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Acoustic levitation is widely used in non-container measurement and non-contact manipulation. Particles in the single-axis acoustic levitation are easily unstable in the radial direction under external perturbations. In order to explore the instability in the acoustic levitation during radial perturbations, a nonlinear acoustic levitation model considering the coupling of radial and axial vibration is proposed to analyze the dominant factors influencing the levitation stability, an acoustic levitation system consisting of a transducer and a plane reflector is established, and high-speed photography is used to observe the vibration behavior of the particle with large radial vibration and the levitation stability. The simulation results are compared and verified with the experiments, which indicate that the reduction in axial trapping stiffness due to radial vibration plays a vital role in the levitation instability. The present model can characterize the radial anti-interference ability of different levitators as well as predict the movement trajectories of levitated particles after being disturbed, which is helpful to optimize the design of acoustic levitators and provide guidance for acoustic manipulation. [ABSTRACT FROM AUTHOR]

To investigate the dynamic response of a hollow cylindrical shell structure subjected to a near-field underwater explosion, underwater explosion experiments were conducted in a 2 × 2 × 2 m water tank, and high-speed cameras were used to record the interactions between the bubbles generated by the underwater explosion and the hollow cylindrical shell. The high-speed photography results showed that the cylindrical shell experienced a minor degree of deformation during the shock-wave stage. However, during the bubble-pulsation stage, the cylindrical shell experienced significant deformation that surpassed the deformation observed during the shock-wave stage. On this basis, combined with the damage results for the cylindrical shell, a numerical model for the hollow cylindrical shell subjected to an underwater explosion was established using LS-DYNA software. The dynamic process and damage mechanism of a hollow cylindrical shell that was subjected to a near-field underwater explosion were revealed by analyzing the pressures and strains of the shell elements, the velocities and displacements of the nodes, and the variations in the energy. [ABSTRACT FROM AUTHOR]

An introduction to high‐speed photography and its entomological impact is provided, emphasizing the importance of high frame rates and high resolution.The take‐off and free flight of Drepanosiphum platanoidis and Myzus persicae were studied in still air using high‐speed photography in HD.The wing tip and body posture were tracked to show how they are displaced during each wingbeat cycle. The important structural elements of the wing are described.The wingbeat is driven by a reinforced leading edge, the pterostigma and costa. The remainder of the coupled fore‐ and hindwing acts as a single aerofoil that deforms during flight, due to sparse venation and a lack of cross veins.During flight, aphids use a 'near clap and fling' mechanism with a body pitch close to 90°. Rapid acceleration about the thoracic lateral axis into wing reversal generates enough lift for take‐off, typically within the first or second wingbeat.Unique footage shows that aphids demonstrate a high degree of flight control and manoeuvrability in the lab, occasionally using forward and inverted flight, two flight modes that are otherwise poorly known.While research into the impact of turbulent convection is needed, we posit that the strength of atmospheric forces presents a formidable challenge to aphid migrants. Above the flight boundary layer, migrating aphids may not easily oppose upwardly moving air, although if used, 'frozen flight' may cause them to descend on average.We evaluate five devices for insect flight research. [ABSTRACT FROM AUTHOR]

EHLA 3D was developed to print nickel-based superalloy parts. The interaction of powder and laser and the behavior of the molten pool was captured by high-speed photography. The thermal cycle of the molten pool was obtained by the thermal imager, which reveals the principle of the EHLA 3D. The microstructure and mechanical properties of specimens made by LMD and EHLA 3D were compared and analyzed. The mechanism of crystal growth and precipitation formation of nickel-based superalloy is illustrated by a comparative analysis of dendrite growth and precipitation phase formation during LMD and EHLA 3D, respectively. The results show that the EHLA 3D molten pool has a higher solidification cooling rate than the LMD molten pool, which is beneficial to grain refinement, dendritic arm spacing reduction, and the coexistence of columnar and equiaxed dendrites. Moreover, the segregation of Nb and Mo can be effectively inhibited, and the formation of Laves phase can be effectively reduced. The ultimate tensile strength, yield strength, and hardness of the specimens prepared by EHLA 3D at 25 °C and 650 °C were higher than those of LMD, especially elongation was improved and the processing efficiency was increased by nearly 60%. [ABSTRACT FROM AUTHOR]

Explosive pellets containing binary mixtures of 1,3,5-trinitro-1,3,5-triazine (RDX) and yacca resin "red gum" (RG) with composition ratios of 90:10, 95:5, and 98:2 RDX:RG were prepared. These were created without use of specialized pressing or casting facilities, making it a convenient formulation for researchers. Red gum, a component of molding powder, was mixed with RDX, both in powder form and in slurry format. The addition of red gum to RDX did not significantly change the sensitivity of RDX to impact or friction nor was thermal stability dramatically altered as judged by differential scanning calorimetry (DSC). Formulations of RDX:RG were pressed to produce pellets with densities ranging from 1.628-1.683 g/cm3. Pressed pellets were assembled in clear cellulose tubes to allow high speed camera photography to assess detonation velocity. Velocities between 8.04-8.50 km/s were determined. Photon Doppler velocimetry (PDV) measured CJ-pressures in the pellets between 24-29 GPa. [ABSTRACT FROM AUTHOR]

Percolation casting technology is used to produce alumina ceramic hollow spheres of different sizes that are neatly and tightly arranged according to certain rules. Then, aluminum metal melt infiltrates the gap of adjacent ceramic hollow spheres, forming a sphere-reinforced aluminum metal matrix syntactic foam (MMSF). To compare the mechanical properties between aluminum foam and MMSF, the same base material and pore size were used. Based on quasi-static testing, split Hopkinson pressure bar experiments were conducted on the MMSF and aluminum foam at different strain rates using pulse-shaping and high-speed photography techniques. The influence of alumina ceramic hollow spheres on the MMSF (including compressive strength, failure process, and energy absorption performance) was analyzed. Results indicate that the addition of alumina ceramic hollow spheres significantly enhances the compressive strength and energy absorption capacity of MMSFs. It also improves the strain rate sensitivity to some extent, rendering the composite formed by aluminum foam and ceramic hollow sphere to be strain rate-sensitive. Furthermore, the energy utilization efficiency and absorbed energy per unit volume of the MMSF were higher than those of the aluminum foam. The MMSF exhibited better strain rate sensitivity in terms of impact resistance than the aluminum foam; the higher the strain rate, the higher the absorbed impact energy. The MMSF has significant application prospects to aerospace engineering and explosion protection in the military. [ABSTRACT FROM AUTHOR]

