Showing papers on "Nozzle published in 2000"

A fully integrated monolithic microchip electrospray device for mass spectrometry

Abstract: A novel microfabricated nozzle has been developed for the electrospray of liquids from microfluidic devices for analysis by mass spectrometry. The electrospray device was fabricated from a monolithic silicon substrate using deep reactive ion etching and other standard semiconductor techniques to etch nozzles from the planar surface of a silicon wafer. A channel extends through the wafer from the tip of the nozzle to a reservoir etched into the opposite planar surface of the wafer. Nozzle diameters as small as 15 μm have been fabricated using this method. The microfabricated electrospray device provides a reproducible, controllable, and robust means of producing nanoelectrospray of a liquid sample. The electrospray device was interfaced to an atmospheric pressure ionization time-of-flight mass spectrometer using continuous infusion of test compounds at low nanoliter-per-minute flow rates. Nozzle-to-nozzle signal intensity reproducibility using 10 nozzles was demonstrated to be 12% with single-nozzle signal...

Numerical and experimental studies of flat-walled diffuser elements for valve-less micropumps

Abstract: An investigation of flat-walled diffuser elements for valve-less micropumps is presented. The diffuser element is a small angle flow channel with a rounded inlet and a preferably sharp outlet. The diverging-wall direction is the positive flow direction. The flow-directing capability under steady flow conditions was determined experimentally for several different diffuser elements. The flow-pressure characteristic was studied in detail for one of them. The result is compared with previously published results on pump performance. Numerical simulations were done using the Computational Fluid Dynamics program ANSYS/Flotran. The simulations show the flow-directing capability of the diffuser elements and predict the flow-pressure characteristics well for Reynolds numbers below 300-400. For higher Reynolds numbers, the simulations show the flow-directing capability, but there is a larger discrepancy between simulations and measurements. Simulations were also done for a nozzle element, a wide-angle flow channel with sharp inlet and outlets used in the micropump with dynamic passive-valves. A nozzle element has the converging-wall direction as positive flow direction. The simulations show differences in the flow patterns for diffuser elements and nozzle elements that explain the opposite positive flow directions. The diffuser element has an ordered flow and takes advantage of the pressure recovery in the diverging-wall direction. The nozzle element has gross flow separation in the diverging-wall direction and there is a vena-contracta effect instead of pressure recovery. The effective cross-sectional area is smaller in the diverging-wall direction than in the converging-wall direction.

The flow structure inside a microfabricated inkjet printhead

Abstract: A micrometer resolution particle image velocimetry system has been adapted to measure instantaneous velocity fields in an inkjet printhead. The technique uses 700-nm-diameter fluorescent flow tracing particles, a pulsed Nd:YAG laser, an epi-fluorescent microscope, and a cooled interline transfer charge-coupled device camera to record images of flow tracing particles at two known instances in time. Instantaneous velocity vector fields are obtained with spatial resolutions of 5-10 /spl mu/m and temporal resolutions of 2-5 /spl mu/s. The relationship between instantaneous velocity fields is compared to instantaneous shapes of the meniscus. The flow in the nozzle is highly unsteady and characterized by a maximum velocity of 8 ms/sup -1/, Reynolds numbers of Re=500, and accelerations of up to 70 000 times gravity (i.e., 70 000 g). Since the flow field is periodic for each ejection cycle, the instantaneous measurements can be phased averaged to determine the evolution of the average flow field. The ejection cycle period is 500 /spl mu/s, and consists of four primary phases: infusion, inversion, ejection, and relaxation. During infusion, the actuator plate is deflected downward creating a low pressure that draws fluid into the inkjet cavity through the orifice and pulls the meniscus into the cavity through the nozzle. The meniscus grows, begins to decrease in size, and then deforms in shape, becoming inverted for approximately 6 /spl mu/s. The meniscus exits the cavity through the nozzle during droplet ejection. During relaxation, the flow undergoes viscously-damped oscillations, and reaches equilibrium before the next ejection cycle begins.

