Ejection Nozzle Research Articles

The Influence of Preparation Parameters on the Morphology and Magnetic Properties of Fe-N Powders Obtained by the Gas Atomization Method

α″-Fe16N2 materials are of increasing interest for their applications in products such as rare earth-free permanent magnets. The lack of a method of mass production for powders as raw materials delays the preparation of such magnets. Through employing the gas atomization method, we managed to prepare α″-Fe16N2 powders whose morphology and magnetic properties were tailored by the preparation parameters. As a result of optimizing the preparation parameters (ejection temperature and pressure, ejection nozzle diameter, and atomization pressure), we managed to prepare powders with a size of about 30 μm and a content of 31% α″-Fe16N2 phase. The value of the saturation magnetization (234.8 emu/g), the reasonable coercivity value (970 Oe) presented by the prepared powders, and the opportunity of scaling up approaches based on the preparation of powders via gas atomization support the feasibility of preparing α″-Fe16N2 powders at an industrial level.

Casting of Thin Aluminum Alloy Wire Using a Single Wheel Caster

Thin aluminum alloy (Al-4.7%Mg) wire was cast using a single-wheel caster. The target cross-sectional area of the thin wire was less than 20 mm2. Use of a copper wheel with a groove and a molten metal ejection nozzle was proposed to cast thin wire. The molten metal ejection nozzle was used to eject a small cross-sectional area of the melt into the narrow groove on the wheel. The relationship among wheel speed, nozzle size, melt ejection speed, stability of the melt on the wheel, and cross-sectional area of the wire was investigated. When the diameter of the nozzle hole was 1.5 or 2 mm, the target was attained. When the nozzle diameter was larger than 3 mm, the cross-sectional area was greater than 20 mm2. When the diameter of the nozzle hole was smaller than 1 mm, the melt flow was unstable. A round wire could be cast at wheel speeds ranging from 9 m/min to 14 m/min. The smallest wire cross-sectional area was 4.7 mm2.

Engineering of the Highest Caliber: Kazimierz Siemienowicz and the Culmination of the Military Revolution

The interregnum between the death of Galileo and the publication of Newton’s Principia produced great advances in military science and technology. Particularly noteworthy are Kazimierz Siemienowicz’s contributions to artillery and to the field of rocketry. The dominating nature of these weapon systems remain as relevant today as it did in 1650 with the publication of his opus, The Great Art of Artillery. Rocket technology defines power relations, whether fired indiscriminately across a national border or positioned menacingly in a silo as an intercontinental ballistic missile. Siemienowicz’s designs, namely his multi-stage rockets with delta-wing stabilizers and ejection nozzles, became instruments of state power. The standardization of the caliber scale, the writing of the science of artillery, the optimization of gunpowder quality, and the pioneering work in rocketry, which became his legacy, qualify him as principal in the culmination of the military revolution.

Improvement of the Cargo Fleet Vessels Power Plants Ecological Indexes by Development of the Exhaust Gas Systems

Abstract Modernisation of the power plants of cargo fleet vessels to satisfy the requirements set out by the International Maritime Organisation is an urgent scientific and technical problem. The article presents the results of developing a solution to this problem that focuses on the exhaust gas system. We propose the use of ejection nozzles as part of this system. It was found that when the ejection coefficient in these nozzles is n = 3, it is possible to exclude the use of SCR reactors, thus reducing the operating costs of the marine power plant. Using a mathematical modelling method, the efficiency of operation of six types of nozzle as part of the exhaust gas system was investigated, and a constructive layout was proposed for the gas ducts and inlet louvres for supplying ambient air. To increase the efficiency of the proposed system, we consider several options for intensifying heat transfer processes through the use of dimple systems in the nozzles and nozzles with swirling flow. We found that these technical solutions would make it possible to further increase the efficiency of the systems by up to 19% abs.

Application of micro-bubbles on oral care.

