scholarly journals Rock-Breaking Properties Under the Rotatory Impact of Water Jets in Water Jet Drilling

2019 ◽  
Vol 9 (24) ◽  
pp. 5417 ◽  
Author(s):  
Zhaolong Ge ◽  
Lei Wang ◽  
Man Wang ◽  
Zhe Zhou ◽  
Songqiang Xiao ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Rotation Speed ◽  
Impact Angle ◽  
Rock Breaking ◽  
Water Jet ◽  
Drill Bit ◽  
Rock Breakage ◽  
Jet Impact ◽  
Tension State ◽  
Optimum Water

Water jet drilling is widely used to develop coalbed methane reservoirs. The water jet drill bit is the core component, and a self-rotating bit is an economical bit because of its high rock-breaking efficiency and low energy consumption. Because the important parameters concerning the rock-breaking efficiency of these drill bits are unclear, this study carried out rock-breaking experiments on water jet rotation under different conditions of drill bit rotation speed, jet pressure, and jet impact angle. How the rock was fractured and eroded under these different conditions was analyzed. The results show that the volume of rock broken under rotary jet erosion increases exponentially with increasing jet pressure. The rock-breaking depth is the most important factor that influences the volume of rock broken, whereas the diameter of the area broken is a secondary factor. There is an optimum water jet rotation speed for the most efficient rock breakage, and this rotation speed is positively correlated with jet pressure. There is also an optimum water jet impact angle for rock breaking, and, in our experiments, this angle was 10°. The rotary impact of the water jet causes the rock to be in a three-way tension state, and this reduces the water cushion effect and jet reflection. This study can be used as a reference and guide for optimizing the design of self-rotating water jet bits and the determination of reasonable drilling parameters.

scholarly journals Study on Rock-Breaking Depth and Damage Area under Particle Jet Impact

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Fushen Ren ◽  
Tiancheng Fang ◽  
Xiaoze Cheng
Keyword(s):  
Mathematical Model ◽  
Impact Velocity ◽  
Particle Diameter ◽  
Rock Breaking ◽  
Water Jet ◽  
Experimental Results ◽  
Damage Area ◽  
Jet Impact ◽  
Mathematical Calculation ◽  
The Mathematical Model

Particle jet impact drilling technology is an efficient method which mainly uses high-velocity particles to break rock. As the important criterion for evaluating rock-breaking effect, rock-breaking depth and damage area were studied in this paper. Firstly, a particle jet impact rock-breaking test device was developed, and laboratory experiments have been carried out. Then, based on the spherical cavity expansion theory, the mathematical model of rock-breaking depth and damage area under particle jet impact was established. Afterward, the effect of water-jet impact velocity, impact angle, and particle diameter on rock-breaking depth and damage area was analyzed by comparing experimental results and mathematical calculation. The results show that rock-breaking depth and damage area would increase with increase of water-jet impact velocity and decrease slightly with increase of particle diameter. And the combination of 8° and 20° is recommended for nozzle layout. The experimental results and mathematical calculation are basically consistent, which could verify the correctness of the mathematical model. The study has significance for development and application of particle jet impact rock-breaking technology and perfection of theoretical research.

scholarly journals Analysis of Application Parameters of Hydraulic Slotting Technology in Jointed Coal Reservoirs

2019 ◽  
Vol 9 (24) ◽  
pp. 5536
Author(s):  
Zhaolong Ge ◽  
Shaojie Zuo ◽  
Yingwei Wang ◽  
Youchang Lyu ◽  
Xinyan Feng
Keyword(s):  
Coal Seam ◽  
Rotation Speed ◽  
Experimental Testing ◽  
Water Pressure ◽  
High Water ◽  
Fracture Network ◽  
Field Application ◽  
Water Jet ◽  
Jet Impact ◽  
Complex Fracture Network

Hydraulic slotting technology is typically used in coal mines to enhance permeability and prevent gas outbursts. Because a coal seam contains many cleats and joints, this study investigated the influence of conventional application parameters on the hydraulic slotting effect by numerical simulation and experimental testing. The cleats in the coal generated stress concentration and initiated with the water jet impact, which promoted the formation of a complex fracture network. The optimized arrangement included angles with an inclination of 20–45° between the borehole and the coal seam strike. The water jet pressure and rotation speed determined the shape of the slot. A high water jet pressure and low rotation speed promoted the formation of cracks at the end of the slot and strengthened the permeability-enhancing effect. Coal fragments could more easily peel off from the sides of the seam and block the borehole. The high water pressure and low rotation speed application parameters were optimized without blocking the borehole. Results obtained by field application revealed that the gas extraction flow after optimization was 1.3 times that of conventional hydraulic slotting. An appropriate angle between the cleats and borehole can more effectively increase the permeability of the coal seam and results in higher gas drainage flow. The results of this study can be useful as guidelines for field applications of hydraulic slotting technology.

