Showing papers on "Nozzle published in 1998"

Gas Dynamic Principles of Cold Spray

Abstract: This paper presents an analytical model of the cold-spray process. By assuming a one-dimensional isentropic flow and constant gas properties, analytical equations are solved to predict the spray particle velocities. The solutions demonstrate the interaction between the numerous geometric and material properties. The analytical results allow determination of an optimal design for a cold-spray nozzle. The spray particle velocity is determined to be a strong function of the gas properties, particle material density, and size. It is also shown that the system performance is sensitive to the nozzle length, but not sensitive to the nozzle shape. Thus, it is often possible to use one nozzle design for a variety of operational conditions. Many of the results obtained in this article are also directly applicable to other thermal spray processes.

Direct experimental determination of laminar flame speeds

Abstract: The stability of premixed flames at ultralow strain rates was assessed experimentally and numerically in the stagnation flow configuration. Results indicate that there are inherent limitations in establishing weakly strained planar flames, and that the accuracy of the laminar flame speeds obtained through linear extrapolations can, thus, be compromised. In view of these limitations, a new methodology is proposed for the direct experimental determination of laminar flame speeds. It includes the use of the stagnation flow configuration and large separation distances betwenn the nozzle and the stagnation plane, which allow for the establishment of Bunsen-type flames as the flow rate is reduced. The flow velocities are measured by using laser Doppler velocimetry. The proposed technique is based on the principle that whereas the planar, strained flames are positively stretched, the Bunsen flames are negatively stretched. Thus, by achieving a smooth, quasi-steady transition between planar and Bunsen flames, the flames pass through a near-zero strain-rate state. Real-time LDV measurements were obtained at numerous fixed spatial locations in the region within which transition occurs. The minimum velocity obtained in these measurements corresponds to the flame speed at the limit of near-zero stretch and is proposed as a representative value of the true laminar flame speed, SHo. Laminar flame speeds were obtained for atmospheric CH4/air, C2H6/air, and C3H8/air mixtures and for a wide range of equivalence ratios. The new Sno values were found to be systematically lower than the values that have been determined by using the traditional stagnation flow technique and linear extrapolations to zero strain rate.

Etching materials with an atmospheric-pressure plasma jet

Abstract: A plasma jet has been developed for etching materials at atmospheric pressure and between 100 and C. Gas mixtures containing helium, oxygen and carbon tetrafluoride were passed between an outer, grounded electrode and a centre electrode, which was driven by 13.56 MHz radio frequency power at 50 to 500 W. At a flow rate of , a stable, arc-free discharge was produced. This discharge extended out through a nozzle at the end of the electrodes, forming a plasma jet. Materials placed 0.5 cm downstream from the nozzle were etched at the following maximum rates: for Kapton ( and He only), for silicon dioxide, for tantalum and for tungsten. Optical emission spectroscopy was used to identify the electronically excited species inside the plasma and outside in the jet effluent.

Process and apparatus for creating a colorful three-dimensional object

Abstract: A process and apparatus for fabricating a colorful three-dimensional object in accordance with a computer aided design (CAD) image of the object. The apparatus includes (a) a supply of one body-building material in filament form; (b) a filament feeding device including one feeding channel and a drive device to drive and regulate the flow of the filament in the channel; (c) a dispensing nozzle having a flow passage communicating with this feeding channel to receive the filament therefrom, a heater for converting a leading portion of the filament to a flowable fluid state, and a discharge orifice to dispense the fluid therethrough; (d) a multi-channel colorant-injecting module including at least one injecting channel in flow communication with the flow passage of the nozzle, at least one colorant reservoir in flow communication with the injecting channel, and control valves to regulate the flow of a colorant therefrom, with the colorant being directed through the injecting channel to mix with a leading portion of the filament for forming a colorant-containing fluid; (e) a platform disposed at a predetermined initial distance from the orifice to receive the colorant-containing fluid discharged therefrom; and (f) motion devices coupled to the platform and the nozzle for moving the nozzle and the platform relative to one another in an X-Y plane and in a Z direction orthogonal to the X-Y plane to deposit the colorant-containing fluid for forming the object. These procedures are automated by a computer system in accordance with the CAD image data files.

