Ultra-high Pressure Water Jet Research Articles

Analysis of Influence of Ultra-High Pressure Water Jet Cutting Pressure Sequence on Pressure Relief and Reflection Improvement of Coal Seam

In order to explore the pressure relief effect of the two combined pressure relief and antireflection technologies of ultra-high pressure water jet cutting before pressure and pressure before cutting, theoretical analysis, numerical simulation, and field test were used to study the main control factors of the combined high-pressure water jet slit cutting and fracturing antireflection technology. This paper introduces the combined technology of ultra-high pressure hydraulic fracturing, and analyses the mechanism of pressure relief and transparency enhancement of the combination of cutting before pressure and pressure relief after cutting. The results show that the starting pressure of the coal seam with ultra-high pressure water jet cutting and pressure relief is 13 MPa, the influence radius of hydraulic fracturing is 45–55 m, the starting pressure of the coal seam with pressure cutting and pressure relief is 16 MPa, and the influence radius of hydraulic fracturing is 35–45 m. Compared with pressure cutting combined pressure relief and permeability enhancement technology, cutting pressure relief and permeability enhancement technology can improve the permeability of coal seams more evenly and effectively, and reduce the stress of coal seams near the hole. The ultra-high pressure cutting and pressure combined technology can make the pressure relief of coal body uniform and sufficient, and the overall permeability coefficient of the coal body is greatly improved. The drilling purity is 2.3 times of the extraction purity of the ordinary single hole drilling, and the extraction influence range is increased, and the extraction effect is significantly improved. At the same time, the stress of coal body is reduced after slitting, and the starting pressure of hydraulic fracturing is reduced. The research results provide a scientific basis for the coal seam pressure relief and permeability enhancement under similar conditions in the mining area and have a broad application prospect.

Experimental Study on Surface Erosion of Grade A Marine Steel by Ultrahigh-Pressure Water Jet

To investigate the interaction and erosion mechanisms between an ultrahigh-pressure water jet and the surface of Grade A marine steel, this study used the ANSYS FLUENT software to simulate the hydrodynamic characteristics of an ultrahigh-pressure water jet. To erode the Grade A marine steel, a water jet with ultrahigh-pressure (200 MPa, 40 L/min) was used. An ASMC2-4 resistance strain gauge collected the dynamic strain signal at the back of the sample during jet impingement, and the simulation results were compared to experimental results. A scanning electron microscope (SEM), X-ray diffractometer (XRD), energy dispersive spectrometer (EDS), and other equipment were used to observe and analyze the phase before impact and the material surface morphology and element distribution after impact. The results reveal that as the wall shear stress increased with the target distance, the energy loss of the jet could be reduced by changing the jet incidence angle, and the peak value of the wall shear stress increased. Under the pressure of 200 MPa, the average microstrain at the back side of the impact center area of the Grade A marine steel was 180 × 10−6, and the microstrain amplitude was 35 × 10−6–50 × 10−6. The impact force of the water jet on the Grade A marine steel produced alternating stress with cyclic fluctuation. The experimental results are consistent with the simulation results. Under the alternating jet stress action, fatigue failure and cavitation failure occurred on the sample surface, which was characterized by a spalling pit, layer erosion, and cavitation hole morphology. The surface stripping model of the Grade A marine steel under an ultrahigh-pressure water jet was established, and the interaction mechanism and erosion mechanism between the ultrahigh-pressure water jet and the surface of the Grade A marine steel were elucidated.

Pressure Drop Model and Jet Features of Ultra High Pressure Water Jet for Downhole Intensifier

Abstract Existing models can hardly provide a reliable guidance in designing intensifier utilizing axial vibration energy of drill strings. The formation process of jet and the pulsation characteristics of flow field had not been reported. Therefore, a new model combined plunger movement and nozzle pressure drop is proposed. The jet formation process, characteristic of water jet distribution, pressurization performance, and impinging pressure under different parameters were studied based on a computational fluid dynamics (CFD) method. The results show that there is a good agreement between the model and the CFD. Increasing the plunger diameter can prolong the holding time of the high-pressure water jet and increase the peak pressure, but it does not affect the pressurization period, which is mainly influenced by the spring. There are three representative stages observed in the forming process of high-pressure water jet, and in stable potential core stage, the inlet pressure does not affect the length of potential core, which is about seven times the nozzle diameter. The impinging pressure decreases with the radial distance, the maximum of which is at the center of the jet. The stand-off distance should be less than 7d, otherwise the impinging pressure will decrease sharply. The research can provide a reference for the optimal design of intensifier and will be beneficial for downhole pressurized jet-assisted drilling techniques.

