Jet Process Research Articles

Optimizing the Ventura Nozzle for Abrasive Jet Plant

Pneumatic abrasive surface treatment is an integral part of many technological processes used for applying coatings, performing repair or doing a restoration work, etc. The operation efficiency of the pneumatic abrasive plant is characterized by several factors. The main factor is the time of surface treatment of the material. The faster the surface treatment, the higher the treatment efficiency since a large amount of compressed air and abrasive material is required for the operation of a pneumatic abrasive plant. The efficiency of the pneumatic abrasive plant is most affected by the operating nozzle, the design of which defines the characteristics of the air-abrasive mixture. The operating nozzle is designed to form a jet and increase the speed of the working flow consisting of continuous and dispersed phases. The effect on the geometric dimensions and design of the nozzle can be varied by its characteristics. The operating characteristics of the nozzle are its main parameters that define the processing time of the material surfaces, in particular the speed of the working mixture at the nozzle outlet, the mass flow rate of the dispersed and continuous phases, the reaction force of the jet, and the value of contact stresses on the processed surface caused by the jet impact. The purpose of this research is to optimize the geometry of the operating nozzle of the pneumatic abrasive plant. The implementation of the set goal is ensured by using the plan of the full factorial experiment, performing a series of numerical studies using the ANSYS software package. The obtained data are verified on a special experimental stand designed for studying the operating nozzles of the pneumatic abrasive plant. Based on the obtained research data we can give practical recommendations for the design of operating nozzles used for the abrasive jet processing of material surfaces.

Study on Explosion Welding of Titanium–Aluminum Laminated Plates with Different Explosive Charges

To explore the effect of different explosive charge height parameters on the bonding interface of titanium–aluminum multilayer composite plates during explosion welding, the smooth particle dynamics method (SPH method) was used to simulate the explosion welding of titanium–aluminum multilayer plates, reproducing the formation process of plasma jet and waveform bonding interface and obtaining the bonding surface conditions at various charge heights. Based on the simulation, experiments were conducted, and the bonding surface quality was verified through scanning electron microscopy (SEM). The elemental distribution of the binding interface was analyzed using an energy-dispersive spectrometer (EDS). The results show that the welding effect of the plate closer to the explosive is better during explosion welding. Within the weldable window, as the charge height increases, the waviness of the bonding interface transitions towards smaller and more continuous ripples, with continuous small ripples accompanied by vortex-like eddies indicating good welding conditions. When the charge height is too large, the plate may experience a brittle fracture, reducing the strength of the bonding interface. The welding effect is best when the charge height is 24 mm. Under a certain distance between the base and overlay plates, with the increase in charge height, the collision speed of the base plate also increases, increasing the pressure between the plates, causing changes in the shapes of the bonding interface ripples, and expanding the melting zone. Excessive collision speed and pressure also promote the generation of cracks, leading to a decrease in the strength of the composite material.

Distribution and mixing mechanism of a liquid jet injected in the tandem backward-facing step cavity in supersonic flow

Mixing process and flow field structures of liquid jet in high speed crossflow (Mach = 2) in the tandem backward-facing step cavity combustion chamber were investigated numerically. The Eulerian–Lagrangian method coupled with Kelvin–Helmholtz/Rayleigh–Taylor instability breakup model was employed in the simulation. Effects of the position of the backward-facing step and the length of the backward-facing step on droplet mixing in the cavity were studied. The simulation results showed good agreement with experimental data. It was revealed that in high speed crossflow, the jet atomization region can be roughly divided into three regions: the mainstream region, the cavity recirculation region, and the backward-facing step recirculation region. According to the flow mode in the cavity, the cavity recirculation region can be divided into four modes: open cavity (mode I), closed cavity (mode II), open cavity with reattachment shock wave uplift (mode III), and closed cavity with reattachment shock wave uplift (mode IV). The number of droplets entering the cavity is lower in modes I and III compared to modes II and IV, where a greater number of droplets enter the cavity.