Advanced Rocket Nozzles.

Abstract: Several nozzle concepts that promise a gain in performance over existing conventional nozzles are discussed in this paper. It is shown that signie cant performance gains result from the adaptation of the exhaust e ow to the ambient pressure. Special attention is then given to altitude-adaptive nozzle concepts, which have recently received new interest in the space industry. Current research results are presented for dual-bell nozzles and other nozzles with devices for forced e ow separation and for plug nozzles with external freestream expansion. In addition, results of former research on nozzles of dual-mode engines such as dual-throat and dual-expander engines and on expansion ‐dee ection nozzles are shown. In general, e ow adaptation induces shocks and expansion waves, which result in exit proe les that are quite different from idealized one-dimensional assumptions. Flow phenomena observed in experiments and numerical simulations during different nozzle operations are highlighted, critical design aspects and operation conditions are discussed, and performance characteristics of selected nozzles are presented. The consideration of derived performance characteristics in launcher and trajectory optimization calculations reveal signie cant payload gains at least for some of these advanced nozzle concepts.

Continuous ink jet printer with asymmetric heating drop deflection

Abstract: A method for controlling a terminal flow of ink droplets from the nozzle of an ink jet printer at the end of a printing operation is provided The printer has a first heating element disposed on one side of the nozzle that is selectively actuated to direct ink droplets away from a recording medium and into an ink gutter during a printing operation The printer also has a second heating element disposed on the side of the nozzle opposite from the first heating element After the first heating element applies its last operational heat pulse to the printing nozzle at the end of a printing operation, the second heating element applies at least one deflection correcting heat pulse of the same duration, magnitude and period as the last operational heat pumps The method prevents ink droplets generated after the end of a printing operation from erroneously striking the printing medium

Thin-wall tube liquifier

Abstract: A rapid prototyping system has a liquifier carried by a extrusion head. The liquifier is formed of a single piece of thin-wall tubing preferably made of metal, encased in a heating block. The thin-wall tube has a inlet end for receiving a filament of molding material and an outlet end for delivering the material in liquid form. A first section of the tube adjacent the inlet end functions as the entrance or cap zone. This first section of the tube is exterior to the heating block. The tube has a second section which passes through the heating block forming a heating zone. A nozzle can be formed by swaging the outlet end of the tube to a nozzle geometry, or, a nozzle may be brazed or welded to the outlet end of the tube. The heating block preferably contains a heating element in heat exchange relation to the second section of the tube to heat the filament to a temperature just above its solidification temperature. The extrusion head may alternatively carry two liquifiers that share a common nozzle, for receiving and dispensing two different materials.

A thermally actuated ink jet

Abstract: Ink jet printer ejection nozzle (2904) has ink drop (2915) ejected by motion (2914) of thermal actuator bending when heated by current flowing through it. 29 embodiments are disclosed where flaps, paddles or nozzle chamber walls are integrally or remotely actuated by thermal bending to produce an ink drop at the nozzle, or where thermal actuators move shutters to open nozzles allowing ink under cyclic pressure to form a drop, or where a thermal actuator unlatches a magnetic flap allowing it to move by magnetic pulse to produce an ink drop. The thermal bend actuators comprise multi-layer metals or metals layered with or embedded in high coefficient of thermal expansion materials. Methods of manufacturing arrangements or arrays of these nozzles as micro electromechanical systems using planar monolithic depositing, lithographic and etching processes are disclosed. Includes 195 pages of description and 681 figures, including 47 page summary of ink jet technology.