A jet impingement sprinkler was designed based on asymmetric collision between the primary and secondary jets to replace traditional rotating sprinklers that require additional water distribution devices to provide suitable water distribution at low pressures. The study focuses on the ratio of apertures between primary and secondary nozzles, deriving a theoretical relationship based on jet momentum. The factors contributing to the variation in hydraulic performance between jet-impingement and non-impinging sprinklers are elucidated by combining hydraulic performance experiments with experiments using high-speed photography (HSP). The results show that the developed jet impingement sprinkler achieved a smoother water distribution trend. The wetted radius and Christiansen's uniformity coefficient of the jet impingement sprinkler were evaluated using the Criteria Importance via the Intercriteria Correlation (CRITIC) method. A comparison of the average scores shows that an aperture ratio of 1.66 performs best under full pressure. By contrast, an aperture ratio of 1.33 exhibited superior performance at low pressure. Jet deflection angle and jet breakup length were obtained through HSP experiments. The relative error between the measured and theoretical jet deflection angles was less than 5%, demonstrating the reliability of the proposed theoretical calculation method. A non-linear curve was used to establish the relationship among the aperture ratio, diameter of the primary nozzle exit, jet breakup length, average measured jet deflection angle, working pressure, and wetted radius. The relative error between the calculated and measured values was within 4%, indicating the suitability of the new formula for calculating the wetted radius of jet impingement sprinklers. • Theoretical formulae for jet momentum relation and synthetic jet direction derived. • Images illustrate differences in hydraulic performance of jet impingement sprinklers. • Jet impingement sacrifices the wetting radius in order to achieve greater uniformity. [ABSTRACT FROM AUTHOR]

In this study, we examined the influences of high in-situ stress and blast loading on granite within deep-tunnel excavation and mining contexts. A large granite specimen (1200 × 1200 × 200 mm3) was subjected to chemical explosion tests under varying confining pressures. The entire granite failure process was visualized using high-speed photography, and a damage characterization method based on three-dimensional scanning technology and digital model reconstruction technology was developed. The failure mode of the granite was divided into three distinct stages: the crushing failure stage, circumferential fracture stage, and stepped fracture stripping stage. Microscale examination of the fracture surfaces revealed the presence of sharp, step-like structures with pronounced directional characteristics. A key finding is the significant variability of the explosion crater features under different confining pressures. Vertical stress significantly impacted the volume of the crater and the area of the damage zone on the granite's surface, exhibiting a positive correlation and elliptical morphology aligned with the static stress direction. Under constant vertical stress, the horizontal stress played an inhibiting role in the failure of the back surface of the granite, leading to a morphological shift from elliptical to nearly circular in the damage zone. Under equal biaxial stresses, a low static stress promoted crushing of the granite, while a higher static stress restrained it. In this study, it was found that under different stress states, the equivalent diameter of the crater was much larger than its average depth, and the morphology of the crater profile exhibited a flat funnel-like shape with ladder-shaped fracture patterns. Highlights: Conducts experiments on large granite specimens under complex stresses to study their damage, fracture process, and morphological characteristics. Introduces a novel damage characterization method using 3-D scanning and digital modeling to analyze granite's post-explosion morphology. Granite specimens' failure occurs in three stages: the crushing failure stage, circumferential fracture stage, and stepped fracture stripping stage. Extracts and calculates granite crater's post-explosion parameters, revealing morphology changes under complex stresses. [ABSTRACT FROM AUTHOR]

The interaction of bubbles with phase interfaces is an important phenomenon in science and industry. In this paper, the variation in bubble behavior and the characteristics of surface liquid film formation and shedding at the oil–water interface are investigated using bubble visualization high-speed photography and numerical simulation. The results show that the bubble rise trajectories can be divided into three different sets when the bubbles rise in a system composed of two mutually incompatible liquids, and the bubble shapes are more stable in white oil compared to water. During the passage of the bubble across the oil–water interface, the water phase is entrained to form a liquid film covering the bubble. We found that the change in the bubble liquid film and the collapse process of the water column are closely related to the bubble size. The trends of Eotvos (Eo) numbers for bubbles of different diameters in the oil–water coexistence system are approximately the same, with the Eo numbers of larger bubbles being much larger than those corresponding to smaller bubbles, from the beginning to the end. After crossing the oil–water interface, the Eo number of larger-diameter bubbles keeps fluctuating over a long distance before finally stabilizing. The Eo number of small-diameter bubbles remains essentially stable after crossing the oil–water interface. [ABSTRACT FROM AUTHOR]

Spatiotemporal visualization of instantaneous flame structures in a hydrogen-fueled axisymmetric supersonic combustor was investigated using multiview planar laser-induced fluorescence of the hydroxyl radical, coupled with high-speed photography and pressure measurement. The axisymmetric cavity generates a loop-shaped recirculation flow and shear layer that sustains the flame. An irregular and wrinkled flame loop with a central hole is formed near the loop-shaped region. Due to turbulent disturbances, multiple small-scale holes and fragmented flames are randomly distributed in the flame loop or near the wrinkled flame front. The combustion near the cavity shear layer is more likely to be stronger and sustained. As the thickness of the cavity shear layer increases along the axial direction, the flame loop is expanded toward the core flow and the cavity. The flame base anchors near the cavity leading edge with a low global equivalence ratio (GER). The increased GER expands the flame loop to compress the high-speed core flow dramatically, promoting the flame base to propagate upstream along the hydrogen jet wake. The flame base is unable to anchor near the thin boundary layer. Consequently, it propagates reciprocally to enhance the combustion oscillation that disturbs the flame structure dramatically. The flame structure becomes more complex and tendentially fragmented, which increases the fractal dimension, especially near the middle part of the combustor. In comparison, the flame structure near the ramp is more resistant to disturbances due to the dramatic expansion of local flame loop, extending the favorable combustion environment. Despite the instantaneous flame structure being severely wrinkled and even tendentially fragmented, it is primarily sustained within a relatively regular loop region near the cavity recirculation flow and the cavity shear layer. [ABSTRACT FROM AUTHOR]

