Jet Technology Research Articles

Roughness surface analysis of samples produced by the additive manufacturing process

The above research consists of a comprehensive analysis of the roughness of samples produced by metal-based additive processes in the engineering and automotive industries. The experimental part consists of a comparison of three manufacturing technologies that work based on the additive process. The SLM technology consists of layering the material in the form of a powder that is selectively melted by a laser. The ADAM technology consists of layering of a metal-metal weave filament followed by sintering in a vacuum. The last fabrication technology, Binder Jetting (BJ), uses a material in powder form, which consists of layering successive layers followed by post-processing. The research is concerned with the analysis and comparison of quality parameters in manufactured samples by each technology, with an emphasis on roughness. Experimental results confirm the significant advantages of Binder Jetting technology. This technology is advantageous due to several parameters, such as production volume, speed of parts production, and overall quality of the produced parts.

Thermo-fluid dynamics modelling of conformal cooling channels produced with material jetting technology

Thermo-fluid dynamics modelling of conformal cooling channels produced with material jetting technology

POLİESTER MONOFİLAMENTTEN ÜRETİLMİŞ BİYOMEDİKAL TEKSTİL İÇİN YÜZEY İŞLEMİ

Foreign Body Reaction is a critical issue to be addressed when polyethylene terephthalate textile implants are considered in the medical field to treat pathologies involving hernia repair, or heart valve replacement. The natural porosity of textile materials tends to induce exaggerated tissue ingrowth which may prevent the implants from remaining flexible. One hypothesized way to limit the Foreign Body Reaction process is to increase the material surface roughness. Supercritical jet particle projection is a technique that provides enough velocity to particles in order to generate plastic deformation on the impacted surface. The aim of this study is to investigate the influence of micro particles laden supercritical nitrogen jet projection parameters like jet static pressure, standoff distance and particle size on the roughness of polyethylene terephthalate fabric surfaces. Results bring out that particles projected by supercritical nitrogen jet generate craters on the surface of monofilament as well as monofilament fabric, allowing topographical modifications at the yarn scale. Thus, this treatment increased the roughness of the monofilament fabric from 0.78 μm to 1.22 μm. Regarding the strength of the textile material, it is only slightly modified with the treatment process, as the tenacity of the yarns decreases by only 10%. In this work, it is revealed that the obtained structures tend to limit the adhesion and slow down the proliferation of human fibroblasts. The results obtained in this work show that it is possible to create a roughness on a polyethylene terephthalate fabric using the nitrogen jet technology.

Numerical investigation of flow resistance in cone-straight nozzle

High-pressure water jet technology is applied to wellbore cleaning, descaling, auxiliary rock breaking, slit penetration, etc. In petroleum engineering. The cone-straight nozzle structure is widely used in the petroleum industry, and its internal flow resistance remains unclear, which plays an important role in nozzle geometry optimization and is the main research content in this paper. Large Eddy Simulations were used to simulate the near-wall flow field at a relatively low Reynolds number, the flow resistance is analyzed based on the numerical calculation data, and the following conclusions are drawn: The friction resistance is mainly distributed at the end of the converging section and the throat section, and there is a peak value, and the viscous force is mainly distributed in the converging section; the streamline structure can effectively reduce the skin friction resistance, and has little effect on the viscous force, which is more sensitive to the length of the nozzle; the streamline structure can change the trend of the total pressure in the nozzle, but has little effect on the kinetic energy conversion efficiency of the entire nozzle; increasing the fluid viscosity significantly increases the flow resistance in the nozzle. The purpose is to reveal the flow resistance inside the nozzle, investigate the factors affecting the flow resistance and provide theoretical support for the optimization of the nozzle structure.