Comprehensive modeling of a deflector jet pressure servo valve and analysis of key influences on the front stage.

The deflector jet pressure servo valve (DJPSV), a critical component of the aircraft brake servo system, requires a precise foundational model for performance analysis, optimization, and enhancement. However, the complexity of the jet process within the V-groove of the deflector plate presents challenges for accurate mathematical modeling. To address this issue, the paper takes the DJPSV as the research object, carries out detailed mathematical modeling of its components, analyzes the influencing factors of the performance of the key component-the front stage-and optimizes the design of the key factors. First, integrating FLUENT velocity field analysis, this study proposes a novel perspective to rationally simplify and parametrically model the injection process in 3D space. Subsequently, a systematic deduction of the mathematical model for DJPSV is undertaken. Employing the AMESim platform and the secondary development module AMESet, a comprehensive simulation model is constructed, facilitating the study of static-dynamic valve characteristics. Additionally, utilizing the Morris theory and an intelligent algorithm, sensitivity analysis, and structural optimization on the critical component, the pre-stage. The results reveal that the width of the receiving diverter wedge (M), the width of the V-groove outlet (b1), and the distance from the V-groove outlet to the receiving diverter wedge (h) exert the most significant influence on the differential pressure of the pre-stage, which are the key parameters affecting the output differential pressure of the pre-stage. The experiment verifies the accuracy of the simulation model, offering a vital theoretical foundation for valve development and related areas.

Investigating effects of air-cold plasma jet on enzymatic activity and nutritional quality attributes of Mangosteen (Garcinia mangostana L.) juice

This study aimed to investigate the effects of air-cold plasma jet processing on the quality of mangosteen juice using an experimental design that varied the duty cycle of the power source (30%–70%), air flow rate (1–5 L/min), and treatment time (2–10 min). Changes in pH, color, ascorbic acid (AA), anthocyanin, flavonoid, phenolic content, enzyme activities, and antioxidant activity were evaluated. The cold plasma jet treatment substantially inactivated polyphenol oxidase, reducing its activity by up to 60% across all tested conditions, while peroxidase activity exhibited varying responses. The optimal treatment conditions (60% duty cycle, 4 L/min air flow rate, and 4 min treatment time) maximized bioactive compound levels, resulting in an 87.75% increase in AA content, along with substantial increases in total anthocyanins, phenolic content, and flavonoids. Cold plasma jet improved antioxidant activity, particularly in the DPPH radical scavenging activity. No notable change in color was observed. This study highlights the effectiveness of cold plasma technology for processing mangosteen juice while preserving its essential nutritional and physical qualities. The method offers a promising nonthermal alternative for maintaining the quality of high-value processing-sensitive mangosteen juice.

Combustion characteristics of Ammonia/Air mixture ignited by flame jet with and without hydrogen injection in Pre-Chamber

Ammonia is one of the important fuels that can promote the achievement of carbon neutrality, but its combustion characteristics are not conducive to its application in engines. Injecting hydrogen in the pre-chamber to form a flame jet to ignite the ammonia/air mixture is a method to improve the combustion of ammonia. This ignition method was investigated with the constant volume combustion chamber, high-speed video camera observation and the main-chamber pressure analysis. The flame behavior and combustion characteristics were compared with those ignited by the ammonia flame jet. Hydrogen flame jet significantly enhanced the combustion of the mixture and extended the lean flammability limit. Under conditions of hydrogen injection, the pressure rise delay and combustion duration became shorter, the average heat release rate became higher, and the combustion process was more stable. The hydrogen flame jet rapidly penetrated the main-chamber and impinged on the lower surface, generating intense turbulence. As a result, the combustion pressure took less time to rise from 10% to 50% than it did to go from 50% to 90%. This was different from the situation without hydrogen injection, where time required for both was similar. The hydrogen flame jet was shuttle-shaped when touching the lower surface owing to the rapid combustion speed of hydrogen, while the ammonia flame jet was spindle-shaped with the flame kernel in the center. The combustion process of the flame jet igniting the mixture exhibited two peaks in the heat release rate, reflecting two combustion stages dominated by the flame jet and flame propagation.