We studied the bubble and resulting jet dynamics near gas-entrapped surfaces experimentally using spark-induced bubbles with a radius of a centimeter and high-speed photography. We found three distinct jetting behaviors, namely direct toward the boundary, direct backward the boundary, and split both toward and backward, which is determined by three dimensionless parameters, i.e., depth ( H ̃ ) and cross section area ( A ̃ ) of the gas cylinder and the standoff distance (γ) of the bubble. Bubble lifetime, maximum radius, and impact velocity of the penetrated jet on the bubble are also investigated. Furthermore, the non-dimensional volume (α) of gas entrapped on the rigid boundary is the dominant parameter in the jet reversal, larger α leads to a stronger reverse. The results and conclusions in this study are useful for resisting cavitation erosion. [ABSTRACT FROM AUTHOR]

Flow control techniques are beneficial for changing the flow and motion characteristics of a vehicle during water entry. Combined with high-speed photography and inertial measurement unit, this paper investigated the cavity evolution and vehicle kinematics during water entry by varying the length, height, and width of a single canard wing. Research indicates that changing the wing length minimally affects the shape and size of fore-end cavity. For the attached cavity on the wing, increasing wing length promotes the formation of the cloudy flow characterized by violent air–water mixing, destroying the integrity of it. As wing height increases, the fore-end cavity profile approaches a rectangle, while the attached cavity on the wing evolves from an ellipse to a triangle. Increasing the wing width shifts the fore-end cavity profile from a rectangle to a trapezoid. There is an impact on the vehicle when the fore-end cavity occurs pinch-off. The impact peak rises with the increase in wing height and width, while the impact duration decreases. Changing wing length has little effect on peak value of pinch-off. Increasing the wing length and height reduces deflection of the vehicle, while increasing the wing width promotes the deflection of the trajectory and attitude. [ABSTRACT FROM AUTHOR]

The waterjet propulsor is a new type of marine propulsion system, which offers the advantages of high speed, good maneuverability, and low vibration and noise. As the core component of the waterjet propulsor, the primary role of the waterjet pump is to provide sufficient thrust for the vessel. However, the waterjet pump is prone to be troubled by the hump phenomenon. As the pump operates in the hump region, it may encounter issues such as flow interference and exacerbated vibration and noise, which are closely related to cavitation phenomenon in the pump. To analyze the evolution of cavitation flow structure in the waterjet pump when operating in the hump region, this study utilized highspeed photography to obtain the cavitation flow structure at different cavitation development stages under the hump peak condition. The cavitation stages involved include the cavitation inception stage, cavitation development transition stage, first critical cavitation stage, critical cavitation stage, and breakdown cavitation stage. During different cavitation development stages under the hump peak condition, the blade tip region exhibits distinct cloud cavitation induced by the tip leakage vortex (TLV). As the NPSH decreases, the frequency of cloud cavitation shedding increases, the scale of the cavitation cloud at the leading edge of the blade decreases, and the scale of the cavitation cloud accumulated at the rear of the flow passage increases. This study on the cavitation flow of the waterjet pump is significant as it contributes to enhancing the anti-cavitation performance and reducing vibration and noise. It provides scientific guidance and engineering practice for improving the safety and stability of waterjet pumps during operation. [ABSTRACT FROM AUTHOR]

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The measurement of the combustion characteristics of a single biomass particle is essential for studying massive biofuel energy conversion process; however, it is challenging due to the small physical scale of the biomass particle flame. In this work, we report an investigation of the combustion behavior of single lignin and single cellulose particle through CO2 absorption spectroscopy and high-speed photography. The biomass samples are prepared with an initial diameter of about 1.0 mm and are ignited on a heating plate placed inside a multi-pass absorption cell. The shape and size transformation of single biomass particle are recorded through high-speed photography, and the combustion temperature and CO2 column densities are measured through laser absorption spectroscopy at 4.172 µm. We find that the maximum combustion temperatures are 1662 ± 38 K and 1569 ± 26 K for lignin and cellulose particle, respectively. Besides, we find that CO2 generation precedes the generation of visible volatile flame for cellulose particle. While for lignin particle, the CO2 generation is found to be almost at the same time as its volatile combustion stage begins. The measurement technique and results presented in this work are of practical interest for biomass combustion studies and arc meaningful for the development of biomass thermal conversion mode. [ABSTRACT FROM AUTHOR]

The pump hump significantly influences the vibration and operational stability of pumps. During the development of the mixed-flow waterjet pump, our team found that the pump performance curve had a hump phenomenon and the platform had vibration, so it was suspected that there was a strong secondary flow in the hump region. The calculation model is the SST k-ω turbulence model. The impeller and diffuser use structured grids. By using high-speed photography technology, we map the cavitation flow structures, thereby demonstrating the evolution of cavitation processes. The hump curve was obtained by an experimental test. By comparing the test data and numerical simulation, the consistency of the method and the hump curve is verified. A comparative analysis is performed to investigate the variations in the distribution of internal vortex structures and the evolution of rotating stalls in the impeller. In the valley condition, the main frequency of pressure pulsation in the inlet section of the impeller is 0.75 times the shaft frequency, the main frequency in the middle and outlet sections of the impeller is 1 times the shaft frequency, and the main frequency in the diffuser basin is 1.5 times the shaft frequency, the main frequency in the peak condition at the points of Span = 0.1 and Span = 0.5 of the impeller is the diffuser frequency, the main frequency at the point of Span = 0.9 is the impeller blade frequency, and the main frequency in the diffuser basin is either the shaft frequency or the diffuser blade frequency. This research reveals the characteristics of vortex flow in the pump under hump conditions. It reveals that the evolution mechanism of the hump offers a guide value for the subsequent hydrodynamic design of the hump. [ABSTRACT FROM AUTHOR]

Adding a certain percentage of hydrogen into the natural gas pipeline network is regarded as an efficient way to store and transport hydrogen. CH4-H2 binary fuel is also considered to be an important means of hydrogen utilization. In this paper, flame acceleration (FA) in stoichiometric CH4/H2/air mixtures with various hydrogen blend ratios (i.e., Hbr = 0%, 20%, 50%, 80%, and 100%) was studied experimentally and numerically. In the experiments, high-speed photography was used to record the FA process. In the numerical simulations, the two-dimensional, fully-compressible, reactive Navier-Stokes equations were solved using a high-order algorithm on a dynamically adapting mesh. The chemical reaction and diffusive transport of the mixtures were described by a calibrated chemical-diffusive model. The numerical predictions agree reasonably with the experimental measurements. The results show that a larger hydrogen blend ratio leads to a faster FA. The difference in FA due to hydrogen blending mainly depends on the property change of the fuel mixtures, the increase of flame surface area and the interactions between flame and pressure waves, corresponding to three different stages. In addition, the heat loss to the channel walls and obstacle surfaces has an impact on the FA process, especially in the mixtures with low hydrogen blend ratios (i.e., Hbr ≤ 20%). This is related to the weakening of interactions between pressure waves and flame under isothermal boundary condition. [ABSTRACT FROM AUTHOR]

