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Journal of Hydrodynamics 2023年第5期35卷 942-953页

作者： Xiang-qing Zhang Xiao-fei Zhang Xu Qiu Dan Gao Yu-ning Zhang Key Laboratory of Power Station Energy Transfer Conversion and System(Ministry of Education) School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China China Atomic Energy Publishing and Media Co.LTD Beijing100048China China Institute of Nuclear Industry Strategy Beijing100048China National Institute of Energy Development Strategy North China Electric Power UniversityBeijing102206China

Based on high-speed photographic experiments,this study presents a detailed qualitative and quantitative analysis of the dynamics of a single cavitation bubble near the boundary of a rigid wall in asymmetric *** main findings are reported as follows:(1)The non-sphericity of the bubble interface decreases with increasing spacing between the bubble and the boundary,and the asymmetry of the bubble becomes more significant with increasing asymmetry angle.(2)The motion mode of the bubble cluster in the second oscillation cycle can be divided into two typical modes depending on the direction of movement.(3)The angle between the oblique jet pointing towards the upper wall surface and the horizontal direction in the second oscillation cycle decreases as the dimensionless spacing decreases.

关键词： Asymmetry boundary cavitation bubble high-speed photography jet non-sphericity

Experimental investigations of mechanical and reaction responses for drop-weight impacted energetic particles

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Acta Mechanica Sinica 2017年第1期33卷 65-70页

作者： Xiao-Wei Bao Yan-Qing Wu Ming-Yang Wang Feng-Lei Huang State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology Beijing 100081 China

Low-velocity drop-weight impact experiments on individual and multiple Cyclotetramethylene tetranitramine (HMX) energetic particles were performed using a modified drop-weight machine equipped with high-speed photography components. Multiple particles experienced more severe burning reactions than an individual particle. Comparisons between impacted salt and HMX particle show that jetting in HMX is mainly due to the motion of fragmented particles driven by gaseous reaction products. Velocity of jetting, flame propagation, and area expansion were measured via image processing, making it possible to quantify the chemical reaction or mechanical deformation violence at different stages.

关键词： HMX energetic particle Drop-weight impact high-speed photography Ignition and combustion Jetting

UNDERWATER ACOUSTICS AND CAVITATING FLOW OF WATER ENTRY

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Acta Mechanica Sinica 2004年第4期20卷 374-382页

作者：施红辉 KUME Makoto State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100080China College of Mechanical Engineering and Automatic ControlZhejiang University of SciencesXiasha Higher Education ZoneHangzhou 310018China Department of Mechanical Engineering Nagoya Institute of TechnologyGokiso-choShowa-kuNagoya 466-8555Japan

The fluid mechanics of water entry is studied through investigating the underwater acoustics and the *** acoustic signals in water entry are extensively measured at about 30 different positions by using a PVDF needle *** the measurements we obtain (1)the primary shock wave caused by the impact of the blunt body on free surface;(2)the vapor pressure inside the cavity;(3)the secondary shock wave caused by pulling away of the cavity from free surface;and so *** supercavitation induced by the blunt body is observed by using a digital high-speed video camera as well as the single shot *** periodic and 3 dimensional motion of the supercavitation is *** experiment is carried out at room temperature.

关键词： water entry underwater acoustics supercavitation PVDF hydrophone high-speed photography

Experimental investigation on ice-breaking performance of a novel plasma striker

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Chinese Journal of Aeronautics 2022年第1期35卷 307-317页

作者： Tianxiang GAO Zhenbing LUO Yan ZHOU Shengke YANG Wenqiang PENG Xiong DENG Pan CHENG College of Aerospace Engineering National University of Defense TechnologyChangsha 410073China China Aerodynamics Research and Development Center Mianyang 621000China

Aircraft icing has long been a plague to aviation for its serious threat to flight ***,researches about a newly proposed deicing method based on Plasma Synthetic Jet Actuator(PSJA)have just *** meet the requirements of in-flight deicing,structure of PSJA needs to be *** paper completed the detailed design and experimental validation of a novel plasma striker,which was a modified version of *** of mass of the moving part and rod shapes on the ice-breaking performances were also ***,a“conical-nosed rod configuration”was *** purpose was to ensure a good ice-breaking performance of the plasma striker on long ice,by generating a splitting *** show that,though mass of the moving part was just several grams,ice-breaking performance was better when the mass was *** rectangular rod could generate an elliptical circumferential crack,whose major axis was parallel to the direction of the long side of the rectangular *** the“conical-nosed rod”concept was verified to be able to generate a splitting crack which can spread completely to the far end of long ice,and the crack direction was parallel to edge line of the *** general,the plasma striker has the advantages of simple structure,low energy consumption,little harm to the flow field and the aircraft *** will be carried out in future works to study in detail the working process of the plasma striker.

