Showing papers on "Nozzle published in 2001"

Electrospinning and electrically forced jets. II. Applications

Abstract: Electrospinning is a process in which solid fibers are produced from a polymeric fluid stream (solution or melt) delivered through a millimeter-scale nozzle. This article uses the stability theory described in the previous article to develop a quantitative method for predicting when electrospinning occurs. First a method for calculating the shape and charge density of a steady jet as it thins from the nozzle is presented and is shown to capture quantitative features of the experiments. Then, this information is combined with the stability analysis to predict scaling laws for the jet behavior and to produce operating diagrams for when electrospinning occurs, both as a function of experimental parameters. Predictions for how the regime of electrospinning changes as a function of the fluid conductivity and viscosity are presented.

Influence of jet exit conditions on the passive scalar field of an axisymmetric free jet

Abstract: The influence of initial flow conditions on the passive scalar field of a turbulent free jet issuing from the round nozzle is investigated in this paper by a review of the literature and a detailed experimental study. Two sets of distinctly different initial conditions are generated using two nozzle types: a smooth contraction and a long straight pipe. The present measurements of the passive scalar (temperature) field were conducted in a slightly heated air jet from each nozzle at a Reynolds number of 16 000 using identical experimental facilities and a single measurement technique. Significant differences between the flows from the two nozzles are revealed throughout the measured flow region which covers the axial range from 0 to 70 jet exit diameters. The study suggests that the differences observed in the statistics of the scalar field may be related to differences in the underlying turbulence structure of the jet in the near field. The present findings support the analytical result of George (1989) that the entire flow is influenced by the initial conditions, resulting in a variety of self-similar states in the far field.

Rapid magnetic reconnection in the Earth's magnetosphere mediated by whistler waves.

Abstract: Magnetic reconnection has a crucial role in a variety of plasma environments1,2,3 in providing a mechanism for the fast release of stored magnetic energy. During reconnection the plasma forms a ‘magnetic nozzle’, like the nozzle of a hose, and the rate is controlled by how fast plasma can flow out of the nozzle. But the traditional picture of reconnection has been unable to explain satisfactorily the short timescales associated with the energy release, because the flow is mediated by heavy ions with a slow resultant velocity. Recent theoretical work4,5,6 has suggested that the energy release is instead mediated by electrons in waves called ‘whistlers’, which move much faster for a given perturbation of the magnetic field because of their smaller mass. Moreover, the whistler velocity and associated plasma velocity both increase as the ‘nozzle’ becomes narrower. A narrower nozzle therefore no longer reduces the total plasma flow—the outflow is independent of the size of the nozzle. Here we report observations demonstrating that reconnection in the magnetosphere is driven by whistlers, in good agreement with the theoretical predictions.

Emulsification in High-Pressure Homogenizers

Abstract: High-pressure homogenizers are frequently employed for the homogenization of low-viscosity emulsions containing a proportion of disperse phase which is not too high. High-pressure homogenizers essentially consist of a high-pressure pump and a homogenizing nozzle. The design of the homogenizing nozzle influences the flow of the emulsion in the nozzle itself and hence the results of droplet disruption. It is shown which mechanism in frequently used homogenizing nozzles is usually responsible for disruption. Experimental results reveal the effects of the dispersed phase content and the viscosity of the disperse and continuous phases in different nozzles. The results can be explained on the basis of the mechanisms of disruption. Finally, the homogenizing nozzles presented are directly compared with one another.

Inkjet printhead assembly having very high nozzle packing density

Abstract: An inkjet printhead assembly includes a substrate having an ink feed slot formed therein including a first side and second side along a vertical length of the ink feed slot. A first column of drop generators is formed along the first side of the ink feed slot. A second column of drop generators is formed along the second side of the ink feed slot. Each drop generator includes a nozzle. A nozzle packing density for nozzles in the first and second columns of drop generators including the area of the ink feed slot is at least approximately 100 nozzles per square millimeter (mm 2 ).

