Water Jet Research Articles

Abrasive waterjet machining of titanium alloy using an integrated approach of taguchi-based passing vehicle search algorithm

AbstractThe titanium alloy, Ti6Al4V, is a popularly used material in aerospace and medical applications due to its specific attributes, such as excellent strength-to-weight ratio and resistance to corrosion. Ti6Al4V is challenging to machine using conventional methods due to its poor thermal conductivity, which necessitates the use of unconventional machining methods like abrasive water jet machining (AWJM). In this work, AWJM was preferred for machining Ti6Al4V, considering three key process variables: nozzle traverse speed (Tv), abrasive flow rate (Af), and stand-off distance (Sd). The performance of the AWJM process was assessed using three main metrics: Material removal rate (MRR), Surface roughness (SR), and Kerf taper angle (θ), which were crucial for evaluating the effectiveness of the AWJM. Taguchi’s L9 array, a design of experiments method, was used to plan the experiments. The adequacy of the developed models was assessed by analysis of variance (ANOVA). ANOVA results have shown that Tv, Af, and Sd were found to have a significant effect on MRR, SR, θ with contributions of 73.15%, 49.72%, and 78.35% respectively. The Passing Vehicle Search algorithm was adopted to find the global optimal solution. Simultaneous optimization results using the PVS algorithm have shown the optimal MRR, SR, and θ values of 0.17 g/min, 3.28 μm, and 2.45, respectively, at Tv of 237 mm/min, Af of 450 g/min, and Sd of 2.0 mm. The optimization results with Pareto points will help to achieve desired outcomes by selecting appropriate input conditions.

The effects of submerged laser peening, cavitation peening, and shot peening on the improvement of the torsional fatigue strength of powder bed fused Ti6Al4V produced through laser sintering

This study demonstrates the improvement in the fatigue strength of additive manufacturing (AM) metals such as laser-based powder bed fusion of metals by post-processing. Titanium alloy samples manufactured by powder bed fused (PBF) Ti6Al4V produced through laser sintering (LS), treated by submerged laser peening (SLP), cavitation peening (CP), and shot peening accelerated via a water jet (SPwj), were subjected to torsional fatigue testing and compared with the as-built specimen. At SLP, the samples were treated by laser ablation (LA) and laser cavitation (LC) which was developed following LA. A cavitating jet was used for CP. For comparison, conventional post-processing using SPwj was also performed. To characterize the microstructural modification caused by the three post-processing methods, the cross-section of the treated surface was observed by electron backscatter diffraction. The fatigue strengths at 107 cycles were found to be 217, 361, 313, and 285 MPa for the as-built, SLP, CP, and SPwj specimens, respectively. The primary factors contributing to fatigue strength improvement by post-processing were surface smoothing and the introduction of compressive residual stress. The experimental observations were used to derive correlation formulas to estimate the fatigue life improvement due to post-processing as the function of the surface roughness and surface residual stress.

Stress relief cracking and permeability improvement by high-pressure water jet slotting to enhance coalbed methane extraction

Extracting coalbed methane (CBM) is important for energy development. Improving coal seam permeability is the key to high-efficiency CBM extraction. High-pressure water jet (HPWJ) slotting is an effective method for improving permeability. However, the mechanism by which this technology improves coal seam permeability is unclear. Therefore, in this paper, the mechanism by which HPWJ slotting causes stress relief cracking and permeability improvement to enhance CBM extraction is studied in terms of the stress relief effect and the changes in fracture field and flow field induced by HPWJ slotting. Significant changes occur in facture field and flow field. The process, coal mass stress relief → fracture development → permeability improvement → CBM extraction enhancement, is triggered by HPWJ slotting. A field experiment indicates that after HPWJ slotting, the total CBM production and its average pure quantity are 4.41 and 4.20 times those under traditional drilling conditions, suggesting that HPWJ slotting can effectively improve permeability and enhance CBM extraction. The study results have important significance for revealing the mechanism by which HPWJ slotting improves permeability and for achieving high-efficiency underground CBM extraction.