Method of manufacture of a thermally actuated ink jet including a tapered heater element

Abstract: A method of manufacture of an ink jet printing nozzle arrangement on a wafer is disclosed, the arrangement including: an ink chamber having an ink ejection nozzle in one wall thereof for the ejection of ink from the ink chamber; a moveable paddle vane located within the ink chamber, the paddle vane including a concave surface in the area adjacent the ink ejection nozzle; and an actuator means adapted to move the paddle vane so as to cause ink within the ink chamber to be ejected from the ink ejection nozzle; the method comprising the steps of; (a) starting with a silicon wafer layer having requisite circuitry deposited thereon; (b) depositing and etching a first sacrificial layer to form a cavity for the paddle vane and a portion of the nozzle chamber; (c) depositing and etching a series of layers simultaneously forming the operational portions of the actuator means and the paddle vane; (d) depositing a second sacrificial layer forming a cavity for the ink chamber walls and remaining portions (if any) of the actuator; (e) depositing the chamber walls and remaining portions of the actuator; (f) forming a nozzle chamber roof including an ink ejection nozzle; (g) etching the sacrificial layers away. Preferably, the step (c) includes utilizing a single mask to etch the layers and step (c) further includes depositing two layers of substantially the same thermal properties, one of the layers including an operational portion of the actuator, such that, upon cooling of the layers, the two layers are in a state of thermal tension between one other.

Surface bend actuator vented ink supply ink jet printing mechanism

Abstract: An ink jet print head includes a nozzle chamber for storage of ink to be ejected from an ink ejection nozzle formed in one wall of the nozzle chamber; and a movable paddle actuator mechanism formed in a first wall of the nozzle chamber, one end of the paddle actuator traversing along a second wall of the nozzle chamber, the second wall being substantially perpendicular to the first wall; the one end further including a flange having a surface abutting the second wall, the movable paddle actuator mechanism being operable to cause the ejection of ink from the ink ejection nozzle with the flange moving substantially tangentially to the second wall.

Pulverized coal burner

Abstract: The present invention is directed to a pulverized coal burner comprising a venturi 4 for contracting flow of a mixture 62 of pulverized coal and primary air toward a central axis of a fuel nozzle 2; a spindle having a cone 10, provided coaxially with the central axis, gradually expanding from an upstream side to a downstream side and causing the mixture to impinge thereon and diffuse, a column 11, extending from the cone 10 and being parallel to the central axis of the fuel nozzle 2, and a cone 12, extending from the column 11 and gradually narrowing from an upstream side to a downstream side; and a distributor 14, having a cone 15 gradually narrowing coaxially with the central axis 3 on the downstream side of the spindle 9 and cylinder 17 extending from the cone 15 and being coaxial and parallel with the central axis of the fuel nozzle 2, and coaxially dividing the flow path.

Ink jet printhead nozzle plates

Abstract: The invention relates to improved nozzle plate designs for ink jet printers and to apparatus and methods for making the nozzle plates (10). The nozzle plates (10) of the invention are made from a polymeric material having a thickness sufficient to provide a plurality of flow features (12,14) and nozzle holes (16) aligned substantially along opposed edges of the nozzle plate (10) wherein the flow features (12,14) are ablated in the nozzle plates (10) with depths which provide decoupling of the flow features (12,14) from the nozzle holes (16) so that the flow features (12,14) and nozzle holes (16) can be independently designed in order to optimize the nozzle plate to provide improved performance.

An axisymmetric 'fluidic' nozzle to generate jet precession

Abstract: A continuously unstable precessing flow within a short cylindrical chamber following a large sudden expansion is described. The investigation relates to a nozzle designed to produce a jet which achieves large-scale mixing in the downstream field. The inlet flow in the plane of the sudden expansion is well defined and free from asymmetry. Qualitative flow visualization in water and semi-quantitative surface flow visualization in air are reported which identify this precession within the chamber. Quantitative simultaneous measurements from fast-response pressure transducers at four tapping points on the internal walls of the nozzle chamber confirm the presence of the precessing field. The investigation focuses on the flow within the nozzle chamber rather than that in the emerging jet, although the emerging flow is also visualized. Two flow modes are identified: a 'precessing jet' mode which is instantaneously highly asymmetric, and a quasi-symmetric 'axial jet' mode. The precessing jet mode, on which the investigation concentrates, predominates in the geometric configuration investigated here. A topologically consistent flow field, derived from the visualization and from the fluctuating pressure data, which describes a three-dimensional and time-dependent precessing motion of the jet within the chamber is proposed. The surface flow visualization quantifies the axial distances to lines of positive and negative bifurcation allowing comparison with related flows involving large-scale precession or flapping reported by others. The Strouhal numbers (dimensionless frequencies) of these flows are shown to be two orders of magnitude lower than that measured in the shear layer of the jet entering the chamber. The phenomenon is demonstrated to be unrelated to acoustic coupling.

