Water-jet Test Research Articles

Experimental study on optimization of abrasive water jet process parameters

Abstract In order to improve the mining speed of coal mine roadway and fundamentally solve the problem of mining imbalance, the abrasive water jet technology is used to cut rocks in front of mechanical tools to achieve efficient improvement of coal mine roadway mining efficiency. Based on the existing high pressure pure water jet test equipment, the abrasive water jet test platform was built, and the uniaxial compressive strength of soft and hard rock was obtained by testing the rock mechanical properties. The effect of jet pressure, target distance, transverse velocity and jet impact Angle on rock cutting is studied by using control variable method. According to the single factor test analysis, L16 (44) four-factor four-level orthogonal test analysis table is selected to carry out orthogonal tests on granite and sandstone respectively. The results of range analysis and variance analysis show that the main and secondary relationships of abrasive water jet factors are as follows: transverse velocity > jet pressure > jet inclination > target distance. The optimal jet parameters are when jet pressure is 40 MPa, target distance is 5mm, transverse velocity is 2mm/s and jet inclination is 10°.

Silicon–carbon superhydrophobic nano-structure for next generation semiconductor industry

Abstract Superhydrophobic surfaces are important in waterproof applications that withstand harsh chemical exposure, ultraviolet radiation, and heat. Surface energy modification of the surface, such as silanization or (fluoro)polymer coatings, increases the hydrophobicity of the nanostructure. The present study follows a bilayer architecture that turns hydrophilic silicon into a superhydrophobic one. The first step creates a unique silicon–graphene hybrid structure on the silicon surface by coating graphene on the P-type silicon substrate. In the second step, low surface energy material (a combination of hexadecyltrimethoxysilane and hexamethyldisilazane) is coated by the dip coating process. This study investigates the durability of superhydrophobicity under severe mechanical, thermal, and chemical conditions. High-temperature tolerance and water jet tests are also performed. The present work also involves the study of coating regeneration. This approach can be applied to all shapes and sizes of silicon–graphene surfaces and is proven to be excellent in the semiconductor industry.

A comprehensive investigation of uncertainties in cavitating waterjet experiments

This paper systematically examines the sources of uncertainty in cavitating waterjet test setups and provides illustrative case studies to conduct thorough uncertainty analyses for erosion tests using cavitating waterjet method. Within this study, utilizing examples of uncertainty analysis presented by the International Towing Tank Conference (ITTC) for various testing techniques, a novel uncertainty analysis implementation suitable for cavitating waterjet tests has been conducted. Firstly, cavitation erosion experiments were carried out on samples aluminum (Al 6063) material under cavitation number conditions (σ = 0.02 to σ = 0.033 range) as part of the validation study. Subsequently, within the scope of uncertainty analysis calculations, five erosion tests were conducted for each of the two different cavitation numbers (σ = 0.03 and σ = 0.05). The study aims to examine the bias and precision uncertainty components separately for the test results of erosion rate and establish a reliable and repeatable procedure for predicting the uncertainty level of cavitating waterjet tests. For the first time in the literature, the uncertainty components of cavitating waterjet tests were investigated in detail and the uncertainty level in cavitating waterjet tests, including bias and precision errors, was predicted in accordance with specific ITTC guidelines and procedures. Based on the results, the primary bias error source was identified as the pressure inside the cavitation chamber, with the nozzle pressure being the second most significant bias error source. Consequently, it is recommended to perform the bias error prediction based on the ratio of these two, known as the cavitation number. Precision error, crucial for uncertainty, was estimated using five sets of erosion rate values, emphasizing its importance in cavitating waterjet tests. It is anticipated that the suggested methodology will serve as a benchmark for predicting uncertainty levels in cavitating waterjet tests.

A systematic study into the cavitation erosion test for marine propeller materials by cavitating jet technique

This paper presents an experimental investigation of cavitation erosion on widely used marine propeller materials by the cavitating jet technique as an alternative to cavitation tunnel tests, following the American Society for Testing and Materials (ASTM) standards. The cavitation erosion tests on aluminium samples were, initially, conducted to investigate the effect of stand-off distance and to compare the results with the available data in the literature. The comparative study confirmed that the erosion on the materials has practically the same pattern even if the nozzle diameter and sample size are different for the same cavitation number and at the optimum stand-off distance condition. Following this validation, the samples made of copper-based alloy marine propeller materials, specifically Cu1, Cu3, and Cu4, were tested for the first time in the literature to assess their erosion resistance at various cavitation numbers and test durations by considering various characteristics, such as erosion area, rate and intensity through comprehensive examinations. Among the materials examined, the Cu1, which has the lowest mechanical strength, was found to be the most susceptible to cavitation erosion. Interestingly, despite the Cu4 having the highest mechanical strength, the Cu3 demonstrated better erosion resistance, suggesting that the nickel and copper contents play a crucial role in the material's resistance to erosion. In order to evaluate and assess the cavitation effect more accurately the erosion damage on the material should be examined not only on the surface, but also in the depth. Based on the findings of this study, the cavitating jet technique may be a good alternative to investigate the cavitation erosion characteristics of propeller materials, if a relationship or scaling law between the water jet test technique and full-scale propeller loading, surface conditions, turbulence intensity, and bubble dynamics in operation can be established.

