High-pressure Water Jet Research Articles

Effect of confining pressure on rock breaking by high-pressure waterjet-assisted TBM

High-pressure waterjet-assisted tunnel boring machine (WTBM) is an efficient method for improving the tunneling performance of a tunnel boring machine (TBM) and reducing the wear of its disc cutters in hard rock with high geostresses. Confining pressure directly affects the efficiency of rock breaking and the configuration of the disc cutters. In this study, we evaluated the effect of confining pressure on WTBM rock breaking by developing a self-designed and manufactured experimental system, including confining pressure loading, TBM disc-cutter penetration, and high-pressure waterjet. The macro fracture, acoustic emission (AE), peak normal force drop, and specific energy (SE) were analyzed for four different confining pressures (10, 20, 30, and 35 MPa). The results showed that the cutting depth of the waterjet increased linearly as the waterjet pressure increased and decreased with the gradual increase in the nozzle moving speed. The expansion and development of cracks formed rock debris, and the size of the rock fragments decreased with an increase in confining pressure. When the waterjet pressure was 280 MPa, the nozzle moving velocity was 800 mm/min and the kerf space was 75 mm, which indicated that the confining pressure, which was 23.16 MPa, minimized the cutting SE under this condition. However, regardless of the confining pressure, the maximum normal force of WTBM was less than that of a TBM, whereas the SE of WTBM was less than that of complete TBM cutting mode (CTCM). The average force drop and average drop rate of SE were approximately 25%, and 80%, respectively. The results of this study can inspire the design and mechanism of a TBM assisted by a high-pressure waterjet.

Flow Field Simulation and Nozzle Parameter Optimization of Rust Removal Robot Based on High-Pressure Water Jet Technology

To enhance the safety and longevity of large ships, employing high-pressure water jet technology for rust removal is crucial in this article, the qualitative relationship among the key parameters of high-pressure water jet rust removal is analyzed theoretically. Secondly, the flow field simulation is carried out using Computational Fluid Dynamics (CFD) software to verify the relationship among the key parameters. Finally, the influence of different nozzle length-diameter ratios on jet characteristics is analyzed. The simulation results show that the nozzle end length is 0 mm and the nozzle diameter is 1mm for the straight-cone convergent nozzle with a shrinking angle of 30° when the diameter of the length-diameter ratio remains unchanged and the length of the nozzle end is changed. Simultaneously, the highest values are observed for the nozzle exit velocity and the impact force on the target surface. The impact range of target shear force takes the maximum value when the length-diameter ratio is 1. Further, by changing the length of the nozzle-end and the nozzle diameter in the length-diameter ratio, the influence on the jet characteristics can be concluded that the nozzle diameter has a greater influence on the nozzle exit velocity than the nozzle-end length. On this basis, the optimized nozzle parameters can be obtained i.e., the nozzle-end length is 1 mm and the nozzle diameter is 1 mm, such that the effective striking area of the jet is the largest and the striking effect is the best.

Research on the high-pressure water jet impacting on the different solids based on improved SPH method

Research on the high-pressure water jet impacting on the different solids based on improved SPH method

Influence of the cutting edge preparation of carbide punching tools for punching of ultra-high strength steel strips

In order to ensure a robust punching process of ultra-high strength steel spring strips using carbide punching tools, a high stability of the cutting edge is required. Here the cutting edge preparation process has a significant influence. In the presented study, high-pressure abrasive water jet technology for cutting edge preparation was designed, investigated and analysed. For defining the optimal cutting edge shape regarding stresses, a numerical analysis using LS-DYNA was conducted. Within this analysis, the influence of the cutting edge rounding and symmetry was numerically tested and evaluated. Based on the results, two cutting edge shapes were selected and prepared using the high-pressure abrasive water injection jet technology. The tools were applied in the punching process up to 50,000 strokes in order to analyse the cutting performance and tool wear. With regard to a highly wear resistant tool for punching, a combination of the abrasive water injection jet preparation routine and a CVD diamond coating are under further investigation and first insights are presented additionally.