A bubble collapsing near an interface may result in the formation of a liquid jet protruding from the distal bubble side, through the bubble, towards the interface. Ultrasound assisted jetting has been observed when subjecting, by approximation, infinite fluids to acoustic amplitudes above the inertial cavitation threshold, limiting the possibility of ultrasoundguided, bubble-assisted drug or gene delivery. However, the vascular system can be regarded as a finite fluid. The purpose of this study was to investigate the feasibility of lowamplitude jetting for fluid containing biocompatible cavitation nuclei, by placing the region of interest in a confined space to ensure a standing wave field. Droplets of QuantisonTMultrasound contrast agent were pipetted into a Perspex cylindrical compartment of 8-mm diameter and 2-mm height, which was part of an imaging system. The contrast agent was subjected to 3-cycle ultrasound pulses with a centre frequency of 1MHz whilst being observed at a frame rate of ten million frames per second. Jetting was observed to occur with microbubbles nucleated from the contrast agent in an acoustic regime whose free-field mechanical index was 0.6. Empirical curve matching showed a pulse amplification by a factor of six owing to the chosen geometry. Visible jet lengths of twice the bubble radius on the verge of collapse were measured. Owing to the confined space, the local acoustic amplitude was amplified to surpass the cavitation threshold. This finding is of interest for medical ultrasonic applications where the local environment comprises reflectors. [ABSTRACT FROM AUTHOR]

This erratum corrects an error in calculating the failure strain of additively manufactured stainless steel by comparing the metal shell's geometry at the time of fracture with its unloaded geometry. The corrected failure strain of the AM 316L stainless steel shell is 0.135. The study also examines the effect of surface grooves on fragmentation behavior and finds that the failure strain is lower than that of wrought 304 due to early failure at stress concentrations. The authors provide analytical calculations and visual evidence to support their findings. [Extracted from the article]

Laser-arc hybrid welding (LAHW) technology is a versatile and widely used method that has garnered significant attention, particularly in the thick plate welding required for shipbuilding. One of the most crucial parameters in LAHW is the laser-arc distance, which has a significant impact on the interaction between the laser and arc, especially in high-power laser and high-speed welding processes. As such, investigating the effects of laser-arc distance on the welding process is of great theoretical importance for both future research and industrial applications. This study utilizes high-speed photography to capture the welding process, focusing on how the laser-arc distance affects droplet transition and the stability of weld pool flow. Additionally, numerical simulations are used to explore the mechanisms underlying welding defect formation. The results indicate that an optimal laser-arc distance can produce a well-formed weld without significant defects. When the laser-arc distance (DLA) is too small, the coupling effect between the laser and arc becomes overly strong, causing unstable droplet transition and weld pool flow, which leads to defects such as spatter and undercutting. Conversely, when the laser-arc distance is too large, the coupling effect weakens, resulting in reduced weld reinforcement and the occurrence of porosity defects. The findings of this study offer valuable insights for optimizing welding parameters and improving weld quality in industrial applications of LAHW. [ABSTRACT FROM AUTHOR]

The acoustic Lichtenberg figure (ALF) in an ultrasonic cleaner with a frequency of 28 kHz at different power levels was observed using high-speed photography. The nonlinear response of the cavitation structure was analyzed by the entropy spectrum in the ALF images, which showed the modulation influence of the primary acoustic field, exhibiting the fluctuations of the bubble distribution with time. Typical Y-branches predict the paths by which surrounding bubbles are attracted and converge into the structure, the branches are curved due to bubble-bubble interactions, and the curvature increases as the bubbles are approaching the main chain. The average travelling speed of bubbles along the branches is about 1.1 m/s, almost independent of power level of the ultrasonic cleaner. A theoretical model consisting of free bubbles and a straight bubble chain of finite length was developed to explore the evolutionary mechanism of branching. It was found that the bubble trajectories showed a bending tendency similar to the experimentally observed Y-branches, and the stationary straight bubble chain parallel to the main chain could evolve into a curved chain and eventually become a branch of the main chain. The theoretical predictions agree well with the experimental results, verifying the evolutionary mechanism of Y-branches in ALF. [ABSTRACT FROM AUTHOR]

The effects of different number and thickness ratios on the structural damage mechanism of aramid/epoxy composite and ultra-high molecular weight polyethylene (UHMWPE) fibers were investigated. Six sets of composite target plates with different thickness ratios were selected. Ballistic impact experiments were carried out with 7.62-mm lead core bullets at the speed of 460±10 m/s. The damage morphology of the surface of the composite target plate and the cross-section of the bullet hole and combining with the process of bullet penetration into the target plate were recorded by high-speed photography. The damage form and degree of the target plate were analyzed to determine the antipenetration performance of the target plate. The failure mechanisms of composite target plates were different. Whereas the front plate, the aramid target plate suffered mainly the shear failure, the back plate was damaged by extrusion. When the UHMWPE target plate was used as the front plate, the projectile surface was damaged in shear, and a bulge was generated. When the UHMWPE target plate was used as the back plate, the projectile surface was subjected to the shear and tension. The results obtained showed that the damage mechanism of the same composite target plate was related to the location of impact and the number of impacts. The damage mechanism of different composite target plates was related to the location and thickness ratio of the target plate. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms behind the cavitation erosion resistance of elastic materials is the basis for the development of new cavitation erosion resistance materials. This paper employs underwater low-voltage discharge to induce cavitation bubble, combined with high-speed photography, shadowgraph methods, and transient pressure measurement systems to experimentally investigate the evolution and intensity of shockwave from bubble collapse near elastic-rigid composite boundary. Under the condition of constant elastic material thickness, with the bubble–wall distance increasing, shockwave shape evolves from multi-layers to single-layer. The peak pressure of the shockwave shows a trend of decreasing, then increasing, and finally stabilizing with increase in the bubble–wall distance. Furthermore, it was found that the elastic-rigid composite boundary causes the shockwave to reflect twice. As the material thickness increases, the intensity of the first reflected shockwave from the elastic surface decreases initially, then increases, and eventually stabilizes. However, that of the second reflected shockwave decreases. The total energy of the two reflections at the elastic interface is less than 4% of the mechanical energy of the bubble at its maximum volume. Finally, after the energy dissipation by the two reflections and material deformation, the elastic layer substrate withstands over 70% of the total mechanical energy of the cavitation bubble. There is an optimal elastic material thickness to minimize the shockwave load on the elastic layer substrate under the condition that the elastic-rigid composite boundary does not affect the evolution of cavitation bubble shape. These findings are significant for understanding bubble dynamics near elastic-rigid composite boundaries and provide theoretical support for developing cavitation erosion-resistant materials in engineering. [ABSTRACT FROM AUTHOR]