Method of manufacture of a planar thermoelastic bend actuator ink jet printer

Abstract: A method of manufacturing an ink jet printhead includes providing a substrate A doped layer is deposited on the substrate and is etched to create an array of nozzles on the substrate with a nozzle chamber in communication with each nozzle Planar monolithic deposition, lithographic and etching processes are used to form a thermoelastic bend actuator arranged in the nozzle chamber and being displaceable, when activated, towards the nozzle to effect ink ejection, at least that surface of the actuator facing a floor of the nozzle chamber being hydrophobic to facilitate the formation of an air bubble between the actuator and the floor

A novel nozzle for more efficient sperm orientation to improve sorting efficiency of x and y chromosome-bearing sperm

Abstract: Efficient high-resolution detection of DNA for flow cytometric sorting of X and Y chromosome-bearing sperm is dependent on effectively orientating the sperm head to the laser beam in orthogonally configured flow systems. Normally, a beveled needle is required to enlarge the fraction of properly orientated sperm (flat side facing the laser beam). In this report, a modification to a standard jet-in-air nozzle for improved sperm orientation is presented. Inside the modified nozzle (novel nozzle), orientation forces are applied lower in the nozzle than in the current beveled injection needle system. The nozzle was tested with sperm heads from several species. This study shows that use of the nozzle to orientate cattle, swine, rabbit, mouse, and human sperm effectively improves the percentage of sperm that are properly oriented. The percentage of sperm heads oriented by use of the former system (beveled needle) ranges around 30% for most species. With the newly designed nozzle, that percentage ranges around 60%. At least a twofold increase in analysis is achieved. It was found that, unlike results with the beveled needle, the percentage of properly oriented sperm was independent of the sample rate. The introduced nozzle is a significant improvement over the beveled needle system for the analysis and sorting of sperm on the basis of DNA content. In addition to the improvement in sorted sperm production brought about by the novel nozzle when fitted to standard-speed cell sorters, it clearly also has significant potential for improving the efficiency of the Beltsville Sperm Sexing Technology for separating X and Y chromosome-bearing sperm when adapted to high-speed cell-sorting systems. Cytometry 33: 476–481, 1998. Published 1998 Wiley-Liss, Inc.

Micronozzle/diffuser flow and its application in micro valveless pumps

Abstract: The nozzle/diffuser flow with different Reynolds number ranges and conical angles is analyzed first. It is found that the flow coefficients of nozzle/diffuser ξn and ξd vary with angle with different trends for large (> 105) and small (<50) Reynolds number ranges. The flow model of valveless pumps with nozzle/diffusers is proposed, and the relationship between nozzle/diffuser flow coefficients and the performance of the valveless pumps is investigated. In experiments, silicon nozzle/diffuser elements with conical angles of 5°, 7.5° and 10° and a silicon micro valveless pump wafer are fabricated. The experimental ξd, ξn, and ξn/ξd decrease with increasing nozzle/diffuser angles in the Re range ( 2000) of the experiment. The pumping direction of the fabricated valveless pump agrees with the nozzle/diffuser flow experiments and analysis. The pump works successfully with the output flow rate of 28 μl/min under the input power of 50 mW and 500 Hz.