The Generation Methods and Applications of Cavitating Jet by Using Bubble Collapse Energy

Cavitation is a dynamic process characterized by the formation, growth, and collapse of vapor or gas vacuoles in liquids or at the liquid–solid interface, initiated by a local pressure drop. This phenomenon releases concentrated energy through microjet impacts and shock waves, leading to a violent exchange of energy with the surrounding environment. While cavitation is often perceived as detrimental, certain aspects can be harnessed for practical applications. Relevant studies have shown that cavitating jets provide high operating efficiencies, reduce energy consumption per unit, and have the potential for waste treatment. This paper presents three types of cavitating jets: central body cavitation, oscillatory cavitation, and shear cavitation. Additionally, the formation process of a cavitating jet and the effects of various factors on jet performance are discussed. Following an in-depth examination of the cavitation phenomena, subsequent chapters explore the applications of cavitating jets in material surface enhancement, cleaning, and energy exploration. Furthermore, recommendations for future research on cavitating jets are provided. This paper provides a comprehensive literature review on cavitating jets.

Multiscale analysis of the textural atomization process of a rocket engine-assisted coaxial jet

Multiscale analysis of the textural atomization process of a rocket engine-assisted coaxial jet

Research on jet ignition phases and control parameters in an active pre-chamber optical engine under ultra-lean combustion conditions

The active pre-chamber (APC) jet ignition system is one of the primary technologies for achieving ultra-lean combustion and high thermal efficiency in engines. The impact of the jet process within the engine, as well as its control parameters, on emission pollutants (particularly soot particles) remains unclear. This study focuses on examining the effects of various low-flow injection control strategies on engine combustion and emissions by using optical experiments and numerical simulations. It also explores the impact of different ignition advance angles (ignition timings) based on a short pre-chamber mixing interval to observe ignition combustion, flame propagation, and emission characteristics under ultra-lean conditions (λ = 2.0). The main conclusions are as follows. Appropriately increasing the injection mass can enhance engine load. However, further increases in injection mass significantly raise particulate emissions, resulting in an increase in particle number by up to more than 37-fold, especially for small particles in the 5–––10 nm size range. The chemical reaction between the luminous jet flame and the bright incandescent wake jet flame, as captured by high-speed photography, effectively characterizes the various stages of jet ignition. To reduce particulate matter emissions, it is crucial to avoid the foreseeable wake jet flame caused by the enrichment of the jet mixture in the pre-chamber. The low-flow injection timing should neither be too early nor close to the ignition spark timing. The early injection causes fuel to accumulate at the top of the pre-chamber, hindering the jet flame’s propagation into the main combustion chamber. Late low-flow injection leads to fuel enrichment, resulting in uneven mixing and poor atomization and diffusion due to short mixing times. Ignition after a short mixing time interval tends to increase knocking, resulting in intense combustion and an advanced phase, which slightly reduces load and combustion stability. Regarding the heat release ratio, the total heat release from the two combustion stages in the pre-chamber should ideally account for about 5–6 % of the heat release in the main chamber.