An experimental study of ultra-high pressure water jet-induced fracture mechanisms and pore size evolution in reservoir rocks

Ultra-high pressure water jets (UHP-WJ) rock breaking is a promising technology for developing unconventional natural gas reserves . In this study, rock-breaking experiments were conducted using typical reservoir rock samples such as sandstone , shale, and coal. The failure patterns in rocks after impact by UHP-WJ were analyzed. Moreover, the 3D damage field model of the rock was reconstructed based on CT scanning, and the internal crack distribution was visualized and examined. Furthermore, the fracture mechanisms of three types of reservoir rocks under the UHP-WJ impingement were studied. The results indicate that intergranular fractures produced due to shear stress are the dominant type of fracture in sandstones, tensile failure due to stress wave was the main type of fracture observed in shale, and coal exhibited the double breaking characteristics of stress wave effect and water wedge effect. The fragments size distribution of samples shows the largest fragments in shale, followed by coal, and the smallest fragments are observed in sandstone. Finally, the evolution of rock pore structure before and after the impact of UHP-WJ was monitored by nuclear magnetic resonance (NMR) methods. The results reveal that the micropores transform into mesopores and macropores in the sandstone, where the total porosity increased by 14.3%–24.8%. As the jet pressure exceeds 100 MPa, the porosity of shale increases significantly, such that the total porosity of the shale sample increased by 7.6%–37.1%. The mesopores transform into macropores and fractures with the influence of the water wedge effect in coal samples, resulting in the reduction of mesopores and the increase of macropores, where the total porosity of the coal sample increased by 14.6%–40%. The complexity and heterogeneity of pores were reduced under UHP-WJ with the increasing jet pressure. The findings provide a theoretical reference for optimizing the recovery from unconventional natural gas reservoirs .

Breaking Mechanism and Damage Evolution Rule of Ultra-High-Pressure Water Jet Impacting Steel Fiber Reinforced Concrete

Based on smooth particle hydrodynamics (SPH) method, this paper carried out the numerical simulation of ultra-high-pressure water jet (UHP-WJ) impacting steel fiber reinforced concrete (SFRC), verified the established numerical model by UHP-WJ impacting SFRC and computed tomography (CT) scanning experiments, and explored breaking mechanism and damage evolution rule of SFRC impacted by UHP-WJ. Results indicate that in the weak effect zone of steel fiber, the failure of concrete is generated and developed along the axial direction of UHP-WJ into a bowl-shaped crater with the combining action of compressive stress and shear stress. In the affected area of steel fiber, due to the inhomogeneity in the contact area of steel fiber and concrete, the stress concentration in the contact area is produced, causing the formation of propagated crack along the steel fiber. And the steel fiber has an obstruction effect on the development of broken bodies on the upper and lower sides of steel fiber. With the sustained action of UHP-WJ, the steel fiber in the intense radiation area of stress waves takes place fracture and finally the broken bodies on the upper and lower sides of steel fiber fuse. In addition, based on the CT scans and digital image processing technology, this paper also comparatively analyzed the internal fragmentations of SFRC and the ordinary concrete subjected to UHP-WJ impact, and it is found that compared with the ordinary concrete, there is smaller dimension of crater and it is difficult to engender macrocrack for SFRC, with lower damage and higher damage attenuation speed along the axial and radial directions.

