Kinds Of Nozzles Research Articles

Modeling the Spray Atomization of Emulsion Embedded Agricultural Solutions

Abstract A typical agricultural chemical spray process involves atomizing a liquid stream of diluted pesticide solution through hydraulic spray nozzles that inherently produce a wide spectrum of spray droplet sizes. Finer droplets have higher potential for off-target movement or drift, which is of concern due to its potential impact on neighboring crops and livestock, sensitive ecological resources, and human health. Research by the Spray Drift Task Force and others has demonstrated that, although spray nozzle selection and application parameters are the key factors to produce the desired droplet size spectrum, the physical properties of the spray solution have significant effects on the droplet size distribution for various kinds of nozzles. One of these properties of many spray fluids is the inclusion of an oil phase in the form of an emulsion. The effect of oil-in-water emulsions on the spray droplet size distribution has been demonstrated by previous work. However, the mechanisms of this effect are largely unknown. In this study, a method to model this effect was proposed. A characteristic dimensionless number for connecting the bulk spray properties and the microscopic emulsion droplet properties was defined as the ratio between the emulsion recovery time and the spray atomization time. This study will help in the design of agricultural spray nozzles and the optimization of anti-drift spray additives.

Effect of Bottom Structure of Submerged Entry Nozzle on Flow Field in Ultra-Thick Slab Continuous Casting Mold

Submerged entry nozzle (SEN) bottom structure plays an important role in determining the flow pattern in continuous casting process. This work applies a water model to evaluate the pointed-bottom, flat-bottom and recessed-bottom nozzle performance in ultra-thick slab mold. The jet properties and surface flow are compared for the three kinds of nozzles quantitatively. The results show that flat-bottom and recessed-bottom nozzles are similar in flow pattern, but the pointed-bottom nozzle has smaller jet angle, thinner flow pattern, larger surface asymmetry rate, and higher surface flow intensity.

High-Pressure Water Spray Research Based on Neural Network

The spray cleaning method is important and universal in many industrial processes and other occasion. Because the size of the waterdrop is one of key factors for cleaning, this paper not only studied the relationship between the size of waterdrop and other influencing factors, but also researched the forecasted method for the size of waterdrop. In lab, by measuring the size of the waterdrop, jetted by one kind of nozzle, data were acquired and were used to train the Back Propagation Neural Network ( BPNN ). Through comparing those diameters, between measured in lab and calculated by BPNN after trained. It was acquired that the maximum errors was smaller than 1.62%, between the computed results and the factual measured ones. The experimental results showed that BPNN is an effective tool to predict the variation of the non-linear waterdrop diameter.

S1904-2-2 ラバールノズルでの対流熱伝達を利用した推力・比推力の向上(大気突入・減速技術(2))

The one-dimensional analysis has been performed using the analysis program for the flow of the propellant of Laval nozzles. The propellant is nitrogen. Two kinds of nozzle that has a throat diameter of 0.5 mm and 1 mm are assumed. Heat flow to the propellant by convective heat transfer in the supersonic region is increased by elongating of the divergent section of the nozzle. The ratio of the exhaust velocity with the heat transfer in the nozzle to the exhaust velocity without the heat transfer is not affected by the throat diameter, inlet pressure, and temperature difference between the nozzle wall and the propellant. In the case that the throat diameter of 0.5 mm, inlet pressure of 1 MPa, temperature difference of 300 K and length of the divergent section of 200 mm, the ratio of the exhaust velocity becomes 1.05.

Fabrication of fine microcapsulated red phosphorus particles by SCF-RESS with a new structure nozzle

A novel process of preparing microencapsulated red phosphorus particles by rapid expansion of supercritical fluids (RESS) was tested, in which a new kind of nozzle and supercritical CO2 as a solvent were used. The structure of the microencapsulated red phosphorus particles were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). These results show that red phosphorus particles can be effectively encapsulated with paraffin by using the method. At the same time, how the moisture absorption ratio of microencapsulated red phosphorus particles was dependent on the experimental conditions was further investigated. The results suggest that paraffin-microencapsulated red phosphorus particles show a lower moisture absorption ratio within the experimental conditions of the extraction column and nozzle temperature of 120°C, extraction column pressure of more than 16 MPa, and a mass flow of core particles (0.5 g/min).

