Ice breaking by a high-speed water jet impact

2022 ◽  
Vol 934 ◽  
Author(s):  
G.-Y. Yuan ◽  
B.-Y. Ni ◽  
Q.-G. Wu ◽  
Y.-Z. Xue ◽  
D.-F. Han
Keyword(s):  
High Speed ◽  
Water Jet ◽  
Crack Development ◽  
Water Tank ◽  
Water Jets ◽  
Cold Room ◽  
Water Region ◽  
Jet Impact ◽  
Plate Size ◽  
Series Of Experiments

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.

An experimental and simulation study of the flow pattern characteristics of water jet impingements in boreholes

2021 ◽  
pp. 014459872110520
Author(s):  
Yabin Gao ◽  
Xin Xiang ◽  
Ziwen Li ◽  
Xiaoya Guo ◽  
Peizhuang Han
Keyword(s):  
High Speed ◽  
Impact Force ◽  
Jet Impingement ◽  
Flow Patterns ◽  
Water Jet ◽  
Solid Boundary ◽  
Force Model ◽  
Water Jets ◽  
Contact Surfaces ◽  
The Impact

Hydraulic slotting has become one of the most common technologies adopted to increase permeability in low permeability in coal field seams. There are many factors affecting the rock breaking effects of water jets, among which the impact force cannot be ignored. To study the influencing effects of contact surface shapes on jet flow patterns and impact force, this study carried out experiments involving water jet impingement planes and boreholes under different pressure conditions. The investigations included numerical simulations under solid boundary based on gas–liquid coupling models and indoor experiments under high-speed camera observations. The results indicated that when the water jets impinged on different contact surfaces, obvious reflection flow occurred, and the axial velocity had changed through three stages during the development process. Moreover, the shapes of the contact surfaces, along with the outlet pressure, were found to have impacts on the angles and velocities of the reflected flow. The relevant empirical formulas were summarized according to this study's simulation results. In addition, the flow patterns and shapes of the contact surfaces were observed to have influencing effects on the impact force. An impact force model was established in this study based on the empirical formula, and the model was verified using both the simulation and experimental results. It was confirmed that the proposed model could provide important references for the optimization of the technical parameters water jet systems, which could provide theoretical support for the further intelligent and efficient transformation of coal mine drilling water jet technology.

Non-Traditional Machining Using Pulsed Water Drops

2004 ◽  
Author(s):  
M. J. Jackson
Keyword(s):  
Experimental Data ◽  
Plane Surface ◽  
Water Jet ◽  
Surface Cracks ◽  
Response Characteristics ◽  
Water Jets ◽  
Jet Impact ◽  
Water Drops ◽  
Pulsed Water Jet ◽  
Traditional Manner

This paper discusses water jet machining of selected materials using a non-traditional way of delivering water jets in the form of a series of discrete pulses. The theory of water jet impact has been used to demonstrate the principle of removing material by exploiting the existence of a Rayleigh wave that excites the formation of surface cracks and the lateral outflow of water that extends the cracks and removes material. A mathematical model has been developed that predicts changes in the response characteristics of materials owing to an idealised representation of a finite jet of water impacting a plane surface. The analytical approach used is applicable to the first stages of impact where the compressibility of water in the droplet is significant. The predicted response characteristics are compared with experimental data generated using controlled water jet impacts produced by a specially constructed pulsed water jet machining centre. The predicted response of selected materials compare well with experimental data. The results presented in this paper illustrate the importance of using pulsed water jets as a way of machining materials in a non-traditional manner.

scholarly journals Response of High-Pressure Micro Water Jets to Static and Dynamic Nonuniform Electric Fields

2018 ◽  
Vol 6 (2) ◽  
Author(s):  
Yi Shi ◽  
Jian Cao ◽  
Kornel F. Ehmann
Keyword(s):  
High Pressure ◽  
Electric Fields ◽  
High Speed ◽  
Water Jet ◽  
Dynamic Responses ◽  
Order System ◽  
Loop Control ◽  
Time Frequency ◽  
Water Jets ◽  
The Stability