Farmer perception, knowledge and management of the scale insect pest complex infesting crops and trees in Coastal Kenya

Scale insects and mealybugs (Hemiptera: Sternorrhyncha: Coccomorpha) are serious plant sap-sucking pests affecting a wide range of cultivated crops and tree species. The insects are highly diverse and can have devastating effects on yields due to lack of farmer awareness and inappropriate management practices. Recent alien mealybug invasions in Kenya include among others, papaya mealybug (Paracoccus marginatus), a highly invasive pest that is spreading quickly. Farmer experience with diverse crop pests can support development of a successful pest management strategy and contribute to reduced impacts on both crop yields and agro-biodiversity. This socio-economic survey was carried out in three coastal counties of Kenya (Mombasa, Kilifi and Kwale) to establish the impact of scale insect and mealybug pests on farmer livelihoods and to document the perception, knowledge and management practices used by smallholder farmers. Data from oral interviews using ODK were administered to respondents and analysed using Excel and GENSTAT. It emerged that 26% of the respondents were familiar with scale insects and 51% with mealybugs, respectively. Of these, 78.13 % and 94% acknowledged having encountered scale insects and mealybugs, respectively, on their farms. The farmers confirmed that scale insect pests affected a high diversity of crops and trees. About 56% of the respondents used pesticides to control the pests while 25% did not apply any management strategy. The remaining 19% practiced cultural control methods such as field sanitation and intercropping with less susceptible crops. Pesticides were reported to be moderately effective (41-70%) at controlling scale insects and mealybugs. Other management options reported by farmers included farm hygiene, the use of high-pressure water jets, and applications of ash and bio-pesticides such as home-made neem extract. Based on the findings, it is recommended that capacity building for farmers and input providers be undertaken to enhance the knowledge of scale insect and mealybug pest biology, symptoms of crop and tree attack, host ranges and management practices. Additonally, training on the use of low-risk pest control products and innovative control methods should be undertaken to reduce the impact of the pest on crop production and agro-biodiversity. Keywords: Farmer knowledge, management, mealybugs, scale insects and socio-economic survey.

Analysis of the Process and Results of High-Pressure Abrasive Water Jet Multilayer Cutting of Electrical Steel.

Electrical steels are magnetically soft materials and are widely used in the electrical industry for the construction of power transformer cores, distribution transformers, current transformers, and voltage transformers. An important parameter of electrical components, which determines the efficiency of devices, is energy loss during remagnetization. Energy losses are caused by eddy currents, hysteresis, and magnetic delay associated with the low quality of the cut edge after the cutting of steels, and material deformations and excessive stress concentration in the surrounding cutting zones. Common techniques for cutting electrical materials in industrial lines include mechanical cutting and laser cutting. Work has shown that mechanical cutting of electrical steel single layers results in the occurrence of large deformation zones, and in cutting processes with a high-pressure abrasive water jet (AWJ), significant uplifts of material and burrs at the bottom edges of sheets occur. The problem of increasing the cutting quality was solved through selecting the stream parameters for bundle cutting of electrical steels. It has been shown that in the process of cutting electrical sheet bundles, the height of burrs on the cut surface and the zone of plastic deformation are reduced. The work also presents comparison and analysis of characteristic features of the cut edge of electrical sheets obtained through high-pressure abrasive water jet and mechanical cutting processes. The influence of the type and processing parameters on the characteristic features of the material hysteresis loop was determined.

A comprehensive study of diverse techniques for enhanced physicochemical and structural properties of bio-calcium from hybrid catfish bone