Studies on Mixing Process and Performance Improvement of Jet Pumps (Effect of Nozzle and Throat Shapes)

This study focuses on the mixing process of the driving jet and the induced flow in the throat to improve the efficiency of jet pumps used in Boiling Water Reactors. The effect of nozzle and throat shapes on the performance of jet pumps are examined experimentally under normal temperature and small-scale model conditions using three kinds of nozzles (i.e., circular, notched, and flower-shaped) and two kinds of throats (i.e., conventional straight throat and diverging throat with a very gentle gradient). A nozzle throat area ratio, which influences the flow rate ratio at peak efficiency, is kept constant to avoid significantly changing the flow rate ratio. The velocity profile and local skin-friction coefficient in the throat are investigated experimentally to evaluate the effect of nozzle and throat shapes on the mixing process. The following results are obtained. The diverging throat reduces skin-friction loss and improves efficiency for all three nozzles. The efficiency curve of the circular nozzle with eight notches slightly shifts to higher flow rate region by the reduction of the jet size compared with the circular nozzle. The flower-shaped nozzle decreases efficiency owing to the increase of the skin-friction loss caused by enhanced mixing. The circular nozzle with a diverging throat improves the peak efficiency about 2% without changing the nozzle throat area ratio.

Development of Neutral Molecular Beam Injector for Two-Dimensional Edge Density Measurement

A sheet-shaped thermal lithium beam probe has been developed for two-dimensional density measurements in the edge region of the torus plasma. For the production of an intense and uniform beam, the optimization of the nozzle shape and slit width of the beam injector has been performed. Beam density profiles at the observing region in the plasma were estimated with numerical calculations using a Monte Carlo technique for several kinds of nozzles and combinations with slits. Experiments on the test stand were also carried out, and pretty good agreement was found between numerical and experimental results. Based on these examination and optimization for the nozzle and slits, we have constructed a sheet-shaped beam injector for the large helical device. In spite of the long distance (about 3 m) from the injector, it is estimated that the thickness of the sheet-shaped beam is ∼90 mm (full width at half maximum).

Flowfield analysis of a linear clustered plug nozzle with round-to-square modules

The plug nozzle is one of the advanced expansion devices proposed to improve the overall performance of launcher liquid rocket engines. The present work investigates the three-dimensional flow field generated on this kind of nozzle by partitioning the primary nozzle into modules. A linear plug nozzle has been designed together with modules having two different geometries: a rectangular cross section and round-to-square module. Numerical simulations have been carried out considering the case where all modules of the primary nozzle are active and the case where one module is turned off. The solutions are compared and specific three-dimensional flow structures taking place inside the modules and on the plug are identified. The relationship between these structures and the skin friction distribution within the module and along the plug surface is investigated. Finally, the effect on performance of these three-dimensional flow features is emphasized.

MHD stabilities of liquid metal jet flows with gradient magnetic field

Liquid metal free surface flows (films, jets and droplets) are considered as prospective coolants in diverter/limiter system and first wall in fusion reactor, but the knowledge of liquid metal free surface, particularly jet flows, is very limited. In this article, the stability of a jet flow under a gradient magnetic field is investigated, and its MHD effects are the top concern. Firstly, a simplified model is developed to analyze the MHD effects of the jet flow and to explain the reason why it can keep stable, and the examination of the induced electric potential and currents of the jet flow is also included. Secondly, numerical simulation based on the approach of solving the electric potential equation was proceeded to support the theoretical analysis. Finally, experiments with different value of B 0 (maximum value of the magnetic field) and v 0 (average fluid velocity at the nozzle exit), and different kind of nozzle were performed on the Liquid Metal Experimental Loop (LMEL) in Southwestern Institute of Physics (SWIP), and there's a good agreement with experimental data and theoretical results. Qualitatively, a jet flow under a gradient magnetic field can keep its shape stable due to electromagnetic (EM) force in its direction and the compressed EM force in its cross-section, meanwhile, the reduction in velocity leads to a shorter range distance and a lager radius of cross-section of the jet flow. These effects are closely related to the parameters of the radius of the nozzle, the values of B 0 and v 0 .