Improving the Machining Performance of Polymer Hybrid Composite by Abrasive Water Jet Machining for Precise Machining

Improving the Machining Performance of Polymer Hybrid Composite by Abrasive Water Jet Machining for Precise Machining

CFD-Based Study on the Flow and Kinetic Energy Characteristics of a Supercritical Suspended Abrasive Water Jet in the Deep-Sea Environment

A supercritical suspended abrasive water jet with dual inputs of pressure and heat is proposed to improve the cutting performance of the conventional suspended abrasive water jet in deep-sea environments. The paper studies the flow and kinetic characteristics of the supercritical suspended abrasive water jet. The CFD simulation method is proposed to investigate these characteristics by integrating a programmed database of supercritical water material properties with Ansys Fluent. The simulation and comparison show that abrasive particle density, abrasive particle size, inlet pressure, and water temperature affect the acceleration process of the abrasive particles. At the nozzle outlet, the velocity of the abrasive particles reaches over 95% of the supercritical water velocity. With the proposed supercritical abrasive water jet, the jet velocity is increased by 192.2% to 402.40 m/s compared to the conventional suspended abrasive water jet, reducing the amount of water used by 67.7% at a specified temperature of 773.15 K. Correspondingly, the medium kinetic energy is increased by 177.7% and the medium kinetic energy ratio is 2.78. The particle kinetic energy is increased by 723.2% and the particle kinetic energy ratio is 8.23.

Evolution of cavitation clouds under cavitation impinging jets based on three-view high-speed visualization

Cavitation cloud is an important index for evaluating the unsteady behaviour of cavitation water jets. However, when cavitation jets are applied in a restricted space, the optimal standoff distance is not applied. To study the evolution and collapse mechanisms of cavitation clouds at small standoff distances, this study conducted visualization research on the behaviour of submerged cavitation water jet impacting the target surface at three standoff distances from three-view using a high-speed visualization system. The effect of the optimal standoff distance and the small standoff distance on the morphology of cavitation clouds was explored by observing their shedding behaviour and evolution on the target surface, obtaining a pattern for the morphological evolution of cavitation clouds. The evolution of cavitation clouds under impact flow conditions can be divided into stages: incipient cavitation, ring vortex cavitation, spindle-shaped cavitation cloud, mushroom-type cavitation cloud, cavitation ring, ring vortex cavitation, and collapse. The periodicity of cavitation clouds on the target surface was confirmed by monitoring the grayscale change at the center of the target. Furthermore, the changing of cavitation jet structures is illustrated through Proper Order Decomposition (POD) analysis, showing that the frequency of cavitation clouds increased with the decrease of standoff distance within a certain range. The behaviour of cavitation flow impinging on the target surface at optimal standoff distance and small standoff distance was simulated using the Large Eddy Simulation (LES) turbulence model combined with the Zwart-Gerber-Belamri (ZGB) cavitation model. The results show that the numerical simulation can capture the high-pressure zone generated when the cavitation cloud collapses, and the area of the high-pressure zone increases with the standoff distance within a certain range, the concentration of cavitation bubbles on the target surface did not represent the intensity of erosion. The transient vortex structures of the flow field at different standoff distances were investigated based on the Q-criterion. The findings of this study not only provide critical technical support for the application of cavitation jets in confined spaces, but also contribute to a broader understanding of the erosion mechanism of cavitation jets.

Behavior and morphology combine to influence energy dissipation in mantis shrimp (Stomatopoda).

Animals deliver and withstand physical impacts in diverse behavioral contexts, from competing rams clashing their antlers together to archerfish impacting prey with jets of water. Though the ability of animals to withstand impact has generally been studied by focusing on morphology, behaviors may also influence impact resistance. Mantis shrimp exchange high-force strikes on each other's coiled, armored telsons (tailplates) during contests over territory. Prior work has shown that telson morphology has high impact resistance. I hypothesized that the behavior of coiling the telson also contributes to impact energy dissipation. By measuring impact dynamics from high-speed videos of strikes exchanged during contests between freely moving animals, I found that approximately 20% more impact energy was dissipated by the telson as compared with findings from a prior study that focused solely on morphology. This increase is likely due to behavior: because the telson is lifted off the substrate, the entire body flexes after contact, dissipating more energy than exoskeletal morphology does on its own. While variation in the degree of telson coil did not affect energy dissipation, proportionally more energy was dissipated from higher velocity strikes and from strikes from more massive appendages. Overall, these findings show that analysis of both behavior and morphology is crucial to understanding impact resistance, and suggest future research on the evolution of structure and function under the selective pressure of biological impacts.