This research examined the impact of various comparative preparation methods on enhanced physicochemical, and structural properties of bio-calcium (BC) from hybrid catfish bone. Raw hybrid catfish bones (RB) were used to make bio-calcium in four steps. High-pressure water jet processing produced washed bone (WB), soaking the bone in an alkaline solution to remove proteins (PR), immersing it in ethanol to remove lipids (LR), then bleaching, and grinding it to make bio-calcium powder. The BC had greater lightness values (L*) (p < 0.05), and contained significant calcium, and phosphorus. The SDS-PAGE showed three significant protein bands with molecular weights of 250, 133, and 116 kDa. The crystalline structure of hydroxyapatite in BC was confirmed using X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. The percentage of crystallinity of BC had a notable rise, increasing from the RB to BC of 36.25%–45.32%. The BC powder exhibited a consistent distribution of particle sizes, ranging from 2 to 10 μm. Additionally, the analysis of elemental profiles, and mappings using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) revealed that BC exhibits a significant concentration of calcium, and phosphorus. BC showed superior %bioavailability of calcium (18.94%) in an in vitro simulated gastrointestinal system (GIMs) compared to RB (10.58%), and calcium carbonate (11.19%). Hence, the BC production process proved to be a viable method for acquiring premium-grade BC, which holds potential for further development as a calcium dietary supplement.

Experimental and numerical investigation of the novel downhole intensifier controlled by electromagnetic valve

Stress release with rock slotting by ultra-high-pressure water jet is an effective method in reducing rock strength in the bottom hole caused by high in-situ stress in deep formation. The characteristics of duration and frequency of the water jet are vital for forming different grooves to release downhole stress. To improve the duration of the high-pressure water jet and modulate different jet frequency, a kind of downhole intensifier controlled by electromagnetic valve was developed and proposed. The water jet performance and the motion characteristics of the plunger of the intensifier were studied in various input pressure and switch frequency of the electromagnetic valve based on experiments, and a series of numerical simulations were conducted considering the input pressure, stroke, and area ratio of the plunger. The results indicate that the output waveform of the intensifier goes like a square shape. Increasing the input pressure and the area ratio of the plunger can enhance the output pressure while the duration of the peak pressure decreased. The stroke of the plunger shows a significant effect on the duration of the peak pressure and jet frequency. Adjusting the switching frequency of the electromagnetic valve can easily change the duration of peak pressure, which is beneficial for forming grooves with different characteristics. The research is believed to provide an important reference in drilling Engineering for deep and ultra-deep wells.

Study on Mechanism and Regularity of Rock Breaking by Pulsed Water Injection with Particles

In recent years, the drilling technology applied to deep and ultra-deep formations has developed rapidly, but the drilling speed for hard formations is low. Therefore, it is very important to study the drilling methods for deep and hard strata. Particle pulsed jet drilling is a new drilling method based on particle jet impact drilling technology and high-pressure pulsed water jet impact drilling technology. In this paper, the mathematical models of the shear layer amplification coefficient and wave velocity are established based on a similar network theory, and the motion equations of a single particle and particle swarm are established according to the motion of particles in a pulsed jet environment. Then, based on the self-designed particle jet impact rock-breaking experimental platform, the numerical simulation results are compared, analyzed, and verified. The results show that the rock-breaking efficiency increases with the increase in the average velocity of the particle pulsed jet. When the average speed exceeds 160 m/s, the rock-breaking efficiency increases significantly. With the increase in the particle concentration, the rock-breaking efficiency of the particle pulsed jet also increases, but there is an optimal value. When the concentration is too high, the impact of particles on the rock is affected by the collision between particles, and the wear of the drill intensifies. This research is helpful for understanding deep-well drilling-speed-increasing technology and promotes the development and engineering applications of particle jet impact drilling theory.

Analysis of the pulsating properties of a high-pressure water jet generated in a self-excited head for erosion processing

Water jet is an extensively used method for materials processing due to the possibility of operating in different environments (air, water), its safety during working with hazardous materials, and efficiency while cutting hard and brittle rock blocks. In this article, we have presented results of the research on processing aerated concrete by means of pulsating water jest. The discontinuity in water flow through the nozzle was achieved using an own-construction self-excited head. The intermittent flow had the greatest effect during operating in water environment. Machining efficiency for continuous and pulsating water jest was indicated by measuring erosive effects on processed materials. The occurrences of pulsations were confirmed while measurement of water jet thrust forces acting on piezoelectric sensor. It was concluded that pulsating water jet had greater processing effectiveness in a certain circumstances compared to the continuous flow, during the surface processing of concrete blocks.

