A numerical study on high-speed water jet impact

Ice breaking has become one of the main problems faced by ships and other equipment operating in an ice-covered water region. New methods are always being pursued and studied to improve ice-breaking capabilities and efficiencies. Based on the strong damage capability, a high-speed water jet impact is proposed to be used to break an ice plate in contact with water. A series of experiments of water jet impacting ice were performed in a transparent water tank, where the water jets at tens of metres per second were generated by a home-made device and circular ice plates of various thicknesses and scales were produced in a cold room. The entire evolution of the water jet and ice was recorded by two high-speed cameras from the top and front views simultaneously. The focus was the responses of the ice plate, such as crack development and breakup, under the high-speed water jet loads, which involved compressible pressure ${P_1}$ and incompressible pressure ${P_2}$ . According to the main cause and crack development sequence, it was found that the damage of the ice could be roughly divided into five patterns. On this basis, the effects of water jet strength, ice thickness, ice plate size and boundary conditions were also investigated. Experiments validated the ice-breaking capability of the high-speed water jet, which could be a new auxiliary ice-breaking method in the future.

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An Experimental and Numerical Study of Dieless Water Jet Incremental Microforming

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4042790 ◽

2019 ◽

Vol 141 (4) ◽

Cited By ~ 1

Author(s):

Yi Shi ◽

Weizhao Zhang ◽

Jian Cao ◽

Kornel F. Ehmann

Keyword(s):

Numerical Model ◽

Sheet Metal ◽

Process Parameters ◽

High Speed ◽

Tool Path ◽

Numerical Study ◽

Single Point ◽

Thin Sheet ◽

Water Jet ◽

Truncated Cone

Conventional single-point incremental forming (SPIF) is already in use for small batch prototyping and fabrication of customized parts from thin sheet metal blanks by inducing plastic deformation with a rigid round-tip tool. The major advantages of the SPIF process are its high flexibility and die-free nature. In lieu of employing a rigid tool to incrementally form the sheet metal, a high-speed water jet as an alternative was proposed as the forming tool. Since there is no tool-workpiece contact in this process, unlike in the traditional SPIF process, no lubricant and rotational motion of the tool are required to reduce friction. However, the geometry of the part formed by water jet incremental microforming (WJIMF) will no longer be controlled by the motion of the rigid tool. On the contrary, process parameters such as water jet pressure, stage motion speed, water jet diameter, blank thickness, and tool path design will determine the final shape of the workpiece. This paper experimentally studies the influence of the above-mentioned key process parameters on the geometry of a truncated cone shape and on the corresponding surface quality. A numerical model is proposed to predict the shape of the truncated cone part after WJIMF with given input process parameters. The results prove that the formed part's geometric properties predicted by the numerical model are in excellent agreement with the actually measured ones. Arrays of miniature dots, channels, two-level truncated cones, and letters were also successfully fabricated on stainless-steel foils to demonstrate WJIMF capabilities.

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Structure of Emulsion Cavitation Jet and Jet Peening Impact on the Fatigue of Plan Carbon Steel Q235A

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.189-193.476 ◽

2011 ◽

Vol 189-193 ◽

pp. 476-483

Author(s):

Zhi Sun ◽

Yan Wei Sui ◽

Jun Li ◽

Yan Ni Zhou

Keyword(s):