This study proposed a method of using a modified micro-bubble generator with its ejection nozzle connected to an ergonomically designed soft teeth-tray for plaque removal. The applicability of this method was verified and the influence on plaque removal efficacy of some parameters of this device was clarified. The micro-bubble generator used in this study has 5 rotation speed settings, 5 nozzle sizes, and a soft teeth-tray ejection pore diameters. These were used as independent variables to investigate their effect on the ejected flow volume, velocity and micro-bubble dimension, and how they eventually affect the plaque removal efficacy from a denture. When the micro-bubble generator coupled with large (4.8 mm) ejection pore teeth-tray and the largest (1.2 mm) nozzle diameter more than 98% of plaque can be removed; its applicability on cleaning denture can be verified. In general, the larger nozzle diameter and teeth-tray ejection pore diameter will remove more plaques; while the higher the flow velocity and the smaller the micro-bubble of the ejected stream, better cleaning efficacy can be achieved. The application of micro-bubble on plaque removal seems effective, although at this moment it is applied on denture cleaning. The finding of the influence of some critical design parameters of micro-bubble generator and variables of ejected stream can be referred to further design a new micro-bubble cleaner for effective plaque removal from the teeth in human oral cavity.

The efficacy of oral hygiene by micro-bubbles cleaning.

Objective: Patients with periodontitis often have difficulty in maintaining oral hygiene with toothbrushes during treatment periods, especially for patients with severe conditions where brushing may cause bleeding of the gingiva and increase the chance of bacterial infection. Patients who have oral cancer, or who are bedridden long-term due to chronic diseases, also experience similar inconveniences in being unable to maintain oral hygiene through brushing their teeth and must do so through other means. Methods: We explored the method for dental washer, using the micro-bubble generator connect the ejection nozzle to an ergonomically designed soft teeth-tray that fits with the tooth configuration of a typical human oral cavity to clean oral plaque bacteria. Five levels of rotor speed and 4 type of ejection hole diameter, totally, were using 20 combinations to clean oral plaques bacteria. Results: Our results showed that with various combinations of motor speed settings and pore diameters, a clearing rate of 56% or more (average 79.55%) could be achieved, while in some combinations a clearing rate of 91.64% was possible. The nozzles with smaller diameters coupled with low speed motor had higher cleaning efficiency; the larger the diameter, the higher the volume and the larger the bubble dimensions and better bacteria removal. Conclusion: The experimental verification is effective by controlling ejection hole diameter and soft tooth-tray on better bacteria removal. For future, it is hoped that can definitely solve the dental hygiene issue for long-term bed-ridden patients who could not use toothbrush.

Analytical study of ultrasound influence on the molten metals atomization

This paper focuses on the study of influence of ultrasound on liquid atomization using ejection nozzles. Two principles of influence of ultrasound on the atomization process such as a change of conditions on gas-liquid boundary during the generation of ultrasound oscillation in the gas and liquid jet (film) disintegration under the action of capillary forces in cases of generation of ultrasound oscillation in the liquid are considered. The optimal values of the ultrasound oscillation frequencies are calculated. Two constructions of the nozzles patented are proposed.

Mathematical modelling of the liquid atomization process by cocurrent gas flow

This paper focuses on the physical-mathematical model of liquid atomization in the spray pattern of an ejection nozzle. A flow field of a gas phase behind the nozzle section is computed using the Ansys Fluent package. Dynamics of molten metal droplets in the gas phase within a trajectory approach is calculated. Using the presented model, numerical calculation results are given.

Influence of operational parameters and design of the ejection nozzle on characteristics of finely dispersed aluminum powder: Part I. Influence of operational parameters of the nozzle

The results of analyzing the influence of operational parameters of the ejection nozzle on the characteristics of highly dispersed aluminum powder in production conditions at OOO SUAL-PM are presented. Measurements of dispersed characteristics of the spray when spraying the aluminum melt by the ejection nozzle are performed when varying the consumption and temperature of spraying gas in ranges of 0.17–0.21 m3/s and 873–933 K, respectively, as well as the melt temperature in limits of 1153–1253 K. The results of determining the median diameter of the particles (dm) and content of the highly dispersed fraction (z) (with a particle diameter no larger than 10 μm) in the spray are presented. It is shown that, when modifying the operation parameter of the nozzle, the value of dm decreases by 3.7–12.4%, while the magnitude of z increases by 0.4–3.2%. It is established that an increase in temperature of spraying gas affects the powder properties most effectively.

A Study on the Deposit Uniformity and Profile of Cu Electroplated in Miniaturized, Laboratory-Scale Through Mask Plating Cell for Printed Circuit Board (PCBs) Fabrication

A miniaturized lab-scale Cu plating cell for the metallization of electronic devices was fabricated and its deposit uniformity and profile were investigated. The plating cell was composed of a polypropylene bath, an electrolyte ejection nozzle which is connected to a circulation pump. In deposit uniformity evaluation, thicker deposit was found on the bottom and sides of substrate, indicating the spatial variation of deposit thickness was governed by the tertiary current distribution which is related to <TEX>$Cu^{2+}$</TEX> transport. The surface morphology of Cu deposit inside photo-resist pattern was controlled by organic additives in the electrolyte as it led to the flatter top surface compared to convex surface which was observed in the deposit grown without organic additives.