A new optimization strategy, the influence of hollow electrode chamfers on the development of helium atmospheric pressure plasma jets

This work suggests applying chamfering treatment to the plasma generator of the empty electrode structure. Enhancing the electrodes’ physical structure can significantly improve plasma characteristics without requiring intricate control systems. Experiments have shown that changes in the electrode’s shape can lead to changes in the formation of the atmospheric pressure plasma jet. Specifically, our observations indicate that an increase in the chamfer radius leads to an increase in the ignition voltage and a greater density of reactive species inside the jet. We developed a multi-channel equivalent circuit model to describe the discharge process of a plasma jet. Then, using the mixed layer theory, we investigated the effect of the chamfer radius on the plasma jet. Our findings suggest that chamfering increases the effective discharge area, resulting in more discharge channels in the model. This leads to a higher density of reactive species. Additionally, chamfering improves the mixing of helium and air, increasing the concentration of N2 and O2. This consumes some of the avalanche electrons and raises the ignition voltages, ultimately enhancing the chemical reactivity of the plasma jet. This work provides new ideas for the optimization strategy of atmospheric pressure plasma radiation devices.

Enhanced Oxygen Evolution Reaction Performance of NiMoO4/Carbon Paper Electrocatalysts in Anion Exchange Membrane Water Electrolysis by Atmospheric-Pressure Plasma Jet Treatment.

NiMoO4 was grown on carbon paper (CP) by a hydrothermal method. A rapid and high-temperature atmospheric-pressure plasma jet (APPJ) process was used to generate more oxygen-deficient NiMoO4 on the CP surface to serve as an electrode material for the oxygen evolution reaction (OER). After 60 s of APPJ treatment, the overpotential of the electrode at 100 mA/cm2 decreased to 790 mV and that at 10 mA/cm2 decreased to 368 mV. Additionally, the charge transfer resistance decreased from 2.8 to 1.2 Ω, indicating that APPJ treatment effectively reduced the electrode overpotential and impedance. The effect of NiMoO4/CP/APPJ-60 s on the anion exchange membrane water electrolysis (AEMWE) system was also tested. At a system temperature of 70 °C and current density of 100 mA/cm2, the energy efficiency reached 95.1%, and the specific energy consumption decreased from 4.02 to 3.83 kWh/m3. These results demonstrate that the APPJ-treated NiMoO4/CP electrode can effectively enhance the OER performance in water electrolysis and improve the energy efficiency of the AEMWE system. This approach shows promise in replacing precious metal electrodes, thereby potentially reducing the cost and providing an environmentally friendly alternative.

Prediction and Analysis of Borosilicate Glass Surface Deformation Induced by Flame Jet

To address the issues of low processing efficiency, poor forming accuracy, and internal damage in glass material processing, this study proposes the use of flame jet forming. However, the mechanism of flame jet processing requires further elucidation. This research investigates the relationship between the indentation morphology on the glass surface and the inlet velocity of the flame jet. A theoretical model was established through mathematical analysis to reflect this relationship. The model’s accuracy was validated using numerical simulation methods. By comparing experimental data with theoretical model results, surface tension was incorporated, and the model was iteratively optimized using MATLAB R2024a. The final optimized model demonstrated an absolute error range of 0.009 to 0.069 mm. This study confirms the feasibility of flame jet processing and enriches the understanding of its mechanism, providing a novel, efficient, and precise method for processing glass materials.

Numerical simulation of boiling dynamics in liquid Lead-Bismuth injected with multi-rupture high-pressure water jets

Once a steam generator tube rupture (SGTR) accident occurs in a lead-based fast reactor, it can trigger a domino effect of heat transfer tube ruptures, leading to a loss-of-flow accident involving multiple ruptures. This paper employs numerical methods to investigate the jet boiling phenomenon associated with the injection of sub-cooled water into high-temperature lead‑bismuth eutectic (LBE) through multiple nozzles. It explores how nozzle spacing, number, and diameter impact jet characteristics. Additionally, it analyzes flow characteristics and heat transfer mechanisms from the perspective of jet interaction. The study identifies critical areas within the multi-nozzle jet, specifically the three-phase mixing region, LBE entrainment region, water core region, and steam plume region. In scenarios where nozzle spacing is narrow or nozzle diameters differ significantly, the jet's base may undergo fragmentation. The jet process is categorized into two stages: the transition stage and the stable stage. During the stable stage, the mass flow rate of sub-cooled water remains relatively constant, with nozzle spacing exerting minimal influence on it. When considering the cross-sectional area of a single nozzle, an increase in nozzle diameter elevates the normalized mass flow rate, whereas the number and diameter of nozzles have little effect on it. Jet penetration depth is inversely related to nozzle spacing. As the number and diameter of nozzles increase, penetration depth initially rises and then decreases. Nozzle spacing has a minor influence on the jet's steam volume, while the number and diameter of nozzles are positively correlated with steam volume. Conversely, the number and diameter of nozzles negatively correlate with normalized steam volume.