Experimental and numerical simulation study on the relationship between cutting depth of high-pressure water jet with high traverse speed and disc cutter penetration of TBM in hard rock tunnel

The disc cutting load of a TBM is insufficient to induce crack propagation in hard rock tunnels due to the high strength of the rock. High-pressure water jets, considered an auxiliary rock-breaking method, enhance the disc cutter's capacity to penetrate cracks by creating pre-existing fissures. In order to examine the correlation between cutting depth achieved by a high-pressure water jet operating at high traverse speeds and the penetration capability of TBM disc cutters, we conducted rock cutting experiments employing varying traverse velocities for the water jet. Additionally, we performed linear disc cutting experiments using full-size disc cutters equipped with grooves. These experiments were conducted using high-strength granite from China's Bei Shan region. We utilized the Discrete Element Software PFC2D to construct a rock breaking model based on Tyson polygons, enabling us to investigate the microfine influence mechanism of grooves with symmetry. The experiments involving high-pressure water jet grooving at high traverse velocities revealed a logarithmic decrease in groove depth as the nozzle's traverse velocity increased. These findings suggest that when high-pressure water jets are employed as an auxiliary method in TBM operations, increased distance from the center of the disc hob leads to higher traverse velocities, resulting in less efficient rock breaking. Nonetheless, increasing the nozzle diameter can enhance the rock-breaking effect. Linear disc cutting experiments indicate that, at a penetration depth of 4 mm, grooves with depths less than 4 mm have minimal impact on assisting in disc cutter rock breaking. However, when the groove depth exceeds 4 mm, there is a noticeable improvement in the disc cutter's breaking performance. The numerical simulation results provide initial validation for the linear disc cutting experiment. Lastly, considering the specific conditions of the Beishan tunnel, we propose a design scheme that involves the zoned arrangement of water jets. Additionally, we recommend appropriately reducing the rotational speed when employing high-pressure water jets as an auxiliary method for rock breaking. The research findings presented in this paper can serve as valuable references for the design and implementation of high-pressure water jet-assisted TBM cutter rock breaking.

Field and laboratory experimental studies on hard-rock tunnel excavation based on disc cutter coupled with high-pressure waterjet

Field and laboratory experimental studies on hard-rock tunnel excavation based on disc cutter coupled with high-pressure waterjet

Water jet guided laser grooving of SiCf/SiC ceramic matrix composites

Water jet guided laser micro-machining is a novel processing technique that utilizes the synergistic effect of high-pressure water jets and lasers. To qualitatively and quantitatively investigate and evaluate the sensitivity of ablation depth, material removal rate, taper angle, surface morphology, and elemental composition to processing parameters, multiple characterization techniques, including scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and industrial computed tomography (CT), was undertaken. The experimental results show a high sensitivity of the ablation depth, volume material removal rate, and surface morphologyprocess parameters. At the same time, the taper angle is more sensitive to the laser power. Furthermore, a maximum aspect ratio was achieved under certain conditions, reaching up to 7.5. In practical machining, suitable laser processing parameters are selected based on different expected objectives (processing efficiency and quality). This experimental study can provide valuable guidance for the high-quality water-guided laser micro-machining of ceramic matrix composites (CMCs).

Development and Performance Evaluation of a Pressure-Adjustable Waterjet Stubble-Cutting Device with Thickness Detection for No-Till Sowing