Study on the Erosion Morphology of Cohesive Soil under the Vertical Impact of a High-Pressure Moving Water Jet

In the in situ leaching process of ionic rare earth ore, high-pressure moving water jet technology has been applied to improve floor leakage problems. However, it has been found that the morphology of the erosion surface formed by a moving water jet cannot be accurately predicted. The range of the erosion surface has an important influence on the stability of liquid collection engineering and the liquid collection rate of rare earth resources, which is an important basis for the design of liquid collection engineering. To study this, soil-breaking tests using high-pressure moving water jets for a Pingnan mine were conducted. The influences of jet pressure and nozzle moving speed on soil-breaking morphology were analysed. The mechanism of erosion surface formation was revealed by erosion theory, and a method of predicting the erosion surface geometry based on jet pressure and nozzle speed is proposed. The results show that, in the jet pressure range of 5~10 MPa, with increases in jet pressure and decreases in nozzle speed, the geometric shape of the erosion surface tends to expand, and these parameters have no effect on the morphological characteristics of the erosion surface. In the soil-breaking process, the erosion speed decreases with increases in jet distance. As the nozzle speed becomes greater, the degree of the attenuation of erosion speed at a given jet pressure also becomes greater. Soil-breaking depth has a quadratic relationship with jet pressure and a 0.5 power function relationship with nozzle speed. The geometry of the erosion surface has self-similarity and can be divided into straight and curved sections. Accordingly, an empirical formula of the erosion surface geometric shape is proposed. The error of predicting the soil-breaking depth is less than 11%, which can provide a reference for engineering applications.

Aerodynamic shape optimization of co-flow jet airfoil using a multi-island genetic algorithm

The co-flow jet is a zero-net-mass-flux active flow control strategy and presents great potential to improve the aerodynamic efficiency of future fuel-efficient aircrafts. The present work is to integrate the co-flow jet technology into aerodynamic shape optimization to further realize the potential of co-flow-jet technology and improve co-flow jet airfoil performance. The optimization results show that the maximum energy efficiency ratio of lift augmentation and drag reduction increased by 203.53% (α = 0°) and 10.25% (α = 10°) at the Power-1 condition (power coefficient of 0.3), respectively. A larger curvature is observed near the leading edge of the optimized aerodynamic shape, which leads to the early onset of flow separation and improves energy transfer efficiency from the jet to the free stream. In addition, the higher mid-chord of the optimized airfoil is characterized by accelerating the flow in the middle of the airfoil, increasing the strength of the negative pressure zone, thus improving the stall margin and enhancing the co-flow jet circulation.

MEMPERKUAT KINERJA KARYAWAN DENGAN MEREDUKSI FAKTOR STRES DAN MEMBANGUN LINGKUNGAN KERJA YANG NYAMAN

This study aims to determine and analyze the effect of work stress and physical work environment on employee performance at PT. Jet Technology Express (J&T Express) Ciledug Tangerang Drop Center Branch, either partially or simultaneously. The method used is descriptive quantitative. The sampling technique used saturated sampling where the entire population was used as a sample, in this study there were 55 respondents. Data analysis used validity test, reliability test, classic assumption test, regression analysis, coefficient of determination analysis, and hypothesis testing. The results showed that there was a positive influence between work stress and employee performance partially. Where is the simple linear regression equation Y = 16.243 + 0.678 X1 means that it has a positive effect, the reliability test r = 0.948 is included in the strong category, the coefficient of determination is 48.9% and the remaining 51.1% is influenced by other factors, the t test is tcount 7.115 > ttable 2.00665 then Ha is accepted and Ho is rejected. The results showed that there was a positive influence between the physical work environment and employee performance partially. Where is the simple linear regression equation Y = 31.298 + 0.328 X2 means that it has a positive effect, the reliability test r = 0.881 is included in the strong category, the coefficient of determination is 20.6% and the remaining 80.4% is influenced by other factors, the t test is tcount 3.706 > ttable 2.00665 then Ha is accepted and Ho is rejected. The results showed that there was a positive influence between the variables of work stress and the physical work environment on employee performance simultaneously, where the multiple regression equation Y = 15.932 + 0.805X1 +0.125X2 means a positive effect, the reliability test r = 0.956 is included in the strong category, the coefficient of determination of 50.1% and the remaining 49.9% which is influenced by other factors, the f test of fcount 26.134 > ftable 3.172 means that it can be concluded that the variables of work stress and physical work environment have a significant effect on employee performance.Keywords: Work Stress, Physical Work Environment, Employee Performance

Machine Learning Method to Predict Solid Propellant Breakage Efficiency of Cavitation Water Jet