Study on the mechanism of breaking concrete by ultra-high pressure water jet

The concrete breaking mechanism of ultra-high pressure water jet is divided into two parts: the characteristics of ultra-high pressure water jet and the characteristics of concrete under the action of water jet. Through the analysis of the water wedge and water hammer under the action of the jet on the concrete breaking, ultra-high pressure water jet pressure and jet on the concrete strike force is a linear relationship.

Optimization of technological parameters of water jet cutting of red oak and bamboo based on three-dimensional surface topography measurement

In order to accurately and reliably optimize the process parameters of ultra-high pressure water jet cutting for wood, water jet processing was conducted on red oak and bamboo floor specimens, and the materials were scanned for three-dimensional surface topography. The surface roughness value of the cut surface of the test piece was measured by the orthogonal measurement method as an evaluation index to determine the optimal arrangement of the influencing factors and the process parameters. Finally, the water cutting mechanism and three-dimensional shape of the processed test piece were analyzed. The factors affecting were as follows: cutting pressure > feeding speed > abrasive flow rate > target distance > air-dry density. The optimal experimental scheme included an abrasive flow rate of 35 kg/h, cutting pressure of 310 kPa, feed speed of 250 mm/s, target distance of 3 mm, and air dry density of 620 kg/m3. Under these processing conditions, the surface roughness values of water jet red oak and bamboo specimens were relatively small, and the processing quality was the best. The results of the above-mentioned research can provide a reference for the research and application optimization design of wood and bamboo processing for ultra-high pressure water jet technology.

Anti-blocking performance of ultrahigh-pressure waterjet assisted furrow opener for no-till seeder

No-till planting method is widely used for maize-wheat two-crops-a-year area in the North China Plain. However, cruel soil conditions, especially the large number of maize stalks which are hard to cutoff covering, often cause an unsatisfying planting quality. Based on the authors’ previous investigation, ultrahigh-pressure (UHP) waterjet is capable to solve this problem and obtain qualified seedbeds. Thus, a UHP waterjet assisted furrow opener for no-till seeder was designed. Field tests showed that double-disc furrow openers worked well with UHP waterjet, since the sharpened disc blades could help to cut soil and residue, meanwhile, minimize soil disturbance. Response surface method (RSM) was used to investigate the relationship among forward speed, waterjet pressure, jet impingement angle and anti-blocking performance (stalks cutoff ratio and depth of soil cutting), and a Box-Behnken three-factor design was used to identify the optional operation parameters. A total of 17 combinations were conducted, and the results showed all three operation parameters significantly affected anti-blocking performance. Stalks cutoff ratio and depth of soil cutting increased with the increase of waterjet pressure, jet impingement angle, and decreased with the increase of forward speed. The optimization analysis indicated that when waterjet pressure was 267-280 MPa, jet impingement angle was 80.2° to 90.0° and forward speed was 4.00-4.42 km/h, the overall performance of UHP waterjet assisted double-disc furrow opener for no-till seeder was maximized. Stalks cutoff ratio could be above 95% and no blockage occurred. This study may provide a new approach and reference for the anti-blocking technology of no-tillage seeding. Keywords: waterjet, ultrahigh-pressure, conservation tillage, maize stalks, cutting, no-till, anti-blocking DOI: 10.25165/j.ijabe.20201302.5630 Citation: Hu H N, Li H W, Wang Q J, He J, Lu C Y, Wang Y B, et al. Anti-blocking performance of ultrahigh-pressure waterjet assisted furrow opener for no-till seeder. Int J Agric & Biol Eng, 2020; 13(2): 64–70.

A laboratory evaluation of waterjet cutting of crop residue using the Aqua-Till® liquid coulter

