scholarly journals Analysis on the Shape and Impact Pressure of the High-Pressure Water Jet during the Hydraulic Flushing Cavity Technique

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Shouqing Lu ◽  
Chengfeng Wang ◽  
Wei Wang ◽  
Mingjie Li ◽  
Dongti Zhang
Keyword(s):  
High Pressure ◽  
Rotation Speed ◽  
Water Pressure ◽  
Water Jet ◽  
Impact Pressure ◽  
Coal Seams ◽  
Soft Coal ◽  
Pressure Water ◽  
High Pressure Water Jet ◽  
The Impact

A large proportion of minable coal seams in China belong to low-permeability soft coal seams. Such coal seams suffer serious coal and gas outburst hazards and endure a high incidence of major disasters in coal mines. The adoption of the high-pressure water jet (HPWJ) hydraulic flushing cavity can effectively promote the gas drainage efficiency and volume and eliminate the hidden danger of gas disasters. Nevertheless, the shape and impact pressure of rotating HPWJ are rarely researched. In this study, on the basis of the numerical simulation, the axial and radial stress distributions of HPWJ and the energy-gathering effect of a conical-cylindrical combined nozzle were analyzed. It is concluded that the submerged condition will accelerate the attenuation of jet velocity and reduce the impact strength of the jet. The jet diffusion angle grows with the increases in the nozzle diameter and water pressure, and 24° is the optimal contraction angle. Finally, the influences of factors such as the rotation speed on the shape and impact pressure of HPWJ were explored, and the results show that the rotation speed should be controlled within 90 r/min. The research findings lay the foundation of the study on the mechanism of coal crushing by HPWJ and provide technical support for the research and development of drilling and flushing integrated equipment.

scholarly journals Calculation Model of High-Pressure Water Jet Slotting Depth for Coalbed Methane Development in Underground Coal Mine

2019 ◽  
Vol 9 (23) ◽  
pp. 5250 ◽  
Author(s):  
Jianguo Zhang ◽  
Yingwei Wang ◽  
Zhaolong Ge ◽  
Songqiang Xiao ◽  
Hanyun Zhao ◽  
...  
Keyword(s):  
High Pressure ◽  
Rotation Speed ◽  
Initial Period ◽  
Calculation Model ◽  
Water Jet ◽  
Nozzle Diameter ◽  
Coal Seams ◽  
Jet Impact ◽  
Pressure Water ◽  
High Pressure Water Jet

In underground coal mines, high-pressure water jet slotting is effective at improving coal seams’ permeability. The slotting depth determines the effect of pressure relief and permeability enhancement in coal seams. However, there is no effective and feasible way of determining the slotting depth; thus, the operational parameters and borehole layout are unknown. This study determined the effects of key parameters, including the nozzle diameter, jet pressure, rotation speed, and slotting time, on the slotting depth. A water jet slotting depth calculation model was established and verified according to the slotting experiments under different operational conditions. The slotting depths were investigated based on the results of field slotting experiments. The results revealed that there exists an optimal nozzle diameter for a higher jet impact velocity. The slotting depth linearly increased with the jet pressure and decreased as a power function with the increase of the jet translation speed. The slotting depth increased with the slotting time, but the growth rate gradually decreased and tended to be stable. As the rotation speed increased, the slotting depth became greater at the initial period and the limit depth was reached faster. Laboratory and field slotting experiments were conducted to verify the model, and the experimental results are approximately in agreement with the theoretical predictions. The results of this study can be useful as guidelines for the hydraulic parameter selection of water jet slotting and for optimizing the layout of coal gas drainage boreholes.