Dispersiveness of Liquid Droplets Sprayed with Cocurrent Gas Flow

Pneumohydraulic stand, equipped with a set of aerosol systems laser diagnostics devices, are presented. The results of experimental measurements of the aerosol liquid-drop size distribution in the ejection nozzle spray pattern are provided.

INFLUENCE OF MODE PARAMETERS AND DESIGN OF THE EJECTION NOZZLE ON CHARACTERISTICS OF HIGHLY DISPERSED ALUMINUM POWDER. PART 2. INFLUENCE OF THE NOZZLE DESIGN

The influence of the design of an ejection nozzle on characteristics of highly dispersed aluminum powder in industrial conditions at the LLC «SUAL-PM» enterprise is performed. Measurements of dispersed characteristics of the spray product when spraying the aluminum melt by the ejection nozzle are performed for six variants of modified nozzles. The results of determining the median diameter of particles ( d ) and content of a highly dispersed phase ( z ) (with the particle diameter no larger than 10 μm) in the spray product are presented. It is shown that the most efficient method of modifying the spray nozzle is profiling the cone part of a protective bush and imposition of ultrasonic vibrations on a nozzle case (a decrease in d m by ~31,6 % and an increase in z by ~8,5 %).

Influence of Duty Parameters and Design of Ejection Nozzle on Characterizes of Aluminum’s Dispersed Powder Part I. Influence of Duty Parameters of Nozzle

There were presented results of analysis regard to influence of duty parameters of ejection nozzle on characteristics of highly dispersed powder of alu- minum under the conditions of production of enterprise LLC «SUAL-PM». There were conducted measurements of dispersed indices of spray product under condition of aluminum melt spraying by ejection nozzle at various flow rate and temperature of atomizing gas, consequently, at the range of 0,17–0,21 m 3 /s and 873–933 K, as well as temperature of melt in the range of 1153–1253 K. There were presented results of medium particle diame- ter determination ( d m ) and content of highly dispersed fraction ( z ) (with particles diameter ≤ 10 μm) in spray product. There was showed that under modification of duty parameters of nozzle value of d m is decreasing by 3,7–12,4 %, and value of z is increasing by 0,4–3,2 %. There was established that most effective factor influencing on powder properties, is increasing of temperature of atomizing gas.

Assembly of a Versatile Micro Dispenser Using Off-The-Shelf Components for Applications in Microfluidics

AbstractWe designed and constructed a drop-on-demand (DOD) droplet dispenser using the piezo inkjet technique that is simple to construct and operate and makes use of readily available components. The droplet dispenser can be easily fitted with cost effective glass nozzles and can be readily tuned to produce consistent drop sizes. The dynamics of the droplet motion are obtained using a calibrated analog video imaging system. We observed very high accelerations for the ejected droplets that corroborate with the applied drive pulse amplitudes. The acceleration measured, near the ejection nozzle, was many times the acceleration of gravity with the largest value of 34g’s. We successfully dispensed glycol water solutions and aqueous suspensions of titanium oxide nanoparticles, with values greater than 10 in the measured pH. For the inkjet droplets deposited on smooth gold/chromium substrates (±3nm surface roughness variation), we observed the well-known coffee ring effect using optical microscopy and nanoparticle morphology using an atomic force microscope.

A possible precession period for superluminal ejection in QSO 3C 279

The search for periodic features in flux variability and superluminal ejection in blazars has been an important subject, which is helpful for providing significant clues to the understanding of the structure and kinematics of relativistic jets (physical processes of acceleration and collimation) and their association with central energy engines (black hole/accretion disk systems). The wobbling of the ejection position angle of VLBI knots in superluminal sources has been interpreted in terms of the precession of the jet ejection nozzle as one of the alternative interpretations. We study the change with time of the initial position angle of superluminal knots in QSO 3C 279, using VLBI-data collected from the literature spanning more than ∼30 yr and propose a jet-nozzle precession model which has very small viewing angles (less than 2°) to fit the long-term trends in both variations in the inner-jet position angle (Chatterjee et al.) and the ejection position angle of the VLBI components. It is shown that an ejection-nozzle precession period of ∼25 yr could be appropriate to fit the long-term trend in the variation of the ejection position angle. However, the short-term swings and fluctuations in the ejection position angle cause some uncertainties. We also fit a model to the trajectory of component C4, correcting its non-ballistic motion near the core.