Kinetic spray coating method and apparatus

Abstract: A method and apparatus is disclosed for kinetic spray coating of substrate surfaces by impingement of air or gas entrained powders of small particles in a range up to at least 106 microns accelerated to supersonic velocity in a spray nozzle. Preferably powders of metals, alloys, polymers and mixtures thereof or with semiconductors or ceramics are entrained in unheated air and passed through an injection tube into a larger flow of heated air for mixing and acceleration through a supersonic nozzle for coating of an article by impingement of the yieldable particles. A preferred apparatus includes a high pressure air supply carrying entrained particles exceeding 50 microns through an injection tube into heated air in a mixing chamber for mixing and acceleration in the nozzle. The mixing chamber is supplied with high pressure heated air through a main air passage having an area ratio relative to the injection tube of at least 80/1.

Restricted Shock Separation in Rocket Nozzles

Abstract: In overexpanded rocket nozzles the e ow separates from the nozzle wall at a certain pressure ratio of wall pressure to ambient pressure. Flow separation and its theoretical prediction have been the subject of several experimental and theoretical studies in the past decades. Two distinctive e ow separation phenomena, the freeshock and restricted-shock separation, were observed in experiments with nozzles. Both phenomena are discussed in detail, and the system of recompression shocks and expansion waves is described. For the free-shock case three different shock structures in theplume can occur, namely the regular shock ree ection, the Mach disk, or a cap-like shock pattern. Theappearanceofthesedifferentplumepatternsis discussed. Theseshock structuresareconserved for the full-e owing, but overexpanded, nozzle. Numerical results obtained for existing rocket nozzles, e.g., Space ShuttleMain EngineorVulcain, show a qualitativegood agreement with experimental photographs.Furthermore, an explanation for the appearance of restricted shock separation, which has been widely unknown up to now, is given, analyzing why and under what conditions it occurs. The type of nozzle contour strongly ine uences this form of e ow separation, and restricted shock separation also occursin full-scale, thrust-optimized rocket nozzles. Based on the results established for e ow separation, an outlook on the generation of side loads is given.

Ink jet apparatus having amplified asymmetric heating drop deflection

Abstract: Apparatus for controlling ink in a continuous ink jet printer includes an ink delivery channel; a source of pressurized ink communicating with the ink delivery channel; a nozzle bore which opens into the ink delivery channel to establish a continuous flow of ink in a stream, the nozzle bore defining a nozzle bore perimeter; a drop generator which causes the stream to break up into a plurality of drops at a position spaced from the ink stream generator; and a drop deflector. The drop generator includes a heater having a selectively-actuated section associated with only a portion of the nozzle bore perimeter, whereby actuation of the heater section produces an asymmetric application of heat to the stream to partially control the direction of the stream. The drop deflector includes a gas flow source producing an additional control to the stream between a print direction and a non-print direction.

Acoustics and Trust of Separate-Flow Exhaust Nozzles With Mixing Devices for High-Bypass-Ratio Engines

Abstract: The NASA Glenn Research Center recently completed an experimental study to reduce the jet noise from modern turbofan engines. The study concentrated on exhaust nozzle designs for high-bypass-ratio engines. These designs modified the core and fan nozzles individually and simultaneously. Several designs provided an ideal jet noise reduction of over 2.5 EPNdB for the effective perceived noise level (EPNL) metric. Noise data, after correcting for takeoff thrust losses, indicated over a 2.0-EPNdB reduction for nine designs. Individually modifying the fan nozzle did not provide attractive EPNL reductions. Designs in which only the core nozzle was modified provided greater EPNL reductions. Designs in which core and fan nozzles were modified simultaneously provided the greatest EPNL reduction. The best nozzle design had a 2.7-EPNdB reduction (corrected for takeoff thrust loss) with a 0.06-point cruise thrust loss. This design simultaneously employed chevrons on the core and fan nozzles. In comparison with chevrons, tabs appeared to be an inefficient method for reducing jet noise. Data trends indicate that the sum of the thrust losses from individually modifying core and fan nozzles did not generally equal the thrust loss from modifying them simultaneously. Flow blockage from tabs did not scale directly with cruise thrust loss and the interaction between fan flow and the core nozzle seemed to strongly affect noise and cruise performance. Finally, the nozzle configuration candidates for full-scale engine demonstrations are identified.