Demonstration Test on Concrete With Epoxy Resin Coating Using Ultra-High Pressure Water Jet Decontamination Technology

2013 ◽  
Author(s):  
Akihiro Tagawa ◽  
Masashi Tezuka ◽  
Yoshihiro Terakura ◽  
Masayuki Naitou ◽  
Kenji Miyazima
Keyword(s):  
High Pressure ◽  
Nuclear Power ◽  
Power Plants ◽  
Water Pressure ◽  
Decontamination Factor ◽  
Water Jet ◽  
Ultra High Pressure ◽  
Pressure Water ◽  
High Pressure Water Jet ◽  
The Impact

It is one of the most urgent issues to remediate the nuclear power plants contaminated by radioactive materials discharged following the accident at the TEPCO’s Fukushima Daiichi NPS. Concrete walls of nuclear power plants in Japan are coated an epoxy resin coating for easily performing decontamination. We experimented a cutting test in Fugen Decommissioning Engineering Center using maximum 280MPa pressure and 30L/min water quantity, ultra-high pressure water jet system and 40m3/min air quantity vacuum system. We are conducting a study of decontamination technology in environmental pollution using this decontamination system. This decontamination system has achieved a decontamination factor 10 to 100. In environment experiments, we achieved more than 10 decontamination factor in water pressure of more than 150MPa. Thus, we have confirmed the change in a cutting ability by changing parameters. Parameters are the water pressure, the water quantity and air quantity. The impact force for water jet is a function that contains the test parameters. We have considered it using this function. The results of the test showed that there is a correlation between the impact force for water jet and a cutting capability. This decontamination technology can decontaminate radioactive material of the surface adhesion contamination and reduce the amount of waste generated for a thin cutting. In addition, we have experimented that the water can be recycled by chemical precipitation. After we experimented flocculation test using aluminum sulfate and zeolite flocculant, we have confirmed that it. can clean water up to the level of suspended solids 5mg/L, in turbid water using zeolite flocculant. This suspended solids concentration can be passed to the water processing system in nuclear power plant. From the test results, we found that ultra-high pressure water jet decontamination technology has a possibility that it can be used for decontamination of Fukushima Daiichi nuclear power plant.

Semi-active accumulator absorbing pressure pulsation in high-pressure water-jet propulsion system

2011 ◽  
Vol 225 (9) ◽  
pp. 2052-2061 ◽  
Author(s):  
X Luo ◽  
Z Shi ◽  
J Hu ◽  
Z Niu
Keyword(s):  
High Pressure ◽  
Steady State ◽  
Pressure Pulsation ◽  
Rotation Speed ◽  
Water Jet ◽  
Water Pump ◽  
Jet Propulsion ◽  
Pressure Water ◽  
High Pressure Water Jet ◽  
State Pressure

Large-capacity and high-pressure plunger water-pump is often used as power supply in high-pressure water-jet propulsion system (HWPS). Generally, the flow pulsation and pressure pulsation generated in the working process of HWPS is absorbed by a passive accumulator. If work condition of HWPS changes, the function of passive accumulator absorbing pressure pulsation will weaken. In order to solve this problem, the mathematical model of passive accumulator was established; then, the ability of passive accumulator absorbing pressure pulsation was theoretically analysed when rotation speed of the water-pump and steady-state pressure of HWPS changed. Thereafter, a semi-active accumulator was advanced on the basis of the analytical theory. In order to get the best effect of absorbing pressure pulsation, the semi-active accumulator employed the messages of HWPS pressure and the water-pump rotation speed to regulate the cross-sectional area of its anterior pipeline, thereby to alter its natural frequency. Results of simulation and experiment revealed that pressure pulsation was absorbed better by semi-active accumulator than by passive accumulator when the rotation speed and steady-state pressure changed.