This research integrates experimental visualization via high-speed photography with numerical simulations, leveraging large eddy simulation and the Schnerr–Sauer (S-S) cavitation model, to examine cavitation dynamics on a flat-plate hydrofoil across a range of tip clearance settings. We identify three distinct cavitation patterns caused by tip clearance (CT) in terms of the flow structures and interactions of tip leakage vortex cavitation, tip separation vortex cavitation (TSVC), and shear layer cavitation. The flat-plate hydrofoil demonstrates stronger TSVC and more pronounced vortex interactions compared to National Advisory Committee for Aeronautics 0009 hydrofoils. A phase diagram is established to predict the cavitation patterns of CT under different operational conditions of the cavitation number σ and the angle of attack α. We also observe a downwash effect from the vortices, influencing the cavitation length on the suction side of the hydrofoil. The findings are significant for optimizing hydrofoil designs in fluid machinery where effective cavitation management is critical. [ABSTRACT FROM AUTHOR]

The droplet dynamics and spray mechanism of air-assisted intermittent atomization were experimentally investigated, with a particular focus on the effect of injection timing (duration of fuel injection ranged from 1 to 10 ms, and the interval between fuel injection and air injection varied from −0.5 to 2 ms) on jet atomization. Droplet velocities, sizes, and arrival times at a selected location were obtained by applying a phase Doppler particle analyzer (PDPA) with the combination of high-speed photography for spray visualization. The results indicate that droplet dynamics and velocity distribution are substantially influenced by fuel injection duration. Specifically, two peaks in the droplet velocity distribution are identified when the fuel injection duration exceeded 6 ms. Reconstruction of the gas-phase velocity using tracer particles reveals that the gas-phase velocity and stability are similarly affected by the fuel injection duration, and the gas flow tends to be stable for fuel injection durations longer than 6 ms. Droplets in the two velocity peaks exhibit different dynamic characteristics. The phenomenon of two peaks in droplet velocity is attributed to fuel accumulation inside the air-assisted atomizer, with the analysis given in terms of spray concentration and fuel state in the atomizer. Fuel accumulation and twin-peak droplet velocity caused by extended fuel–air injection intervals are predicted and validated. [ABSTRACT FROM AUTHOR]

To study the spatiotemporal evolution process of particle wakes behind the impeller in the centrifugal pump, this paper utilized high-speed photography to capture the particle motion characteristics under different solid-phase particle concentrations (1%, 1.5%, and 2%). First, this paper studies the changes in hydraulic performance of the centrifugal pump under solid–liquid two-phase flow conditions. It then introduces the evolution process of the impeller particle wake, comparing the differences in particle wake evolution under varying solid-phase concentrations. Finally, the impact of the solid-phase concentration on the wear of the volute's partitions is investigated. This study found that as the solid-phase particle concentration increases, the hydraulic performance of the pump gradually declines. Under the design conditions, when the solid-phase concentration increases by 0.5%, the efficiency of the centrifugal pump decreases by 0.56% and 0.35%. There is mutual transport of particles between adjacent wakes, and the movement of particle wakes within the volute passage is not equidistant over time. As the solid-phase particle concentration increases, wake cutting occurs at the volute partitions, and there is a significant solid–liquid separation between the particle wakes. The spatial evolution of the particle wakes is significantly influenced by the solid-phase concentration. Wear at the volute partitions intensifies with increasing solid-phase concentration and is also affected by changes in the particle wakes. The research results provide a basis for further exploration of the solid–liquid two-phase flow dynamics within centrifugal pumps. [ABSTRACT FROM AUTHOR]

The formation of a circular water film by a coaxial liquid jet impinging onto a horizontal plate is a phenomenon largely unexplored in the literature. To investigate the effects of velocity ratio and area ratio on such coaxial impinging jets, a coaxial jet nozzle with an inner diameter of 2 mm and an outer diameter of 8 mm was designed. Experiments and numerical simulations were conducted using this nozzle. The experimental research employed high-speed photography to capture the circular water film formed by the coaxial jet impacting the plate. The influence of velocity ratios ranging from 0 to 0.28 was studied at a fixed inner jet flow rate. Numerical simulations were conducted with a constant outer-to-inner nozzle diameter ratio of 4, focusing on the effects of varying area ratio on the flow patterns of the coaxial impinging jet. The results demonstrate that the simulation strategy accurately predicts the radius of the circular water film, liquid film thickness, and wall shear stress. At a fixed inner jet flow rate, the water film radius increases with the velocity ratio, while the turbulence level within the film initially increases and subsequently decreases. Under a fixed total flow rate of 6 l/min, a larger area ratio leads to stronger interactions between the inner and outer jets, significantly impacting the coaxial jet structure, which is highly dependent on the velocity ratio. Similar to single jets, the coaxial jet exhibits good normalization and self-similarity after fully merged. The mutual interactions between the inner and outer jets of the coaxial impinging jet result in more bubbles in the water film, and a slower decay of wall shear stress than that of single jets, both of which are beneficial for surface cleaning. [ABSTRACT FROM AUTHOR]