No-till maize (Zea mays L.) sowing is often affected by stubble. The high-pressure waterjet at a constant rate is powerless to precision applications of stubble cutting and causes water waste. In this study, a pressure-adjustable stubble-cutting device with a stubble-thickness detection device was designed. Through experiments, the quantitative analysis of the moisture content and electrical conductivity (EC) of the field soil and stubble during the spring sowing period was conducted, and the effect of soil moisture content (SMC), soil compaction (SC) and machine forward speed (V) on the stubble-thickness detection error (STDE) was explored. On this basis, the optimal parameters of the device were analyzed and evaluated, and a verification experiment was applied. The results showed that STDE decreased with the increase of SMC and SC and increased with the increase of V. The response time of the pressure adjustment system is 0.12 s. The stubble-cutting device with thickness detection for two-level pressure regulation reduced the water consumption (WC) by 13.22% under the condition that the stubble-cutting rate (SCR) remained unchanged. The WC increased with the increase of waterjet pressure (P) and decreased with the increase of V. The SCR increased first and then decreased with the increase of cutting angle (α). The response surface optimization analysis showed that when P was 26 MPa, α 90.45° and V was 3.36 km/h, the performance was optimal with a 3.03% STDE, a 95.49% stubble SCR and a 49.98 L/ha WC. The measured value of the field verification experiment had a 4.11% relative error existing in STDE, a 4.06% relative error existing in the SCR and a 1.81% relative error existing in WC compared with the predicted value of the regression model. In contrast to the constant rate waterjet cutting device, the application of this device can save WC by 13.22%. This study can provide a reference for the application of waterjet technology and conductivity detection technology in the agricultural field.

Rock-Breaking Characteristics of High-Pressure, Dual-Stranded Water Jets

Because of the unclear understanding of the characteristics associated with coupled rock breaking using multiple water jets, a numerical model combining smoothed particle hydrodynamics (SPH) and the finite element method (FEM) was established to investigate the rock-breaking capacity of a high-pressure, double-stranded water jet structure. The effectiveness of this model was verified through field experiments. The study further examined the specific energy required for rock breaking using the high-pressure double water jets and analyzed the effects of jet pressure, nozzle diameter, jet impact angle, and impact point spacing on rock-breaking volume. The results demonstrate that the rock-breaking ability of a high-pressure double water jets is better than that of a single water jet. When the impact angle of the high-pressure double water jets was 15° and the distance between impact points was 2.0 d, the rock damage effect was the best. By comparing the specific energies for rock breaking of a single water jet and a double water jet, it was concluded that the best rock-breaking nozzle diameter is 1.6 mm. Furthermore, an orthogonal testing approach was employed to determine the main and secondary factors influencing the rock-breaking energy of the high-pressure double water jet. The order of significance was found to be jet pressure &gt; impact angle &gt; impact point spacing &gt; nozzle diameter. These findings provide valuable guidance and reference for application in the coal mining industry.

Graffiti removal from granite cladding by abrasive water-jet

This study focuses on the assessment of a graffiti removal system based on abrasive water-jet technology (AWJ). Spray paints were applied on samples of an important Italian granite commercially-named as “Rosa Limbara”. This granite has been used worldwide as dimension stone for paving and cladding. Two different commercial abrasives have been added in the high-pressure water-jet in order to clean the granite saw-plane surfaces from graffiti. After a check by the naked eye, different criteria have been chosen for assessing the effectiveness of the cleaning process: the similarity in roughness (Ra, Rz, and Rmax) between the original surface and the one resulted after cleaning, the total colour difference (ΔE) and the depth of material removed by the AWJ action. The tests showed that excellent cleaning results can be achieved with both abrasives by correctly combining the operational parameters of the technology (i.e., water pressure, spacing between passes, stand-off distance, travel speed and abrasive flow-rate) without giving any damage to the stone material. The two abrasives showed good results in total colour difference although one of them gave better results in both roughness difference and material removal. Economic considerations on paint removal with AWJ technology are also offered.

Analysis of Rock Breaking Parameters and Simulation of Mechanical Characteristics of Multi-Nozzle Jet Impact