Modeling and computation of unsteady cavitation flows in injection nozzles

Abstract: This paper deals with the numerical simulation of cavitation phenomena inside injector nozzles. The numerical approach combines the Volume-of-Fluid technique (VOF) with a model predicting the growth and collapse of bubbles. To model the turbulence effect a k–ω model is introduced for the two-phase flow. Calculations show that the numerical method is able to reproduce complex cavitation phenomena as observed in injection nozzle experiments.

Supersonic Combustion Experiments with a Cavity-Based Fuel Injector (Postprint)

Abstract: : Recent results from combustion experiments in a direct-connect supersonic combustor are presented. Successful ignition and sustained combustion of gaseous ethylene have been achieved using an injector/flameholder concept with low-angle, flush-wall fuel injection upstream of a wall cavity. Two interchangeable facility nozzles (Mach 1.8 and 2.2) were used to obtain combustor inlet flow properties that simulate flight conditions between Mach 4 and 6 at a dynamic pressure of 47.9 kPa. Mainstream combustion was achieved at equivalence ratios between 0.25 and 0.75 using only a spark plug and no other external ignition aids. Delta-force levels between 667 and 1779 N were measured, with corresponding combustor pressure ratios between 3.1 and 4.0. Video records of the flame zone show an intensely active combustion zone with rapid flame spreading. One-dimensional performance analysis of the test data indicates a combustion efficiency around 80% with an average combustor skin friction coefficient of 0.0028.

The internal flow of diesel fuel injector nozzles: A review:

Abstract: Diesel fuel injector nozzles have a significant effect on the quality of spray and charge preparation. However, the mechanism and degree of this effect is unclear. The complexity of the internal nozzle flow has hindered the study of the fuel injection process. Diesel fuel injector nozzle flows are highly turbulent and usually two-phase. Several experiments have shown the presence of cavitation in the nozzles to be a dominating effect. Recent experimental work has revealed new qualitative details about the cavitation in fuel injector nozzles. The cavity tends to be smooth near the inlet, transitioning to a more ruffled appearance downstream. These flows are also strongly asymmetric in realistic geometries. Additionally, photographs have shown string cavitation inside the sac volume extending into the nozzles. The strings appear to be a form of stratified two-phase flow, like the cavities near the inlet corner. Like the cavities, the strings break down into bubbly flow near the exit of the nozzle. F...

High mass throughput particle generation using multiple nozzle spraying

Abstract: Spraying apparatus and methods that employ multiple nozzle structures for producing multiple sprays of particles, e.g., nanoparticles, for various applications, e.g., pharmaceuticals, are provided. For example, an electrospray dispensing device may include a plurality of nozzle structures, wherein each nozzle structure is separated from adjacent nozzle structures by an internozzle distance. Sprays of particles are established from the nozzle structures by creating a nonuniform electrical field between the nozzle structures and an electrode electrically isolated therefrom.

Electrospray ion source

Abstract: An electrospray ion source is fitted with plural spray nozzles. A nebulization gas is supplied to the nozzles. The supply of the nebulization gas to at least a selected one of the spray nozzles is cut off for a given time. The application of the high voltage to the spray nozzle, for which the supply of the nebulization gas is cut off, is synchronously ceased.

Theoretical description and experimental observation of aerosol transport processes in laser ablation inductively coupled plasma mass spectrometry