Numerical Analysis of Convective Heat Transfer in Quenching Treatments of Boron Steel under Different Configurations of Immersed Water Jets and Its Effects on Microstructure

In this work, the effects of jet impact angle and water flow on the heat-transfer coefficient in boron steel probes were analyzed. Angles of 90°, 75° and 60° were used with stirring flows of 33 l·min−1, 25 l·min−1, 13 l·min−1 and 6 l·min−1. The aim consisted of determining the heat-extraction rates by analyzing the correlation programmed in the Ansys Fluent 2020R2 software when different cooling conditions are used, avoiding many experiments, and establishing quenching conditions free of surface defects on the workpiece. This process is currently used in heavy machinery, requiring high hardness and wear resistance. The fluid-dynamic field was validated using a scale physical model using the particle image velocimetry technique, PIV. In contrast, the thermal field was validated with transient state experiments solving the inverse heat conduction problem, IHCP. The results show that for high flows (33 l·min−1), the jets with an angle of 90° impact the entire surface of the piece, but their cooling rate is slower compared to the other angles, being 243.61 K·s−1, and 271.70 K·s−1, 329.56 K·s−1 for 75° and 60°, respectively. However, for low flows (6 l·min−1), the impact velocities are very similar for the three cases, promoting more homogeneous cooling rates of 58.47 K·s−1, 73.58 K·s−1 and 63.98 K s−1 for angles of 90°, 75° and 60°, respectively. Likewise, through the use of CCT diagrams, it was determined that regardless of the cooling rate, the final structure will always be a mixture of martensite–bainite due to the effect of boron as determined experimentally, which implies a more significant proportion of martensite at higher cooling rates.

Study on Dynamic Evolution and Erosion Characteristics of Cavitation Clouds in Submerged Cavitating Water Jets

The dynamic evolution behavior of submerged water jet cavitation clouds was studied by combining experiments and simulation. The formation, development, shedding, and collapsing process of a void cloud was analyzed by high-speed camera technology, and the influence of jet pressure was studied. Cavitation water jet erosion experiments were carried out on AL6061 specimens with standard cylindrical nozzles, and the correlation between cavitation cloud evolution and material erosion was studied by surface analysis. The results showed that the evolution of a cavitation cloud has obvious periodicity, that one period is about 0.8 ms, and its action region can be divided according to the attenuation rate of the jet velocity of the nozzle axis. The attenuation rate of the jet velocity at the nozzle axis in the central jet action zone is less than or equal to 82.5%, in the mixed action zone greater than 82.5% and less than 96%, and in the cavitation action zone greater than or equal to 96%. The erosion damage characteristics in different regions of the mixed action zone are significantly different.

Influence of Awj Parameters on Material Removal Rate, Surface Roughness, and Kerf Angle during Machining of Prosopis Juliflora Bark Fibres/Carbon Reinforced Hybrid Polymeric Composites

This study investigates the impact of changing the settings of the Abrasive Water Jet (AWJ) on the material removal rate (MRR), surface roughness, and kerf angle during the machining process of carbon-reinforced hybrid polymeric composites and Prosopis juliflora bark fibres. The hybrid nature of these materials presents unique machining opportunities as well as difficulties. As a result, optimizing the AWJ settings is essential for productive and efficient machining. The findings demonstrate the intricate connections between the AWJ parameters and the machining characteristics of the hybrid composite. To optimize MRR while minimizing surface roughness and controlling the kerf angle, the optimal parameter combinations are identified. The findings provide valuable insights for the manufacturing industry, particularly concerning sustainable materials and hybrid composites.