Ultra-high pressure (UHP) waterjet cutting technology is used across a multitude of industries. An agricultural application recently developed by the South Australian No-Till Farmers Association consists of an innovative crop residue cutting ‘liquid coulter’ - known as Aqua-Till®. The wheat straw stem cutting capacity of the device was evaluated under controlled laboratory conditions at the University of South Australia, using a purpose-made straw holding tray moving at a controlled speed under the path of a stationary UHP nozzle. The impacts of technology settings and straw conditions were measured. The cutting performance was assessed based on the degree of fully cut straw stems, integrating the extent of partially cut stems, from a quantity calibrated to an equivalent dry stem load in Mg/ha. Results showed that when operated at 380 MPa pressure, the device delivered very high cutting capacity of wheat straw stems of 10−35 Mg/ha across the range of nozzle orifice diameters (0.15-0.3 mm) and forward speeds (6−12 km/h) tested. The UHP waterjet cutting unit was found to operate most effectively when the residue was wet and placed under compression. Halving travel speed increased the cutting capacity by an average 12 % indicating a non-linear impact of speed. No effect of nozzle to target distance could be detected over the 5−70 mm range tested. The cutting performance of wet, compressed residue was mapped against the water volume rate required over a range of speeds and orifice diameters. Correction factors for extending cutting performance estimations to dry and/or loose residue conditions were also determined. Across the range of nozzle orifice diameters and speeds investigated, the laboratory data for wet compressed residue indicate that a nominal 150 L/ha volume of water, deemed acceptable under Australian dryland cropping conditions, could provide straw stem cutting capacities of up to 12.5 Mg/ha, 19 Mg/ha and 35 Mg/ha at 300 mm, 500 mm and 1000 mm nozzle row spacing, respectively, at a nominal 380 MPa operating pressure. In this study, the waterjet technology demonstrated very effective residue cutting, which could be maximised under specific residue conditions and technology settings. The results indicate that the technology could become an effective tool for assisting residue handling in no-till planting applications, particularly in wet stubble and soft soil environments where traditional mechanical coulters fail. Further research is required to develop accurate operational guidelines for a range of field residue type and conditions, as well as clarify the technology cost-effectiveness in order to facilitate adoption within the no-till cropping industry.

Establishing sex-specific reference interval for the Beckman Coulter UniCel DxI 800 TSH (3rd IS) in Chinese euthyroid population based on a multicenter study

Ultra-high pressure (UHP) waterjet cutting technology is used across a multitude of industries. An agricultural application recently developed by the South Australian No-Till Farmers Association consists of an innovative crop residue cutting ‘liquid coulter’ - known as Aqua-Till®. The wheat straw stem cutting capacity of the device was evaluated under controlled laboratory conditions at the University of South Australia, using a purpose-made straw holding tray moving at a controlled speed under the path of a stationary UHP nozzle. The impacts of technology settings and straw conditions were measured. The cutting performance was assessed based on the degree of fully cut straw stems, integrating the extent of partially cut stems, from a quantity calibrated to an equivalent dry stem load in Mg/ha. Results showed that when operated at 380 MPa pressure, the device delivered very high cutting capacity of wheat straw stems of 10−35 Mg/ha across the range of nozzle orifice diameters (0.15-0.3 mm) and forward speeds (6−12 km/h) tested. The UHP waterjet cutting unit was found to operate most effectively when the residue was wet and placed under compression. Halving travel speed increased the cutting capacity by an average 12 % indicating a non-linear impact of speed. No effect of nozzle to target distance could be detected over the 5−70 mm range tested. The cutting performance of wet, compressed residue was mapped against the water volume rate required over a range of speeds and orifice diameters. Correction factors for extending cutting performance estimations to dry and/or loose residue conditions were also determined. Across the range of nozzle orifice diameters and speeds investigated, the laboratory data for wet compressed residue indicate that a nominal 150 L/ha volume of water, deemed acceptable under Australian dryland cropping conditions, could provide straw stem cutting capacities of up to 12.5 Mg/ha, 19 Mg/ha and 35 Mg/ha at 300 mm, 500 mm and 1000 mm nozzle row spacing, respectively, at a nominal 380 MPa operating pressure. In this study, the waterjet technology demonstrated very effective residue cutting, which could be maximised under specific residue conditions and technology settings. The results indicate that the technology could become an effective tool for assisting residue handling in no-till planting applications, particularly in wet stubble and soft soil environments where traditional mechanical coulters fail. Further research is required to develop accurate operational guidelines for a range of field residue type and conditions, as well as clarify the technology cost-effectiveness in order to facilitate adoption within the no-till cropping industry.

