Numerical Investigation of Symmetrical and Asymmetrical Characteristics of a Preloading Spiral Case and Concrete during Load Rejection DOI Open Access
Zhenwei Zhang,

Yutong Luo,

Guisheng Yang

et al.

Symmetry, Journal Year: 2024, Volume and Issue: 16(10), P. 1277 - 1277

Published: Sept. 27, 2024

During the transient process of load rejection, hydraulic pressure applied to pump-turbine and plant concrete changes dramatically induces high dynamic stress on spiral case. The preloading case has been widely used in large-scale pumped-storage power stations due its excellent load-bearing capacity. However, studies impact structural response during rejection are still few number. In this paper, 3D flow domain models a prototype designed analyze characteristics flow-induced behavior steel under different pressures rejection. results show that asymmetric design logarithmic lines ensures an axially symmetric potential within with uniform distribution. Higher provides larger clearance, leading greater deformation stress, their maximum values located at mandoor inner edge, respectively. combined effect asymmetrical shape, internal unbalanced force leads clearance distribution, resulting distribution along axial direction but symmetrical characteristic near waistline response. Stress variations sections between share similar It follows same trend as lower pressures, while there is delayed peak contact phenomenon when reaches static head. conclusions provide scientific guidance for optimizing selection stable operation units.

Language: Английский

Impact of the motion effect of the cutoff facility on the dynamic energy loss of the prototype axial flow pump system during the startup process DOI
Xiaowen Zhang, Giorgio Pavesi, Chongyang Hu

et al.

Physics of Fluids, Journal Year: 2025, Volume and Issue: 37(1)

Published: Jan. 1, 2025

Large pumping systems have emerged as one of the primary areas energy consumption. During startup process (SUP) axial flow pump system (AFPS), a complex interaction unfolds involving motion cutoff facilities (COF), acceleration pump, and phenomenon dissipation. The kinematic characteristics COF significantly influence patterns, dynamic loads, transfer experienced by system. This study investigates dissipation mechanism prototype AFPS (PAFPS) during SUP, utilizing combination experiments on engine starting characteristics, computational fluid dynamics, in-field measurements PAFPS. Two modes are compared, revealing that accelerated gate opening improves transition efficiency reduces Key findings highlight minimizes turbulence-induced losses near exit suppresses high entropy production regions in impeller domain, leading to smoother more energy-efficient operations. These insights offer actionable strategies enhance performance SUP.

Language: Английский

Citations

0
Numerical investigation of no-load startup in a high-head Francis turbine: Insights into flow instabilities and energy dissipation DOI Open Access
Longgang Sun, Lei Liu, Zhuofei Xu

et al.

Physics of Fluids, Journal Year: 2024, Volume and Issue: 36(3)

Published: March 1, 2024

The presented paper numerically investigates the internal flow behaviors and energy dissipation during no-load startup process toward a Francis turbine. Passive runner rotation is implemented through angular momentum balance equation accompanied by dynamic mesh technology user defined function. Three phases of rotational speed are identified: stationary, rapid increase, slow increase. Head exhibits monotonic decrease, rise fall, eventual fluctuation. Flow rate shows quasi-linear pressure fluctuations in vaneless region primarily dominated frequencies induced Rotor-Stator Interaction broad frequency range below 50 Hz, 30 Hz draft tube. Runner inlet experiences positive to negative incidence angles, causing intense separation unstable structures. Draft tube large-scale recirculation evolving vortex Energy loss analysis based on entropy production method highlights as primary contributors. within an initial subsequent then again stationary increase phases. While phase Turbulent significantly contribute loss, with trends matching total production. Maximum locations correspond wall, emphasizing importance generation. This study establishes foundational insights into hydrodynamics modes hydraulic turbine startup, paving way for further research.

Language: Английский

Citations

3
Dynamic behavior and energy dissipation analysis of pump turbine in unstable S characteristic zone DOI
Pengcheng Guo, Yanyan Li, Longgang Sun

et al.

Journal of Energy Storage, Journal Year: 2024, Volume and Issue: 102, P. 114275 - 114275

Published: Oct. 21, 2024

Language: Английский

Citations

2
Numerical assessment of transient flow and energy dissipation in a Pelton turbine during startup DOI
Longgang Sun,

Z Wang,

Hengte Zhou

et al.