Effect of Special-Shaped Nozzle Structure on Water Jet Performance

The impact force and effective impact area of are water jet are two important indexes for evaluating jet performance, and the outlet shape of the nozzle has a great influence on jet performance. In this study, five nozzles with different outlet shapes were designed, and water jet test experiments were conducted at different inlet pressures using an independently built water jet impact test platform, and the influence law of nozzle shape on the center impact pressure and flow coefficient of the water jet was investigated. The influence of nozzle shape on the effective impact area and entrainment rate of water jet was further investigated by numerical simulation. The results showed that the center impact pressure of the circular nozzle was the greatest when the inlet pressure and the target distance were small. The center impact pressure, the flow coefficient, and the effective area of the triangular nozzle with sharp edges were better than the traditional circular nozzle when the inlet pressure and the target distance were increased. Although the center impact pressure of the square nozzle is lower than that of the circular nozzle, its flow coefficient and effective impact area are higher than those of the circular nozzle with increasing target distance. The water jets of the elliptical and cross nozzles were the most divergent, and the jet performance was poor.

A comparative study of mechanical and chemical durability of non-wetting superhydrophobic and lubricant-infused surfaces

Fabrication of bioinspired non-wetting superhydrophobic surfaces (SHS) and lubricant-infused surfaces (LIS) has been studied extensively on a variety of materials. In contrast, durability of the surfaces exposed to harsh mechanical and chemical environments has been the subject of little attention. This study considers the mechanical and chemical durability of SHS and LIS copper surfaces fabricated via facile electrodeposition and chemical etching methods. The as-fabricated surfaces demonstrate excellent non-wetting characteristics with water contact angle of 160° and sliding angle below 5°. The surfaces are subject to mechanical wear through scratch test and water jet impingement at 15 psi and 20 psi as well as accelerated corrosion following the ASTM-E407 standard. The performance of the electrodeposited and etched non-wetting surfaces is systematically assessed in terms of contact and sliding angles and corrosion rate in a simulated marine environment. All surfaces are shown to be robust to mechanical wear after scratch test, with excellent stability of contact and sliding angles, and up to two orders of magnitude reduced corrosion rate compared to bare copper surface. SHS retained steadfast non-wetting characteristics under high-pressure water jet tests compared to the other surfaces while LIS, regardless of texturing method, showed one to two orders of magnitude reduced corrosion rate compared to bare copper surface throughout water jet impingement and chemical durability tests. The study presents for the first time a systematic comparison of durability of SHS and LIS through a common set of fabrication and testing protocol and helps identify appropriate non-wetting surfaces and fabrication methods based on the use environment.

Fabrication of Superhydrophobic Aluminum Surfaces Using Modified Nanoparticles and Ionizable Surfactants

In this study, plates of aluminum are made superhydrophobic via wet etching followed by deposition of nanostructure and microstructure. Etched surfaces are coated with modified nanoalumina using an ionizable surfactant. Key parameters governing the hydrophobicity such as type of the etching solvent, type of the surfactant, etching time, nanoparticle size distribution, surfactant concentration and annealing temperature are investigated. Infrared spectroscopy (IR), dynamic light scattering (DLS), scanning electron microscopy (SEM) and water contact angle (WCA) measurements are used to characterize the treated surfaces. A WCA greater than 150∘ is obtained and in order to estimate the efficiency and mechanical durability of the coatings the samples are tested in emulated sea-water. Water jet tests prove the mechanical stability of the samples. Our fabrication method results in good hydrophobicity and self-cleaning behavior of the Al surface and the obtained results may be useful for industrial applications.