Quick disconnect nozzle assembly

Abstract: A spraying system having a plurality of spray nozzle assemblies mounted on a common liquid supply header. The spray nozzle assemblies each include a nozzle body fixed to the header and a spray tip secured to the body as an incident to rotation of the spray tip relative to the body. Each spray tip has an elongated discharge orifice adapted for emitting a flat spray pattern and is formed with radial gripping wings in aligned relation to the elongated discharge orifice which enable the user to know the orientation of the discharge orifice, and hence the orientation of the flat discharging spray pattern, prior to start up of a spray operation. The nozzle bodies further each are formed with at least one pair of indicator nibs, which when disposed in longitudinal alignment with the liquid supply header, automatically establishes an orientation of the spray tip elongated discharge orifice at a predetermined relative small angle to the axis of the header so as to avoid impingement of the discharging flat spray patterns of adjacent nozzle assemblies. An alternative embodiment of a spray tip has a slightly modified locking lug design for effecting mounting of the spray tip in the common body with the discharge orifice aligned with the axis of the fluid supply header. Further alternative embodiments include a spray nozzle with a swivel mounted adapter and quick disconnect spray tip, or with an adapter having a screw-in orifice defining insert for the particular spray application.

Ceramic turbine nozzle

Abstract: A turbine nozzle includes ceramic outer and inner bands, with a ceramic vane forward segment integrally joined thereto. A ceramic vane aft segment has opposite ends trapped in complementary sockets in the bands.

Misregistration correction for bidirectional printing in consideration of inclination of nozzle array

Abstract: A correction value, which is used to correct misalignment of recording positions in a main scanning direction, is determined using a representative nozzle sub-array as a reference. The representative nozzle sub-array is within a predetermined range around the center of a nozzle array provided on a print head. The correction value is set, based on a positional misalignment test pattern printed with the representative nozzle sub-array. The misalignment of recording positions in the main scanning direction in the course of bidirectional printing is corrected with the correction value.

Enhanced X-ray emission in the 1-keV range from a laser-irradiated gas puff target produced using the double-nozzle setup

Abstract: X-ray emission from a double-stream gas puff target irradiated with a nanosecond Nd:glass laser pulse was studied for the first time. The target was formed by pulsed injection of a high-density gas into a gas cloud by using the double-nozzle setup. This new concept allows a high-density gaseous target to be formed at a relatively large distance from the nozzle output. Enhanced X-ray emission in the 1-keV energy range and a smaller source size were observed as compared to the ordinary gas puff target created by pulsed injection of gas into vacuum. This new approach should be useful in the development of a laser-produced X-ray source for various applications.

Self-cooled oxygen-fuel burner for use in high-temperature and high-particulate furnaces

Abstract: A self-cooled oxidant-fuel burner consisting novel fuel and oxidant nozzles and three compartment refractory burner block design is proposed. The new oxidant-fuel burner can fire in high-temperature (2200° F. to 3000° F.) and high-particulate (or high process volatiles/condensates) furnaces without over-heating or causing chemical corrosion damage to it's metallic burner nozzle and refractory burner block interior. Using various embodiments of nozzle and block shape, the burner can offer a traditional cylindrical flame or flat flame depending on the heating load requirements. The new features of this burner include unique fuel nozzle design for the streamline mixing of fuel and oxidant streams, a controlled swirl input to the oxidant flow for desired flame characteristics, a controlled expansion of flame envelope in the radial and axial dimensions, and efficient sweeping of burner block interior surface using oxidant to provide convective cooling and prevent any build up of process particulates. In addition, a relatively thick wall metallic nozzle construction with heat conduction fins enable efficient heat dissipation from the nozzle tip and providing a maintenance free burner operation.

Effects of Slot Bleed Injection Over a Contoured Endwall on Nozzle Guide Vane Cooling Performance: Part I — Flow Field Measurements

