Fluid-induced vibration evolution mechanism of multiphase free sink vortex and the multi-source vibration sensing method

Mechanical Systems and Signal Processing, Journal Year: 2022, Volume and Issue: 189, P. 110058 - 110058

Published: Dec. 30, 2022

Language: Английский

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Energy performance evaluation of an axial-flow pump as turbine under conventional and reverse operating modes based on an energy loss intensity model

Physics of Fluids, Journal Year: 2022, Volume and Issue: 35(1)

Published: Dec. 21, 2022

As a low-cost scheme for small-scale hydropower generation, pump as turbines (PATs) are used at different hydrosites around the world. Nevertheless, big number of recently conducted studies on PAT performance have mainly focused centrifugal type, despite fact that axial-flow type has comparatively large flow capacity, thus disposing higher power density. Therefore, this article seeks to investigate dynamics an and associated energy loss characteristics, under both turbine operating modes. It adopts numerical simulation method uses entropy production theory propose intensity model in cylindrical coordinate system, which quantitatively gives spatial variation pattern losses In addition, correlation between instability is deeply analyzed, where characteristics modes evaluated. shown within impeller guide vane fields, modes, because turbulent production. The proportion direct wall found be relatively small. velocity gradient, vorticity, turbulence intensity, passages been closely related. However, owing difference there significant location losses. unstable phenomena, such impact blade inlet, deviation outlet, separation, back-flow, vortex, main reasons This study serves reference design, optimization, application PATs.

Language: Английский

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Dynamic behaviors of multiphase vortex-induced vibration for hydropower energy conversion

Energy, Journal Year: 2024, Volume and Issue: 308, P. 132897 - 132897

Published: Aug. 22, 2024

Language: Английский

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Energy dissipation mechanism of tip-leakage cavitation in mixed-flow pump blades

Physics of Fluids, Journal Year: 2024, Volume and Issue: 36(1)

Published: Jan. 1, 2024

Tip leakage flow is one of the significant factors influencing internal stability mixed-flow pumps, and in severe cases, it can lead to channel blockage energy loss. In order gain a deeper understanding dissipation mechanism induced by tip vortex cavitation, this study based on Wray–Agarwal (WA) turbulence model homogeneous model, investigating cavitation characteristics pumps. Additionally, entropy production theory employed evaluate losses within pump analyze components loss impeller guide vanes. The research results reveal that with increasing intensity, low-pressure region at leading edge blade extends toward trailing edge, static pressure distribution blade's side. Leakage spatial vortices move closer suction side intensity. Cavitation primarily affects region, turbulent being main source High zones are concentrated blade, correlating recirculation trailing-edge vortices. This provides theoretical insights practical implications for enhancing performance offering valuable guidance design operation.

Language: Английский

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Study on the Bubble Collapse Characteristics and Heat Transfer Mechanism of the Microchannel Reactor

Processes, Journal Year: 2025, Volume and Issue: 13(1), P. 281 - 281

Published: Jan. 20, 2025

Microreactors have the advantages of high heat and mass transfer efficiency, strict control reaction parameters, easy amplification, good safety performance, been widely used in various fields such as chip manufacturing, fine chemicals, biomanufacturing. However, narrow microchannels microreactors often become filled with catalyst particles, leading to blockages. To address this challenge, study proposes a multiphase flow model based on lattice Boltzmann method (LBM) investigate dynamic changes during bubble collapse process temperature distribution regularities. Based developed three-phase dynamics model, delves into shock evolution analyzes Then, patterns under different particle density conditions are explored. The found that action wave, stable structure liquid film is destroyed, deforms collapses. At moment collapse, energy rapidly transferred from potential kinetic field. Subsequently, converted pressure waves. This results rapid generation extremely field, creating high-velocity jets intense turbulent vortices, which can enhance effects flows. certain phenomenon will be formed at region relatively chaotic random. waves generated significant impact motion trajectories while influence high-density particles small. offer theoretical basis for understanding mechanisms flow. Moreover, these findings practical implications advancing technologies industrial applications, including manufacturing chemical transport.

Language: Английский

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Investigate on the Fluid Dynamics and Heat Transfer Behavior in an Automobile Gearbox Based on the LBM-LES Model

Lubricants, Journal Year: 2025, Volume and Issue: 13(3), P. 117 - 117

Published: March 10, 2025

With the rapid development of new energy vehicle market, demand for efficient, low-noise, low-energy consumption, high-strength, and durable gear transmission systems is continuously increasing. Therefore, it has become imperative to conduct in-depth research into fluid heat transfer lubrication dynamics within gearboxes. In systems, interaction between fluids solids leads complex nonlinear characteristics gears lubricants, making resolution gearbox thermodynamic models highly challenging. This paper proposes a model based on LBM-LES coupling study dynamic laws process. The results indicate that intense shear effects caused by high speeds generate vortices, which are particularly pronounced larger gears. mixing effect in these vortex regions better, achieving more uniform dissipation effect. Furthermore, flow lubricant closely related speed temperature. Under high-temperature conditions (such as 100 °C), diffusion range increases, forming wider oil film, but its viscosity significantly decreases, leading greater stirring losses. By optimizing selection lubricants parameters, efficiency reliability system can be further improved, extending service life. provides comprehensive analytical framework multi-stage clarifying mechanisms offering insights theoretical foundations future engineering applications this field.

Language: Английский

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Effect of Different Guide Vane Configurations on Flow Field Investigation and Performances of an Axial Pump Based on CFD Analysis and Vibration Investigation

Experimental Techniques, Journal Year: 2023, Volume and Issue: 48(1), P. 69 - 88

Published: April 7, 2023

Language: Английский

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Spatial-temporal evolution of tip leakage cavitation with double-hump in a mixed flow pump with tip clearance

Physics of Fluids, Journal Year: 2023, Volume and Issue: 35(4)

Published: April 1, 2023

Tip clearance in pump induces tip leakage vortex (TLV), which interacts with the main flow and leads to instability of pattern decrease performance. In this work, a closed-loop experimental rig high-speed observation for mixed is established, numerical simulation on cavitation conducted validation. A new double-hump first observed pump. Results show that primary develops from linear banded and, finally, pattern. The spatial–temporal evolution can be classified into four stages: incepting stage, growing merging propagating stage. inception front hump found correspond periodic specific passage vortex-tip (PV-TLV) pair. Affected by propagation high-pressure area at outlet, PV wanders downstream passage, greatly affects intensity flow. away motion brings stronger results intensified TLV lower core pressure. As result, incepts, grows, travels downstream. Finally, it merges rear together propagates passage.

Language: Английский

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Unstable pressure fluctuations in the vaneless space of high-head reversible pump-turbines – A systematic review

Journal of Energy Storage, Journal Year: 2023, Volume and Issue: 72, P. 108397 - 108397

Published: July 20, 2023

Language: Английский

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Flow instability and energy performance of a coastal axial-flow pump as turbine under the influence of upstream waves

Energy, Journal Year: 2023, Volume and Issue: 272, P. 127121 - 127121

Published: March 6, 2023

Language: Английский

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