Performance evaluation of the new Beckman Coulter DxH-900 haematology analyzer

Ultra-high pressure (UHP) waterjet cutting technology is used across a multitude of industries. An agricultural application recently developed by the South Australian No-Till Farmers Association consists of an innovative crop residue cutting ‘liquid coulter’ - known as Aqua-Till®. The wheat straw stem cutting capacity of the device was evaluated under controlled laboratory conditions at the University of South Australia, using a purpose-made straw holding tray moving at a controlled speed under the path of a stationary UHP nozzle. The impacts of technology settings and straw conditions were measured. The cutting performance was assessed based on the degree of fully cut straw stems, integrating the extent of partially cut stems, from a quantity calibrated to an equivalent dry stem load in Mg/ha. Results showed that when operated at 380 MPa pressure, the device delivered very high cutting capacity of wheat straw stems of 10−35 Mg/ha across the range of nozzle orifice diameters (0.15-0.3 mm) and forward speeds (6−12 km/h) tested. The UHP waterjet cutting unit was found to operate most effectively when the residue was wet and placed under compression. Halving travel speed increased the cutting capacity by an average 12 % indicating a non-linear impact of speed. No effect of nozzle to target distance could be detected over the 5−70 mm range tested. The cutting performance of wet, compressed residue was mapped against the water volume rate required over a range of speeds and orifice diameters. Correction factors for extending cutting performance estimations to dry and/or loose residue conditions were also determined. Across the range of nozzle orifice diameters and speeds investigated, the laboratory data for wet compressed residue indicate that a nominal 150 L/ha volume of water, deemed acceptable under Australian dryland cropping conditions, could provide straw stem cutting capacities of up to 12.5 Mg/ha, 19 Mg/ha and 35 Mg/ha at 300 mm, 500 mm and 1000 mm nozzle row spacing, respectively, at a nominal 380 MPa operating pressure. In this study, the waterjet technology demonstrated very effective residue cutting, which could be maximised under specific residue conditions and technology settings. The results indicate that the technology could become an effective tool for assisting residue handling in no-till planting applications, particularly in wet stubble and soft soil environments where traditional mechanical coulters fail. Further research is required to develop accurate operational guidelines for a range of field residue type and conditions, as well as clarify the technology cost-effectiveness in order to facilitate adoption within the no-till cropping industry.

Recycling waste tire rubber by water jet pulverization: powder characteristics and reinforcing performance in natural rubber composites

Abstract Pulverization is a general strategy used prior to any practical application of recycled waste tire rubber (WTR). Mechanical grinding, in use currently, is an inefficient technique due to low-quality rubber powder production and certain indispensable additional pretreatments. The aim of this study is to propose a novel pulverization technique of WTR by ultrahigh pressure water jet. Efficient pulverization of WTR was accomplished by water jet without any pretreatment. Powder characteristics, including particle size distribution (PSD), surface area, thermal behavior and chemical structure changes, were investigated. The curing, mechanical and morphological properties of natural rubber (NR) vulcanizates filled with ground tire rubber (GTR) from water jet pulverization (WJPULV) were evaluated. The results indicate that GTR granules from WJPULV possess a quite fine PSD and large surface area, show similar thermal degradation behaviors to the original WTR and have been partially devulcanized. The improvement of tensile and tear strength of the composites reveals that GTR from WJPULV can be added up to 40 phr without adverse effect. The morphological analysis corroborates the homogeneity of GTR in the NR matrix. All findings confirm that water jet can be an excellent choice for pulverization of WTR.

Cavitation desulfurization in vulcanized rubber recycling under ultra-high pressure water jet

Abstract Ultra-high pressure water jet is proposed for recycling of vulcanized waste rubber, and cavitation desulfurization in the recycling process is analyzed. The chemical effects of mechanical shearing, pyrolysis, free radical oxidation, and supercritical oxidation produced by bubble collapse are considered the main causes of desulfurization. Scanning electron microscopy, Fourier transform infrared spectrometry, differential scanning calorimetry, nuclear magnetic resonance test, and X-ray photoelectron spectroscopy are used to determine the performance of rubber powder. Gel fraction of rubber powder is measured to analyze the effect of jet pressure on desulfurization. Results indicate that the vulcanized rubber could achieve partial desulfurization. The glass transition temperature of the rubber powder slightly increases after crushing. With the increase of jet pressure, the gel fraction of rubber powder initially decreases and then increases, as well as achieves a minimum value at the jet pressure of nearly 220 MPa, which is ideal for desulfurization.