Abstract: Endwall heat transfer has become a major issue in the design of the inlet nozzle guide vane region of modern gas turbine engines. To compensate for high rates of convective heat transfer and the uncertain flow pattern along endwall surfaces, coolant flows are often excessive and distributed in a less than optimum fashion. In many instances, coolant is carried away or mixed into the core flow by the secondary flows without being effective. There is a need for more effective cooling concepts. In this paper, the results of an experimental study examining the thermal performance of bleed injection through an inclined slot positioned upstream of the nozzle airfoil leading edge plane are presented. This paper demonstrates that this type of combustor bleed cooling is a promising cooling concept. Testing is performed in a large-scale, guide vane cascade comprised of three airfoils between one contoured and one flat endwall. The Reynolds number, based upon approach velocity and true chord length, is 350,000 and the approach flow is with large-scale, high-intensity (9.5%) turbulence. Combustor bleed cooling flow is injected ahead of a contoured endwall with bleed-to-core mass flow ratios as high as 6%. Measurements are taken to document core flow temperature distributions at several axial positions within the cascade to evaluate surface adiabatic effectiveness values and local heat transfer coefficients. This film cooling arrangement offers significant thermal protection. The coolant is shown to provide thermal protection over most of the endwall as well as portions of the pressure and suction surfaces of the airfoils. To achieve this coverage, combustor bleed flow must be strong enough to overcome the influence of endwall region secondary flows.Copyright © 2000 by ASME

Non-lethal personal defense device

Abstract: A non-lethal personal defense device that may be carried by a user includes a housing, a nozzle having a discharge orifice, a control valve coupled to the nozzle, a pressurized source containing a bio-active agent and coupled to the nozzle, a rangefinder for determining a range to a target, a trigger mechanism for activating firing of the device and a firing controller. The firing controller operates the control valve to discharge an aerosol plume of the bio-active agent through the nozzle in response to activation of the trigger mechanism and in response to the range determined by the rangefinder. The nozzle may include a spray orifice for discharging a pulsed aerosol spray plume at relatively long range and a mist orifice for discharging a pulsed mist aerosol plume at relatively short range. The pulse parameters are varied in response to the sensed range to the attacker. The personal defense device may optionally include a one or more cameras and a wireless communication link for transmitting status information, images and audio to a monitoring station.

Vaporizing liquid microthruster

Abstract: MEMS technology is expanding into increasingly diverse applications. As part of a micropropulsion system, microthruster attitude controls have been micromachined in silicon. This paper presents the microthruster design, fabrication, and test results. Fluid injected into a microchamber is vaporized by resistive silicon heaters. The exiting vapor generates the thruster force as it exits a silicon micro-nozzle. The vaporization chamber, inlet and exit nozzles were fabricated using anisotropic wet etching of silicon. With a 5 W heater input, injected water could be vaporized for input flow rates up to a maximum of 0.09 cc/s. Experimental testing produced thruster force magnitudes ranging from 0.15 mN to a maximum force output of 0.46 mN depending on fabrication parameters: chamber length, nozzle geometries, heater power, and liquid flow rates.

Rapid comestible fluid dispensing apparatus and method

Abstract: A nozzle assembly (40) is disclosed that is capable of controlling pressure of comestible fluid exiting the nozzle assembly (40). The nozzle assembly (40) further includes a hand held comestible fluid dispenser (16) capable of cooling and selectively dispensing one of several comestible fluids supplied thereto.

Method and apparatus for fluid jet formation

Abstract: A method and apparatus for controlling the coherence of a high-pressure fluid jet directed toward a selected surface. In one embodiment, the coherence is controlled by manipulating a turbulence level of the fluid forming the fluid jet. The turbulence level can be manipulated upstream or downstream of a nozzle orifice through which the fluid passes. For example, in one embodiment, the fluid is a first fluid and a secondary fluid is entrained with the first fluid. The resulting fluid jet, which includes both the primary and secondary fluids, can be directed toward the selected surface so as to cut, mill, roughen, peen, or otherwise treat the selected surface. The characteristics of the secondary fluid can be selected to either increase or decrease the coherence of the fluid jet. In other embodiments, turbulence generators, such as inverted conical channels, upstream orifices, protrusions and other devices can be positioned upstream of the nozzle orifice to control the coherence of the resulting fluid jet.

Machining head and laser machining apparatus

Abstract: A machining head of a laser machining apparatus comprises a main assist gas nozzle at the center portion of the machining head for supplying a main assist gas and one or more annular sub assist gas nozzles surrounding the main assist gas nozzle, whose jet outlet of the innermost diameter is larger or equal to the jet outlet of main assist gas. The jet outlet of the main assist gas nozzle is positioned at upstream of said jet outlets of the respective sub assist gas nozzle. According to the above construction, the jet gas pressure and the jet gas velocity vary continuously at the assist gas jet outlet and the jet gas pressure and flow velocity fluctuation of the main assist gas are increased.