Analysis of the Internal Structure of Brenna Sandstone Samples with Respect to the Differences in Measured Quasi-elastic Moduli

The Young’s modulus and Poisson’s ratio determined for the rocks under uniaxial or triaxial loading conditions represent necessary input parameters for solving many geotechnical tasks. However, these effective stiffness moduli, particularly the Poisson’s ratios, measured on different samples sometimes substantially differ, even for visually compact and macroscopically homogeneous rock. This has been observed for Brenna sandstone, especially under conditions of conventional triaxial extensions. The aim of this study was, thus, to reveal differences in rock structure that could cause such behavior. Several complementary methods were used to investigate the structure of this sandstone: X-ray computed tomography (CT), visual analysis using optical scanning and stereo-microscopy, and a new method combining water jet erosion with these visualization techniques. Analyses of this structure revealed mechanically more resistant compact thick and adjacent thin weak layers. In rock samples, these layers have different patterns and orientations. To demonstrate the influence of layer orientation on effective stiffness moduli measured under different loading conditions, FEM calculations were performed for idealized structural models. The outcomes of this numerical analysis are in qualitative agreement with the results of the loading experiments and the layered structure revealed in the samples. The ability of the proposed method using water erosion to analyze the rock structure in detail was verified. The method offers an interesting alternative to standard visual and X-ray CT techniques. The numerical calculations indicate the importance of latent layered defects in sedimentary rocks for fine measurements of stiffness moduli (especially the Poisson’s ratios) used as inputs for geotechnical applications.

Toward the eco-friendly cosmetic cleansing assisted by the micro-bubbly jet.

While numerous types of chemical cosmetic cleansers have been presented, those with sensitive skin may still experience some irritation while using them. Moreover, the environmental issue of chemical agents has been documented repeatedly. To address these, we suggest the potential application of a micro-sized bubble-laden water jet to cleanse the cosmetics without (or less) using chemical detergents. We devised a venturi-type nozzle with a mesh and air holes capable of generating massive fine bubbles. By testing with the foundation and lip tint (known to be highly adhesive) coated on the synthetic leather and artificial skin surfaces, we measured that the cleansing performance of the bubbly jet is much better (even without the chemical agent) than the single-phase liquid jet. As a mechanism for enhanced removal, it is understood that the greater kinetic energy of the jet due to the acceleration of the effective liquid-air mixture flow and the direct bubble-cosmetic collisions play essential roles. We believe that the present results will spur the development of environment-friendly cleaning methods.

Analysis and Basics of Improving the Process of Cutting Electrical Sheet Bundles with a High-Pressure Abrasive Water Jet.

Electrical steels are widely used in the electrical industry in the construction of many devices, e.g., power transformer cores and distribution transformers. An important parameter of electrical components that determines the efficiency of devices is energy loss during remagnetization. These losses are influenced, among other factors, by steel cutting processes. The common techniques for cutting electrical materials on industrial lines are mechanical cutting and laser cutting. High-pressure abrasive water jet (AWJ) cutting, unlike the technologies mentioned above, can ensure higher quality of the cut edge and limit the negative impact of the cutting process on the magnetic properties of sheet metal. However, the correct control of the process and the conditions of its implementation comprise a complex issue and require extensive scientific research. This work presents a new approach to cutting electric sheets, involving bundle cutting, which significantly increases the processing efficiency and the dimensional and shape accuracy of the cut details. The tests were carried out for bundles composed of a maximum of 30 sheets, ready to be joined in a stator and rotor in a motor. The influence of processing conditions on the quality of the cut edges of sheet metal, the width of the deformation zone, and the burr height were analyzed. The detailed analysis of the quality of the cut edges of electrical bundled sheets creates new possibilities for controlling the AWJ cutting process in order to obtain a product with the desired functional and operational properties.