Effects of Hook, Interceptor, and Water Jets on LCS Resistance/Power, Sinkage, and Trim

Verification and validation of computational fluid dynamic simulations are performed at model and full scales for the high-speed littoral combat ship (LCS) surface combatant, including the effects of hook, interceptors, and water-jet propulsion. Predictions of the body force thrust, sinkage, and trim use a speed controller for attaining self-propulsion. Two methods for water-jet performance are used: 1) evaluation of forces based on integration of the stress over the wetted area of the hull and water-jet duct, pump casing, and nozzle (integral method) and 2) ITTC (2005) water-jet test procedure (control volume method). The comparison errors at model (resistance, sinkage, and trim) and full (power and trim) scales are satisfactory using both Froude (Fr) scaled model- and full-scale trial data, including the effects of the interceptors and water jets (WJ) on resistance/power, sinkage, and trim. For the model-scale model without WJs, the negative bottom hydrodynamic pressure near the water-jet inlets are observed without and with the hook simulations, and experiments with the hook. The negative bottom vertical force near the water-jet inlets for the simulations without the hook supports Savitsky’s (2014) assertion that semi-displacement monohulls do not exhibit hydrodynamic lift and disproves Giles’ (1992) assertion to the contrary. The hook and interceptors do not affect the pressure distribution significantly near the water-jet inlets. For the full scale model, the WJs induce bow up trim for the simulations and interpolated (between conditions)- and Fr scaled model-scale experiments. The negative bottom pressure and vertical force near the water-jet inlet for the simulations disprove Giles’ (1992) assertion that the WJs provide additional hydrodynamic lift. This is further supported by the comparisons of the vertical force % thrust vs. inlet velocity ratio for the LCS, with results shown in Bulten (2005) for a high-speed motor yacht. Bulten (2005) shows positive vertical force for inlet velocity ratios ≥ 1.25. However, LCS operates in the regime of an inlet velocity ≤ 1.2; thus, consistent with Bulten (2005), the vertical force is negative. The nonlinear effects between the interceptors and WJs are small such that a linear combination can provide a reasonable approximation.

Water-Jet Erosion of Grade-A Ship Steel: Experimental Research

A water-jet erosion test was carried out on grade-A ship steel to study the interaction and erosion mechanism of the water jet on the steel surface. When the water jet impacted, a STSS-1 stress-detection module was used to collect the dynamic strain signal on the rear of the ship’s plate, and a scanning electron microscope, transmission electron microscope, X-ray diffractometer, and other equipment were used to analyze the microstructure and phase of the grade-A ship steel before impact. The surface morphology of the material after impact was studied and analyzed. The impact stress of the water jet on the grade-A steel was an alternating stress, and the jet pressure decayed in the radial direction. The material surface was fatigued under the action of the jet alternating stress. After the water-jet erosion, the central area of the grade-A steel was dominated by an elongated cementite hard phase, and the peripheral area had a pearlite structure. A model for the jet erosion and peeling of grade-A ship steel was established to clarify the mechanism of erosion by the water jet.

Fabrication of durable corrosion-resistant polyurethane/SiO2 nanoparticle composite coating on aluminium

In this work, SiO2 nanoparticle–embedded polyurethane superhydrophobic coating on aluminium substrate was fabricated using spin coating technique. By embedding SiO2 nanoparticles into the polyurethane matrix, superhydrophobicity is successfully achieved with water static contact angle of 156 ± 3° and tilt angle of 6 ± 1°. Coating exhibits excellent self-cleaning and antifouling properties. Wetting stability of coating was further evaluated by performing water jet, bending, sand falling, tape peeling, floating, annealing, and chemical stability tests. It is found that coating is mechanically, thermally, and chemically stable. Water droplet impact test shows the bouncing, pinning, and splashing behaviour of water droplets at different impact velocities. The electrochemical experiment has demonstrated that the corrosion potential of aluminium after coating increases and the corrosion current density decreases, revealing the corrosion resistance property of coating. We envision that the self-cleaning, antifouling, and anticorrosive superhydrophobic coating of the polyurethane/SiO2 nanoparticle composite can effectively prevent the corrosion of aluminium and the aforesaid coating has great industrial applications.

Experimental and numerical studies of boat waterjets with increased seakeeping performance

