Dynamics of single cavitation bubble collapse jet under particle-wall synergy

Physics of Fluids, Год журнала: 2024, Номер 36(10)

Опубликована: Окт. 1, 2024

The interaction between a particle and cavitation bubble significantly influences the erosive effect on wall surface of flow passage components in fluid machinery. This paper investigates dynamics single collapse jet under synergetic effects wall, using Kelvin impulse theory high-speed photographic experiments. A theoretical model to predict intensity direction at arbitrary locations near is constructed basis image method Weiss's theorem. accuracy verified by comparison with large number experimental results. mechanisms underlying relative contributions behavior are explored. key parameters also quantitatively analyzed, including positions particle, dimensionless radius. main conclusions as follows: (1) will cause deflection leading formation attraction zone. proposed effectively predicts spatial location this (2) There exists region which weak, there equilibrium point zero wall. position gradually approaches nonlinear manner increasing size quasi-linear decreasing particle–wall distance. (3) When same distance from changes toward vertical bubble–particle increases. Moreover, effective range particle's influence decreases decreases.

Язык: Английский

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The evolution of the bubble collapse morphology between two cylinders within a confined space

Physics of Fluids, Год журнала: 2024, Номер 36(10)

Опубликована: Окт. 1, 2024

This work investigates the dynamic bubble behaviors between two cylinders within a confined space using high-speed photographic experiments and Kelvin impulse theory. First, evolution of collapse morphologies bubbles located at origin along y axis is qualitatively investigated. The effects cylinder spacing ordinate on characteristics deformation liquid velocity are then explored. variations interface velocities, roundness cross section, radius quantitatively analyzed. conclusions can be summarized as follows: (1) experimental phenomena divided into three cases: hourglass-shaped collapse, “8”-shaped capsule-shaped collapse. Bubble also scenarios: awl-shaped spindle-shaped inverted triangle-shaped (2) significantly affect theoretical flow field. (3) High-velocity regions generated around when it oscillates freely, nearby always lead to low-velocity them bubble. closer cylinder, smaller larger high-velocity regions.

Язык: Английский

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Dynamics of a laser-induced bubble near a cylinder within a confined space

Physics of Fluids, Год журнала: 2024, Номер 36(10)

Опубликована: Окт. 1, 2024

The collapse of a laser-induced bubble near cylinder within confined space is investigated using high-speed photography and the Kelvin impulse theory. On basis an analysis liquid flow field impulse, effects bubble–cylinder distance radius ratio on behavior are investigated. Furthermore, motion during first oscillation period quantitatively explored main conclusions this study as follows: (1) When not restricted by cylinder, three cases jets observed—strong jet, medium weak jet. deformation observed—fan-shaped collapse, ellipse-shaped quasi circular shaped collapse. (2) mainly affects velocity surrounding through term point sink, from bubble. (3) intensity exhibits exponentially decreasing trend with increasing distance, which in good agreement experimentally observed jet velocities.

Язык: Английский

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Bubble dynamics near a flat wall and a cylinder within confined spaces

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

Опубликована: Янв. 1, 2025

This study systematically investigates the impact of a flat wall and cylinder on bubble dynamics within confined space. Based circle theorem image method, Kelvin impulse theoretical model considering motion is established. high-speed photography experiments, typical experimental phenomena oscillation are qualitatively exhibited. The morphology evolution centroid compared with results liquid velocity impulse. influence mechanisms explored, quantitatively explored. main conclusions summarized as follows: (1) distribution can effectively predict centroid's movement interface motion, respectively; (2) when comparable size, wall's surface greater than that cylinder's surface, field much cylinder; (3) bubble–cylinder bubble–wall distances increase, velocities away from decrease in final stage collapse.

Язык: Английский

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Unequal splitting phenomenon of cavitation bubbles near rigid boundaries within a narrow gap

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

Опубликована: Янв. 1, 2025

The present work investigates the unequal splitting of cavitation bubbles near rigid boundaries within a narrow gap. Based on high-speed photographic experiments, typical phenomenon bubble is shown, and parametric partitions in proximity to cylinder flat wall are presented. Kelvin impulse theory, underlying physical bubble-splitting mechanisms explored. In addition, impacts main parameters quantitatively analyzed. conclusions as follows. (1) Under different cylinder–bubble distances, splits into three cases: an upper larger part lower smaller part, two equal-sized parts, part. (2) caused by inconsistencies between directions bubble-collapse jet centroid movement. (3) As radius cylinder–wall distance increase, shifts from case 1 3, suggesting effect increases flat-wall decreases.