Visual observations of steam–air submerged horizontal jets at low mass flux

Steam jet condensation at low mass flux is important especially in start-up, shutdown or accident conditions of various applications. Visual experiments of steam–air submerged jets through horizontal pipe were conducted in the ranges of mass flux 0–––20 kg/m2s, air mass fraction 0–––0.02, and water temperature 20 − 80℃. In pure steam jets, three condensation regimes of no bubbling, intermittent bubbling, and continuous bubbling were identified in steam jets. In no bubbling regime, rolling up and billows of plane shear flow were observed. In intermittent bubbling regime, large bubble was generated, detached and collapsed intermittently, accompanied by fluid oscillations. The bubble forming frequency increased with the rise of water temperature. Condensation heat transfer coefficients tends to decrease as the steam mass flux increases. In continuous bubbling, fluid oscillation no longer occurred. The bubble forming frequency decreased with the rise of water temperature. Condensation heat transfer coefficients increase as the steam mass flux increases. In the cases with shallow submerged depth, air-entrained vortex, surface water jets, and splash were observed after bubble condensation. In steam–air jets, condensation became stable and small bubbles increased. The condensation regime transitioned from intermittent bubbling to continuous bubbling earlier.

Influence of square jets in Oxygen transfer in an Open Channel

Plunging jets are popular for aeration in wastewater treatment plants due to low energy needs. In the present study, square jets were evaluated to determine their effectiveness in providing aeration efficiency by plunging jets in an open channel flow. The study seeks to add to the existing knowledge and provide insight into the performance of single and multiple square plunging jets in wastewater treatment plants. Passing a water sample from the pool through an open channel, via square water jet(s), has shown that variables such as a higher number of jets, and discharge have a significant impact on aeration efficiency (E20). The findings demonstrate that the increase in E20 was found to be 85.22% to 117.6% with Nj=64 over the single jet when discharge was varied from 3.41L/s to 4.75L/s, further affirming the remarkable effectiveness of plunging jets in promoting aeration in open channel flows. Furthermore, it was observed that Fr. No. is the parameter that has the most impact on calculating E20 with correlation of 0.95311.

The influence of pulse frequency on the energy evolution law and rock-breaking effect of pulsed abrasive water jet

Compared to continuous abrasive jet and high-pressure water jet, pulsed abrasive water jet can intermittently generate high water hammer pressure and is commonly used in applications such as coal mining and petroleum engineering for rock-breaking purposes. Pulse frequency is one of the key factors affecting the evolution of abrasive acceleration and jet impact energy, thereby influencing the system's energy transfer efficiency and cutting ability. The equation of motion for abrasive acceleration is established based on the two-phase flow theory, and the variation law of abrasive velocity with pulse frequency is solved. Fluent-EDEM (Extended Discrete Element Method) was used to simulate the abrasive water jet flow field structure and abrasive acceleration process under different pulse frequency conditions, and the intrinsic influence mechanism of pulse frequency on impact energy was clarified. Combined with rock-breaking experiments using pulsed abrasive water jets, the following conclusions are drawn: as the pulse frequency increases, the inertia of the abrasive makes it unable to respond in a timely manner to the high pulsation frequency of water, resulting in a reduction in the exchange rate of intermittent energy and a gradual decrease in the maximum velocity of the abrasive. This trend is more pronounced at a higher pulse frequency. Within the same time period, the cumulative impact energy of the pulsed abrasive water jet decreases first and then increases with the increase in pulse frequency, indicating the existence of an optimal impact frequency that maximizes the cumulative impact energy of the pulsed abrasive water jet. Under fixed jet pressure conditions and the same erosion time, the pulsed abrasive water jet with a frequency of 30 Hz exhibits the best rock-breaking capability.

The Effect of Welding Process Parameters on the nilon-6 Plate Friction Stir Welded Joint

