Showing papers on "Nozzle published in 2006"

Upstream nozzle shaping effects on near field flow in round turbulent free jets

Abstract: Isothermal, incompressible round turbulent free jets of air, issuing from a sharp-edged orifice and from a contoured nozzle into still air surroundings, have been used to study the effects of upstream nozzle shaping on near field jet evolution experimentally. The Reynolds number, based on the diameter of the orifice or the nozzle, was 1.84 × 10 5 in both jets. Hot-wire anemometry and a pitot-static tube were used to obtain the measured quantities which included the mean streamwise velocity, the turbulent Reynolds normal and shear stresses, the autocorrelation coefficients and one-dimensional energy spectra of the fluctuating streamwise velocity and the mean static pressure. The mean streamwise velocity decay on the jet centerline and the jet half-velocity widths were obtained from the mean streamwise velocity data. To the extent that the results showed that mixing in the sharp-edged orifice round jet was higher than in the contoured nozzle round jet, upstream nozzle shaping was found to affect jet evolution in the near flow field. The distribution of the autocorrelation coefficients of the streamwise fluctuating velocity showed a marked difference in the evolution of the two jets, one of which had a uniform, and the other a non-uniform, exit plane mean streamwise velocity profile. The one-dimensional energy spectra results and also those of the distribution of the autocorrelation coefficients indicated the presence of coherent structures in the near field of the jets and the sharp-edged orifice jet was found to be more “energetic” than the contoured nozzle jet.

No-moving-part hybrid-synthetic jet actuator

Abstract: In contrast to usual synthetic jets, the “hybrid-synthetic jets” of non-zero time-mean nozzle mass flow rate are increasingly often considered for control of flow separation and/or transition to turbulence as well as heat and mass transfer. The paper describes tests of a scaled-up laboratory model of a new actuator version, generating the hybrid-synthetic jets without any moving components. Self-excited flow oscillation is produced by aerodynamic instability in fixed-wall cavities. The return flow in the exit nozzles is generated by jet-pumping effect. Elimination of the delicate and easily damaged moving parts in the actuator simplifies its manufacture and assembly. Operating frequency is adjusted by the length of feedback loop path. Laboratory investigations concentrated on the propagation processes taking place in the loop.

Liquid-jet head and liquid-jet apparatus

Abstract: A liquid-jet head includes: a plurality of head bodies, each having: a nozzle plate having a plurality of nozzles bored therein; a passage-forming substrate having a pressure generating chamber formed therein, which communicates with the nozzle and receives a pressure for use in ejecting a liquid droplet from a pressure generating element; and a head case disposed on the passage-forming substrate at a surface opposite to the nozzle plate and having paths for supplying liquid to the pressure generating chamber therethrough; and a fixing member bonded onto a side of the nozzle plate of each of the plurality of head bodies, to positionally fix the head bodies thereto at predetermined intervals, wherein a reinforcing portion made of a predetermined adhesive agent, which is charged in a clearance between the head bodies fixed to the fixing member, followed by setting, is disposed at the clearance.

Fuel-dispensing nozzle inhibitor

Abstract: A nozzle inhibitor is included in a fuel tank filler neck closure assembly. The nozzle inhibitor blocks full insertion of a small-diameter unleaded fuel nozzle into the filler neck closure assembly yet allows full insertion of a large-diameter diesel fuel nozzle into the filler neck closure assembly.

Scaling laws for pulsed electrohydrodynamic drop formation

Abstract: A pulsed electrohydrodynamic jet can produce on-demand drops much smaller than the delivery nozzle. This letter describes an experimentally validated model for electrically pulsed jets. Viscous drag in a thin nozzle limits the flow rate and leads to intrinsic pulsations of the cone jet. A scale analysis for intrinsic cone-jet pulsations is derived to establish the operating regime for drop deployment. The scaling laws are applicable to similar electrohydrodynamic processes in miniaturized electrospraying systems.

Evolution of a compound droplet attached to a core-shell nozzle under the action of a strong electric field

Abstract: The shape evolution of small compound droplets at the exit of a core-shell system in the presence of a sufficiently strong electric field is studied both experimentally and theoretically. It is shown that the jetting effect at the tip of the shell nozzle does not necessarily cause entrainment of the core fluid, in which case the co-electrospinning process fails to produce core-shell nanofibers. The remedy lies in extending the core nozzle outside its shell counterpart by about half the radius of the latter. The results also show that the free charges migrate very rapidly from both fluids and their interface to the free surface of the shell. This reflects the fact that most of the prejetting evolution of the droplet can be effectively described in terms of the perfect conductor model, even though the fluids can be characterized as leaky dielectrics. The stress level at the core-shell interface is of the order of 5×103g∕(cms2), the relevant value in assessing the viability of viruses, bacteria, DNA molecule...

Propulsive performance of airbreathing pulse detonation engines

Abstract: The propulsive performance of airbreathing pulse detonation engines at selected flight conditions is evaluated by means of a combined analytical/numerical analysis. The work treats the conservation equations in axisymmetric coordinates and takes into account finite-rate chemistry and variable thermophysical properties for a stoichiometric hydrogen/air mixture. In addition, an analytical model accounting for the state changes of the working fluid in pulse detonation engine operation is established to predict the engine performance in an idealized situation. The system under consideration includes a supersonic inlet, an air manifold, a valve, a detonation tube, and a convergent-divergent nozzle. Both internal and external modes of valve operation are implemented. Detailed flow evolution is explored, and various performance loss mechanisms are identified and quantified. The influences of all known effects (such as valve operation timing, filling fraction of reactants, nozzle configuration, and flight condition) on the engine propulsive performance are investigated systematically. A performance map is established over the flight Mach number of 1.2-3.5. Results indicate that the pulse detonation engine outperforms ramjet engines for all the flight conditions considered herein. The benefits of pulse detonation engines are significant at low-supersonic conditions, but gradually decrease with increasing flight Mach number.