AbstractAs the number of obsolete solid rocket engines increases, determining methods to disassemble and reuse these engines has garnered increasing attention. The separation of solid propellants from the engine shell in an effective and safe way has important research significance. In this study, cavitation water jet technology was employed to extract solid propellant from the engine shell owing to its high breakage efficiency with low working pressure. The effects of the target distance and incident pressure on the breakage efficiency of solid propellants were investigated based on a cavitation water jet experimental system that we designed. A nonlinear relationship between the breakage efficiency and both the target distance and incident pressure was discovered, and the mechanism of solid propellant breakage by a cavitation water jet was proposed. To reduce the cost and time associated with the experiments, a machine learning approach was designed to predict the failure efficiency. Back propagation neural networks, support vector regression, genetic programming, and Gaussian process regression were adopted to construct the models. The results demonstrate that the back propagation neural network achieved the highest accuracy with a value of 0.974, followed by support vector regression with an accuracy value of 0.914 for predicting the mass loss rate. Therefore, machine learning technology is an effective tool for predicting the solid propellant breakage efficiency impacted by cavitation water jets.

IMPROVING ENERGY PARAMETERS OF OIL JET PUMPS

The difficulty of extracting oil from great depths due to the huge amounts of sand, water and other impurities has led to the fact that well jet oil pumps are becoming more common. Their use in oil production is facilitated by such factors as practical insensitivity to the content of gas and other impurities dissolved in oil compared to other types of pumps; simplicity of design and the absence of moving parts, which is inherent in all jet technology. The reliability and durability of jet pumps are an order of magnitude higher than those of any other pumps used in oil and gas production. Obtaining excellent characteristics of a jet oil pump requires a systematic approach to the analysis of characteristics and modeling of the pump flow. Pumping oil is a complex task because there is a fairly large variety of oil and substances that can be included in it in various fields. This leads to problems when modeling pump operation and using more complex fluid flow models from rheological models to modeling cavitation. The complication of mathematical models of the flow provokes an increase in modeling errors, complications of flow verification and finding rational coefficients and corrections to turbulence models. In the paper, the energy parameters of oil jet pumps are improved by calculation. A jet pump for pumping oil has been designed and numerical calculations have been carried out with different models of turbulence and aggregate states of media. The kinematic characteristics of the flow are obtained and the efficiency of the pump is calculated. As a result of the calculation of the model with cavitation, it was obtained that the pump efficiency is 10 %, which is 3 times higher than the calculation result without cavitation. The increased efficiency is consistent with asymptotic methods for calculating pump characteristics.

KINEMATIC PARAMETERS OF THE OIL FLOW IN A VORTEX CHAMBER PUMP

The difficult operating conditions of oil pumps require high levels of reliability, durability and efficiency from hydraulic machines. The gas dissolved in oil leads to the appearance of regions with variable density in the pumps flow parts and to a breakdown in performance. The use of jet pumps is limited due to low efficiency. Therefore, the operation of new vortex chamber pumps for oil production and transportation is quite promising due to the increase in pumping efficiency indicators using the advantages of centrifugal and jet technology in these pumps. On the other hand, to date, no studies have been carried out on the behavior of vortex chamber pumps when pumping oil. In this paper, based on the numerical calculation of the oil flow in a vortex chamber pump, the kinematic parameters of the flow are obtained with and without the dissolved gas in the oil. The calculation was made on the basis of solving the Reynolds equations, continuity and Rayleigh-Plesset equations in the Ansys CFX software package. For the first time for the vortex chamber pump when pumping oil, the distributions of the oil velocity and dissolved gas, the distributions of volumetric and mass concentrations, and the graphs of velocity distributions in various horizontal planes of the vortex chamber were obtained, which makes it possible to take into account the kinematic flow parameters in the vortex chamber for further optimal design. For the first time, on the basis of numerical calculations, the possibility of using vortex chamber pumps for pumping oil has been confirmed. At the same time, the efficiency is approximately 15%, which is almost twice the efficiency of direct-flow jet pumps used for this purpose. The choice of the model, according to which the calculation is carried out by numerical methods, has a significant impact on the accuracy of calculating the integral characteristics of the vortex chamber pump operation.