Fuel injection nozzle and method of use

Abstract: Atomized particles within a desired size range (eg, 1 micron to about 5 microns) are produced from two immiscible fluids, the first a fuel source containing the formulation to be atomized, and a second fluid source which is contained in a pressure chamber surrounding at least the area where the first liquid is to be provided The invention provides a method for the formation of small, relatively uniform fuel particles for use in internal combustion engines and a nozzle-type apparatus for providing the particles to a combustion chamber

A field acutated ink jet

Abstract: The ink jet printer ejection nozzle comprises a solenoid (11) which when operated, attracts the moveable plate (15) towards the fixed plate (13). This movement imparts momentum to the ink within the nozzle chamber (17). This momentum causes ejection of ink from the chamber. In addition there have been disclosed a large number of embodiments dealing with such items as: shutter means, linear stepper actuation, shape memory alloys, and methods of manufacturing a semiconductor wafer for use in an ink jet printer nozzle. The description includes 130 pages of description and 347 figures, and includes a summary of ink jet technology.

Inverted radial back-curling thermoelastic ink jet printing mechanism

Abstract: A nozzle arrangement for an ink jet printhead includes a wafer substrate having a nozzle chamber defined therein. The nozzle arrangement has a nozzle chamber wall that defines an ink ejection port and a rim about the ink ejection port. A series of radially positioned actuators are connected to the wafer substrate and extend radially inwardly towards the rim. Each actuator is configured so that a radially inner edge of each actuator is displaceable, with respect to the nozzle rim, into the chamber, upon actuation of the actuator and so that, upon such displacement, a pressure within the nozzle chamber is increased, resulting in the ejection of ink from the ejection port.

Wellbore wash nozzle system

Abstract: A wash nozzle for wellbore washing operations has been invented, the wash nozzle, in one aspect having a central mandrel with a top, a bottom, and a fluid flow bore therethrough from top to bottom, at least one mandrel port through the central mandrel for fluid flow from within the central mandrel's fluid flow bore to an exterior of the central mandrel, a hollow sleeve rotatably mounted around the central mandrel, and at least one sleeve port through the sleeve for fluid flow from within the sleeve from the exterior of the central mandrel to an exterior of the sleeve, the at least one sleeve port defined by a wall on the sleeve. In one aspect the wash nozzle includes apparatus for selective rotation of the sleeve about the mandrel. In one aspect flow through the wash nozzle is stopped to effect sleeve rotation and, in one particular aspect, flow through the nozzle is then re-established. Methods have been invented using such wash nozzles for wellbore washing operations and/or cuttings removal.

Experimental, Theoretical, and Computational Investigation of Separated Nozzle Flows

Abstract: A detailed experimental, theoretical, and computational study of separated nozzle flows has been conducted. Experimental testing was performed at the NASA Langley 16-Foot Transonic Tunnel Complex. As part of a comprehensive static performance investigation, force, moment, and pressure measurements were made and schlieren flow visualization was obtained for a sub-scale, non-axisymmetric, two-dimensional, convergent- divergent nozzle. In addition, two-dimensional numerical simulations were run using the computational fluid dynamics code PAB3D with two-equation turbulence closure and algebraic Reynolds stress modeling. For reference, experimental and computational results were compared with theoretical predictions based on one-dimensional gas dynamics and an approximate integral momentum boundary layer method. Experimental results from this study indicate that off-design overexpanded nozzle flow was dominated by shock induced boundary layer separation, which was divided into two distinct flow regimes; three- dimensional separation with partial reattachment, and fully detached two-dimensional separation. The test nozzle was observed to go through a marked transition in passing from one regime to the other. In all cases, separation provided a significant increase in static thrust efficiency compared to the ideal prediction. Results indicate that with controlled separation, the entire overexpanded range of nozzle performance would be within 10% of the peak thrust efficiency. By offering savings in weight and complexity over a conventional mechanical exhaust system, this may allow a fixed geometry nozzle to cover an entire flight envelope. The computational simulation was in excellent agreement with experimental data over most of the test range, and did a good job of modeling internal flow and thrust performance. An exception occurred at low nozzle pressure ratios, where the two-dimensional computational model was inconsistent with the three-dimensional separation observed in the experiment. In general, the computation captured the physics of the shock boundary layer interaction and shock induced boundary layer separation in the nozzle, though there were some differences in shock structure compared to experiment. Though minor, these differences could be important for studies involving flow control or thrust vectoring of separated nozzles. Combined with other observations, this indicates that more detailed, three-dimensional computational modeling needs to be conducted to more realistically simulate shock-separated nozzle flows.