The manipulation of the trajectory of high-pressure micro water jets has the potential to greatly improve the accuracy of water jet related manufacturing processes. An experimental study was conducted to understand the basic static and dynamic responses of high-pressure micro water jet systems in the presence of nonuniform electric fields. A single electrode was employed to create a nonuniform electric field to deflect a high-pressure micro water jet toward the electrode by the dielectrophoretic force generated. The water jet's motions were precisely recorded by a high-speed camera with a 20× magnification and the videos postprocessed by a LabVIEW image processing program to acquire the deflections. The experiments revealed the fundamental relationships between three experimental parameters, i.e., voltage, pressure, and the distance between the water jet and the electrode and the deflection of the water jet in both nonuniform static and dynamic electric fields. In the latter case, electric signals at different frequencies were employed to experimentally investigate the jet's dynamic response, such as response time, frequency, and the stability of the water jet's motion. A first-order system model was proposed to approximate the jet's response to dynamic input signals. The work can serve as the basis for the development of closed-loop control systems for manipulating the trajectory of high-pressure micro water jets.

Some Results in the Erosion of Prestressed Materials due to Water-Jet Impact

1973 ◽  
Vol 15 (4) ◽  
pp. 295-301 ◽  
Author(s):  
G. W. Vickers ◽  
W. Johnson
Keyword(s):  
Brittle Material ◽  
Stress Ratio ◽  
Water Jet ◽  
Ductile Material ◽  
Fracture Modes ◽  
Impact Stress ◽  
Water Jets ◽  
Compressive Stresses ◽  
Jet Impact ◽  
Prestressed Materials

Two methods are described of applying uniaxial and biaxial tensile and compressive stresses to specimens subject to the erosive action of repetitive water jets which have speeds in the range 30–220 m/s. The influence which prestress has on erosion is examined in a ductile material, α-brass, and in a brittle material, Perspex. The behaviour of these materials contrasts sharply due to their different fracture modes. Also the values of prestress to impact stress ratio and the type of stress applied, are shown to have a bearing on results.

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

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.

Effects of Hook, Interceptor, and Water Jets on LCS Resistance/ Power, Sinkage, and Trim

2021 ◽  
pp. 1-24
Author(s):  
Timur Dogan ◽  
Hamid Sadat-Hosseini ◽  
Frederick Stern
Keyword(s):  
High Speed ◽  
Water Jet ◽  
Full Scale ◽  
Scale Model ◽  
Vertical Force ◽  
Scaled Model ◽  
Inlet Velocity ◽  
Model Scale ◽  
Water Jets ◽  
Sinkage And Trim

Verification and validation of computational fluid dynamic simulations are performed at model and full scales for the high-speed littoral combat ship (LCS) surface combatant, including the effects of hook, interceptors, and water-jet propulsion. Predictions of the body force thrust, sinkage, and trim use a speed controller for attaining self-propulsion. Two methods for water-jet performance are used: 1) evaluation of forces based on integration of the stress over the wetted area of the hull and water-jet duct, pump casing, and nozzle (integral method) and 2) ITTC (2005) water-jet test procedure (control volume method). The comparison errors at model (resistance, sinkage, and trim) and full (power and trim) scales are satisfactory using both Froude (Fr) scaled model- and full-scale trial data, including the effects of the interceptors and water jets (WJ) on resistance/power, sinkage, and trim. For the model-scale model without WJs, the negative bottom hydrodynamic pressure near the water-jet inlets are observed without and with the hook simulations, and experiments with the hook. The negative bottom vertical force near the water-jet inlets for the simulations without the hook supports Savitsky’s (2014) assertion that semi-displacement monohulls do not exhibit hydrodynamic lift and disproves Giles’ (1992) assertion to the contrary. The hook and interceptors do not affect the pressure distribution significantly near the water-jet inlets. For the full scale model, the WJs induce bow up trim for the simulations and interpolated (between conditions)- and Fr scaled model-scale experiments. The negative bottom pressure and vertical force near the water-jet inlet for the simulations disprove Giles’ (1992) assertion that the WJs provide additional hydrodynamic lift. This is further supported by the comparisons of the vertical force % thrust vs. inlet velocity ratio for the LCS, with results shown in Bulten (2005) for a high-speed motor yacht. Bulten (2005) shows positive vertical force for inlet velocity ratios ≥ 1.25. However, LCS operates in the regime of an inlet velocity ≤ 1.2; thus, consistent with Bulten (2005), the vertical force is negative. The nonlinear effects between the interceptors and WJs are small such that a linear combination can provide a reasonable approximation.

