Laser-induced cavitation bubble near boundaries

Journal of Hydrodynamics, Год журнала: 2023, Номер 35(5), С. 858 - 875

Опубликована: Окт. 1, 2023

Язык: Английский

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Theoretical and experimental investigation of a bubble collapsing near an asymmetric hydrofoil

Physics of Fluids, Год журнала: 2024, Номер 36(2)

Опубликована: Фев. 1, 2024

In the present paper, restricted cavitation bubble dynamics near an asymmetric Joukowsky hydrofoil are investigated theoretically and experimentally. This investigation employs conformal transformation, image method, Kelvin impulse model, together with high-speed photographic experiments. The characteristics of collapse deformation wall movement analyzed qualitatively quantitatively, spatial distributions liquid velocity revealed by theoretical predictions. main conclusions include (1) deformations can be divided into three typical cases: penetrating (mostly occurs when γ<2 γ defined as bubble-hydrofoil dimensionless distance), triangular depression 2<γ<4), arc-shaped γ>4). (2) acting on is governed a point source sink, which dominant, inversely correlated distance, corresponds to experimental results. (3) exhibits different at tail, head, middle regions hydrofoil, angle remains basically unchanged in concave region hydrofoils (i.e., range 240°<θz<350° θz position angle).

Язык: Английский

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Dynamic behaviors of a bubble near a rectangular wall with a bulge

Physics of Fluids, Год журнала: 2024, Номер 36(2)

Опубликована: Фев. 1, 2024

In this paper, the cavitation bubble dynamics near a rectangular wall with bulge are theoretically investigated. High-speed photography is employed to provide experimental verification of theoretical results. Through series conformal transformations and image method, analytical description how complex configuration affects shown be equivalent superposition eight virtual bubbles. The physical meaning bubbles can divided into four groups, corresponding influence left wall, bottom angle formed by two flat walls, bulge. on liquid velocity distribution, as well intensity direction Kelvin impulse exerted bubble, explored for cases in which located at symmetric asymmetric positions. main findings given follows: During collapse, high-velocity area exists side farthest from bulge, three stagnation points low-velocity areas appear surface. mainly influences when position. existence causes attain minimum distance between increases. For larger radius, changes become more complicated position

Язык: Английский

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Interpreting proper orthogonal decomposition modes extracted from partial cavity oscillation

Physics of Fluids, Год журнала: 2025, Номер 37(1)

Опубликована: Янв. 1, 2025

This study employs the two-dimensional proper orthogonal decomposition approach to analyze pressure, vapor fraction, and streamwise velocity flowfields of partial cavity oscillation. The interrelations among mode, energy ratio, temporal coefficient, flowfield reconstruction are thoroughly examined, thereby augmenting comprehension cavitating flow mechanism bubble dynamics. It is found that first modes contain 56.31%, 36.37%, 31.81% energy, respectively; decrease in ratio results variation its coefficient close sinusoidal configurations. Moreover, mode varies closely related flowfield-relevant variable. significantly different, but all have two highlighted structures self-variable system. strong nonlinearity high dimensionality cavitation render precise using a limited number exceedingly challenging. data approximate original snapshot more when field reconstructed with greater modes. Although location relatively root mean square error different nine used for reconstruction, order magnitude less than system, discrepancy fixed, equal 1.

Язык: Английский

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Doxycycline degradation via hydrodynamic cavitation combined photocatalysis: optimization of geometric and operational parameters

Chemical Engineering and Processing - Process Intensification, Год журнала: 2025, Номер 209, С. 110154 - 110154

Опубликована: Янв. 5, 2025

Язык: Английский

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Application and comparison of dynamic mode decomposition methods in the tip leakage cavitation of a hydrofoil case

Physics of Fluids, Год журнала: 2023, Номер 35(2)