Nylon-6 is one of the most extensively used engineering thermoplastics. Due to its durability, reduced weight, low coefficient of friction, and abrasion resistance, this polymer is an excellent substitute for various materials, including metals and rubber. Despite being those, nylon-6 materials are joined together utilizing multiple welding processes. The current work examined the viability of the friction stir welding (FSW) method on nylon 6 plates that were 4 mm thick to investigate the effect of tool diameter ratio and feed rate on nylon-6 sheets with the FSW method on the tensile properties of the joints. The 4 mm thickness of the nylon-6 plate was cut into the dimensions of 115 mm x 100 mm. The sliced plates were then joined through the FSW process using ST80-based tools with various parameters in the shoulder to pin diameter ratio (D/r ratio) of 10/3, 15/3, and 20/3 and feed rates (FR) of 4 mm/minute, 6 mm/minute, and 8 mm/minute at a rotational speed (RS) of 5800 RPM. Afterward, the weld joint is cut using water jet cutting according to the tensile testing standard ASTM D638 type IV. Following this, characterization of the speci-mens, including macrograph examination, hardness testing, and tensile testing, was carried out. The results show that the highest tensile strength was obtained at a tool diameter ratio of 10/3 mm with a feed rate of 6 mm/minute, with a tensile strength value of 19 MPa reaching up to circa 90% of joint efficiency. The strength of the welded joint then decreases as the diameter ratio of the tool increases with each feed rate. Some defects appeared at the higher tool diameter ratios welded joint, including incomplete fusion, flash, thinning, and lack of bonding. In conclusision the combination of a D/d ratio of 10/3 and a FR of 6 mm/min at RS 5800 RPM can provide the optimal conditions for a strong nylon-6 friction stir welded joint.

Static and dynamic analysis of silicone/polyurethane embedded GFRP composite for magnetorheological elastomer

The current study focuses on the static and dynamic properties of GFRP composites embedded with a silicone(Si)/polyurethane(PU) blend used in automobile vibration dampening. Epoxy resin, glass fiber, and Si/PU blends of various compositions were used to create the hybrid composite specimens. For the present study, five different Si/PU blend compositions were considered to make five Si/PU embedded GFRP composite laminates were fabricated by hand layup method. The fabricated laminateswere cut to the standard sizes using water jet machining for mechanical and vibration testing. All tests were carried out in accordance with ASTM standards. Free Vibration test of five elastomeric composite specimens was carried out by impulse hammer method under fixed-free boundary condition. The current study found that the hybrid composite specimen with 0% Si and 100% PU elastomer has higher tensile strength, impact energy, and natural frequency than the other Si/PU blend elastomeric composite specimens.The better interfacial adhesion of PU rubber helps to transfer stress across interfaces more effectively and thereby enhancing the overall mechanical integrity of the composite laminate.

Experimental study on generation and growth of bubbles in external flash-boiling spray regime

High-performance liquid propulsion systems, such as hypersonic scramjets and liquid rockets, utilize regenerative cooling by employing fuel as a coolant to shield components from thermal damage. The flash-boiling spray, resulting from superheated liquid injection and prevalent in regenerative cooling, has received considerable research interest for enhancing atomization and combustion efficiency. In this study, superheated water jets at various temperatures between 30 and 90 ℃ were injected into a vacuum chamber at different pressures above 5 kPa, and their spray patterns were acquired through diffusive backlight imaging. Images were analyzed to determine key parameters, such as bubble nucleation flux, bubble growth rate, and spray angle, in an external flash-boiling spray regime. The estimated nucleation flux agreed well with the predictions the model based on nucleation theory in the region of sufficiently high superheat. The dynamics of bubble growth was investigated and explained using a bubble growth model. The jet-expansion energy was computed by measuring the spray angle and compared with the available energy. By mapping the evolution of flash-boiling spray in relation to relevant nondimensional numbers, the study underscores the necessity of accounting for the pressure inside the injector to adequately model bubble generation inside the injector. Furthermore, this study substantiates the feasibility of visually recognizing and analyzing individual bubbles in the external flash-boiling regime, thereby enabling the generation of experimental data crucial for the validation of bubble nucleation and growth models.

Design, Analysis and Fabrication of 360 Degree Fire Protection System

Abstract: Large factories, warehouses, and industrial production facilities always run the risk of fires breaking out. Lack of appropriate firefighting measures could result in disastrous consequences and along with financial losses might even lead to massive loss of human life. In such situations, it is ideal to install a Fire Monitor also known as a deluge gun. Fire monitors are an aimable and controllable high-capacity water jet used to deal with large fires. Unlike Fire extinguishers, Fire Monitors are permanently installed and cannot be moved. Using an array of heat sensors, this fire monitor detects any changes in ambient temperature and sends the user an alert about the same.