scholarly journals The High-Speed Photography and Numerical Simulation of Cavitation Bubbles near a Solid Wall

1990 ◽  
Vol 10 (1Supplement) ◽  
pp. 111-114
Author(s):  
Yukio TOMITA ◽  
Kotaro SATO ◽  
Akira SHIMA
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Solid Wall ◽  
High Speed Photography ◽  
Cavitation Bubbles

scholarly journals A Photographic Study of Spark-Induced Cavitation Bubble Collapse

1972 ◽  
Vol 94 (4) ◽  
pp. 825-832 ◽  
Author(s):  
C. L. Kling ◽  
F. G. Hammitt
Keyword(s):  
Cavitation Bubble ◽  
High Speed ◽  
Bubble Collapse ◽  
Solid Boundary ◽  
High Speed Photography ◽  
Minimum Volume ◽  
Cavitation Bubbles ◽  
Flowing System

The collapse of spark-induced cavitation bubbles in a flowing system was studied by means of high speed photography. The migration of cavitation bubbles toward a nearby solid boundary during collapse and rebound was observed. Near its minimum volume the bubble typically formed a high speed microjet, which struck the nearby surface causing individual damage craters on soft aluminum.

Experiment and Numerical Simulation of Extrudate Swell in the Polymer Extrusion Process

2011 ◽  
Vol 314-316 ◽  
pp. 401-404 ◽  
Author(s):  
Min Zhang ◽  
Chuan Zhen Huang ◽  
Guo Wen Chen ◽  
Yu Xi Jia
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Three Dimensional ◽  
Simulation Method ◽  
Extrusion Process ◽  
High Speed Photography ◽  
The Finite Element Method ◽  
Polymer Extrusion ◽  
Extrudate Swell ◽  
Rate Profile

The extrudate swell of the polymer extrusion process was studied with the experiment and simulation method. The extrudate swell process was recorded by the high-speed photography apparatus. The swell rate at the different time was calculated. It is found that the extrudate swell rate increase at the first five seconds. The maximum swell rate is about 4.37%. The three-dimensional numerical simulation model of the experiment die path was founded. The extrusion process including the extrudate swell was simulated used the Finite Element Method. Such simulated results as the velocity vector, the shear rate profile and the end of the swell zone were analyzed. The extrudate swell end got by the simulation is similar with the experiment result.

Numerical simulation on surface deformation for rotating mirrors of ultra-high-speed photography

2007 ◽  
Author(s):  
Hongbin Huang ◽  
Jingzhen Li ◽  
Xiangdong Gong ◽  
Fengshan Sun ◽  
Bin Hui
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Surface Deformation ◽  
High Speed Photography ◽  
Ultra High Speed

scholarly journals The Penetration–Explosion Effects of Differently Distributed Inactive/Active Composite Shaped Charge Jets

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 344
Author(s):  
Jiacheng Peng ◽  
Jianwei Jiang ◽  
Jianbing Men ◽  
Jinlin Li ◽  
Dongkang Zhou ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Double Layer ◽  
High Speed ◽  
Shaped Charge ◽  
The Other ◽  
High Speed Photography ◽  
Active Composite ◽  
Deformation Area ◽  
Full Height

An analysis of the penetration–explosion (PE) effects of four distributions of inactive/active composite jets shows that a well-designed inactive/active double-layer liner can promote composite jet damage. Penetration experiments were then carried out for shaped charge jets having a single inactive (Cu) liner or an inactive/active (Cu/Al) double-layer liner with variable liner height. The behaviors and firelight patterns of the different jets were captured by high-speed photography. The perforation, deformation area, and deflection were measured for each plate, showing that the Cu/Al jets have stronger PE effects. Numerical simulation shows that the tip of the composite jet generated from the full-height liner is only Cu, whereas for the other jet, from the double-layer liner, Cu is almost wrapped entirely by Al.

scholarly journals DEM-CFD Simulation and Experiments on the Flow Characteristics of Particles in Vortex Pumps

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2444
Author(s):  
Xiongfa Gao ◽  
Weidong Shi ◽  
Ya Shi ◽  
Hao Chang ◽  
Ting Zhao
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Cfd Simulation ◽  
Flow Characteristics ◽  
Solid Particles ◽  
Experimental Results ◽  
High Speed Photography ◽  
Inlet Section ◽  
Impeller Blade ◽  
Vortex Pump