Physics of Fluids, Journal Year: 2024, Volume and Issue: 36(9)

Published: Sept. 1, 2024

The Pelton turbine, known for its high application water head, wide efficient operating range, and rapid start-stop capability, is ideal addressing intermittent stochastic load issues. This study numerically analyzes the transient two-phase flow energy dissipation during startup of a turbine. Dynamic mesh technology controlled nozzle opening changes, momentum balance equations managed runner rotation. Findings showed that speed initially increased rapidly then more slowly, rate matched variations. Runner torque first rose linearly, decreased, with fastest decline closing. Hydraulic efficiency peaked early in reduction but dropped sharply. Strong vortices formed due to upstream inflow downstream backflow impact distributor pipe. jet needle guide vane improved converging section nozzle, began diffuse stroke. Initially, spread fully on bucket surface, later only affected tips. Pressure fluctuations supply mechanism were primarily motion, higher amplitude movement lower when stationary. These propagated upstream, weakening over distance. Reynolds stress work turbulent kinetic generation, respectively, dominated transmission dissipation, their maximum contribution exceeding 96% 70%. High-energy clusters corresponded positions, highlighting jet-bucket interference as crucial transport. established performance evaluation method turbine startups, supporting further investigation into characteristic parameters, evolution, patterns.

Language: Английский

Citations

1
Instability mechanism and vibration performance of a pumped storage power station under runaway conditions DOI
Yi Liu, Xiaodong Yu,

WeiXin Qiu

et al.

Physics of Fluids, Journal Year: 2024, Volume and Issue: 36(10)

Published: Oct. 1, 2024

With the large-scale access of renewable energy to grid, load rejection pumped storage power stations (PSPSs) has become increasingly frequent, thus increasing possibility runaway accidents. This study aimed investigate instability mechanism and vibration performance a PSPS by considering coupling effect pressurized pipe pump-turbine under condition. First, models based on elastic water-column (elastic model) rigid (rigid were established. Subsequently, performances compared. The comparison revealed that characteristics mainly manifested as high-frequency large-amplitude caused water-column, which was not observed in model. Therefore, elasticity normally been neglected or simplified using previous studies, significant stability. Finally, effects other factors stability clarified. determined operating point. discharge-head relationship coefficient (S5) for quantifying point extracted. Moreover, friction loss could suppress instability. Additionally, water inertia only affected but result. Overall, findings deepen understanding physical nature provide guidance runner design stable operation PSPSs.

Language: Английский

Citations

1
Effect of the Motion Characteristics of the Cut-Off Facility on the Prototype Axial Flow Pump System Dynamic Energy Loss During Start-Up Process DOI
Xiaowen Zhang, Giorgio Pavesi, Zhe Xu

et al.

Published: Jan. 1, 2024

Download This Paper Open PDF in Browser Add to My Library Share: Permalink Using these links will ensure access this page indefinitely Copy URL DOI

Language: Английский

Citations

0
Numerical Investigation of Symmetrical and Asymmetrical Characteristics of a Preloading Spiral Case and Concrete during Load Rejection DOI Open Access
Zhenwei Zhang,

Yutong Luo,

Guisheng Yang

et al.

Symmetry, Journal Year: 2024, Volume and Issue: 16(10), P. 1277 - 1277

Published: Sept. 27, 2024

During the transient process of load rejection, hydraulic pressure applied to pump-turbine and plant concrete changes dramatically induces high dynamic stress on spiral case. The preloading case has been widely used in large-scale pumped-storage power stations due its excellent load-bearing capacity. However, studies impact structural response during rejection are still few number. In this paper, 3D flow domain models a prototype designed analyze characteristics flow-induced behavior steel under different pressures rejection. results show that asymmetric design logarithmic lines ensures an axially symmetric potential within with uniform distribution. Higher provides larger clearance, leading greater deformation stress, their maximum values located at mandoor inner edge, respectively. combined effect asymmetrical shape, internal unbalanced force leads clearance distribution, resulting distribution along axial direction but symmetrical characteristic near waistline response. Stress variations sections between share similar It follows same trend as lower pressures, while there is delayed peak contact phenomenon when reaches static head. conclusions provide scientific guidance for optimizing selection stable operation units.

Language: Английский

Citations

0