The Measurement of the Velocity Outside the High Pressure Water Jet and Abrasive Water Jet Nozzle Based on the Energy Transfer Method

2010 ◽  
Vol 135 ◽  
pp. 361-364 ◽  
Author(s):  
Rong Guo Hou ◽  
C.Z. Huang ◽  
H.T. Zhu ◽  
Z.W. Niu
Keyword(s):  
High Pressure ◽  
Energy Transfer ◽  
Water Jet ◽  
Abrasive Water Jet ◽  
Impact Forces ◽  
Pressure Water ◽  
High Pressure Water Jet ◽  
Transfer Method ◽  
The Impact ◽  
Core Part

The energy transfer method is used to measure the flow velocity of the outside the high pressure water jet (WJ) and Abrasive water jet (AWJ) nozzle. The impact forces of the flow measured by the piezoelectricity ergometer will be transformed to the velocity value, the average velocity of the flow outside the nozzle will be obtained. The result indicates the velocity will reduce along the direction of the flow, and the velocity of the AWJ flow will reduced greatly than the WJ flow, which indicates that the length of the core part of the AWJ flow is shorter than the WJ Flow, the stand-off should be within the 0mm-15mm ranges to gain the most effective machining.

Research on the Decoating Effect and Microstructure of Surface Damage of High-Pressure Waterjet

2014 ◽  
Vol 541-542 ◽  
pp. 180-184
Author(s):  
Qi Guo ◽  
Xiu Jie Jia ◽  
Shuo Li ◽  
Yan Yan Nie ◽  
Shun Xin Ge
Keyword(s):  
Surface Roughness ◽  
High Pressure ◽  
Impact Test ◽  
Surface Damage ◽  
Water Jet ◽  
Surface Damages ◽  
Pressure Water ◽  
High Pressure Water Jet ◽  
Coated Surfaces ◽  
The Impact

The high-pressure water jet is utilized to perform impact test on coated surfaces with different hardness. The decoating effect is measured and the surface roughness change can be tested by White-light Interferometer (WLI). Also the microstructure of surface damage after impact test is analyzed. The result shows that when utilizing high-pressure water jet to clean the coating, it’s a better choice to start at the place where the coating is broken. The gap will be enlarged rapidly and the decoating velocity will increase linearly. Otherwise, the impact of water jet will cause surface damages and generate holes of particular shape. This kind of hole is flat in the middle, then forming a sunken district and apophysis successively along the radius outwards.

Research on Effects of Accuracy in Variable Loading on the High-Pressure Water Jet Incremental Forming

2013 ◽  
Vol 774-776 ◽  
pp. 1021-1025 ◽  
Author(s):  
Ling Yun Zhang ◽  
Li Nie
Keyword(s):  
Finite Element ◽  
High Pressure ◽  
Finite Element Simulation ◽  
Incremental Forming ◽  
Water Pressure ◽  
Water Jet ◽  
Layered Manufacturing ◽  
Element Simulation ◽  
Pressure Water ◽  
High Pressure Water Jet

High-pressure Water Jet Increment Sheet Metal Forming adopt the idea of layered manufacturing to scatter a complex three-dimension shape to many 2-dimension layers along z axis, and then the water jet machine partially on these layers. We did a research on that the distance from square processing trajectory to center and the water pressure affect the limits of forming height by finite element simulation of high-pressure water jet box-shape piece incremental forming with the thought of layered manufacturing. Based on this, puts forward a new method of different 2-dimension layers is loaded on different water pressure to improve water jet incremental forming accuracy. This method was proved feasibility by finite element simulation.

The mechanism and application of high-pressure water jet technology to prevent compound dynamic disaster

2021 ◽  
Vol 14 (13) ◽  
Author(s):  
Zeng-qiang Yang ◽  
Chang Liu ◽  
Feng-shuo Li ◽  
Lin-ming Dou ◽  
Gang-wei Li ◽  
...  
Keyword(s):  
High Pressure ◽  
Water Jet ◽  
Pressure Water ◽  
Dynamic Disaster ◽  
High Pressure Water Jet

Crowning Carrots with a High Pressure Water Jet

1988 ◽  
Vol 4 (4) ◽  
pp. 340-343 ◽  
Author(s):  
John H. Posselius ◽  
Jr.. Glenn T. Conklin
Keyword(s):  
High Pressure ◽  
Water Jet ◽  
Pressure Water ◽  
High Pressure Water Jet
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