Pulverization of end-of-life tires by ultra-high pressure water jet process

Abstract Crumb rubber (CR), as a final product from end-of-life tires through size reduction process, has proved an appropriate end product for accumulated discard waste tires all around the world. Unlike pre-existing pulverization methods, such as ambient or cryogenic grinding and solid-state shear extrusion, an entire cool pulverization process utilizing ultra-high pressure water jet (UHPWJ) was proposed in this paper. Pulverization experiments under various processing parameters were designed and conducted. The particle size distributions of produced CR were obtained using laser particle analyzer. Microscopic morphologies of CR and rubber fracture surface were observed under scanning electron microscopy. The crosslink density and gel fraction of produced CR were experimentally determined. Influence of four main processing parameters as pump pressure, transverse velocity, standoff distance and impacting angle was discussed in detail, and the most suitable processing parameters were recommended. The results show that the particle size distribution of produced CR with UHPWJ is between 45 μm and 200 μm, and the surface of CR is coarse and porous. High compressive shear effect and erosion are the main mechanisms in UHPWJ pulverization. Besides, the produced CR has already been partly devulcanized after UHPWJ pulverization, and polymer degradation occurred in the meanwhile.

A novel tool to improve the rate of penetration by transferring drilling string vibration energy to hydraulic energy

The ultra-high pressure water jet assisted mechanical drilling technology is an effective approach to improve the rate of penetration (ROP), however, due to unreasonable design ideas and low reliability of the existing down-hole supercharger, this technology is not applied widely. To make breakthrough of this technology, a new idea of utilizing the drill string vibration energy to modulate ultra-high pressure jet is first proposed, and a novel down-hole supercharger, down-hole drill string absorption & hydraulic supercharging device (DSAHSD), is developed. The DSAHSD combines the advantages of reducing the axial drill string vibration and generating ultra-high pressure jet to effectively assist rock breaking. When the drilling fluid flows through this tool, part of the drilling fluid will be modulated to the ultra-high pressure jet by periodic compression of piston drove by drill string vibration. Because of hydraulic auxiliary rock breaking of the ultra-high pressure jet, the drillability of rock and the ROP will be enhanced. To analyse the feasibility and influence factors of the tool, mathematical model were established, the results show that the tool could produce more than 140MPa pressure and the outer pressure increases with the increase of weight on bit and rotary speed. Moreover, there is an optimal diameter of ultra-high pressure nozzle to optimal performance of the tool. This tool has been applied to more than 60 wells in four oil fields throughout China. The results indicate that the maximum density of the test drilling fluid is 1.9g/cm3, the single maximum footage is 1480m, and the operation time of the tool is more than 200h. Furthermore, the average ROP was increased by approximately 11–831%. In conclusion, the DSAHSD has the characteristics of a simple structure, has a long lifetime, is able to adapt well with existing drilling equipment, and can provide guarantee for wide application of the ultra-high pressure jet technology in oil fields.

Stress Analysis and Dissociation of Radial Tyre under Water Jet Impact

A new method to recycle radial tyre is studied, using Ultra-High Pressure Water jet to cut the tread rubber. The dynamic constitutive model of radial tyre material is builded, fitting model parameters with least square method. And the stress distribution law and dissociation characteristics of rubber block under impact are studied by finite element analysis.Through the SEM observation of cross section, the relationship is preliminarily discussed between stress distribution and micro-morphology of fracture interface and dissociation pathways. The split Hopkinson pressure bar apparatus is used to obtain the dynamic response law of material in a wide range of Strain Rate. The experimental results show that viscoelasticity of the rubber material is not fully reflected from the perspective of the stress wave propagation. The rubber material has a brittle transition and eventually forming fine powder. And the experimentally measured material crushing threshold is found agreed well with the numerical simulation results. It provides important mechanical foundation for further research on the mechanical force desulfurization of material.