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.

A Study on Erosion Performance of Monocrystalline Silicon in Ultrasonic Vibration-Assisted Abrasive Water Jet Machining

2013 ◽  
Vol 797 ◽  
pp. 39-45 ◽  
Author(s):  
Zhong Wei Zhang ◽  
Hong Tao Zhu ◽  
Chuan Zhen Huang ◽  
Jun Wang ◽  
Peng Yao ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Ultrasonic Vibration ◽  
Flow Rate ◽  
Abrasive Particle ◽  
Particle Diameter ◽  
Impact Angle ◽  
Water Jet ◽  
Monocrystalline Silicon ◽  
Abrasive Water Jet ◽  
Jet Impact

Ultrasonic vibration-assisted machining (UVAM) is an effective and promising technology for processing hard and brittle materials, it has been explored in many experimental and theoretical investigations. In this paper, a study on the erosion performance of monocrystalline silicon with UVAM is presented and discussed. In the erosion experiments, monocrystalline silicon wafers were eroded by the abrasive water jet machine assisted with an ultrasonic vibration system. A contrast experiment was carried out firstly to study the influence of the ultrasonic vibration, and then an orthogonal experiment investigation was carried out to understand the effect of process variables (the abrasive particle diameter, jet impact angle, standoff distance, abrasive mass flow rate and ultrasonic vibration power) on the depth of erosion and material removal rate (MRR). The experimental results revealed that ultrasonic vibration-assisted abrasive water jet erosion (UVA-AWJE) can obviously improve the depth of the erosion and MRR compared with those in traditional AWJE and the variation trends of the effect of the abrasive particle diameter, jet impact angle, standoff distance and abrasive mass flow rate on the erosion performance in UVA-AWJE are very similar to those effect in the traditional AWJ machining.

Experimental and Numerical Investigation on Flow Characteristics of a Water Jet Impingement

2014 ◽  
Vol 1025-1026 ◽  
pp. 122-127 ◽  
Author(s):  
Chatchai Kitcharoenpaisarn ◽  
Viboon Tangwarodomnukun
Keyword(s):  
Flow Characteristics ◽  
Jet Impingement ◽  
Target Surface ◽  
Water Layer ◽  
Impact Angle ◽  
Water Jet ◽  
Workpiece Surface ◽  
Jet Impact ◽  
Surface Liquid ◽  
Experimental Findings

Water jet impingement on a flat target surface can be seen in cooling and cleaning applications, where the flow velocity, static and dynamic pressures are the three main parameters to be considered. Although the jet impingement is a basic free-surface liquid flow, the understanding of flow characteristics after the impingement is essentially needed to elucidate the flow behaviors and its influences to some specific processes. Therefore, the aim of this study is to investigate the flow characteristics of water jet impingement on a solid surface through the computational fluid dynamics and experiments. An obstacle with different thickness was added into the target surface, representing the uneven morphology of workpiece surface to be cooled or cleaned. The parameters considered were the jet impact angle and obstacle thickness, and the water layer formed radially from the stagnation point was observed and analyzed. According to the results, there was a good agreement between the numerical and experimental findings. The jet impact angle was found to remarkably affect all the performance characteristics examined in this study. The water flow characteristics were found to be changed after the flow impinged and passed over the obstacle. In addition, the static and dynamic pressures caused by the impingement were also presented and discussed.