Micromachined Ultrasonic Print-Head for Deposition of High-Viscosity Materials

The recent application of inkjet printing to fabrication of three-dimensional, multilayer and multimaterial parts has tested the limits of conventional printing-based additive manufacturing techniques. The novel method presented here, termed as additive manufacturing via microarray deposition (AMMD), expands the allowable range of physical properties of printed fluids to include important, high-viscosity production materials (e.g., polyurethane resins). AMMD relies on a piezoelectrically driven ultrasonic print-head that generates continuous streams of droplets from 45 μm orifices while operating in the 0.5–3.0 MHz frequency range. The device is composed of a bulk ceramic piezoelectric transducer for ultrasound generation, a reservoir for the material to be printed, and a silicon micromachined array of liquid horn structures, which make up the ejection nozzles. Unique to this new printing technique are the high frequency of operation, use of fluid cavity resonances to assist ejection, and acoustic wave focusing to generate the pressure gradient required to form and eject droplets. We present the initial characterization of a micromachined print-head for deposition of fluids that cannot be used with conventional printing-based rapid prototyping techniques. Glycerol-water mixtures with a range of properties (surface tensions of ∼58–73 mN/m and viscosities of 0.7–380 mN s/m2) were used as representative printing fluids for most investigations. Sustained ejection was observed in all cases. In addition, successful ejection of a urethane-based photopolymer resin (surface tension of ∼25–30 mN/m and viscosity of 900–3000 mN s/m2) was achieved in short duration bursts. Peaks in the ejection quality were found to correspond to predicted device resonances. Based on these results, we have demonstrated the printing of fluids that fall well outside of the accepted range for the previously introduced printing indicator. The micromachined ultrasonic print-head achieves sustained printing of fluids up to 380 mN s/m2, far above the typical printable range.

202 空気流による薄板状物体の非接触把持 : 噴出口付近の圧力分布について(流体パワーによる駆動と制御I)

202 空気流による薄板状物体の非接触把持 : 噴出口付近の圧力分布について(流体パワーによる駆動と制御I)

Flow field simulation of the thin metal ribbon formed by twin-belt rapid solidification

The flow field formed when an aluminum ribbon is produced by twin-belt rapid solidification is simulated with the solution algorithm (SOLA)-volume of fluid (VOF) method, and the influence of casting speed and cooling-belt velocity on the flow field is analyzed for a given ejection nozzle size. It has been found that the flow field can be filled well when the width of the ejection nozzle outlet is the same as that of the up slit of the cooling belt. When the ejection nozzle outlet is wider than the up slit of the cooling belt, the aluminum fluid can fill well if only the casting speed matches the cooling-belt velocity properly, otherwise under filling occurs in some areas in the cooling zone.

Droplet ejection and the induced flowfield by microthermal bubble during growth/collapse process

Numerical predictions on the entire process of droplet ejection by the growth/collapse of an explosive microthermal bubble are achieved by first principle equations coupled with extended Rayleigh equations and Asai's pressure model. Supporting experiments such as the bubble size/shape image histories by high-speed camera and bubble-induced flowfield by microparticle image velocimetry are conducted for the impulsive and explosive process during the bubble growth/collapse. Excellent agreements between measurements and computations are obtained. Finally, the parameter studies on droplet ejections are conducted to seek the optimal designs for the ejection nozzle size, ink refilling chamber height, heat flux imposed, and the operating temperature.

Technological development of a micro-array of individually addressable ejectors

The conception and fabrication of an ejection micro-systems, devoted to local deposition of chemical or biological reagents for low cost and highly flexible biochips or lab on chip fabrication is described. The ejection micro-systems is an array of individually addressable bubble jet ejectors. These ejection micro-arrays have been fabricated using monolithical silicon technologies. Individual ejectors are 140 μm apart corresponding to 4096 ejectors/cm 2 and are supported by a dielectric and stress-free SiO 2/SiN x membrane, avoiding thermal interactions between neighbours. Ejection nozzles have been realized using SU8 photoresist in order to increase the jet directionality. Ejection has been demonstrated for water, ethanol and acetonitrile for power consumption ranging from 41 mW to 1.1 W and for electrical pulse ranging from 50 μs to 50 ms. Depending on the operating conditions the ejected droplets can have nanolitres to picolitres volume.