Study on Water Jet Characteristics of Square Nozzle Based on CFD and Particle Image Velocimetry

Water jet technology is widely used in various fields, in which the nozzle is an important element to form the jet. To solve the problem of low water jet operation efficiency of square nozzles, the internal flow channel structure of the nozzle of the key jet device is studied. Through the combination of computational fluid dynamics (CFD) and particle image velocimetry (PIV) experiments, the influence of main structural parameters such as the contraction angle and length-to-diameter ratio of the inner flow channel on the velocity and length of the constant-velocity core region is explored. Since the jet flow structure is a symmetrical structure along the axial direction, the model of the jet flow structure was built half of the model along the axial direction. The results show that a smaller length-to-diameter ratio and a smaller contraction angle of the nozzle result in better jet cohesion and lower dynamic pressure in the constant-velocity core area, which is more suitable for long-distance, low-pressure water jet operations.

Influence of binder jet 3D printing process parameters from irregular feedstock powder on final properties of Al parts

• The possibility of using irregular particles of aluminum in the Binder Jet 3D printing technology has been demonstrated. • The influence of the printing parameters on the properties and quality of the final parts was determined. • Vacuum sintered parts obtained a higher density than those sintered in argon or hydrogen. • The printed parts showed a linear shrinkage of up to 2% and 43–50% of the theoretical density. • Increased porosity of the samples leads to a rougher surface. This work for the first time presents the results of optimization of printing parameters in the Binder Jetting technology in terms of the possibility of using an irregular aluminum powder which is much cheaper and more common than spheroidal. The influence of binder saturation (15–100 %), roller traverse speed (10–110 mm/ sec ), layer thickness (30–90 µm), and sintering atmosphere (vacuum, argon, hydrogen) on the quality of aluminum printed parts has been investigated. The study included the density, shrinkage, porosity, surface topography, and roughness of printed, and sintered aluminum parts. An anisotropy of linear contraction in the X, Y, and Z directions was observed, with the largest linear shrinkage occurring in the Z direction. In terms of roughness, the top surfaces (XY direction) turned out to be the smoothest and the side surfaces (YZ direction) were the roughest. Samples that were sintered under vacuum resulted in higher density, lower shrinkage, and lower porosity compared to those sintered in argon or hydrogen. On the basis of results, it was found that generally, increasing the saturation level and layer thickness causes a decrease in density and increases the shrinkage and the porosity of additive manufactured parts.

Design of an Acoustic Synthetic Jet Actuator for Flow Control

Synthetic jet technology is widely adopted in active flow control. An actuator with an oscillating diaphragm is a commonly used excitation device for synthetic jet generation. However, it has a disadvantage wherein the volume at the cross-section of the cavity varies unevenly when the diaphragm vibrates, which makes it difficult to use multiple jets corresponding to one diaphragm. In this paper, an acoustic synthetic jet actuator that can generate multiple jets with one diaphragm was designed. The diaphragm vibrated in a cylindrical cavity, transferring air to another constant-volume square cavity through pipes. The square cavity was covered with a multiple-orifice plate for the expulsion and suction of the ambient air. Through this means, the implementation of multiple jets corresponding to one diaphragm was achieved. The multiple jets are called distributed synthetic jets in this paper. Governing parameters that determined the performance of the distributed synthetic jets were given by theoretical derivation. It was found that, under specific geometry conditions, the governing parameters were mainly the frequency and voltage of the input signal to the actuator. Then, the velocity characteristics of the distributed synthetic jets were measured by using a constant-temperature anemometer and the parameter space was determined. The results showed that it was practicable to apply the acoustic actuator to turbulent boundary layer flow control.