Object and purpose of research. The object of the research is a fundamentally new waterjet, intended for installation on ships of increased seakeeping performance with discrete-variable bottom deadrise. The purpose of the research is to develop and test three waterjet designs that can be installed on vessels with large deadrise, operating in severe weather conditions.
 Materials and methods. Experimental data of waterjet tests as a part of self-propelled models obtained in deep-water and cavitation test tanks of KSRC. Numerical simulation of the flow in water conduits of full-scale vessel taking into account the waterjet performance.
 Main results. As a result of the performed experimental and computational studies, the characteristics of three waterjet designs with partial-pressure water inlets were obtained: two waterjets with isolated single-elbow water ducts and inlets on the bottom section with medium deadrise, "II"design; two waterjets with combined water duct and inlets on the bottom section with maximum deadrise and double jet, “X” design; single waterjet with bifurcating two-elbow water duct and a pair of water inlets on the bottom section with maximum deadrise, “Y” design.
 Conclusion. The studies have shown that all the developed innovative waterjet designs are practically equal to conventional ones (or even better than them), and air suction creates a smooth, rather than a sharp force decrease on the impeller. The preference is given to a high-pressure water inlet with a bifurcated water inlet and a combined water conduit, because in intense waves, even if one of the inlets is aerated, the vessel will not abruptly lose speed or run off the course.

Experimental Study on Blasting Energy Distribution and Utilization Efficiency Using Water Jet Test

The blasting stress wave and blasting gas generated by explosive blasting are the two main motive powers of rock fragmentation. An experimental method based on water jet test is used to study the energy distribution ratio of blasting stress wave and blasting gas; the utilization efficiency of blasting energy under different borehole constraint conditions is also analyzed. It proves that the blasting stress wave does not cause the water jet, and the blasting gas is the only power of the water column jet. The results show that the energy of the blasting gas and blasting stress wave respectively account for about 64% and 36% of the total energy generated by the explosion of lead azide. The utilization efficiency of the blasting gas energy under strong, medium, and weak constraint conditions is 100%, 80%, and 52%, respectively. The borehole constraint condition is crucial for the effective utilization of blasting energy.

Superhydrophobic PVC/SiO2 Coating for Self‐Cleaning Application

AbstractA lotus leaf like self‐cleaning superhydrophobic coating has high demand in industrial applications. Such coatings are prepared by alternative dip and spray deposition techniques. A layer of polyvinyl chloride is applied on glass substrate by dip coating and then spray coated a suspension of hydrophobic silica nanoparticles at substrate temperature of 50 °C. This coating procedure is repeated for three times to achieve rough surface morphology which exhibits a water contact angle of 169 ± 2° and sliding angle of 6°. The superhydrophobic state of the coating is still preserved when water volume of 1.2 L is used to impact the water drops on coating surface. The stability of the wetting state of the coating is analyzed against the water jet, adhesive tape and sandpaper abrasion tests. The prepared superhydrophobic coating strongly repelled the muddy water suggesting its importance in self‐cleaning applications.

Experimental Research on Water Droplet Erosion Resistance Characteristics of Turbine Blade Substrate and Strengthened Layers Materials.

In this paper, the water droplet erosion (WDE) performance of typical martensitic precipitation substrate 0Cr17Ni4Cu4Nb in steam turbine final stage, laser solid solution strengthened sample, laser cladding sample and brazed stellite alloy samples have been studied based on a high-speed rotating waterjet test system. The WDE resistance of several materials from strong to weak is in sequence: Brazed stellite alloy > laser cladding sample > laser solid solution sample > martensitic substrate. Furthermore, the WDE resistance mechanism and the failure mode of brazed stellite alloy have been revealed. It is found that the hard carbide in the stellite alloy is the starting point of crack formation and propagation. Under the continuous droplet impact, cracks grow and connect into networks, resulting in the removal of carbide precipitates and WDE damage. It is proved that the properties of the Co-based material itself is the reason for its excellent WDE resistance. And the carbides have almost no positive contribution to its anti-erodibility. These new findings are of great significance to process methods and parameter selection of steam turbine blade materials and surface strengthened layers.

Experimental investigation on effect of surface strengthening process and roughness on water droplet erosion behavior in turbomachinery

In this paper, the water droplet erosion (WDE) performance of a typical martensitic blade material 17-4 PH (0Cr17Ni4Cu4Nb), surface strengthened laser cladding stellite and brazed stellite alloy is studied based on high-speed water jet test system. The WDE resistances from high to low are the brazed stellite alloy, laser cladding stellite alloy and 17-4 PH. For the same material, the greater the initial roughness of the target surface, the more severe is the WDE damage. Improving the surface finish of the target is conducive to the diversion and expansion of the liquid flow, prolonging the incubation period, and thus enhancing the WDE resistance.

