near the crown. The dynamic stress amplitude of the runner at monitoring point S1 (located on the runner blade near the crown) is 37 MPa. This stress has a dominant frequency of 4.8fn, while the monitoring point S2 (located on the runner blade near the band) is 4 MPa, and the dominant frequency is 1.8fn. Using these findings, the design of the variable-speed pump turbine’s runner can be optimized, and the unit’s stable and secure operation can be guided accordingly.

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“…Svarstadand and Nielsen [19] performed laboratory and field measurements of reversible pump turbines during the transition process and concluded that the pressure pulsation changes during the rapid switch from pump mode to turbine mode had a small amplitude but a significant numerical value. Liao et al [20] conducted research on the low compressibility of hydraulic fluids and simulated both stable and unstable internal flow conditions in turbines. They found significant pressure fluctuations in both the runner region and the draft tube under conditions of small blade openings.…”

Section: Introductionmentioning

confidence: 99%

Hydraulic Characterization of Variable-Speed Pump Turbine under Typical Pumping Modes

Shang,

Cao,

Wang

et al. 2023

Processes

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The pump turbine is a crucial component of pumped storage hydropower plants. When operated at a constant speed, it does not respond well to variations in the grid frequency. To improve the hydraulic efficiency of pumped storage units, variable-speed units have been introduced. However, the mechanism of variable-speed pump turbines has not been extensively studied numerically. In this study, the flow characteristics of a variable-speed pump turbine were computed under two typical pumping modes, the maximum head and minimum flow rate condition, as well as the minimum head and maximum flow rate condition. The computed results aligned with experimental results, and the changing trends of hydraulic thrust under these two pumping modes were discussed. The error for the Hmax, Qmin condition was 1.3%, and the error for the Hmin, Qmax condition was −1.9%. These error values fell within a reasonable range. The research findings indicate that in the Hmax, Qmin condition, the flow within the flow passage exhibited higher velocity, which was 84.87 m/s, increased flow turbulence, larger pressure fluctuations, and poorer unit stability. On the other hand, in the Hmin, Qmax condition, both the axial hydraulic thrust and radial forces were greater, and there were sudden changes in the extreme values of pressure fluctuations over a certain period of time. It is recommended to avoid operating the variable-speed pump turbine under these two conditions during pumping operations.

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Pressure pulsation in small opening operating mode of pump turbine’s turbine mode

Cited by 4 publications

References 1 publication

Inter-Blade Vortex and Vortex Rope Characteristics of a Pump-Turbine in Turbine Mode under Low Flow Rate Conditions

Inter-Blade Vortex and Vortex Rope Characteristics of a Pump-Turbine in Turbine Mode under Low Flow Rate Conditions

Analysis of Flow and Runner Dynamic Response Characteristics under Pump Conditions of Variable-Speed Pump Turbine

Hydraulic Characterization of Variable-Speed Pump Turbine under Typical Pumping Modes

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