Application and evaluation of dynamic Bradshaw coefficient in shear stress transport turbulence model for hydraulic machinery DOI
Hao Wang, Fujun Wang, C.Y. Wang

et al.

Physics of Fluids, Journal Year: 2024, Volume and Issue: 36(7)

Published: July 1, 2024

The Bradshaw assumption, that the ratio of Reynolds shear stress to turbulence kinetic energy (TKE) is a constant roughly equal 0.3, introduced into eddy viscosity and TKE dissipation term transport model (SST). This calibrated by zero-pressure-gradient plate boundary layer test. not applicable rotating separation flows in hydraulic machinery, while its dynamic effects are usually ignored. In this article, comprehensive evaluation coefficient (DBC) SST conducted. First, theoretical analyses existing typical DBCs carried out, suitable expression form driven single number adopted view well-reflected high robustness. According equation structures SST, three strategies proposed, including only introducing DBC (SST-M1), (SST-M2), both (SST-M1 + M2). Second, classical case around hydrofoil employed evaluate application these strategies. results show SST-M1 exhibits severe lift/drag oscillations at large angles attack accompanied fluctuations, indicating poor numerical stability potential risk strategy. contrast, SST-M2 M2 can effectively improve deficiencies overestimating lift underestimating drag attack, which attributed promotion earlier larger flow separation. consistency between two implies plays key role enhancing prediction SST. Therefore, strategy recommended extend applicability for machinery.

Language: Английский

Energy dissipation mechanism of tip-leakage cavitation in mixed-flow pump blades DOI Open Access
Wei Li, Haoming Li, Mingjiang Liu

et al.

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

Citations

31
Large eddy simulations of cavitation around a pitching–plunging hydrofoil DOI Open Access
Ali Alavi, Ehsan Roohi

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

Published: Dec. 1, 2023

In this study, we numerically examine the behavior of NACA (National Advisory Committee for Aeronautics) 66 hydrofoil under combined oscillatory motion, considering different cavitation numbers. The large eddy simulation method is used turbulence modeling. vertical oscillation (combined oscillation) creates an effective angle attack, leading to reduced drag force. Our findings indicate that increasing speed leads a delayed onset and increased production cavity clouds. Moreover, increase in attack during motion decreases detachment length bubbles. Further investigations show on hydrofoil's surface can accelerate shift from laminar turbulent boundary layer, reinforcing layer's strength thereby delaying flow separation. Additionally, accurately terms vorticity transport equation research. It evident dilatation term forms near layers close correlates well with vapor volume fraction. This plays vital role inception process.

Language: Английский

Citations

33
Interaction mechanism between cloud cavitation and micro vortex flows DOI
Ning Qiu, Han Zhu, Bangxiang Che

et al.

Ocean Engineering, Journal Year: 2024, Volume and Issue: 297, P. 117004 - 117004

Published: Feb. 13, 2024

Language: Английский

Citations

15
A Multiscale Euler–Lagrange Model for High-Frequency Cavitation Noise Prediction DOI
Xincheng Wang, Mingtai Song, Huaiyu Cheng

et al.

Journal of Fluids Engineering, Journal Year: 2024, Volume and Issue: 146(6)

Published: Feb. 22, 2024

Abstract To simulate the microscale bubble distribution and its effect on high-frequency cavitation noise, we present a two-way transition coupling Euler–Lagrange model. The model accounts for both cavity fission environmental nucleation as sources of bubbles, which are limited in traditional mesh-based Euler models. We evaluate with experimental data truncated NACA0009 hydrofoil well measured size distributions, showing satisfactory results velocity distribution, patterns, power law scalings size. Based an acoustic analogy, find that produces sound waves smaller wavelengths higher frequencies than model, mainly attributed to two factors: (1) bubbles high natural frequency (2) intense multiple collapse/rebound behavior. This is promising predicting full-spectrum noise.