Turbine nozzle assembly

Abstract: A turbine nozzle assembly includes a plurality of nozzle segments and a nozzle support for supporting the nozzle segments. Each nozzle segment includes an outer band, an inner band and at least two vanes disposed between the outer and inner bands. A retention flange extends radially inwardly from the inner band and has a first hole formed therein. The nozzle support includes a recess formed therein and a mounting flange extending therefrom. The mounting flange is disposed in contact with the retention flange and has a second hole formed therein. A pin is disposed in the first and second holes to position the flanges with respect to one another. A pin retainer is disposed in the recess and has a holding flange for retaining the pin in place. The nozzle support includes a substantially conical portion and an air seal integrally formed thereto.

Electrostatic ink jet printing mechanism

Abstract: This patent describes an ink jet printer where ink is ejected from a nozzle chamber by means of the utilisation of the electrostatic attraction between two parallel plates. An electrostatic actuator includes a first planar electrode formed within a bottom and a moveable second planar electrode arranged above the first planar electrode. The second planar electrode is moveable to a pre-firing position adjacent to the first planar electrode, thereby causing a corrugated border portion of the second electrode to concertina. Upon reduction of a potential difference, the corrugated border returns to its quiescent position, thereby causing the ejection of ink from the nozzle chamber. Between the first planar electrode and the second planar electrode is an air gap interconnected to an external atmosphere at a side of the nozzle chamber such that air flows into and out of the gap upon movement of the actuator.

Annular premix section for dry low-NOx combustors

Abstract: An annular premix section that reduces NO x and CO emissions of a gas turbine combustor by providing a more homogeneous fuel/air mixture for main stage combustion is provided. A gas turbine combustor according to the present invention includes a nozzle housing, a main fuel nozzle, and a main fuel swirler. A main combustion zone is located adjacent to the nozzle housing. The main fuel nozzle extends through the nozzle housing and is attached to a nozzle housing base. The tip of the main fuel nozzle is located downstream of the nozzle housing base. The main fuel swirler surrounds a portion of the main fuel nozzle, with a downstream end of the main fuel swirler located downstream of a main fuel injection port and upstream of the main fuel nozzle tip. The main fuel swirler is adapted to receive a flow of compressed air and to mix a fuel with the flow of compressed air to form a fuel/air mixture flow. An annular premix section, adjacent to the downstream end of the main fuel swirler, is adapted to receive and expand the fuel/air mixture flow. A contraction zone is located downstream of the premix section and upstream of the main combustion zone. The contraction zone is adapted to increase the velocity of the fuel/air mixture flow into the main combustion zone.

Apparatus for freeform fabrication of a three-dimensional object

Abstract: An improved apparatus and method for forming a three-dimensional object by planar deposition of forming materials includes containers for holding molten forming materials, mechanical piston or screw members in the containers for pressurizing the molten forming materials in each of the containers, and an adjustable planar nozzle mechanism coupled to the containers through which the pressurized molten forming materials flow to form variable width planar jets that are deposited in layers onto a substrate movable along three axes to form the three-dimensional object. The adjustable planar nozzle mechanism includes cooperating position controllable plates for forming a variable width planar nozzle opening. The edges of the planar nozzle opening are advantageously non-parallel at the ends of the nozzle opening to ensure uniform thickness of the deposited planar jets.

Mathematical Modeling and Experimental Verification of Stationary Waterjet Cleaning Process

Abstract: The use of stationary waterjet for the removal of coating material from the substrate is investigated analytically and experimentally. In the analysis, the cleaning width as a function of standoff distance, water pressure, and nozzle radius is derived by considering the structure of waterjet and the cleaning mechanism. Also derived are the relations of the optimal cleaning standoff distance and maximum cleaning width to the critical cleaning standoff distance, and how the water pressure and nozzle radius affect this critical standoff distance. These derived analytical relations are verified with experimental results.