Tip leakage flow and induced unstable cavitation can significantly damage the performance of axial waterjet pumps. This study investigated the impact of blade numbers on cavitating conditions in an axial waterjet pump by conducting tests of performance characteristics and high-speed photography experiments on three-blade and four-blade impellers. The results showed that the critical cavitation number σc of the three-blade impeller was larger, while the four-blade impeller flow pattern deteriorated more rapidly after σc. Various cavitation structures in the tip region were observed under different conditions, including clearance cavitation, shear layer cavitation, tip leakage vortex cavitation, and suction-side-perpendicular cavitating vortices (SSPCVs). Tip cavitation maps of the test impellers were drawn based on the flow rate coefficient and cavitation number variation. The three-blade impeller exhibited a wider range of severe cavitation, particularly with an increased occurrence of SSPCVs. With the cavitation number and flow rate coefficient decreased, the SSPCV generated from triangular cavitation cloud shedding presented an increased trend in scale and quantity. Conversely, in the case of the four-blade impeller, SSPCVs were often disrupted by the adjacent blade during migration and interfered with the tip cavitation in the neighboring flow passage. [ABSTRACT FROM AUTHOR]

Hydrogen, as a clean and promising energy carrier, is considered a viable alternative fuel for the future. However, accidental hydrogen leakages and explosions pose considerable safety concerns in hydrogen energy applications and process industries. This study investigated the flame propagation characteristics of non-uniform premixed hydrogen-air mixtures in a rectangular closed duct with a length-to-diameter ratio of 5.78, taking into account varying equivalence ratios and diffusion times. First, numerical simulations using FLUENT were conducted to model the hydrogen diffusion process in a confined space, determining the hydrogen concentration evolution post-leakage. After approximately 200 s of diffusion, the premixed hydrogen-air mixtures remained in a state of homogeneous mixing, with the hydrogen concentration stabilizing at approximately 1.25 × 10−2 kg/m³. Subsequently, experimental observations were performed using a visual pipeline system, high-speed photography, and flame structure analysis. These experiments examined inhomogeneous hydrogen-air mixtures under seven different equivalence ratios and five different diffusion time conditions. The effects of equivalence ratios and diffusion times on flame propagation characteristics were analyzed. The results revealed that equivalence ratio significantly influenced the flame structure, with higher equivalence ratios producing more pronounced flame surface wrinkles. However, the typical evolution of the tulip flame remained consistent. At a constant equivalence ratio, flame propagation velocity exhibited an initial increase followed by a decrease over time. These findings demonstrate that turbulence intensity accelerated the flame propagation in non-uniform premixed hydrogen-air mixtures. This study underscores the importance of further research on hydrogen safety fundamentals and technologies to develop comprehensive safety standards. • The evolution law of hydrogen concentration field in confined space was determined by FLUENT. • The flame propagation characteristics of the non-uniform premixed hydrogen-air mixtures were investigated. • Effects of equivalence ratios and diffusion times on the flame propagation characteristics of the premixed gas were analyzed. • A detailed comparative analysis was conducted on characteristics such as flame structure and propagation velocity. [ABSTRACT FROM AUTHOR]

AbstractDirectional fracturing blasting is effective for rock engineering, but it is inevitably disturbed by multiple reflected waves from different directions in natural rock mass due to discontinuous boundaries. Reflected waves affect both crack-tip stress and crack propagation, hence affect the results of directional fracturing blasting. In this paper, with the aid of high-speed photography, an optical caustics method is used to study effects of multiple reflected P waves on a directional blast-induced crack in a polymethyl methacrylate (PMMA) plate, specifically on crack path, crack fracturing mode, crack-tip stress and crack velocity. Crack-tip stress field is indicated by the shape of caustics pattern. Before the loading of reflected P waves, the mode I directional crack driven by blast-induced gases propagates in a straight path; crack-tip stress field is K-dominated, and crack-tip caustics pattern is consistent with classical caustics theory. On the contrary, under the loading of reflected P waves, the directional crack changes to be mixed-mode I + II and propagates in a curved path; Crack-tip stress field is non-K-dominated due to transient stress superposition of reflected P waves, and crack-tip caustics pattern is consistent with modified caustics theory. Transient stress superposition is not obvious for reflected P waves with a longer reflection distance. The tension loading of reflected P waves plays a more important role than the compression loading, which increases crack-tip stress intensity factors and crack velocity. This study provides a comprehensive understanding of effects of multiple reflected P waves from different directions on directional fracturing blasting. [ABSTRACT FROM AUTHOR]

The factors that influence the symmetry of an imploding detonation are investigated experimentally and theoretically. Detonations in sub-atmospheric acetylene–oxygen were initiated and made to converge in an apparatus that followed that of Lee and Lee (Phys Fluids 8:2148–2152, 1965). The width of the test section was controlled with a wave-shaping insert, which formed the test section against the viewing window, creating an effectively two-dimensional problem with a channel width comparable to the detonation cell size. The convergence of the detonation was observed via self-luminous open-shutter photography and high-speed videography. The resulting videos were analyzed to quantify the wave speed, degree of asymmetry, and direction and magnitude of the offset in the center of convergence. To determine the experimental parameters that influence the symmetry of the imploding wave, the wave-shaping insert was intentionally canted by 0. 3 ∘ -- 0. 6 ∘ , accentuating the asymmetry of the imploding detonation. The experiment was modeled using a Huygens construction wherein the detonation is treated as a collection of wavelets, each assumed to propagate locally at a velocity determined by the channel width. The results of the model reproduced the observed offsets in detonation convergence from the center of the apparatus, confirming that velocity deficits resulting from the narrow channel width control the observed asymmetry. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) and three-dimensional (3D) numerical models are commonly employed to investigate the kinematic and hydrodynamic characteristics of fish maneuvers. In this study, we captured the posture characteristics of zebrafish during C-type maneuvers using high-speed photography and constructed a midline curvature model via the tandem principal characteristics method, which exhibited a "double peak and single valley" structure. Based on this curvature model, self-propelled simulations were conducted using the immersed boundary method with adaptive mesh refinement. The results showed that, under identical deformation conditions, the 2D simulation exhibited a 16.8% higher centroid velocity, 6.1% greater overall angular velocity, and an 11.9% larger turning angle compared to the 3D simulation. This discrepancy is primarily due to the 2D model's inability to accurately represent the fish body's mass distribution and force characteristics, resulting in artificially elevated performance. Nevertheless, 2D simulations remain applicable for studying the propulsion performance of fish with elongated cross-sections and large fin areas. Comparison between the simulated and real motion performance reveals that, under the self-propelled computational model, both 2D and 3D numerical simulations consistently capture the qualitative motion patterns. The quantitative results also reflect the actual swimming performance of the fish within an acceptable margin of error. [ABSTRACT FROM AUTHOR]