Behaviors of the long penetration mode with a hot counterflowing jet

When an aircraft flies at hypersonic speeds, a large aerodynamic drag and a significant amount of aerodynamic heat are generated around it. As an active flow control technology, counterflowing jets can effectively reduce the drag and heat flux and have therefore attracted broad attentions. However, the oscillation problem that accompanies counterflowing jets remains to be studied further. The present study aims to investigate the oscillation properties of the flow around a hypersonic vehicle with a hot counterflowing jet using a numerical solver with a single-temperature multi-component chemical reaction model. A hypersonic hemispherical-nosed is selected and the solver is developed on the OpenFoam platform. The drag reduction efficiency, the flow field structure, and the flow instability characteristics for different jet temperatures are discussed in detail. It is found that a high-temperature jet can reduce the amplitude of the drag force significantly and even suppress the flow oscillation, and the drag reduction efficiency per unit mass increases with the jet temperature. For the same efficiency, a high-temperature jet has a smaller mass flow rate which may reduce the load of flight and lead to savings in space and cost. Therefore, within the allowable range of heat flux, increasing the jet temperature might be a more effective method for reducing drag and stabilizing the flow field than increasing the jet pressure ratio as usually thought. It is hoped that the present results serve to advance the application and the development of hypersonic counterflowing jet technology.

Micro-nano twins appearing in ultrafine-grained Ti–6Al–4 V alloy induced by high-pressure water jet technology

In this study, the surface of an ultrafine-grained Ti–6Al–4 V alloy was treated with high-pressure water jet technology (HPWJT). Then, the microstructure of the alloy was investigated using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). Three obviously different microstructural characteristics were observed from the treated surface to the matrix: ultrafine equiaxed grains with diameters from hundreds of nanometers to a few micrometers, micro-nano twins inside ultrafine equiaxed α grains, and an initial undeformed microstructure with ultrafine equiaxed grains. Formation of micro-nano twins in the subsurface was related to the special misorientation angle of neighboring grains. We proved the dependence of twinning on the crystallographic orientation and grain size of the α phase. In addition, the quantitative contributions of the micro-nano twins to the surface hardness of the alloy were calculated; micro-nano twins significantly improved the surface hardness of the alloy. This study provides a new easy method for introducing micro-nano twins on the surfaces of Ti and its alloys, and it may further improve the mechanical properties of these alloys.

Identifying the processes and characterizing the pressure zone of water jet impacting on solid surface

The difficulty in understanding the flow characteristics of water jets impacting on solid surfaces made the water jet technology requiring further investigations. The Arbitrary Lagrange-Euler (ALE) method is used to develop a numerical model of the water jet impacting on a solid surface. It is also utilized in describing the flow characteristics of water and the pressure evolution in water during the impact process, understanding the formation mechanism of the pressure zone, and clarifying the influence factors of the stagnation pressure zone. The results showed that the pressure zone was characterized by the shock wave produced by the water jet impacting the solid surface. When the shock wave was contained in the water, it was the water hammer pressure stage. However, when the shock wave in water was disappeared, the stage was identified as the stagnation pressure. Besides, the water hammer pressure caused a high speed radial jet, and the stagnation pressure resulted in a low speed and stable radial jet. The stagnation pressure zone was the self-buffer zone of the water jet impacting the object, and the geometric characteristics of this zone were affected by the water jet diameter and the impact angle.

A Highly Efficient Microwave Plasma Jet Based on Evanescent-Mode Cavity Resonator Technology

This article introduces a novel low-power and highly efficient atmospheric pressure microwave plasma jet (APPJ). Specifically, a capillary tube passing through the critical gap area of a high- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> evanescent-mode (EVA) cavity resonator provides a controlled gas flow rate to realize microwave gas breakdown and plasma jet formation even with milliwatts range input power. The theory, simulation, fabrication, and characterization of the introduced plasma jet technology are discussed. A prototype 2.45 GHz device can operate at powers as low as 400 mW with >80% power efficiency and provides up to a 6-mm-long plasma jet with electron density in the range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{15}$ </tex-math></inline-formula> cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-3}$ </tex-math></inline-formula> in a 1 to 7 slpm helium flow rate. Considering its high plasma density as well as low operating power and jet temperature, this device is a viable and safe solution for a wide range of applications, including emerging plasma medicine needs.