A discussion on deformation of solids by the impact of liquids, and its relation to rain damage in aircraft and missiles, to blade erosion in steam turbines, and to cavitation erosion - Some aspects of rock cutting by high speed water jets

1966 ◽  
Vol 260 (1110) ◽  
pp. 295-310 ◽  
Keyword(s):  
Pressure Distribution ◽  
High Speed ◽  
Frictional Heating ◽  
Water Jet ◽  
Short Exposure ◽  
Maximum Pressure ◽  
Steam Turbines ◽  
Target Plate ◽  
Water Jets ◽  
The Impact

When rocks are cut in coal mines by steel picks, frictional heating sometimes causes ignition of methane; high speed water jets may provide a method of cutting which is free from this hazard. A high speed water jet emerging from a nozzle slows down with increasing distance from the nozzle and breaks up into water drops. Studies were made of the behaviour of water jets: in most of the experiments the jets were produced by pressures of 600 atm., but some results are given of experiments at pressures up to 5000 atm. The jets were examined by short exposure optical photography with several different methods of illumination (parallel transmitted, diffuse, and schlieren) and by X-ray photography. In order to find out how the jet velocity decays with distance from a nozzle, and to compare nozzle designs, a target plate containing a hole smaller than the jet diameter was placed so that the jet impinged at right angles on to it, and the target plate was moved until the maximum pressure at the hole was found: this was measured for different distances from the nozzle. Nozzle shapes suggested in literature for minimizing jet dispersion were studied and an empirical investigation of a variety of nozzle shapes was carried out. Several nozzle shapes were found which gave good results, i.e. the maximum pressure on the target plate was half the pump pressure at a distance of about 350 nozzle diameters. In many cutting applications the first stage in the process would be the impingement of a water jet on a surface at right angles. The initial cutting would depend upon the stress distribution within the target, which in turn would depend upon the pressure distribution produced by the water jet on the surface. A theory is given of the pressure distribution on the target plate, which predicts that the pressure will fall to zero at about 2.6 jet radii: this was found to be in good agreement with experiments. Preliminary studies were made of the penetration of several types of rock by water jets of velocities up to about 1000 m/s (pressures about 5000 atm). It was found that a 1 mm diameter jet drills a cylindrical hole about 5 mm in diameter. The pressure that the water jet produces at the bottom of such holes was measured and shown to fall off to about one-tenth of the nozzle pressure at a hole depth of about 4 cm.

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

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.

The role of rapidly compressed gas pockets in the initiation of condensed explosives

1974 ◽  
Vol 340 (1620) ◽  
pp. 113-128 ◽  
Keyword(s):  
High Speed ◽  
Thermal Contact ◽  
Gas Bubbles ◽  
Lead Azide ◽  
High Speed Photography ◽  
Water Tank ◽  
Minimum Volume ◽  
Specific Heats ◽  
Series Of Experiments ◽  
Minimum Volumes

The mechanism of initiation of explosion by the rapid compression of gas spaces has been studied by means of high-speed photography at framing rates up to 10 7 frames s -1 . Single crystals of silver azide, lead azide and PETN were mounted in a water tank and gas bubbles of chosen composition and size (diameter in the range 50 μm to 1 mm) collapsed on to them by water shocks of strength about 0.1 GPa (1 kbar). The gas bubbles collapsed to minimum volumes in times of the order of 1 μs (depending on the initial bubble size). Initiation of fast reaction occurred in the azides within ca . 5 × 10 -8 s of the bubble reaching minimum volume provided the bubble made thermal contact with the explosive. During the collapse, the bubble involuted to form a jet of velocity of a few 100 ms -1 , and after reaching minimum volume, expanded giving an expansion shock. The importance of these phenomena in the initiation of explosion, as well as possible initiation by shock perturbation, was assessed in a series of experiments designed to separate the various possible mechanisms. The conclusion is that adiabatic heating of the gas in the bubble was the prime cause for initiation. Calculations, and experiments with gases such as argon and helium (high value of γ ; the ratio of the specific heats) and butane (low γ ) supported this conclusion. Finally, the relevance to other explosive situations is discussed.

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

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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