Effect of Laser Processing on the Qualitative Parameters of Protective Abrasion-Resistant Coatings

The wear of centrifuge screws, common components in industrial and municipal wastewater treatment plants, is studied. The TN-20 tungsten-free hardmetal serves for protecting screw flights against abrasive wear. The 12Kh18N10T steel is primarily used in the manufacture of centrifuge screws. A combined technique of depositing protective wear-resistant coatings is proposed. The technique includes electrospark deposition of a T15K6 hardmetal electrode, application of a metal polymer material (MPM), and final laser processing. To reinforce the MPM, small portions of a VK6 hardmetal mixture were added to a two-component epoxy system filled with ferrosilicon and thoroughly stirred. The reinforcement content was ~60%. This technique produces coatings up to 600 μm thick, with 7.3–10.0 GPa microhardness and 100% continuity. Abrasive water jet tests of the 12Kh18N10T steel samples with protective coatings show that their wear resistance is 7.5 times higher than that of the uncoated samples.

Robust transferrable superhydrophobic surfaces

ABSTRACTIn this study, we present a simple and inexpensive method for enhancing the robustness of aluminium-based superhydrophobic surfaces and identify a method for reliably evaluating the degradation of such surfaces. A superhydrophobic aluminium surface was prepared by a chemical etching and hydrophobic coating. Hydrophobized aluminium particles on the surface were then transferred to adhesive strips. Scanning electron microscopy and contact angle measurements were conducted before and after water-jet and mechanical abrasion tests to evaluate the robustness of the superhydrophobic surfaces. Following the tests, the advancing contact angle remained unchanged while the receding contact angle depended on the adhesive strength of the surface. The receding contact angle on the superhydrophobic adhesive strip was found to decrease at a reduced rate, as compared to the original superhydrophobic aluminium surface. The receding contact angle was also measured to increase with the adhesive strength of the strips, demonstrating better overall superhydrophobic performance.

Highly Reliable Superhydrophobic Surface with Carbon Nanotubes Immobilized on a PDMS/Adhesive Multilayer.

We propose a new superhydrophobic surface that contains a carbon nanotube (CNT)-implanted poly(dimethylsiloxane) (PDMS)/adhesive multilayer. The adhesive provides very strong adhesion between the CNT-implanted PDMS layer and the substrate, and the CNTs on the surface exhibit superhydrophobicity. Therefore, the CNT-implanted PDMS/adhesive (CIPA) layer provides a highly reliable surface for superhydrophobicity. The fabricated CIPA surface performs far better than previously reported surfaces in terms of stability tests, such as contamination and solvent tests, and physical contact, including thermal pressure, bending, adhesion, and water jet tests. If a portion of the CIPA surface is destroyed, the surface is immediately restored because the material can regenerate the surface to its initial state. The surface can therefore maintain its superhydrophobicity even when damaged in rough environments, without self-healing or additional repair. Furthermore, because the adhesive is sprayed and coated on the surface of the substrate, a CIPA surface can be formed on three-dimensional shapes, including curved surfaces, and on various substrates.

Fiber optic distributed sensing technology for real-time monitoring water jet tests: Implications for wellbore integrity diagnostics

Distributed fiber optic sensing (DFOS), a rapidly evolving fiber-optic based technology for permanent well-based and geophysical monitoring for CO2 geological storage (CGS) has attracted more attentions to investigate in multiple scales. In this study, two field trial wells were drilled, one well with 300 m depth in Mobara and the other well with 880 m in Ichihara, Japan and DFOS cables were deployed behind well casings. High-pressure water jet tests are performed at constant location of 127 m depth and at changeable jet locations with 1.33 m/min and 0.51 m/min pulling speeds in the 300 m well. Then, this DFOS system was utilized to monitor the water jet along the entire length of the 880 m well with 1.2 m/min descending speed. The temperature profiles induced by water jet could be real-time monitored and analyzed the cementing quality to further evaluate the wellbore integrity. The results show that the temperature abnormal zones have a good reverence with poor cementing in the two wells, which compared well with geophysical well logging data. Therefore, permanently installed DFOS wells will enable an efficient and simpler tool to diagnose the wellbore integrity for the CGS monitoring projects via the field water jet tests.

Cavitation bubbles dynamics and cavitation erosion in water jet

Abstract A water jet test rig is used to the cavitation test of the brass samples. The single crater and the pits-group, are found on the specimen surfaces after 15 h test. A water jet cavitation model with the sound interaction among bubbles, is developed by applying a water pressure of water jet flow fields into the Keller-Miksis equation, so as to obtain the dynamic characteristics of the bubbles. The theorical results reveal that, the volume concentration of the bubbles has an slight influence in the excursion time of bubble in water jet test; while a higher water jet velocity or a higher pressure difference between nozzle entrance and exit can lengthen the bubble expansion and compression time. The results also show that, the cavitation erosion pits can form on the specimen surface at stage II, while cannot form at stage I and stage III, which are well verified by the present theoretical model as well as the available experiment results.