Abstract: The transport efficiency of laser-induced aerosols mainly influences the detection capabilities for high spatial resolution laser ablation microanalysis. Therefore, the volume of the ablation cell, the geometry, the gas flow pattern and the transfer tube to carry the aerosol into the ICP are important influences on the transport process and the signal structure. Four different ablation cell volumes, ranging from 0.25 to 63 cm3, in combination with various transfer tubes of different diameters and lengths were investigated. The signal structure was significantly modified by reducing the volume of the sample chamber by a factor of approximately 250. The peak height of single laser shot (aerosol density) was increased by a factor of 6, the signal width (aerosol dispersion) was reduced by a factor of 7 and the rinse time of the sample chamber was consequently shortened to approximately 1 s, thereby eliminating processes of sample recirculation within the cell. The gas flow pattern inside the cell was experimentally traced by introducing powder of different sizes (grain size <1 µm and <65 µm) inside the cell. An angle of 40° at the apex of the gas injection cone was observed at the tip of the inlet nozzle, for a 0.5 mm id nozzle and 1 L min−1 gas flow. The gas inlet nozzle ensured a steady, high efficiency flow, influencing the precision of the measurements. The amount of transported material was constant within the precision of the ablation process for optimized transport and ionization conditions in all ablation cells. The ablation in a sample cell of volume of 0.25 cm3 showed slightly reduced sample transport and a slightly longer rinse time than for a 1.5 cm3 cell, which could be an indication that with extremely reduced cell volumes aerosol–wall interaction might limit the transport efficiency. The variation of the transport tube diameter (4–7 mm) and length (1.5–6 m) showed an influence on the signal structure, but the total amount of sample transferred was not influenced. Nevertheless, the variation of the dispersion as a function of the total volume of the transport system (cell and tube) showed that cell volume more significantly influenced the signal structure. A mathematical model was developed to describe the structure of the signal in relation to the parameters of the ablation set-up and its scope is discussed.

Variable area nozzle for gas turbine engines driven by shape memory alloy actuators

Abstract: A gas turbine engine includes a variable area nozzle having a plurality of flaps. The flaps are actuated by a plurality of actuating mechanisms driven by shape memory alloy (SMA) actuators to vary fan exist nozzle area. The SMA actuator has a deformed shape in its martensitic state and a parent shape in its austenitic state. The SMA actuator is heated to transform from martensitic state to austenitic state generating a force output to actuate the flaps. The variable area nozzle also includes a plurality of return mechanisms deforming the SMA actuator when the SMA actuator is in its martensitic state.

Mixing Characteristics of Axisymmetric Free Jets From a Contoured Nozzle, an Orifice Plate and a Pipe

Abstract: The differences in mixing performance between axisymmetric turbulent jets issuing from three common types of nozzle, viz. a contoured (or smooth contraction) nozzle, a sharpedged orifice and a long pipe, are investigated. The investigation is carried out using both qualitative flow visualizations and quantitative measurements of the centerline passive temperature. It is revealed that the jet issuing from an orifice plate provides the greatest rate of mixing with ambient fluid, while the pipe jet has the lowest rate. Physical insight into the differences is explored using a planar imaging technique and measurements of power spectra of the fluctuating velocity

Bubble-jet type ink-jet printhead

Abstract: A bubble-jet type ink-jet printhead is provided. When forming a doughnut-shaped bubble, the printhead allows bubbles to be first grown around the heater that surrounds the central axis of the nozzle at regular angles followed by the formation of another bubble between the earlier formed bubbles, thereby forming a larger doughnut-shaped bubble. Accordingly, this can prevent the formation of an unbalanced doughnut-shaped bubble due to variations in local resistance of the heater, which may be caused by a process error. Furthermore, the printhead allows the center of the doughnut-shaped bubble to be set on the central axis of the nozzle thus causing a droplet formed within the doughnut-shaped bubble to be ejected in a normal manner, that is, in a direction vertical to the nozzle plate.

The features of cold spray nozzle design

Abstract: This article presents the peculiarities of the supersonic nozzle design for the cold gas-dynamic spraying. The procedure to produce the high particle velocity by correct choice of the geometrical dimensions of the accelerating nozzles is described. Numerical and experimental research of wedge-shaped nozzles shows that there is a nozzle with its particular dimensions for a given type of particles that produces the maximum possible particle velocity at the moment of impact on a target surface.

