Rotating stall mechanism of pump-turbine in hump region: An insight into vortex evolution

Xu, Lianchen; Kan, Kan; Zheng, Yuan; Liu, Demin; Binama, Maxime; Xu, Zhe; Yan, Xiaotong; Guo, Mengqi; Chen, Huixiang

doi:10.1016/j.energy.2024.130579

Cited by 17 publications

(1 citation statement)

References 36 publications

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“…In contrast to the general form of the N-S equation, the physical quantities in the RANS equations are all averaged (including temporal and spatial averages). The RANS equations are as follows [20][21][22][23].…”

Section: Theoretical Analysismentioning

confidence: 99%

Numerical Investigation of Micrometer-Sensitive Particle Intrusion in Hydraulic Valve Clearances and Its Impact on Valve Performance

Zhang,

Ji,

Zhao

et al. 2024

Processes

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The intrusion of micrometer-sensitive contaminant particles into the clearance of sliding valves within hydraulic fluids is one of the root causes of valve sticking and reliability issues in hydraulic systems. To reveal the transient process and characteristics of particle intrusion into the clearance process, this paper proposes a numerical method for fluid–particle one-way coupling and verifies it through experimentation. Furthermore, a numerical simulation of the motion trajectory of spherical iron particles inside the valve chamber was conducted in a two-dimensional flow model. It was discovered that in a steady-state flow field with a certain valve opening, micrometer-sized particles in the valve chamber’s hydraulic fluid mainly move with the valve flow stream, and the number of micron particles invading the slide valve clearance and the probability of invasion is related to the slide valve opening and differential pressure. When the slide valve opening decreases, especially in the small opening state, the probability of particles invading the slide valve clearance will increase dramatically, and the probability of invading the clearance is as high as 27% in a valve opening of 50 μm; the larger the pressure difference between the valve ports, the more the number of particles invading the slide valve clearance increases; the particles in the inlet of the slide valve clearance are more prone to invade the slide valve clearance, and invade in an inclined way, touching the wall and then bouncing back. These findings are of great value for the design of highly reliable hydraulic control valves and the understanding of the mechanism of slide valve stalls and provide an important scientific basis for the optimization and improvement in the reliability of hydraulic systems.

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Section: Theoretical Analysismentioning

confidence: 99%

Numerical Investigation of Micrometer-Sensitive Particle Intrusion in Hydraulic Valve Clearances and Its Impact on Valve Performance

Zhang,

Ji,

Zhao

et al. 2024

Processes

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Research on the technical improvement of the turbine runner of a power station based on improving stability

Li,

Yao,

Pang

et al. 2024

Energy Science & Engineering

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In view of problems such as the narrow efficiency area, large hydraulic vibration area, pressure pulsation, and serious sediment wear of turbines at the Futang hydropower station, the technical transformation of turbine runners was carried out by modifying the blade shape and increasing the blade thickness, and a combination of numerical simulations based on shear stress transport k–ω turbulence model and tests was adopted to improve the operational stability of power station units. Calculation and testing demonstrate an enlargement of the high‐efficiency zone. Specifically, the optimal efficiency of the runner increases by 0.37%, while the rated efficiency rises by 0.19%. Significant reductions are observed in pressure pulsation within the draft tube and vaneless area decrease of approximately 50%. There is a high‐frequency pressure pulsation in the vaneless zone and the runner under low‐load conditions, and the influence of dynamic and static interference gradually weakens with the increase of opening. The draft tube is prone to eccentric vortex bands under partial working conditions, which causes the unit to be affected by low‐frequency pulsation. This optimization also leads to a notable decrease in runner blade wear, with the maximum sand and water velocity reduced from 45 to 40 m/s, resulting in a 30% reduction in sand wear. Moreover, there is a substantial enhancement in the runner's stiffness, with the thickness of the blade near the high stress area of the upper crown and lower ring increasing by over 50%, and the weight of each individual blade increasing by more than 50%. These research findings validate that modifying the runner blade effectively improves flow patterns, reduces eddy current generation, minimizes pressure pulsation, widens the high‐efficiency zone, decreases wear, and enhances the operational stability of the unit. The technical transformation method and research results of this study have important guiding significance for similar technical transformation of other power stations

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Analysis of wake and power fluctuation of a tidal current turbine under variable wave periods

Wang,

Zhang,

Zhang

et al. 2024

Energy

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Rotating stall mechanism of pump-turbine in hump region: An insight into vortex evolution

Cited by 17 publications

References 36 publications

Numerical Investigation of Micrometer-Sensitive Particle Intrusion in Hydraulic Valve Clearances and Its Impact on Valve Performance

Numerical Investigation of Micrometer-Sensitive Particle Intrusion in Hydraulic Valve Clearances and Its Impact on Valve Performance

Research on the technical improvement of the turbine runner of a power station based on improving stability

Analysis of wake and power fluctuation of a tidal current turbine under variable wave periods

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