Mechanism of runner high-pressure side on stall characteristics at typical unsteady operating points in both modes of a pump turbine

Physics of Fluids, Journal Year: 2023, Volume and Issue: 35(7)

Published: July 1, 2023

Stall phenomenon, a classical physical phenomenon which is located in the vaneless region of pump–turbine and accompanied by complex vortex evolution process, strongly related to formation hump unsteady at pump mode S turbine mode. In present paper, detached eddy simulation model employed numerically investigate impact runner high-pressure side (HPS) on stall characteristics typical operating points, namely, valley point runaway It found that both investigated points are obviously changed: For point, only three fixed cells exist original plan, while four additional rotating appear rotate speed 0.02nr (nr, rotation speed) optimized plan (OPT). The distinctive coexistence reported for first time attributed controlled HPS; intensity frequency characteristic slightly increased OPT. Moreover, HPS can effectively decrease backflow shroud, resulting significant relative rate within complete flow period, 17.3% 4.8% point. Finally, local hydraulic loss (LHLR) method adopted it high LHLR OPT more concentrated circumferential direction radial vanless points. Based with proposed many might be eliminated some extent.

Language: Английский

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Cross influence of rotational speed and flow rate on pressure pulsation and hydraulic noise of an axial-flow pump

Physics of Fluids, Journal Year: 2023, Volume and Issue: 35(9)

Published: Sept. 1, 2023

Axial-flow pumps may experience significant pressure pulsation and high hydraulic noise when deviating from design conditions, this article investigates the cross influence of rotational speed flow rate on inlet an axial-flow pump based coherence theory through physical model experiments. The energy amplitude is directly proportional to inversely rate, as increases, distribution blade passage frequency (fBPF) within different bands improves. Pressure overall natural device work together define primary secondary frequencies sound level, these eventually move toward 2fBPF, coefficient at fBPF 2fBPF above 0.9. To reduce noise, both should be given sufficient attention.

Language: Английский

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Optimization of a centrifugal pump with high efficiency and low noise based on fast prediction method and vortex control

Energy, Journal Year: 2023, Volume and Issue: 289, P. 129835 - 129835

Published: Dec. 11, 2023

Language: Английский

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A 3D Computational Fluid Dynamics and Acoustics Simulation Approach for Noise Mitigation Prediction in Gerotor Pumps

SAE technical papers on CD-ROM/SAE technical paper series, Journal Year: 2024, Volume and Issue: unknown

Published: April 9, 2024

<div class="section abstract"><div class="htmlview paragraph">Positive displacement pumps are key components in automotive and hydraulic fluid systems, often serving as the primary power source a major of noise both on-highway off-highway vehicles. Specifically, gerotor widely utilized vehicle coolant, lubricating, other systems for conventional electric powertrains. This study introduces novel method predicting by combining Computational Acoustics (CA) approach with 3D Fluid Dynamics (CFD) approach, implemented Simerics–MP+ code. The CFD simulation includes detailed transient motion rotors (including related mesh motion) models intricate cavitation/air release phenomena at varying pump speeds. acoustic employs Ffowcs–Williams Hawkings (FW–H) integral formulation to predict sound generation propagation based on flow field predictions from model.</div><div paragraph">Simulations two different designs were conducted under wide range operating conditions, resulting prediction full pressure spectra across various frequencies. These results compared measurements, revealing that can effectively relative distribution frequency spectrum. Notably, mitigation specific regions frequency–RPM spectrum was accurately captured. paper provides comprehensive insight into modeling methodology, experimental measurement methods, compares obtained simulations experiments. proposed harnesses ability obtain detailed, high–fidelity solutions positive machines demonstrates excellent potential improvements design changes. Thus, it offers valuable insights designing quieter pumps.</div></div>

Language: Английский

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Correlation between hydraulic loss and characteristic vorticities in a mechanical pump

Physics of Fluids, Journal Year: 2023, Volume and Issue: 35(6)

Published: June 1, 2023

The correlative mechanism between the flow loss and vortex evolution involves efficiency stability of space operations during fuel transportation in on-orbit refueling circulation systems. This study described detailed hydraulic characteristic vorticity by adopting entropy wall function local rate method that included dissipation effects. Combined with correlation analysis, characterized parameters distributions dissipated transported were compared based on enstrophy rigid transport equation. results exhibit although occupied a main proportion total loss, cannot be ignored. for shear strength are dominant factors affecting effects respectively. Both strongly related to weakly vorticity. However, two was significantly enhanced. Based this, four sub-items strength, including stretching, dilatation, pseudo-Lamb vector, viscous terms, further investigated elaborate source loss. correlations vector almost identical indicating is mainly derived from shearing motion acceleration

Language: Английский

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The aerodynamic and noise characteristics of centrifugal fan with partially tilted tongue

Physics of Fluids, Journal Year: 2023, Volume and Issue: 35(12)

Published: Dec. 1, 2023

Tilted tongue is one of the very effective solutions to reduce noise centrifugal fans. In this study, accuracy numerical simulations verified by experimentally measured aerodynamic performance and acoustic spectra. Two localized tilting designs are proposed with aim reducing fan. Numerical results show that different approaches significantly affect reduction fan, best design exhibiting up 2.33 dB reduction. The internal flow fields analyzed in conjunction dynamic modal decomposition method reveal effect local tilt on characteristics structural change induces separation vortices at trailing edge blades generation secondary outlet wall volute shell, which main reason for slight degradation causes blade passage frequency (BPF) not identical orders. BPF stems from diminishing source intensity dispersing phase. Noise 2BPF mostly due weakening sound intensity, less conspicuous phase dispersion. This study provides good theoretical support backward curved fans context

Language: Английский

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Investigation of flow-induced sound source generation in a centrifugal pump

Journal of Physics Conference Series, Journal Year: 2024, Volume and Issue: 2752(1), P. 012109 - 012109

Published: June 1, 2024

Abstract This study investigates the mechanism of sound source generation in a centrifugal pump under different flow conditions. The calculated results are good agreement with experimental data by employing delayed detached eddy simulation and flow-acoustic coupling method to compute flow-induced noise. Based on vortex theory vorticity binary decomposition, (STA) is divided into shear-induced (STS) rigid rotation-induced (STR). show that induced shear main factor. fluctuation amplitude STS can be nine times larger than STR at monitor point near tongue design rate condition. There mutual cancellation effect between STR. STA blade passing frequency 86% high conditions, indicating sometimes rotation suppress noise generation.

Language: Английский

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Effects of increasing the gap ratio on performance and pressure pulsations in a mixed-flow reactor coolant pump

Annals of Nuclear Energy, Journal Year: 2024, Volume and Issue: 211, P. 110985 - 110985

Published: Oct. 17, 2024

Language: Английский

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