Damage Analysis and Simulation of Rock under High Pressure Waterjet

2011 ◽  
Vol 462-463 ◽  
pp. 774-779
Author(s):  
Hu Si ◽  
Xiao Hong Li ◽  
Yan Ming Xie
Keyword(s):  
High Pressure ◽  
Damage Mechanics ◽  
Water Jet ◽  
Penalty Function Method ◽  
Impulsive Effect ◽  
Contact Method ◽  
Arbitrary Lagrangian Eulerian ◽  
Rock Breakage ◽  
Pressure Water ◽  
High Pressure Water Jet

The high pressure waterjet is widely applied for mine industry, mechanical manufacture, environmental engineering, and medicine field due to its particular characteristic. Recently, the application of high pressure waterjet for gas drainage in mine has been receiving increasing attention with the development of exploitative technology. The micro-damage mechanism of coal under high pressure water jet is key to drain gas effectively. Based on damage mechanics and rock dynamics, the paper analyzed the micro-structure deformation and damage of rock and the impulsive effect under high pressure water jet and developed the dynamic model. Further, on the assumption of that rock was homogeneous and isotropic, a computational model was established based on the Arbitrary Lagrangian Eulerian (ALE) fluid-solid coupling penalty function method. The rock damage under high pressure water jet was simulated by the dynamic contact method. The results showed that the damage and breakage of ruck was mainly attributed to impacting effect and was characterized by local effect, and the evolvement of rock breakage went through three stages and the figure of rock breakage trended a funnel. On the whole, numerical results agreed with experimental results.

scholarly journals Gas Jet Coal-Breaking Behavior: An Elliptical Crushing Theoretical Model

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Gongda Wang ◽  
Yuanyuan Wang ◽  
Xin Yang ◽  
Xin Song
Keyword(s):  
Theoretical Model ◽  
Coalbed Methane ◽  
Clean Energy ◽  
Rock Breaking ◽  
Gas Jet ◽  
Rock Fracturing ◽  
Efficient Technology ◽  
Methane Drainage ◽  
Experimental Values ◽  
The Impact

Coalbed methane (CBM) is a source of clean energy and has been recovered in past decades all over the world. Gas dynamic disaster is the primary disaster in outburst coal, and methane drainage plays a key role in eliminating this danger. As an efficient technology, a gas jet is widely used in CBM development and methane drainage. In this work, the full impinging process of coal and rock fracturing by a supersonic gas jet was studied. To understand how jet parameters affect coal and rock fracturing results, an elliptical crushing theoretical model was proposed. In addition, a laboratory experiment was designed to examine the proposed model, and four key parameters affecting the fracturing results were studied. The results show that different from the monotonic variation of theoretical values, there is a turning point in the variation of experimental values under some parameters. Considering the influence of the depth and radius of the erosion pit, the rock-breaking effect is better when the nozzle size is 2.75 Ma. The optimal target distance is 30 mm, and the impact pressure of a gas jet should be continuously increased in order to achieve certain rock-breaking effects under the impact of the jet.

scholarly journals Numerical Investigation of Rock Breaking Mechanisms by High Pressure Water Jet

2015 ◽  
Vol 126 ◽  
pp. 295-299 ◽  
Author(s):  
Hailong Chen ◽  
Zhaomin Li ◽  
Zhihan Gao ◽  
Yuanyuan Sun
Keyword(s):  
High Pressure ◽  
Numerical Investigation ◽  
Rock Breaking ◽  
Water Jet ◽  
Pressure Water ◽  
High Pressure Water Jet

Micro-grooving on quartz crystals by an abrasive air jet

2011 ◽  
Vol 225 (9) ◽  
pp. 2161-2173 ◽  
Author(s):  
J Wang ◽  
A Moridi ◽  
P Mathew
Keyword(s):  
Performance Measures ◽  
Process Parameters ◽  
Traverse Speed ◽  
Groove Depth ◽  
Impact Angle ◽  
Quartz Crystals ◽  
Air Jet ◽  
Jet Impact ◽  
Mass Flowrate ◽  
Micro Grooving

An investigation of the micro-grooving performance of abrasive air jet (AAJ) on quartz crystals is presented and discussed. An experimental study was carried out first to understand the effect of process parameters on the major grooving performance measures such as groove depth, groove width, kerf taper, and surface roughness. Plausible trends for these grooving performance measures with respect to the various process variables, such as air pressure, nozzle traverse speed, jet impact angle, and abrasive mass flowrate, are discussed. It is found that AAJ is an effective technology for micromachining of quartz crystals and the grooving performance can be improved or optimized by selecting the process parameters properly. Predictive models are then developed for quantitatively estimating the micro-grooving performance. The models are finally verified by an experiment. It shows that the model predictions are in good agreement with the experimental results under the corresponding conditions.

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