In this paper, high-speed photography was employed to experimentally study the high-speed, shallow-angle water entry of cylinders. By varying the density, length–diameter ratio, and launch speed of the cylinders, three typical trajectories were observed: arc, S, and ricochet trajectories. This study examined the cavity evolution, motion trajectory, force state, and stability of the cylinders under these three typical trajectories. Additionally, the influence of each cylinder's length–diameter ratio and density on the stability of its motion during shallow-angle water entry was explored. The experimental results indicated that during the impact stage, the cylinder generates a head-down torque, resulting in an upward deflection after entry. The combination of head force and angle of attack generates lift, which increases with a positive angle of attack. Consequently, the cylinder's deflection speed accelerates, while it slows with a negative angle of attack. During the tail-slap process, the combined forces from the head and tail both generate lift, but in the opposite directions. The motion stability decreases sequentially in the arc, S, and ricochet trajectories, which is closely related to the first tail-slap. Increasing the cylinder length–diameter ratio or density delays the occurrence of the first tail-slap, thereby enhancing motion stability during shallow-angle water entry. [ABSTRACT FROM AUTHOR]

For the issue of jet impingement on the wall in industrial cooling processes, an experimental setup based on high-speed photography for oblique jet impingement onto the wall was constructed. The experimental focus was on the study of liquid droplet splashing behavior after oblique jet impingement on the wall, discussing the liquid droplet splashing behavior under three jet impingement modes: Rayleigh regime, first wind-induced regime, and secondary wind-induced regime. By employing methods such as trajectory imaging and particle image velocity for liquid droplet parameter image measurement, obtaining the particle size, velocity, and distribution of splashed droplets after oblique jet impact on walls under different working conditions. The impact of jet impingement velocity and angle on droplet splashing parameters was analyzed. The results showed that when the impingement point is before the breakup length, with increasing flow velocity, the surface wave of the liquid column, and the spreading liquid film became more pronounced, but the loss of liquid-phase components due to splashing was relatively small. When the impingement point is after the breakup length, the secondary breakup resulting in a "crown"-shaped liquid film after droplet impingement leads to a significant loss of liquid-phase components through splashing. As the inlet velocity of the jet increases, there is a decreasing trend in droplet size and an increasing trend in droplet velocity. With an increase in jet angle, there is a decreasing trend in droplet size and velocity. Based on the concentration, size, and velocity distribution characteristics of splashing droplets, the area after oblique jet impingement on the wall can be divided into the impingement zone, low-concentration low-velocity zone, high-concentration high-velocity zone, and lateral splashing zone. This has significant implications for understanding the splashing mechanism after oblique jet impingement on the wall and optimizing operating conditions. [ABSTRACT FROM AUTHOR]

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

The frequency characteristics of cavitation fluctuations in high-speed cavitating jets are intricate due to the coupling mechanisms of unsteady behaviors. This study employs high-speed photography to experimentally investigate the relationship between frequency characteristics and the unsteady behavior of cavitating jets with various cavitation numbers. Temporal evolution patterns of the cavitating jets are analyzed through spatiotemporal (s-t) diagrams. The spatial distribution and temporal evolution of cavitation fluctuation frequencies are examined using fast Fourier transform (FFT) and continuous wavelet transform (CWT), respectively. Proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) are employed to identify coherent structures and their corresponding frequencies. In results, the s-t diagrams reveal the distinct regions influenced by cavitation shedding and collapse. FFT results indicate that upstream of the jet trajectory, spectral energy is concentrated in the shedding band, shifting toward lower frequencies with increasing axial distance. The CWT spectrum exhibits a single peak in the upstream, identifying it as the shedding frequency. POD modes associated with shedding dominate the energy contribution at higher cavitation numbers, while they become less prominent at lower cavitation numbers. DMD extracts and identifies coherent structures associated with shedding through frequency-specific decomposition. [ABSTRACT FROM AUTHOR]

This study examines the processes of expansion, merging, and collapse of multiple underwater explosion bubbles through experimental and numerical methods. A small-scale underwater explosion experiment was conducted in a water tank. The behaviors of three and four bubbles during expansion, merging, and collapse were captured using high-speed photography, and the effects of the quantity and spacing of the explosive charge on the bubble dynamics were analyzed. The results indicate that the evolution of bubble behavior in multiple charge underwater explosions, including the bubble period and radius, is significantly influenced by the spacing between charges. With a decrease in the ratio of the charge spacing to the bubble radius, the period of the merged bubble increases progressively. Independent small bubbles do not interact when the distance between charges exceeds 1.3 times the bubble radius. Furthermore, when the ratio of the spacing to the initial bubble radius (L/rb) is between 1.0 and 1.3, multiple bubbles merge during the contraction phase. When the spacing is less than the maximum radius of the bubbles, multiple bubbles inevitably merge, with fusion occurring during the expansion phase. [ABSTRACT FROM AUTHOR]

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Bandsaw blades are typical band-shaped cutting tools that are characterized by their low stiffness and micro-level cutting depth, resulting in distinct wear mechanisms compared to rigid cutting tools. In this study, the wear curve and wear mechanisms of the bandsaw tooth during the bandsawing of Cr12MoV cold-working steel were investigated. The tool life was divided into two stages: a rapid wear stage (Stage I) and a homogeneous wear stage (Stage II). In Stage I, the wear was dominated by chipping, although multiple wear mechanisms were found due to their relatively low manufacturing accuracy compared to rigid cutting tools, which resulted in remarkable differences in the cutting depth of each tooth. In Stage II, abrasive and adhesive wear were the primary wear mechanisms instead of chipping, which was related to the microstructure of Cr12MoV. Furthermore, methods for increasing bandsaw performance were proposed, based on the tooth wear mechanisms. [ABSTRACT FROM AUTHOR]

C f /SiC composite is widely utilized in aerospace and defense sectors owing to their outstanding high-temperature and mechanical performance. However, this material is a typical hard-to-machining material. Building upon prior research on the novel laser-induced oxidation-assisted milling technology, this paper conducted an in-depth study of the oxidation of C f /SiC composite under laser induction. The study combined thermodynamic analysis with the detection of oxidation products to ascertain the oxidation reaction types of C f /SiC composite. The oxidation process under the induction of lasers with different energy densities was investigated by combining the oxide layer morphology, element distribution, and high-speed photography results. And the oxidation mechanism was elucidated. A second-order response surface model for the oxide layer thickness with respect to the laser energy density, scanning speed, and scanning path spacing was established, and parameter optimization was performed based on this model. Experimental validation demonstrated the reliability of the model predictions. [ABSTRACT FROM AUTHOR]