Studies on Mixing Process and Performance Improvement of Jet Pump (Effects of Nozzle and Throat Shapes)

In order to improve the efficiency of a jet pump used in Boiling Water Reactors, the effects of nozzle and throat shapes on the mixing process between driving flow and induced flow in the throat and the pump efficiency were examined experimentally. The velocity profile and local skin-friction coefficient distribution in the throat were also obtained experimentally. Three kinds of nozzles, conventional throat and throat having a very gentle gradient were used. The following results were obtained. The circular nozzle with eight notches shified the efficiency to a bit high flow rate ratio region by reduced jet size. The flower-shaped nozzle decreased the efficiency by increasing skin-friction loss caused by enhanced mixing. The throat having a very gentle gradient reduced the skin-friction loss and enhanced the efficiency.

저공해와 고안정성을 위한 신개념의 사이클론 제트 하이브리드 연소기의 연소특성

A Promising new approach to achieve low pollutant emissions and improvement of flame stability is tested experimentally using a cyclone jet hybrid combustor employing both premixed and diffusion combustion mode. Three kinds of nozzle are tested for mixing enhancement of fuel and air. The LNG (Liquified Natural Gas) is used as a fuel. The combustor is operated by two methods. One is DC (Diffusion Combustion) mode generated swirl flow by air as general swirl combustor, and the other is HC (Hybrid Combustion) mode. The HC mode consists of diffusion jet flame of axial direction and premixed cyclone flame of tangential direction in order to stabilized the diffusion jet flame. The results showed that the flame stability of HC mode is significantly enhanced than that of DC mode through the change of mixing characteristics by modifications of fuel nozzle. In addition, the reductions of CO and NOx emission in HC mode, as compared with that for the DC mode, is large than about 50% in stable region. Also, even using the low calorific fuel as -blended gas, it is identified that the cyclone jet hybrid combustor has the high performance of flame stability.

Remoção de magnésio de alumínio reciclado através da injeção de cloro no metal líquido

O presente trabalho estudou a eliminação do magnésio do alumínio reciclado através da injeção de cloro no metal líquido. Os ensaios foram feitos variando-se os tipos de lanças. Em escala de laboratório, montou-se um aparato para simular a injeção de cloro e gases inertes, em ligas contendo em média 1,5% de magnésio. No ensaio, onde injetou-se gás inerte, foi promovida a remoção do magnésio, devido à quebra da camada de escória protetora que se forma na superfície do banho, enquanto que nos testes onde injetou-se cloro foi observado que existe uma concentração crítica de magnésio. Abaixo da concentração crítica de magnésio, ocorre a emissão de cloretos. A concentração crítica de magnésio é influenciada pelo diâmetro das bolhas formadas. Quando o cloreto de alumínio formado tem tempo para reagir com o magnésio contido no banho, a concentração de magnésio em função do tempo é linear. Essa situação ocorre para concentrações de magnésio acima da concentração crítica. Quando essa condição não é satisfeita, a concentração do magnésio em função do tempo é uma exponencial.

Design and Performance Evaluation of Multi-Nozzle Virtual Impactors for Concentrating Particles

This paper describes the development and performance evaluation of multi-nozzle virtual impactors used in concentrating aerosol particles. Four virtual impactors were designed: one single-nozzle and three multi-nozzle virtual impactors with 4, 12 and 18 nozzles, respectively. For each of the four designs, two kinds of nozzles were implemented, one that had a flat surface and the other a cut-out nozzle designed with consideration of airflow streamlines inside the impactor. Thus, a total of 8 models of virtual impactors were designed and fabricated to study the internal particle loss and concentration performance. Multi-nozzle devices were provided primarily for applications involving high-volume air sampling. Virtual impactors with cut-out nozzles yielded higher fractional collection efficiencies and lower internal losses than virtual impactors with flat nozzles. It is expected that significant flow turbulence will occur in the space between the acceleration nozzles and the collection probes. This may increase the internal losses arising from back-impaction on the acceleration nozzles and particle deposition on the collection probes with flat nozzles.

脈動噴流に関する研究 第３報 渦の挙動に及ぼす噴出口形状の影響

The purpose of this experiment is to make clear the effect of jet-exit conditions on the vortex formations of pulsating jets. Three exit conditions, two kinds of nozzles and an orifice are used in the experiment. One of these nozzles has a long parallel section, and the other has a short one. The pulsating jets are generated by Scotch yoke mechanism. The flow is visualized by a hydrogen bubble method. Obtained results are as follows: The flow patterns are strongly affected by jet-exit conditions. For the nozzle jets, the fre-quency of vortex formation agrees with that of the jet pulsation. For the orifice jet, a large scale vortex caused by the pulsation and a lot of vortices due to the shear layer in-stability are formed, and the vortices coalesce. The vortices of the orifice jet move down-stream faster than those of the nozzle jets.