Film depositing apparatus and film depositing method

Abstract: PROBLEM TO BE SOLVED: To provide a film depositing apparatus and a film deposition method in which an ALD method can be used with a high productivity without using any high-speed switching valve. SOLUTION: The film depositing apparatus is provided with, in a chamber 11: a substrate support member 12 to support a plurality of substrate W; first treatment gas ejecting nozzles 20 each of which ejects TiCl 4 ; a second treatment gas ejecting nozzle 21 which ejects NH 3 , purge gas ejecting nozzles 22 each of which separates TiCl 4 and NH 3 . Each purge gas ejecting nozzle 22 is arranged in such a manner that the distance between the ejecting port of the purge gas ejecting nozzle 22 and the surface of each substrate W is made wider than that between the ejecting port of the first treatment gas ejecting nozzle 20 and second treatment gas ejecting nozzle 21 and the surface of each substrate W, and TiCl 4 , NH 3 and purge gas are allowed to scan to each substrate W, thus TiCl 4 and NH 3 are alternately adsorbed on each substrate W. COPYRIGHT: (C)2008,JPO&INPIT

Ink jet printer

Abstract: An ink jet printer provided with a horizontal scanning driving unit (3) for driving a printing head (2), which has nozzle arrays (2a, 2b) comprising a predetermined number of nozzles arranged at predetermined intervals, in a horizontal scanning direction on a printing medium (S), a vertical scanning driving unit (4) for driving the printing medium (S) in a vertical scanning direction, a driving unit controller (5) for controlling the horizontal and vertical scanning driving units (3, 4) so as to set the printing head (2) in a predetermined position, and a printing head driving unit (7) for supplying an electric current to the printing head (2) according to printing image data stored in a data storage (6) in which printing image data including multivalued gradation information are stored. The printing head driving unit (7) is adapted to generate a binary output according to whether or not the ink is ejected and a multivalued output by superposing dots on already-formed dots by a position control operation of the driving unit controller (5).

Turbine Nozzle Endwall Film Cooling Study Using Pressure-Sensitive Paint

Abstract: Endwall surface film cooling effectiveness was measured on a turbine vane endwall surface using the pressure sensitive paint (PSP) technique. A double staggered row of holes and a single row of discrete slots were used to supply film cooling in front of the nozzle cascade leading edges. Nitrogen gas was used to simulate film cooling flow as well as a tracer gas to indicate oxygen concentration such that film effectiveness by the mass transfer analogy could be obtained. Cooling mass flow was controlled to be 0.5 to 3.0% of the mainstream mass flow. The freestream Reynolds number was about 283000 and Mach number was about 0.11. The freestream turbulence intensity was kept at 6.0% for all the tests, measured by a thermal anemometer. The PSP was calibrated at various temperatures and pressures to obtain better accuracy before being applied to the endwall surface. Film effectiveness distributions were measured on a flat endwall surface for five different mass flow rates. The film effectiveness increased nonlinearly with mass flow rate, indicating a strong interference between the cooling jets and the endwall secondary flows. At lower mass flow ratios, the secondary flow dominated the near wall flow field, resulting in a low film effectiveness. At higher mass flow ratios, the cooling jet momentum dominated the near wall flow field, resulting in a higher film effectiveness. The comparison between hole injection and slot injection was also made.Copyright © 2001 by ASME

High density gas jet nozzle design for laser target production

Abstract: The optimization of a cylindrical nozzle design to generate a uniform density profile for laser plasmas studies has been investigated using numerical simulations. In addition gas jet flows have been characterized using a Mach–Zehnder interferometer. The experimental results are in very good agreement with the simulation.