Язык: Английский

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Dynamics of single bubble between a moving spherical boundary and a plate structure

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

Опубликована: Янв. 1, 2025

Boundary conditions significantly influence the near-field dynamics of bubbles. This study employs numerical simulations to investigate coupling characteristics high-pressure bubbles near solid boundaries and moving spherical boundaries. It focuses on effects sinking velocity sphere initial bubble–boundary distance bubble evolution loading characteristics. The results indicate that an increase in sphere's or a decrease leads tearing during collapse process. generates high-speed water jets directed either toward center boundary, reducing kinetic energy sphere. shock waves caused by temporarily impede motion, while lagging flow induced expansion contraction has relatively minor impact. As increases, phenomenon gradually weakens may even disappear. attenuation is attributed suppression Bjerknes effect which reduces tendency migrate boundary. Furthermore, intensity affects pressure distribution region around Strong induces double-peaked profile, weak single-peaked profile primarily dominated collapse. reveals critical interactions motion distribution, providing valuable insights for engineering design applications related fields.

Язык: Английский

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Numerical investigation of the needle jets produced by cavitation bubbles near a concave wall

Journal of Mechanical Science and Technology, Год журнала: 2025, Номер unknown

Опубликована: Март 3, 2025

Язык: Английский

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Formation mechanism and evolution properties of double jets induced by cavitation bubble pair

Physics of Fluids, Год журнала: 2025, Номер 37(4)

Опубликована: Апрель 1, 2025

Interactions between bubbles are prevalent in cavitation flow within fluid mechanics. This study develops a Kelvin impulse model suitable for bubble pair and conducts extensive high-speed photographic experiments to investigate the dynamic properties of double jets induced by free-flow field. The effects key parameters, such as phase difference radius ratio pair, on variations jet intensity direction quantitatively evaluated, parameter ranges corresponding typical cases classified. In addition, influence mechanisms radial oscillation boundary effect Bjerknes force another explored. results indicated following: (1) Three double-jet scenarios discovered, including newly observed co-flowing well colliding diverging jets; (2) accurately forecasts changes direction—with an increase difference, intensities both gradually decrease, then inversely, finally tend zero; (3) compared effect, is consistently core factor determining bubble.

Язык: Английский

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The primary resonance of cylindrical bubbles excited by the square wave

Physics of Fluids, Год журнала: 2025, Номер 37(5)

Опубликована: Май 1, 2025

The investigation of nonlinear characteristics cylindrical bubbles plays an important role in engineering fields such as underwater explosions and ship propeller cavitation. In the present paper, behaviors primary resonance excited by square wave are investigated compressible liquids using multi-scale method Lyapunov stability theory. influences excitation intensity, equilibrium bubble radius, polytropic exponent, detuning parameters on explored. findings encapsulated follows: (1) amplitude phase response demonstrate multivalued solutions, jumps, hysteresis phenomena. (2) As intensity radius increase, frequency peak shifts along backbone curve toward smaller parameters, unstable region expands, threshold for chaos is reduced. (3) Compared to results obtained under sinusoidal excitation, demonstrates values, a narrower range regions, higher threshold.

Язык: Английский

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Dynamic characteristics of a single bubble collapsing near an angular wall

Physics of Fluids, Год журнала: 2025, Номер 37(5)

Опубликована: Май 1, 2025

Cavitation is easily activated by sudden changes in velocity and pressure the liquid surrounding bubbles narrow spaces formed angular walls. In this study, collapsing dynamics of a single bubble around angled walls with an inferior angle are investigated through high-speed imaging system jet prediction model. At symmetrical asymmetrical positions relative to wall, influence position bubble-wall vertex on collapse analyzed, including morphology, direction intensity, bubble's oscillation period. The intensity distribution directional sensitivity at different included wall angles studied. results indicate that can be categorized into four types: wide, triangular, elongated, inapparent. As decreases, extension effect period increases significantly, index exceeding 1.7. Kelvin impulse effectively predicts for angles. reaches its maximum when approaches while highest near bisector.

Язык: Английский

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