Precipitation of ultrafine benzoic acid by expansion of a supercritical carbon dioxide solution through a porous plate nozzle

A method for the crystallization of ultrafine powders by rapid expansion of a supercritical solution, the RESS process, has been developed using a porous sintered metal plate instead of an orifice or a capillary tube as an expansion nozzle. The effects of the various process parameters on the characteristics of the crystals obtained with this kind of nozzle were investigated using the benzoic acid/carbon dioxide system. The habit of the precipitated crystals and their average size were analyzed. The crystals were faceted and mostly isometric in shape, with an average size < 1 μm. A number of crystals of 2–10 μm and larger were also observed. Benzoic acid crystals precipitated with a capillary nozzle had an average size of 2 to 6 μm.

An Experimental Study on Supersonic Jet Issuing from Gas Atomizing Nozzle (I)

Supersonic axisymmetric jets issuing from various kinds of nozzles with a throat diameter of a few millimeters were experimentally investigated. The exit Mach number and Reynolds number based on the throat diameter of nozzle were in the range of 1.0 ~ 5.9 and 8.4 ~ 2.9, respectively. The nozzle pressure ratio was varied from 5 to 85. Present paper aims to offer fundamental information of the supersonic free-jets, with an emphasis to give data with which the shape of the free-jets can be depicted under a specified condition. Experimental data are summarized to enable an estimation of the shape of the supersonic free-jets. The result shows that the shape of free-jets is dependent on only the nozzle pressure ratio.

New xenon excimer lamps excited by quasi-CW jet discharges

New xenon excimer lamps in vacuum ultraviolet (VUV) have been developed in quasi-CW jet discharges. Quantitative characteristics of xenon clusters produced with two different kinds of nozzles were studied to verify the xenon excimer formation mechanisms in jet discharges. Experimental results strongly indicate the xenon excimer emission at 174 mn as a result of the direct excitation of the xenon clusters. Output powers and pulse widths of the lamps were thus controlled by changing cluster formation parameters. The maximum output power of 1.5 W with an efficiency of 3.0% was obtained at 174 nm when the conical nozzle was used. The VUV emission lasted 5 ms (FWHM). >

IMPINGING JET DRYER

ABSTRACT In coating and gravure printing, an impinging jet nozzle with high thermal efficiency for drying of coated film was developed. Trial production 0f 40 kinds of nozzle enables to develop a high-performance impinging jet nozzle with heat transfer coefficient 1.5 times larger than that of current slit nozzle, through measurement of heat transfer coefficient, visualizations of air flow and heat transfer, and measuremenu of jet velocity and turbulence distribution. The purpose of the trial production was to expand a range of high heat transfer and promote turbulence compared with the current nozzle. Paying attention to mass transfer within gravure ink coated film, drying characteristic of the film was analyzed by numerical solution of a set of equations governing the drying process in which concentration dependencies 0f the diffusion coefficient and the equilibrium vapor pressure were considered. Applying these analyses. an industrial scale dryer with excellent drying efficiency has finally been developed.

Transmission scanning electron microscopical investigation of a gas microjet

AbstractExpansion flows from different kinds of nozzles (pipe, orifice) into the specimen chamber of a scanning electron microscope (JSM 50A, JEOL, Tokyo) were imaged by means of a transmitted electron detection device using its dark field mode of operation.The experimental videosignal distribution has been numerically transformed in order to get particle number density distributions. Absolute quantification using a thin known foil target yields reasonable particle number densities.The experimental investigation of a nonstationary gaseous microjet ejected from a circular orifice (20 μm in diameter) in the wall of a closed vessel (6 cm3 volume) provides for another estimation of the particle number density at an arbitrarily selected point on the microjet axis.

Reduction of noise from a nozzle by use of air-jet force.

An experimental study was made of the relation between the noise generated by a nozzle and the air-jet force. The noise reduction may be achieved by reduction of the air-jet velocity according to M. J. Lighthill's acoustic analogy. And the reduction of noise is inevitably accompanied by the decrease of air-jet force. The purpose of the study is to develop a low-noise nozzle with minimum reduction of the air-jet force. Seven kinds of nozzles were tested. It was found that the purpose was achieved by suitable use of the noise characteristics of nozzle, and even the reduction of air-jet force leads to the increase of noise in the case of the diffuser nozzle.