Language: Английский

Citations

14
Cavitation analysis of plunging hydrofoils using large eddy simulations DOI
Ali Alavi,

Maziyar Ghasemnezhad,

Ehsan Roohi

et al.

Ocean Engineering, Journal Year: 2024, Volume and Issue: 311, P. 118836 - 118836

Published: Aug. 10, 2024

Language: Английский

Citations

12
Insights into the characteristics of sheet/cloud cavitation and tip-leakage cavitation based on a compressible Euler-Lagrange model DOI
Xiaotao Zhao, Huaiyu Cheng, Bin Ji

et al.

Physical Review Fluids, Journal Year: 2024, Volume and Issue: 9(10)

Published: Oct. 15, 2024

Language: Английский

Citations

11
Numerical simulation of tip vortex cavitation using a multiscale method DOI

Xinzhen Qin,

Ben Zhang, Yang Li

et al.

International Journal of Multiphase Flow, Journal Year: 2025, Volume and Issue: unknown, P. 105183 - 105183

Published: Feb. 1, 2025

Language: Английский

Citations

2
Experimental investigation of the dynamic evolution of cavity during the free water-exit of a high-pressure venting vehicle DOI
Q. Zhang, Fu-Ren Ming, X. Liu

et al.

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

Published: Dec. 1, 2023

The underwater vehicle is subjected to complex hydrodynamic loads during water-exit process, which seriously affect the structural strength and stability of vehicle. This paper investigates effect high-pressure venting conditions on dynamic evolution characteristics cavity completely free a based self-designed experiments. Some novel phenomena are found in experiment, hypothesis constant acceleration established explain formation mechanism. results reveal that reentrant jet main factor influencing pattern development causes great differences between partial supercavity states. balance initial volume increase gas leakage rate fact increasing launch Froude number state does not cause significant changes size. There stable interval 0.0038 0.03 for entrainment coefficient cavity. influence morphology varies within different ranges. Besides, six patterns closure conditions. coupling interaction vortex tube most process. intervals roughly same. present study aims provide reference active flow control water-exit.

Language: Английский

Citations

20
Numerical investigation on cavitation and induced noise reduction mechanisms of a three-dimensional hydrofoil with leading-edge protuberances DOI Creative Commons
Chen Yang, Jinsong Zhang, Zhenwei Huang

et al.

Physics of Fluids, Journal Year: 2024, Volume and Issue: 36(5)

Published: May 1, 2024

In this work, a National Advisory Committee for Aeronautics 66 hydrofoil with leading-edge protuberances is designed. The large eddy simulation combined the Schnerr–Sauer cavitation model used to obtain satisfactory result as compared experimental measurement, integrating permeable Ffowcs Williams–Hawkings equation cavitation-induced noise analysis. It found that special geometric structure deflects incoming flow, creating two counter-rotating streamwise vortices at peak shoulders. These lead upwash and downwash effects alter pressure distribution on suction side. low localized in trough facilitates advancement of while severely limiting spanwise development cloud cavity, shortening evolution by about 20% reducing maximum volume 35%. Analysis using vorticity transport indicates different splitting terms play dominant roles stages evolution. Although induces disturbances primary vortex, effect limited. Acoustic shows bionic can reduce total sound level 7.8–8.3 dB. spherical reduction not effective expected due similar acceleration processes hydrofoils. However, fluctuation caused collapse cavity reduced suppression, which reduces linear noise. addition, suppress generation large-scale vortex systems transform them into smaller ones, resulting correlation coherence shedding vortices. This critical factor reduction. Finally, we hypothesize unstable related regions. increase momentum exchange within boundary layer, affecting its stability weakening acoustic feedback loop.

Language: Английский

Citations

9
Tip vortex suppression by using dimpled roughness DOI
Yang Li, Lingxin Zhang, Fuqiang Deng

et al.

Ocean Engineering, Journal Year: 2024, Volume and Issue: 299, P. 117348 - 117348

Published: March 4, 2024

Language: Английский

Citations

8