With the continuous development of high-pressure water jet technology, research on the optimization of structural parameters for multi-nozzle configurations, the perforation effect of jet rotational impact rock breaking, and the impact force during rock breaking has received increasing attention. Through the development of a self-designed high-pressure water jet rotational drilling test device, rock breaking experiments were conducted on sandstone of different strengths using jet streams with different inclination angles, various combinations of nozzles, different target distances, and different rotational speeds. The parameters and structure of the multi-nozzle jet drill bit were optimized, and the impact of water jet-rock breaking effects was studied. The rationality of different inclination-angle jet streams in rock breaking was verified using the ALE-FEM coupling method. The changes in the force on the target body and the fragmentation mode during rock breaking with different inclination-angle jet streams were analyzed. The results showed that under the condition of adjustable inclination angles, a smaller inclination angle resulted in greater depth and a smaller diameter of rock breaking, while a larger inclination angle resulted in greater width and a smaller depth of rock breaking. The optimal combination of multi-nozzle jet streams was determined to be 20°, 30°, and 60°, which achieved a balance between rock breaking and borehole expansion performance. The efficiency of multi-nozzle jet rotational rock breaking decreased with increasing target distance, with the optimal range being 2 to 4 mm. The rotational speed of the multi-nozzle jet stream had a significant impact on rock-breaking efficiency. Under the same target distance conditions, as the drilling speed increased, the volume of rock breaking initially increased and then decreased, and the rate of volume attenuation increased with increasing target distance. The forms of rock breaking in multi-nozzle jet streams were not identical. Jet streams with smaller inclination angles mainly caused tensile failure through axial impact, while those with larger inclination angles primarily caused shear failure through radial impact. This study provides valuable guidance for optimizing the structural parameters of multi-nozzle jet drill bits and researching rotational rock breaking.

Experimental Research on the Use of a Selected Multi-Criteria Method for the Cutting of Titanium Alloy with an Abrasive Water Jet.

The use of selected multi-criteria decision methods for the optimization of cutting processes by abrasive water jet methods is increasingly being used in industrial processes. This is due to the complexity of the processes and the need to reduce operating costs. Process optimization methods are available to support organizational processes including the design phase, quality assurance, production automation, and many more. This article presents the current state of research on the water-abrasive cutting process and the use of multi-criteria methods in optimizing this process. This article presents a detailed methodological study of the VIKOR approach to optimization, indicating the applicability conditions, assumptions, and limitations on the example of high-pressure abrasive water jet cutting of elements made of titanium alloy utilizing HPX garnet abrasive. As a result of the research conducted, the best input parameters of the cutting process for abrasive flow rate, pressure, and the traverse speed of the cutting process were determined. The achieved result is consistent with the assumption that the most favorable output parameters are the highest cutting depth and the lowest level of roughness.

APPLING HIGH WATER PRESSURES EJECTOR SYSTEM TO CONTROL DUST IN QUANG NINH UNDERGROUND COAL MINE

In recent years, in Quang Ninh coal underground mine, longwall mining has been increasingly applied to meet the energy demand. This has resulted in the potential for increased mining dust. Coal dust is not only harmful to workers but also creates a risk for coal dust explosions in the mine. Therefore, in order to control the mine dust problem, it is necessary to develop a set of dust removal equipment suitable for underground coal mining. High-pressure water ejector system is selected to control dust in Quang Ninh mine. In addition, parameters and criteria for the design of the high-pressure water jet ejector systems have been presented.

Energy optimization of main hydraulic system in a forging press by simulation and experimental methods

The primary cause of the low energy efficiency of hydraulic presses (HPs) is the mismatch between installed power and demanded power. This study adopts the concept of a high-pressure waterjet cutting system and presents an energy-saving method to reduce the energy dissipation of HPs, where a single drive system composed of multi motor-pumps and superchargers-accumulators, is integrated into an HP and partitioned into several drive zones corresponding to load profiles. Meanwhile, a method for scheduling the above system is presented to realize an orderly energy supply with no conflict and shorten the idle time. Pump units, accumulators, and superchargers were selected according to the different load profiles to energize the actuators in various operation stages. Since the kinetic power of the hydraulic oil output from superchargers are significantly higher than those of a conventional power unit, a press with low installed power could achieve high power load operations. Finally, the proposed system was applied to a 31.5 MN forging HP as a case study. Results showed that the installed power and the energy dissipation were reduced by 56% and 52% in one working cycle, respectively. Moreover, the novel HP displayed a processing performance equivalent to that of the conventional setup.