关键词： Conical shaped rod Deicing Experimental tests high-speed photography Ice fracture Plasma striker

Experimental research of the cavitation bubble dynamics during the second oscillation period near a spherical particle

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Journal of Hydrodynamics 2023年第4期35卷 700-711页

作者： Xiao-yu Wang Hong-chen Su Shao-wei Li Guan-hao Wu Xiao-xiao Zheng Ya-xin Duan Yu-ning Zhang Key Laboratory of Power Station Energy Transfer Conversion and System(Ministry of Education) School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China State Key Laboratory of Clean Energy Utilization Zhejiang UniversityHangzhou310027China

In this paper,the dynamic behaviors of the cavitation bubble near a fixed spherical particle during the second oscillation period are analyzed based on the high-speed photographic *** deformation and motion of the bubble during the second period are investigated by changing the distance between the particle and the bubble and the maximum radius of the ***,the variation of the equivalent radius and the centroid motions are analyzed,and the dynamic behaviors of the bubble are categorized according to the bubble morphological characteristics during the second *** this research,it is found that(1)The dynamic behaviors of the bubble during the second oscillation period could be divided into three typical cases:For case 1,a bulge would exist on the bubble interface away from the particle,and for case 2,a bulge would appear on the bubble interface and evolve towards the particle,while for case 3,the bubble would be divided into two parts.(2)The larger the dimensionless distance between the particle and the bubble,the smaller the maximum bubble equivalent radius in the second period,and the shorter the second oscillation period.(3)When the bubble is close to the particle,a counter-jet appears at the bubble interface away from the particle during the rebound stage.

关键词： Cavitation bubble dynamics particle-bubble interaction second oscillation period high-speed photography

Effect of blade tip geometry on tip leakage vortex dynamics and cavitation pattern in axial-flow pump

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Science China(Technological Sciences) 2017年第10期60卷 1480-1493页

作者： SHI Lei ZHANG DeSheng ZHAO RuiJie SHI WeiDong JIN YongXin Research Center of Fluid Machinery Engineering and Technology Jiangsu University Zhenjiang 212013 China

A series of blade tip geometries, including original plain tip, rounded tip on the pressure side and diverging tip towards the suction side, were adopted to investigate the effect of blade geometry on tip leakage vortex dynamics and cavitation pattern in an axial-flow pump. On the basis of the computation, it clearly shows the flow structure in the clearance for different tip configurations by the detailed data of axial velocity and turbulent kinetic energy. The in-plain trajectory, in aspects of the angle between the blade suction side and vortex core and the initial point of tip leakage vortex, was presented using the maximum swirling strength method. The most striking feature is that the inception location of tip leakage vortex is delayed for chamfered tip due to the change of blade loading on suction side. Some significant non-dimensional parameters, such as pressure, swirling strength and turbulent kinetic energy, were used to depict the characteristics of tip vortex core. By the distribution of circumferential vorticity which dominates the vortical flows near the tip region, it is observed that the endwall detachment as the leakage flow meets the mainstream varies considerably for tested cases. The present study also indicates that the shear layer feeds the turbulence into tip leakage vortex core, but the way is different. For the chamfered tip, high turbulence level in vortex core is mainly from the tip clearance where large turbulent kinetic energy emerges, while it is almost from a layer extending from the suction side corner for rounded tip. At last, the visualized observations show that tip clearance cavitation is eliminated dramatically for rounded tip but more intensive for chamfered tip, which can be associated with the vortex structure in the clearance.

关键词： blade tip geometry tip leakage vortex cavitation numerical simulation high-speed photography

Collapse of cavitation bubbles near air bubbles

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Journal of Hydrodynamics 2020年第5期32卷 929-941页

作者： Jing Luo Wei-lin Xu Rui Li State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan UniversityChengdu 610065China

The cavitation erosion is one of the common damage modes in water *** study of the interaction among cavitation bubbles,air bubbles and the wall is of great significance for understanding the mechanism of the air entrainment to alleviate the cavitation and to enhance the cavitation erosion mitigation effect of *** using the high-speed camera,the regular patterns of the collapse of cavitation bubbles in the vicinity of the wall and the air bubbles are studied in this *** is shown that in the vicinity of air bubbles,the cavitation bubbles may only collapse towards or from air bubbles,while under the dual impacts of air bubbles and the wall,the direction of collapse of the cavitation bubbles depends on the combined vector of the impact forces of the air bubbles and the *** the air bubbles are very close to the cavitation bubbles,the air bubbles will be penetrated and stretched by the cavitation bubbles,when the distance between them is short enough,the cavitation bubbles and the air bubbles will connect to form gas-type cavitation bubbles,and the collapse strength will be significantly decreased,when there are two air bubbles near the cavitation bubbles,they may even be penetrated successively by the cavitation *** it can be concluded that during the air entrainment to alleviate the cavitation,the number of air bubbles is more important than the total air concentration.