Опубликована: Фев. 1, 2023

The cavitation of the tip leakage vortex (TLV) induced by has always been a difficult problem faced turbomachinery, and its flow structure is complex diverse. How to accurately extract main structures that affect cavitating TLV from two-phase field key problem. In this study, mode extraction low order reconstruction accuracy downstream National Advisory Committee for Aeronautics (NACA)0009 hydrofoil two dynamic decomposition (DMD) methods are compared. research shows modes extracted standard DMD method contain large number noise modes, while sparsity-promoting eliminates showing obvious advantages in velocity field. characteristics signals analyzed, divided into four categories, which explains reason why have cavitation. This study provides theoretical basis strong guarantee great significance accelerating prediction multiphase fields based on intelligent pattern learning future. Meanwhile, it also new road introduction artificial intelligence technology future scientific research.

Язык: Английский

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Study of non-constant local cavitation suppression in micro-wedge structure

Physics of Fluids, Год журнала: 2024, Номер 36(1)

Опубликована: Янв. 1, 2024

To alleviate the negative impacts of cavitation phenomenon on hydrodynamic machinery, such as mechanical vibration and noise, a hydrofoil model is established based micro-wedge structure, numerical simulation carried out by using modified turbulence k–omega shear stress transport (SST k–ω) to analyze lift coefficient drag, pressure pulsation, volume fraction, morphology, turbulent kinetic energy distribution, reveal inhibition mechanism chord direction placement height structure coupling. The results show that determined thickness boundary layer an important parameter affecting performance, with smaller will produce better suppression, 0.05 mm has best suppression effect, main frequency pulsation amplitude shows positive effect. arranged can delay change cycle different degrees, in which chordwise position 3.5 rate about 16.7%.

Язык: Английский

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Experimental and numerical studies on the partial cavitation in a Venturi

Journal of Physics Conference Series, Год журнала: 2024, Номер 2752(1), С. 012187 - 012187

Опубликована: Июнь 1, 2024

Abstract To effectively control the adverse effects of cavitation, it is crucial to understand mechanism behind formation cloud cavitation. The transition from sheet or cavitation shedding, can be caused by two mechanisms: re-entrant jet and condensation shock. This study investigated shedding partial in a Venturi using high-speed photography Large-Eddy Simulation. Rankine-Hugoniot equation was used verify that mechanism: shock at σ = 0.37 0.98. Both operating conditions exhibit backflow, which cause variations image grayscale values. relation between backflowing velocity variation identified different mechanisms. When pressure gradient constant, inversely proportional variation, while it. These findings may contribute better understanding mechanism.

Язык: Английский

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Inhibition mechanism of bionic drainage hole on cavitation flow in the regulating valve

Journal of the Brazilian Society of Mechanical Sciences and Engineering, Год журнала: 2024, Номер 46(11)

Опубликована: Окт. 18, 2024

Язык: Английский

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Non-Spherical Cavitation Bubbles: A Review

Fluids, Год журнала: 2024, Номер 9(11), С. 249 - 249

Опубликована: Окт. 25, 2024

Cavitation is a phase-change phenomenon from the liquid to gas phase due an increased flow velocity. As it causes severe erosion and noise, harmful hydraulic machinery such as pumps, valves, screw propellers. However, can be utilized for water treatment, in chemical reactors, mechanical surface radicals impacts at point of cavitation bubble collapse utilized. Mechanical treatment using called “cavitation peening”. peening less pollution because uses treat surface. In addition, improves on traditional methods terms fatigue strength working life parts automobile, aerospace, medical fields. bubbles are peening, study has significant value improving this new technique. To achieve this, many numerical analyses combined with field experiments have been carried out measure stress caused by rebound, especially when occurs near solid boundary. Understanding mechanics help avoid unnecessary damage, enabling more accurate preparation, stability peening. The present introduces three types: single, cloud, vortex bubbles. critical parameters, governing equations, high-speed camera images these types introduced support broader understanding mechanism characteristics Then, results experimental non-spherical summarized.

Язык: Английский

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