Optimization Design and Analysis of Bionic Friction Reducing Nozzle in Oil Shale High-Pressure Jet Mining

The borehole hydraulic mining method has unique advantages for underground oil shale exploitation. Breaking rock with a high-pressure water jet is a crucial step to ensure the smooth implementation of borehole hydraulic mining in oil shale. The hydraulic performance of the nozzle determines the efficiency and quality of high-pressure water jet technology. To obtain a superior hydraulic performance nozzle, based on the bionic non-smooth theory, a circular groove was selected as the bionic unit to design a bionic straight cone nozzle. The structural parameters of the circular groove include the groove depth, width, and slot pitch. The optimization objective was to minimize the pressure drop, where the fluid has the least resistance. A genetic algorithm was used to optimize the structural parameters of the circular grooves in the inlet and outlet sections of the bionic straight cone nozzle. The optimal structural parameters of the nozzle were as follows: the inlet diameter was 15 mm, the inlet length was 20 mm, the outlet diameter was 4 mm, the length-to-diameter ratio was 3, and the contraction angle was 30°. In addition, in the inlet section, the groove width, slot pitch, and groove depth were 3.9 mm, 5.2 mm, and 5.5 mm, respectively, and the number of circular grooves was 2. Moreover, in the outlet section, the groove width, slot pitch, and groove depth were 2.25 mm, 3 mm, and 5.5 mm, respectively, and the number of circular grooves was 2. The CFD numerical simulation results showed that under the same numerical simulation conditions, compared with the conventional straight cone nozzle, the bionic straight cone nozzle velocity increase rate could reach 13.45%. The research results can provide scientific and valuable references for borehole hydraulic mining of high-pressure water jets in oil shale drilling.

Micro injection moulding process with high-temperature resistance resin insert produced with material jetting technology: Effect of part orientation

Material jetting is an additive manufacturing technology used to produce resin parts with high accuracy and good surface finish. It is often used for visual prototypes or for rapid tooling applications to realise moulds for the standard injection moulding process because of the mechanical properties of the material. However, owing to the poor thermal properties of the resin, this technology is limited by the melting temperature of the material and the production rate. Currently, newer resins are able to withstand temperatures up to 250 °C. To enhance the potential of this technology, in this study the authors tested the performance of a mould insert for microinjection moulding application, produced with a high-temperature resin. In particular, it has been analysed how the orientation of the mould insert on the build plate significantly affects the insert resistance and surface roughness and consequently the quality of the moulded part. The results obtained open up new possibilities for testing a series of small batches and highlight new challenges to improve the process performance.

An Umbrella Review on Low-Abrasive Air Powder Water Jet Technology in Periodontitis and Peri-Implantitis Patients

This umbrella review was conducted to assess the existing literature and scientific evidence on air powder water jet technology (APWJT) in periodontal and peri-implantitis therapy. A systematic literature search for systematic reviews and meta-analyses of the last decade on the use of APWJT in periodontitis and implant patients was performed in the databases of MEDLINE/Ovid, Embase, Cochrane library and Scopus. An additional hand search on PubMed and Google Scholar was conducted. Ten articles that fit the inclusion criteria were selected after the full-text screening. Two systematic reviews, including one with a meta-analysis, investigated the use of APWJT in active periodontal therapy. The use of APWJT as an adjunct to conventional scaling and root planing (SRP) in active periodontal treatment showed improved results in the test group. Six articles, including two with a meta-analysis, reported on the use of APWJT as a stand-alone therapy or as an adjunct in supportive periodontal therapy. Similarly significant improved results were reported for the use of APWJT. Regarding the active treatment of peri-implant mucositis and peri-implantitis, four systematic reviews could not show an improved clinical outcome when APWJT was used as an adjunct to conventional treatment measures. Furthermore, one article investigated APWJT as a stand-alone therapy or as an adjunct in supportive peri-implant mucositis and peri-implantitis therapy. In systematic reviews that also investigated patient perception, APWJT was generally well-tolerated by the patient. Within the limitations of this umbrella review, it can be concluded that the use of APWJT with low-abrasive powders such as glycine, erythritol or trehalose as an adjunct in active periodontitis therapy shows similar clinical results compared to conventional SRP alone. In surgical peri-implantitis treatment, APWJT can be used adjunctively. It could be considered that the use of APWJT in supportive periodontal treatment results in a comparable clinical outcome and an enhanced patient perception, as well as a shorter clinical time.