Due to their outstanding anti-clogging ability, vortex pumps have been gradually promoted and applied in recent years. However, when transporting sewage containing solids, they will still encounter problems such as partial clogging, overwork wear, etc., therefore, it is particularly important to master the flow characteristics of solid particles in the vortex pump. In this paper, the Discrete Element Model-Computational Fluid Dynamics (DEM-CFD) coupled calculation method is introduced into the numerical simulation of vortex pumps and particles with diameters of 1, 2 and 3 mm and concentrations of 1% and 5%, were subjected to numerical simulation and study of the flow characteristics of the particles, then rapeseed was used to represent solid particles in tests. It was obvious that the CFD results were in good agreement with the experimental results, whereby the high speed photography experimental results of the pump inlet section show that the experimental results are consistent with the numerical simulation results. The results show that there are three typical movement tracks of solid particles in the vortex pump: in Track A particles flow through the impeller and enter the volute by the through flow, in Track B particles go directly into the volute through the lateral cavity under the influence of circulation flow and in Track C the particles enter the impeller from the front cover end area of the impeller blade inlet and then into the volute through the back half area of blade. It can be found that the particles are mainly distributed at the back of the volute.

scholarly journals Numerical Study of the Pulsation Process of Spark Bubbles under Three Boundary Conditions

2021 ◽  
Vol 9 (6) ◽  
pp. 619
Author(s):  
Chunlong Ma ◽  
Dongyan Shi ◽  
Chao Li ◽  
Dongze He ◽  
Guangliang Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Nonlinear Interaction ◽  
Cavitation Bubble ◽  
High Speed ◽  
Free Field ◽  
Experimental Results ◽  
High Speed Camera ◽  
Cavitation Bubbles ◽  
Bubble Pulsation

In this study, a compressible three-phase homogeneous model was established using ABAQUS/Explicit. These models can numerically simulate the pulsation process of cavitation bubbles in the free field, near the flat plate target, and near the curved boundary target. At the same time, these models can numerically simulate the strong nonlinear interaction between the cavitation bubble and its nearby wall boundaries. The mutual flow of liquid and gas and fluid solid coupling were solved by the Euler domain in simulation. The results of the numerical simulation were verified by comparing them with the experimental results. In this study, we used electric spark bubbles to represent cavitation bubbles. A high-speed camera was used to record the pulsation process of cavitation bubbles. This study first verified the pulsation process of cavitation bubbles in the free field, because it was the simplest case. Then we verified the interaction process between cavitation bubbles and different wall boundaries. In order to further confirm the credibility of the numerical simulation results, for each wall surface, this study used two burst distances (10 mm and 25 mm) for simulation verification. The numerical model established in this study could effectively simulate the pulsation characteristics of cavitation bubbles, such as the formation of jets and annular bubbles. After verification, the simulated cavitation bubble was almost the same as the cavitation bubble captured by the high-speed camera in the experiment in terms of time, volume, and shape. In this study, a detailed velocity field of the cavitation bubble collapse stage was obtained, which laid down the foundation for the study of the strong nonlinear interaction between the cavitation bubble and the target plates of different shapes. Compared with the experimental results, we found that the numerical model established by the simulation could accurately simulate the bubble pulsation and jet formation processes. In the experiment, the interval time for the bubble pictures taken by the high-speed camera was 41.66 μs per frame. Using a numerical model, the bubble pulsation process can be simulated at an interval of 1 µs per frame. Therefore, the numerical model established by the simulation could show the movement characteristics of the cavitation bubble pulsation process in more detail.

Interaction between two laser-induced cavitation bubbles in a quasi-two-dimensional geometry

2009 ◽  
Vol 633 ◽  
pp. 425-435 ◽  
Author(s):  
PEDRO A. QUINTO-SU ◽  
CLAUS-DIETER OHL
Keyword(s):  
Potential Flow ◽  
High Speed ◽  
Three Dimensional ◽  
Interaction Force ◽  
High Speed Photography ◽  
Two Dimensional ◽  
Experimental Conditions ◽  
Numerical Studies ◽  
Cavitation Bubbles ◽  
Good Agreement