An experimental study to investigate the flow of liquid jet issued from a high aspect ratio nozzle slit into an incoming airflow by changing the orientation angle from the incoming free-stream was performed. A two-dimensional liquid sheet emerged from the narrow slit into the subsonic air crossflow. Different orientation angles between 0 and 90 degrees were studied. High-speed photography and shadowgraphy techniques were utilized to visualize the flow physics. The influence of the slit orientation angle on the flow morphology and the flow regimes of liquid sheets was investigated. Some fluid flow parameters were obtained by analyzing the images. The changes in breakup height of different orientations were measured. A model was offered for the breakup height of the liquid sheet based on the liquid-to-gas momentum ratio, gas Weber number, and a new non-dimensional parameter as a representation of the angle of slit orientation. Also, the defined sheet trajectory for each orientation angle was obtained, and the variations were examined. Empirical correlations for the defined trajectory of the sheet in terms of liquid to gas momentum ratio and gas Weber number for each orientation angle were proposed. [ABSTRACT FROM AUTHOR]

A novel jet impingement sprinkler was designed to replace the additional water-dispersing devices usually used in rotating sprinklers to adapt performance for low-pressure conditions. Utilising the asymmetric impingement mode of primary and secondary jets, the design prioritises the secondary nozzle elevation angle. Theoretical expressions were establish between the primary and secondary jet momentum rates. Hydraulic performance experiments, were conducted under intermediate and low-pressure conditions, examining water application rate, wetted radius, and Christiansen's uniformity coefficient at various elevation angles. High-speed photography (HSP) experiments elucidate differences in hydraulic performance, revealing that the impingement jet generally featured a lower maximum water application rate but a smoother distribution compared to its non-impingement counterpart. Using the CRiteria Importance Through Intercriteria Correlation (CRITIC) method, comprehensive scores highlight an optimal arrangement with a 34.5° secondary nozzle elevation angle, illustrating superior performance under low pressure. Comparative analyses between the wetted radius and Christiansen's uniformity coefficient uncover a trade-off, with jet impingement sacrificing wetted radius for increased uniformity. However, this efficiency diminished as jet impingement effects intensify. HSP experiments validate theoretical calculations, with a relative error of less than 4% for jet deflection angle and jet breakup length. Non-linear curve fitting establishes relationships between jet breakup length, mean observed jet deflection angle, operating pressure, and wetted radius. Calculated and measured values exhibited a relative error within 5%, affirming the applicability of the developed equation for predicting wetted radius in jet impingement sprinklers. • A jet impingement sprinkler based on the asymmetric impingement mode was designed. • Theoretical equations for the momentum relationship between the primary and secondary jets were derived. • A non-linear equation for the wetted radius of jet impingement sprinklers was fitted with an error below 5%. [ABSTRACT FROM AUTHOR]

The interaction of laser-induced cavitation bubbles with air bubbles attached to the upper surface of a horizontal plate was studied with high-speed photography. On the cavitation bubble side, the dimensionless distance parameter, γ = 4.5 for vertical jets from cavitation bubbles as proposed in previous research and the dimensionless parameter, γ = 5.8 for oblique upward jets have been established. On the attached air bubble side, the relationship between the dimensionless distance parameter, γ a and the four types of morphology (Omega, hemisphere, hemisphere to hat with split, and hemisphere to hat without split) of attached air bubbles, as well as the three modes of jets (initial, multiple, and delay), has been demonstrated. The split of the small bubble from the attached bubble is primarily due to the vertical velocity differences brought about by the multiple collapses of cavitation bubbles and the pulsation of attached bubbles. Subsequent studies on the detachment behavior of attached bubbles determined the ideal dimensionless distance, γ a = 3.4 for detachment. The surface ripples play a dominant role in promoting the detachment of attached bubbles at greater distances. [ABSTRACT FROM AUTHOR]

Droplet transport is very essential in many industrial applications. This article proposed the concept of employing dual synthetic jets in conjunction with superhydrophobic materials to facilitate the long-distance directional transport of water droplets. Experiments showed that the droplet transport speed could reach approximately 90 mm/s. In addition to linear transport, dual synthetic jets were also capable of achieving curved transport of droplets on superhydrophobic surfaces. High-speed photography captured the details of the droplet transport process. Additionally, simulations analyzed the water droplet's aerodynamic forces and the deformation and breakup mechanisms at the actuator's outlet. The research in this paper was anticipated to contribute to new methods for directed droplet transport on superhydrophobic surfaces. It is eliminated the need for pre-processing the surface to create a path, and there was also no need to incorporate conductive or magnetic substances within the droplets. [ABSTRACT FROM AUTHOR]

An investigation of the multi-cycle dynamics of underwater explosion bubbles near hybrid boundaries is conducted using the experimental method. The experiments are carried out within a square steel tank. The free surface and a freely hanging steel plate comprise the hybrid boundary condition. Bubbles are initially positioned at equal distances from the two boundaries to facilitate a comparison of the relative influence exerted by each boundary. High-speed photography and pressure sensors are utilized to document the dynamics of bubbles and pressures in the flow field. An examination of the bubble behavior is conducted through the analysis of experimental imagery, elucidating the formation of a cone-shaped cavity near the free surface and the subsequent complex distortion behavior of the bubble as it interacts with the wall during the rebound phase. The investigation concentrates on the migratory properties of bubbles across various regions, revealing a spectrum of trajectories due to the varying boundary and buoyancy effects: vertical descent, "L"-shaped trajectory, "U"-shaped trajectory, and diagonal upward trajectory. Unless very close to the free surface, the direction of bubble migration changes at the end of each cycle due to local fragmentation of the bubble surface. Finally, the discussion culminated in an analysis of bubble energy conversion, revealing that the complex bubble behavior near the free surface weakens bubble collapse, resulting in minimal impact on the surrounding fluid dynamics from bubble oscillation. In the region distant from the free surface, when the bubble oscillation is weakly affected by buoyancy and boundaries, the energy emitted by bubble oscillation peaks due to the nearly spherical collapse. [ABSTRACT FROM AUTHOR]