Exhaust emission control device of internal combustion engine

Abstract: To provide an exhaust emission control device of an internal combustion engine able to well atomize a reducing agent and ensure supply of combustion air. Since a controller of the exhaust emission control device also controls a nozzle opening degree of a variable geometry turbocharger for purpose of spraying a urea water, even in the state where the engine works in a low load range of T 1 to T 2 where supercharging pressure normally can not be increased, supercharging pressure P suitable to atomization of the urea water can be obtained by controlling the nozzle opening degree of the variable geometry turbocharger to be closer to a closing side compared to the conventional art (shown by the chain double-dashed line), while the urea water can be securely atomized by a part of the supercharged air. Further, by increasing the supercharging pressure up to the value P, combustion air supplied to the engine is increased, therefore favorable combustion can be realized, and generation of particulates and exhaust of unburned fuel can be reduced.

Combustor mixer having plasma generating nozzle

Abstract: A mixer assembly for use in a combustion chamber of a gas turbine engine. The mixer assembly includes a mixer housing having a hollow interior, an inlet and an outlet. The housing delivers a mixture of fuel and air through the outlet to the combustion chamber for burning. The mixer assembly includes a fuel nozzle assembly mounted in the housing having a fuel passage adapted for connection to a fuel supply. The passage extends to an outlet port for delivering fuel from the passage to the hollow interior of the mixer housing. The nozzle assembly includes a plasma generator for generating at least one of a dissociated fuel and an ionized fuel from the fuel delivered through the nozzle outlet port to the hollow interior of the housing.

Continuous ink jet printhead having two-dimensional nozzle array and method of redundant printing

Abstract: A continuous inkjet printing apparatus is provided The apparatus includes a printhead having a two-dimensional nozzle array with the two-dimensional nozzle array having a plurality of nozzles disposed such that a redundant nozzle pair is formed A drop forming mechanism is positioned relative to the nozzles and is operable in a first state to form drops having a first volume travelling along a path and in a second state to form drops having a second volume travelling along the same path A system applies force to the drops travelling along the path with the force being applied in a direction such that the drops having the first volume diverge from the path

Comparison of Fixed and Rotating Spray Plate Sprinklers

Abstract: A comparative study of two types of spray sprinklers was performed. Rotating spray plate sprinklers (RSPSs) and fixed spray plate sprinklers (FSPSs) were evaluated individually in open field conditions. The water distribution, wind drift, and evaporation losses during the evaluations were measured under low, medium, and high wind speed conditions with three nozzle diameters and two nozzle heights above the soil surface. Individual spray sprinkler water distributions were mathematically overlapped to simulate the water distribution resulting from sprinkler machines. The water distribution of the RSPS had a conical shape, whereas the FSPS concentrated the water application in a circular crown. The uniformity coefficient of the simulated water application in sprinkler machines fitted with RSPSs or FSPSs was >93% in all cases. However, the RSPS could attain a higher uniformity coefficient at higher spacing along the lateral. For the nozzle diameters of 6.7 and 7.9 mm, the wetted width produced by the RSPS was...

Fuel nozzle assembly for reduced exhaust emissions

Abstract: A two-stage fuel nozzle assembly for a gas turbine engine. The primary combustion region is centrally positioned and includes a fuel injector that is surrounded by one or more swirl chambers to provide a fuel air mixture that is ignited to define a first stage combustion zone. A secondary combustion region is provided by an annular housing that surrounds the primary combustion region, and it includes a secondary fuel injector having a radially outwardly directed opening and surrounded by an annular ring that includes openings for providing a swirl chamber for the secondary combustion region. Cooling air is directed angularly between the primary and secondary combustion zones to delay intermixing and thereby allow more complete combustion of the respective zones prior to their coalescing further downstream. The primary combustion region is activated during idle and low engine power conditions and both the primary and secondary combustion regions are activated during high engine power conditions.