We report on experimental and numerical studies of pairs of cavitation bubbles growing and collapsing close to each other in a narrow gap. The bubbles are generated with a pulsed and focused laser in a liquid-filled gap of 15 μm height; during their lifetime which is shorter than 14 μs they expand to a maximum radius of up to Rmax = 38 μm. Their motion is recorded with high-speed photography at up to 500000 frames s−1. The separation at which equally sized bubbles are created, d, is varied from d = 46–140 μm which results into a non-dimensional stand-off distance, γ = d/(2Rmax), from 0.65 to 2. For large separation the bubbles shrink almost radially symmetric; for smaller separation the bubbles repulse each other during expansion and during collapse move towards each other. At closer distances we find a flattening of the proximal bubbles walls. Interestingly, due to the short lifetime of the bubbles (≤14 μs), the radial and centroidal motion can be modelled successfully with a two-dimensional potential flow ansatz, i.e. neglecting viscosity. We derive the equations for arbitrary configurations of two-dimensional bubbles. The good agreement between model and experiments supports that the fluid dynamics is essentially a potential flow for the experimental conditions of this study. The interaction force (secondary Bjerknes force) is long ranged dropping off only with 1/d as compared to previously studied three-dimensional geometries where the force is proportional to 1/d2.

Experimental Investigation of Flow Over a Backward-Facing Step in Proximity to a Flexible Wall

2009 ◽  
Author(s):  
A. Velikorodny ◽  
G. Duck ◽  
P. Oshkai
Keyword(s):  
Reynolds Number ◽  
High Speed ◽  
Manufacturing Industry ◽  
Solid Wall ◽  
Separated Flow ◽  
Maximum Flow ◽  
High Speed Photography ◽  
Paper Sheet ◽  
Backward Facing Step ◽  
Flexible Wall

Turbulent flow between a flexible wall and a solid surface containing a backward-facing step (BFS) was investigated using digital particle image velocimetry (PIV) and high-speed photography. Motivation for this study stems from paper manufacturing industry, where high-speed, wall-bounded jets of air are employed in air clamp devices to precisely position moving sheets of paper at the specified locations with respect to other equipment. In the current investigation, stationary sheet of paper under tension was positioned in proximity to the BFS. The incoming air flow emerged from a planar nozzle that was located in the solid wall upstream of the BFS. Curvature of the nozzle wall resulted in a favorable pressure gradient condition. As a result, the flow upstream of the BFS was attached to the solid wall due to the Coanda effect. Flows corresponding to two values of the Reynolds number (3000 and 3600) based on the step height and the maximum flow velocity at the step location were characterized in terms of patterns of instantaneous and time-averaged velocity, out-of-plane vorticity, streamline topology, and turbulence statistics. In addition, paper sheet oscillation was characterized using high-speed photography. Frequencies of the natural vibration modes of the flexible wall (paper sheet) were well separated from the hydrodynamic frequencies corresponding to the oscillations of the shear layer downstream of the BFS, which resulted in the absence of resonance in the system and low characteristic amplitudes of the paper sheet oscillation. In the time-averaged sense, interaction between the separated flow downstream of the BFS and the flexible wall (paper sheet) resulted in deformation of the paper sheet and formation of diverging channel geometry between the sheet and the solid wall. As the inflow velocity increased, the paper sheet was pulled closer to the surface of the air clamp, which resulted in increased confinement of the incoming Coanda jet. The flow reattachment length calculated on the basis of time-averaged flow patterns increased with the increasing Reynolds number.

scholarly journals Retardant Effects of Collapsing Dynamics of a Laser-Induced Cavitation Bubble Near a Solid Wall

Symmetry ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1051
Author(s):  
Li ◽  
Duan ◽  
Zhang ◽  
Tang ◽  
Zhang
Keyword(s):  
Data Analysis ◽  
Cavitation Bubble ◽  
High Speed ◽  
Solid Wall ◽  
Bubble Collapse ◽  
High Speed Photography ◽  
Bubble Wall ◽  
Interface Evolution ◽  
Wall Distance ◽  
Dramatic Difference

In the present paper, the dynamic behavior of cavitation bubbles near a wall is experimentally investigated with a focus on the retardant effects of the wall on the collapsing dynamics of the bubble. In the present experiments, a cavitation bubble is generated by a focused laser beam with its behavior recorded through high-speed photography. During the data analysis, the influences of non-dimensional bubble–wall distance on the bubble collapsing dynamics are qualitatively and quantitatively investigated in terms of the interface evolution, the velocities of the poles, and the movement of the bubble centroid. Our results reveal that the presence of the wall could significantly affect the collapsing characteristics, leading to a dramatic difference between the moving velocities of interfaces near and away from the wall. With the decrease of the bubble–wall distance, the effects will be gradually strengthened with a rapid movement of the bubble centroid during the final collapse. Finally, a physical interpretation of the phenomenon is given based on the bubble theory, together with a rough estimation of the induced water hammer pressure by the bubble collapse.

Sign in / Sign up

Export Citation Format

Share Document