Carbon Steel ◽

High Speed ◽

Test System ◽

Water Jet ◽

High Speed Photography ◽

Strengthening Effect ◽

Initial Stage ◽

Jet Impact ◽

Upstream Pressure ◽

Crack Initiation Life

Due to developing the strengthening effect of liquid jet peening on the surface modification for metallic materials, in this study, an emulsion jet peening is produced by injecting a high-speed emulsion jet into an emulsion filled tank. The test system and fixed emulsion of cavitation jet was developed. High speed photography technique was used to observe and analysis the structure of emulsion cavitation jet at various upstream pressures . The results indicate that the structure of emulsion cavitation jet in terms of jet impact pressure, intensive degree and uniformity is better than that water jet. The jet structure depends on the jet pressure. The cavitation jet length increases rapidly at the initial stage and then it stabilizes after few milliseconds. The stabilized length of jet increases and the diverges angle decreases with increasing pressures. Specimens made of plan carbon steel (Q235A, China standard) were exposed to emulsion jet peening at the stand-off distances of 20 mm with a constant upstream pressure, 20 MPa for 60 s. The fatigue test shows that the crack initiation life by treatment of emulsion jet peening increases about 12.5% and 20.2% compared to water jet and unpeened specimen respectively.

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A Numerical Study of Underwater Explosion Bubble

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.706-708.1734 ◽

2013 ◽

Vol 706-708 ◽

pp. 1734-1737

Author(s):

Cho Chung Liang ◽

Tso Liang Teng ◽

Ching Yu Hsu ◽

Anh Tu Nguyen

Keyword(s):

Numerical Study ◽

Underwater Explosion ◽

Water Jet ◽

Dynamical Process ◽

Floating Structures ◽

Jet Impact ◽

Long Time ◽

Bubble Pulsation ◽

Short Time ◽

Collapse Phase

The dynamical process of underwater explosion bubble is a very complicated phenomenon with many facets needed to consider. After detonation, shock wave propagates in a very short time while the oscillation of bubble occurs in a long time. Bubble pulsation can cause serious damage for the structures nearby due to the whipping effect, bubble pulse or water jet impact in the collapse phase. This paper presents an application of Finite Element Method (FEM), namely Eulerian technique, to simulate the dynamical process of bubble and numerical results were verified by an experiment. This approach shows it's feasibility in simulating the bubble pulsation as well as the formation of water jet at the end of first contracting circle. Although numerical model was simplified by the boundary conditions, the success of this method is foundation for further study of bubble such as in predicting the damages of both nearby submerged structures as well as floating structures.

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The Application of CEL Technique to Simulate the Behavior of an Underwater Explosion Bubble in the Vicinity of a Rigid Wall

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.902.126 ◽

2020 ◽

Vol 902 ◽

pp. 126-139

Author(s):

Anh Tu Nguyen

Keyword(s):

Finite Element ◽

High Speed ◽

Bubble Dynamics ◽

Underwater Explosion ◽

Flow Simulation ◽

Rigid Wall ◽

Water Jet ◽

Complex Structures ◽

Explicit Finite Element ◽

Jet Impact

The dynamic process of an underwater explosion (UNDEX) is a complex phenomenon that involves several facets. After detonation, the shockwave radially propagates at a high speed and strikes nearby structures. Subsequently, bubble oscillation may substantially damage the structures because of the whipping effect, water jet impact, and bubble pulse. This paper presents an application of explicit finite element analyses to simulate the process of an UNDEX bubble in the vicinity of rigid wall, in which the coupled Eulerian-Lagrangian (CEL) approach was developed to overcome the difficulties regarding the classical finite element method (FEM), large deformations, and flow simulation of fluid and gas. The results demonstrate that the method is well suited to manage the UNDEX bubble problem and can be used to model the major features of the bubble dynamics. Furthermore, the behavior of an UNDEX bubble near a rigid wall was also examined in the present study, which showed that the migration of the bubble and the development of the water jet are influenced strongly by the standoff distance between the initial bubble position and the wall. This method can be used in future studies to examine UNDEX bubbles in the vicinity of deformable and complex structures.

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Water-jet cavitation shocking as a novel array micro-forming technique

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1177/0954405420982222 ◽

2020 ◽

pp. 095440542098222

Author(s):

Fuzhu Li ◽

Peiyu He ◽

Zhipeng Chen ◽

Shangshuan Chen ◽

Jun Guo ◽

...