Mechanism and experimental investigation of ultra high pressure water jet on rubber cutting

The recycle and reuse of rubber materials has become a global environment problem with the fast increasing amount of waste rubber. Compared to traditional recycle methods, ultra high pressure water jet, as a fast developing tool of cool cutting, can be used in recycling rubber materials without damaging the internal organization structure of materials. This paper investigates ultra high pressure jet cutting rubber in mechanism and experiment. Different from metallic materials and brittle materials, rubber materials are cut by the force of shear and tensile under the impinging of ultra high pressure water jet and the erosion of high speed water flow with rubber powder. The overall structure of kerf is Y shape. The upper section of Y shape is caused by shear, the middle section is resulted from both shear and tensile, and the bottom section is a result of the erosion and the tensile. The results of experiment show: (1) a significant linear correlation between cutting depth and pump pressure;(2) 2.0 mm/s is the optimal transverse velocity under the current experiment condition;(3) the cutting depth has a decreasing tendency with the stand-off distance increased. It can be concluded from orthogonal analysis that pump pressure has a signification effect on cutting depth, nozzle transverse velocity is not remarkable, and the effect of stand-off distance is not obvious.

Pressure and Flow Stability for Ultra-High Pressure Water Jet System

The paper introduces system components and working principle of the ultrahigh pressure water jet, with theoretical analysis on fluctuation characteristics of pressure booster pump flow. On the basis of the AMEsim simulation model established on various hydraulic components in the system, through a large number of simulation experiments to compare simulation curve with different parameters. Analysing the system characteristics for pressure and flow affected by some parameters such as: volume, booster pump motion control and the number of nozzles, in order to improve the system stability for pressure and flow and optimize the parameters.

Fracture Mechanism of Radial Tyre Rubber under Ultra-high Pressure Water Jet Impact

A new method to recycle radial tyre is studied. The ultra-high pressure water jet technology is applied to achieve the material recycle of radial tyre rubber, the experiments of ultra-high water jet impinging on tread rubber under non-submerged condition are performed, rubber failure surfaces and rubber particles by jet cutting under different actuating pressures are obtained, rubber particle size analysis and low field nuclear magnetic resonance(NMR) analysis are performed to evaluate the recycle performance of this new method. The stress distribution of rubber material interior under the impact of water jet is computed by establishing the finite element model of tread rubber using fluid-structure interaction(FSI) theory, and the fracture behavior of the tread rubber is studied by using damage criterion. The simulation analysis agrees well with the experiment results. Micro-failure mechanism analysis with scanning electron microscope(SEM) for rubber failure surfaces and rubber particles is performed, the results show that the micro-mechanism of rubber failure due to water jet impingement is brittleness tendency ductile fracture in condition of tensile and shearing stress, intergranular damage and transgranular fracture are the main microscopic failure modes.

Numerical simulation ultrahigh waterjet (WJ) flow field with the high-frequency velocity vibration at the nozzle inlet

This paper presents an investigation of ultrahigh pressure waterjet (WJ) flow field with the high-frequency velocity vibration at the nozzle inlet by computational fluid dynamics method. The velocity field of the flow inside the WJ nozzle is obtained. The influence of vibration parameters, such as amplitude and frequency on the flow field are studied. The results of investigation indicate that the flow velocity at the WJ nozzle outlet has almost the same vibrating type with the inlet velocity vibration. During a vibration cycle, the velocity field of the flow is changing greatly. The serials value of the vibration frequency and amplitude are taken to test their influence on the flow field. The simulation results show that the flow field also changes greatly with the different frequency and amplitude. Based on the obtained results, the mechanism of system pressure vibration influence on the water jet flow field inside the WJ nozzle is obtained, and a new method is provided to optimize the machining process with the aim to improve the machine efficiency and surface quality of the work piece.