Non-global logarithms up to four loops at finite-Nc for V/H+jet processes at hadron colliders

We extend our previous work [1] on calculating non-global logarithms in e+e− annihilation to Higgs/vector boson production in association with a single hard jet at hadron colliders. We analytically compute non-global coefficients in the jet mass distribution up to four loops using the anti-kt jet algorithm. Our calculations are performed in the eikonal approximation, assuming strong energy ordering for the emitted gluons, thus capturing only the leading logarithms of the distribution. We compare our analytical results with the all-orders large-Nc numerical solution. In general, the gross features of the non-global logarithm distribution observed in the e+e− case remain valid for the V/H+jet processes.

Synthesis of TiO2-brookite nanorods and TiO2-Au composites for decomposition of organic dyes in water

This study employed a plasma-liquid interaction technique at room temperature to modify TiO2 nanocrystals in the brookite phase and coat their surface with gold nanoparticles (AuNPs). The technique was further utilized to reduce Au3+ ions to Au0, eliminating the need for chemical agents and reducing reaction time. The resulting TiO2-Au photocatalysts were then tested under visible light to evaluate their ability to degrade the dyes rhodamine 101 (RB101) in water. The findings indicated that the most effective degradation of RB101 molecules occurred at low dye concentrations (10 ppm) and low photocatalyst loadings with a ratio of 4. In comparing two different preparation methods, the TiO2-Au sample created using a micro-plasma process with a direct current (DC) source exhibited higher photocatalytic activity (87 % after 4 hours) compared to the sample created using a plasma jet process with an alternating current (AC) source. This research holds significance for the advancement of photocatalytic materials with potential environmental applications.

Effects of particle size, binder wettability, and sintering atmosphere on the microstructural and mechanical properties of binder jetted 18Ni300 alloy

A fully dense 18Ni300 mold steel was firstly prepared by the binder jetting (BJ) process. We developed a water-based binder characterized by its low viscosity, which significantly enhanced the penetration of binder into the fine powder layer. This process resulted in a deep, narrow cross-section due to reduced flow resistance, leading to strong inter-layer bonding and high surface quality of the green part. The densification behavior of 18Ni300 BJ green parts with different particle sizes was meticulously analyzed. A remarkable tensile property of YS = 783 MPa, UTS = 1012 MPa and EL = 8.8% were obtained in sintered 18Ni300 alloy with fine powder under 1460 °C and 50 mTorr vacuum. Building on thermodynamic theory, we introduced a novel criterion to assess the oxidation reactions in 18Ni300 parts fabricated by the BJ method during sintering under different atmospheric conditions.

The effect of non-perpendicular incidence angles on discharge characteristics in an argon atmospheric plasma jet impinging on metal, water and glass substrates

The spatial–temporal discharge behavior of an AC argon plasma jet tilted at non-perpendicular incidence angles (60°, 45°, and 30°) interacting with an ungrounded metal, water, and glass plate placed on the jet propagation track was studied by the fast-imaging technique. The conductivity of surface and incidence angles plays an essential role in the discharge current and dynamic process of the plasma jet. The nearly consistent time delay between subsequent breakdowns occurred four times for metal and two times for glass treatments. The mean luminous intensity of the plasma in one discharge cycle at the discharge area between ground electrode and target surface region for the water and glass case decreased by 39.5% and 20.5% when the incidence angle decreased from 60° to 30°, respectively. In particular, the incidence angle and gas flow rate notably impacted the spatial extension behavior created on the glass surface but had no significant difference in discharge characteristic of plasma jet with metal case. In addition, two equivalent circuit models were developed based on the simulation of the micro-discharges and the geometry of the “plasma jet–substrate” system, respectively. These results will obtain further insight into the underlying mechanisms of plasma-target interaction and facilitate the designing of appropriate jet for environmental and biomedical applications.