Keyword(s):

High Speed ◽

Thickness Distribution ◽

Water Jet ◽

Impact Zone ◽

Large Area ◽

Micro Forming ◽

Jet Impact ◽

Microscopic Features ◽

The Impact ◽

Metallic Sheet

Micro-feature arrays and large-area complex microscopic features on thin metallic sheet play an important role in micro-components. A novel technique-submerged water-jet cavitation shocking-is presented to generate micro-feature arrays on 304 stainless foils in this paper. High-speed camera shadowgraph images of the cavitation cloud were employed to analyze the impact zone. Then the forming depth, uniformity of forming depth and the thickness distribution of the micro-feature arrays were also studied. The results show that the forming region can be categorized into the jet-impact-zone, the bubble-impact-zone and the periphery-impact-zone radially. Bubble-impact-zone peaks in the depth of array micro-forming. The forming depth increases with time while the uniformity decreases with time. The forming parts have a uniform thickness distribution.

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Erosive Wear Of Natural Gas Pipes Due To High Velocity Jet Impact: Physical Examination And Experimental Study

Jurnal Teknologi ◽

10.11113/jt.v56.898 ◽

2012 ◽

Author(s):

Z. A. Majid ◽

R. Mohsin ◽

M. Z. Yusof

Keyword(s):

High Pressure ◽

Carbon Steel ◽

High Speed ◽

Experimental Testing ◽

Water Jet ◽

Gas Jet ◽

Water Pipe ◽

Pipe Surface ◽

Jet Impact ◽

Pressure Water

A sequential failure of API 5L X42 (NPS8) carbon steel and SDR 17 medium density polyethylene (MDPE) pipes towards the high pressure water pipe was studied. Pipe’s failed specimen was physically examined and experimental testing was conducted by using high speed water jetting facility towards a similar NPS8 pipe specimen. High pressure water jet impact from leaked water pipe forms highly erosive water–soil slurry and this caused severely damaged on NPS8 carbon steel pipe surface. Thus, causing substantial losses of pipe coating materials and subsequent rapid thinning of pipe body occurred. Furthermore, weaker ground support causes instability to the MDPE pipe and leads to vertical descend towards high speed gas jet region exerted from failed NPS8 pipe. High impact gas jet physically hit the MDPE pipe at its opposite direction causing its rapid erosion. Key words: Liquid impact erosion; gas jet impact; solid particle impact; water jet impact

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A Numerical and Experimental Study of Wall Pressure Caused by an Underwater Explosion Bubble

Mathematical Problems in Engineering ◽

10.1155/2018/6139510 ◽

2018 ◽

Vol 2018 ◽

pp. 1-10 ◽

Cited By ~ 3

Author(s):

Yingyu Chen ◽

Xiongliang Yao ◽

Xiongwei Cui

Keyword(s):

High Speed ◽

Bubble Dynamics ◽

Numerical Study ◽

Underwater Explosion ◽

Rigid Wall ◽

Numerical Results ◽

Wall Pressure ◽

Bubble Collapse ◽

Strong Impact ◽

Jet Impact

The bubble dynamics behaviors and the pressure in the wall center are investigated through experimental method and numerical study. In the experiment, the dynamics of an underwater explosion (UNDEX) bubble beneath a rigid wall are captured by high-speed camera and the wall pressure in the wall center is measured by pressure transducer. To reveal the process and mechanism of the pressure on a rigid wall during the first bubble collapse, numerical studies based on boundary element method (BIM) are applied. Numerical results with two different stand-off parameters (γ=0.38 and γ=0.90) show excellent agreement with experiment measurements and observations. According to the experimental and the numerical results, we can conclude that the first peak is caused by the reentrant jet impact and the following splashing effect enlarged the duration of the first jet impact. When γ=0.38, the splashing jet has a strong impact on the minimum volume bubble, a number of tiny bubbles, formed like bubble ring, are created and collapse more rapidly owing to the surrounding high pressure and emit multi shock waves. When γ=0.90, the pressure field around the bubble is low enough only a weak rebounding bubble peak occurs.

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