关键词： Cavitation bubble air bubble high-speed photography air entrainment to alleviate cavitation

Simulation of Metal Transfer in GMAW Based on FLUENT

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Acta Metallurgica Sinica(English Letters) 2013年第3期26卷 265-270页

作者： Xueping DING Huan LI Lijun YANG Ying GAO Tianjin Key Laboratory of Advanced Joining Technology Tianjin University Tianjin Key Laboratory of high speed Cutting and Precision Machining Tianjin University of Technology and Education

A new numerical approach is presented, which is used to simulate the dynamic process of metal transfer. The process of metal transfer in gas metal arc welding is simulated based on FLUENT. A two-dimensional axisymmetric numerical model is developed using volume of fluid method and the distributions of physical quantities including pressure, current density, electric potential in the droplet are investigated. For improving the veracity of the simulated results and decreasing the effect of the uncertain surface tension coefficient on the simulated results, the relationship between the welding current and surface tension coefficient is modified by analysis of regression. Meanwhile for testing the accuracy of simulated results, the welding experiments are performed and the high-speed photography system is used to record the real process of metal transfer. The results show that the simulated results are in reasonably good agreement with the experimental ones.

关键词： Metal transfer FLUENT Dynamic simulation high-speed photography

THE COUNTER-JET FORMATION IN AN AIR BUBBLE INDUCED BY THE IMPACT OF SHOCK WAVES

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Journal of Hydrodynamics 2011年第5期23卷 562-569页

作者： BAI Li-xin XU Wei-lin LI Chao GAO Yan-dong Institute of Acoustics Chinese Academy of Sciences Beijing 100190 China State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan University Chengdu 610065China School of Electronic and Information Engineering Liaoning Technical University Huludao 125105 China

The interaction of an air bubble （isolated in water or attached to a boundary） with shock waves induced by electric sparks is investigated by high-speed photography. The interaction is closely related to the counter-jet induced by the impact of shock waves. The formation of a counter-jet in an air bubble is related to the liquid jet formed in the same air bubble, but the mechanism is different with that of the counter-jet formation in a collapsing cavitation bubble. The formation of a counter-jet in an air bubble is related to discharge energy, air bubble size and radius of shock wave. With a given energy of the spark discharge, the formation of a counter-jet in an air bubble is related to δ / ε （the ratio of the dimensionless bubble-bubble distance to the dimensionless air bubble radius）. The counter-jet will only be produced when δ / ε is in the range of 1.2-2.2. The counter-jet in an air bubble is of an important nuclei-generating mechanism.

关键词： cavitation bubble shock wave counter-jet high-speed photography

Rupture of a rubber sheet by a cavitation bubble:an experimental study

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Acta Mechanica Sinica 2021年第10期37卷 1489-1497,I0001页

作者： Xing-Yu Kan Jia-Le Yan Shuai Li A-Man Zhang College of Shipbuilding Engineering Harbin Engineering UniversityHarbin150001China

Dynamics of spark-generated cavitation bubbles near a deformable rubber sheet are experimentally investigated in this *** transient bubble–rubber interaction is captured by high-speed photography,including the expansion and collapse of the bubble,jetting behaviors,large deformation,and rupture of the rubber *** dependence of bubble behaviors and rubber response on two governing parameters(the bubble–rubber stand-off distanceγand the rubber thickness T)are systematically ***,the bubble collapse patterns or jetting directions are categorized into three *** the bubble is initially located at a largeγfrom the rubber sheet,the jet is directed towards the boundary(regime I).Unexpectedly,when the generated bubble is close to the rubber sheet,it develops a jet away from the boundary(regime III).Bubble splitting and the formation of two axial liquid jets directing in opposite directions can only be observed with an intermediateγ(regime II).A phase diagram of the bubble behaviors is given in theγ–T *** a large rubber sheet thickness(e.g.,T=5 mm),only a downward jet is *** the perspective of jet direction,the effect of such a thick rubber sheet on the bubble dynamics is similar to that of a rigid *** that the jet velocity and jet width may be slightly ***,the results reveal that bubble expansion can cause the boundary to *** strong axial jet towards the rubber sheet can damage and even rupture the rubber boundary.A parameter range within which the bubble jetting can rupture the rubber boundary is ***,for a thin rubber sheet(T≤4 mm),the rupture is more likely to occur in regime *** a thick rubber sheet(e.g.,T=5 mm),the rupture can be seen when the jet directly impacts the rubber sheet(regime I).

关键词： Bubble dynamics Rubber boundary Rupture high-speed photography