Analysis of the unsteady flow characteristics of underwater supersonic gaseous jets

To examine the unsteady flow characteristics of underwater supersonic gaseous jets under different jet expansion conditions, a sophisticated numerical model is created. This model accurately predicts the intricate multiphase flow by considering the compressibility of the jet gas and energy exchange, which is then rigorously validated against experimental data. The development process of underwater supersonic gaseous jets displays notably unsteady features in terms of jet morphology, flow structure, and various flow field parameters when compared to atmospheric conditions. The unsteady phenomena, such as necking, breaking, bulging, and back-attack, are observed alongside significant pressure pulsations. These unsteady phenomena occur at a considerable distance from the nozzle exit under under-expanded conditions, while pressure pulsations do not impact the internal gas flow within the nozzle. However, under full-expanded and over-expanded conditions, unsteady phenomena near the nozzle exit lead to oscillatory pressure, causing shock waves to propagate inside the nozzle. This results in a notable increase in internal pressure pulsation and mass flow rate within the nozzle, ultimately affecting engine performance significantly.

Extreme Drop Durability of Sintered Silver Traces Printed With Extrusion and Aerosol Jet Processes

Abstract Sintered silver is a popular material for printing conductive traces in printed hybrid electronics (PHE). However, due to the novel materials and printing techniques in PHEs, reliability still needs to be adequately characterized for all types of life-cycle application conditions. This paper focuses on characterizing the reliability of printed silver traces fabricated with extrusion printing and aerosol jet printing (AJP) processes, under severe shock conditions up to 40,000 g peak acceleration, resulting in very high strain magnitudes and strain rates. This study utilizes test specimens of cantilever form factor to study the reliability of three-dimensional printed traces and substrates. Traces printed using both techniques were found to withstand repetitive drops at up to 40,000 g peak acceleration. However, extrusion-printed silver traces were found to be more reliable than their AJP counterparts, because of the extruded traces' superior adhesion to the FR4 substrate and lack of sintering shrinkage cracks. Strain gauges revealed strains in excess of 10,000 με during a 40,000 g shock event. A calibrated finite element (FE) model revealed that the strains at the trace location exceeded 15,000 με during a 40,000 g shock event.

Numerical study on heat transfer and pressure performance of different suspension nozzles

The drying process of the lithium battery pole pieces makes extensive use of the suspension nozzle. It is of great significance to study the heat transfer and pressure steady-state characteristics of the suspension nozzle and to select the appropriate nozzle structure for the production of pole pieces. Based on the SSTk-ω\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{SST }}k - \\omega$$\\end{document} turbulence model, this article numerically simulates the impact jet process of suspension nozzles with slits, injection holes, and effusion holes. There is a qualitative and quantitative analysis of the distribution of their velocity field, temperature field, local Nusselt number, average Nusselt number, local pressure coefficient, and average pressure coefficient, and the comprehensive performance index of the nozzle is proposed. The results show that when the weight factor of heat transfer performance α is less than 21.61% and the weight factor of pressure performance β is more than 78.39%, the comprehensive performance of the traditional suspension nozzle with double slits is the best. As the α is increasing, the β is decreasing. The comprehensive performance of the suspension nozzle with effusion holes is the best. The turbulent intermittence, interaction between neighbouring jets, and edge effects affect the heat transfer and pressure uniformity of the suspension nozzle.