Reactor for depositing thin film on wafer

Abstract: A thin film deposition reactor including a reactor block 110 on which a wafer is placed, a shower head plate 120 for uniformly maintaining a predetermined pressure by covering the reactor block 110, a wafer block 140 installed in the reactor block 110, on which the wafer is to be seated, an exhausting portion (not shown) connected to the reactor block 110 for exhausting a gas within the rector block 110 to the outside, a first connection line 121 installed on the shower head plate 120, through which a first reaction gas and/or inert gas supplied flow, a second connection line 122 installed on the shower head plate 120, through which a second reaction gas and/or inert gas supplied flow and a diffusion plate 130 installed under the shower head plate 120. The diffusion plate 130 has a plurality of spray holes 131, which are connected to the first connection line 121 and face the upper surface of a wafer w to spray the first reaction gas and/or inert gas onto the wafer w, and a plurality of nozzles 133, which are connected to the second connection line 122 and look toward the inner side surface of the reactor block 110 to spray the second reaction gas and/or inert gas toward the edges of the wafer w.

CFD modelling and experimental investigation of an ejector refrigeration system using methanol as the working fluid

Abstract: This paper presents results of computational fluid dynamic (CFD) analysis and experimental investigation of an ejector refrigeration system using methanol as the working fluid. The CFD modelling was used to investigate the effect of the relative position of the primary nozzle exit within the mixing chamber on the performance of the ejector. The results of the CFD were used to obtain the optimum geometry of the ejector, which was then used to design, construct and test a small-scale experimental ejector refrigeration system. Methanol was used as the working fluid, as it has the advantage of being an ‘environmentally friendly’ refrigerant that does not contribute to global warming and ozone layer depletion. In addition, use of methanol allows the ejector refrigeration system to produce cooling at temperatures below the freezing point of the water, which of course would not be possible with a water ejector refrigeration system. CFD results showed that positioning the nozzle exit at least 0.21 length of the mixing chamber throat's diameter upstream of the entrance of the mixing chamber gave better performance than pushing it into the mixing chamber. Experimental values of coefficient of performance (COP) between 0.2 and 0.4 were obtained at operating conditions achievable using low-grade heat such as solar energy and waste heat. Copyright © 2001 John Wiley & Sons, Ltd.

Windshield washer system for automotive vehicle

Abstract: A windshield washer system for an automotive vehicle includes a fluid reservoir, a pump mounted within the fluid reservoir, a heater mounted in proximity to the pump so as to provide heat to the fluid contained within the reservoir and a nozzle operatively associated with the pump for applying fluid from the reservoir to an outside surface of the automotive vehicle at an even sub-freezing temperatures, with aqueous-based fluids either none, or minimal freezing point depressants contained therein.

Turbulent flow of liquid steel and argon bubbles in slide-gate tundish nozzles part i: model development and validation

Abstract: The quality of continuous-cast steel is greatly affected by the flow pattern in the mold, which depends mainly on the jets flowing from the outlet ports in casting with submerged tundish nozzles. An Eulerian multiphase model using the finite-difference program CFX has been applied to study the three-dimensional (3-D) turbulent flow of liquid steel with argon bubbles in slide-gate tundish nozzles. Part I of this two-part article describes the model formulation, grid refinement, convergence strategies, and validation of this model. Equations to quantify average jet properties at the nozzle exit are presented. Most of the gas exits the upper portion of the nozzle port, while the main downward swirling flow contains very little gas. Particle-image velocimetry (PIV) measurements are performed on a 0.4-scale water model to determine the detailed nature of the swirling velocity profile exiting the nozzle. Predictions with the computational model agree well with the PIV measurements. The computational model is suitable for simulating dispersed bubbly flows, which exist for a wide range of practical gas injection rates. The model is used for extensive parametric studies of the effects of casting operation conditions and nozzle design, which are reported in Part II of this two-part article.

Ink-jet recording apparatus

Abstract: An ink-jet recording apparatus according to this invention has an ink-head unit, a head holder, and a wiper unit. The ink-head unit extends in a direction that intersects at right angles to the direction a recording medium is transported, for a distance equal to or longer than the width of the recording medium. The head holder holds the ink-head unit. The ink-head unit has a nozzle surface having nozzles for ejecting ink. The wiper unit has a wiper blade, which wipes the nozzle surface.