Ballistic imaging of the near field in a diesel spray

Abstract: We have developed an optical technique called ballistic imaging to view breakup of the near-field of an atomizing spray. In this paper, we describe the successful use of a time-gated ballistic imaging instrument to obtain single-shot images of core region breakup in a transient, single hole atomizing diesel fuel spray issuing into one atmosphere. We present a sequence of images taken at the nozzle for various times after start of injection, and a sequence taken at various positions downstream of the nozzle exit at a fixed time. These images contain signatures of periodic behavior, voids, and entrainment processes.

Direct Liquid Jet-Impingment Cooling With Micron-Sized Nozzle Array and Distributed Return Architecture

Abstract: We demonstrate submerged single-phase direct liquid-jet-impingement cold plates that use arrays of jets with diameters in the range of 31 to 126 mum and cell pitches from 100 to 500 mum for high power-density microprocessor cooling applications. Using parallel inlet and outlet manifolds, a distributed return concept for easy scaling to 40,000 cells on an area of 4 cm was implemented. Pressure drops < 0.1 bar at 2.5 1/min flow rate have been reached with a hierarchical tree-like double-branching manifold. Experiments were carried out with water jets having Reynolds numbers smaller than 900 at nozzle to heater gaps ranging between 3 to 300 mum. We identified four flow regimes, namely, pinch-off, transition, impingement, and separation, with different influences on heat-removal and pressure-drop characteristics. Parametric analysis resulted in an optimal heat-removal rate of 420 W/cm2 using water as a coolant. For a near optimal design with a gap to inlet diameter ratio of 1.2, we measured a heat-transfer coefficient of 8.7 W/cm2 K and a junction to inlet fluid unit thermal resistance of 0.17 Kcm2 /W (720 mum chip), which is equivalent to a 370 W/cm2 cooling performance at a junction to inlet fluid temperature rise of 63 degC, a pressure drop of 0.35 bar, and a flow rate of 2.5 1/min

A comparative study of a spray dryer with rotary disc atomizer and pressure nozzle using computational fluid dynamic simulations

Abstract: Spray drying operations with rotary disc atomizers as well as pressure nozzles as atomizing devices are widely used in diverse industries. The design of spray dryers is typically optimized for the design conditions. However, users sometimes need to use the same spray dryer chamber with some modifications due to the requirements of different products and or production rates. In this paper, we present results of a computational fluid dynamic study carried out to investigate the possibility of multi-functional applications of a specific spray dryer chamber. The predicted airflow pattern is validated by favorable comparison with published data. The airflow pattern and temperature distributions predicted by the model at different levels in the drying chamber are presented and discussed. The effects of different atomizer designs are also investigated. Note that the two types of atomizers yield very different droplet size distributions as well as spray patterns. The volumetric evaporation rate values, heat transfer intensity and thermal energy consumption per unit evaporation are computed and compared for drying of a 42.5% solids maltodextrin suspension in a spray chamber 2.2 m in diameter with a cylindrical top section 2.0 m high and a bottom cone 1.7 m high. Wall regions most susceptible to formation of undesirable deposits are also identified. Computed droplet trajectories for the two spray patterns are shown to display very different flow, temperature and drying characteristics.

Influence of a Conical Axial Injector on Hybrid Rocket Performance

Abstract: This paper was aimed at analyzing the static engine firings results obtained by means of a hybrid rocket where gaseous oxygen was supplied into axial-symmetric polyethylene cylindrical grains through two different injector configurations: an axial conical subsonic nozzle and a radial injector. The axial injector is considered interesting because of its easy design and the remarkable feature that it produces no significant pressure oscillations for the stabilizing effect due to the hot gas recirculation zone established within the combustion port. To take advantage of its qualities, the assessment of the regression rate variations under the flow field generated by this configuration is required. For the investigated set of operating conditions, the instantaneous regression rates exhibit a time-and-space dependence caused by the impinging jet zone dynamics, while the average regression rates are higher and less mass flux dependent than those achieved with the radial injection motor and expected from the turbulent flow through pipes. A comparison to the data from the radial injector was further drawn in terms of combustion efficiency, fuel consumption profiles, and combustion stability. The radial injector, at the same mass flux and pressure, produces lower regression rates, high pressure oscillations and worse combustion efficiency at the same L*, but more uniform fuel consumption.

Substrate processing apparatus and substrate processing method

Abstract: If change arises to the vacuum pressure of the vacuum mechanism in which it is used in order to stabilize surfacing power, the control circuit of a nozzle height position compensation part detects change of the vacuum pressure through a pressure sensor, the control signal which has the fixed response characteristic to change of such vacuum pressure is generated, and drive control of piezo-electric actuator is carried out, and variable control of the height position of a resist nozzle is carried out by the displacement generated from piezo-electric actuator. When the surfacing height of the substrate G is displaced upwards rather than the setting surfacing height Hb according to change of the vacuum pressure of a vacuum mechanism, the displacement of the resist nozzle 78 is carried out the almost same displacement at the same timing as the displacement of the substrate G, and the gap S of the resist nozzle 78 and Substrate G is kept consequent to a setting value.

Removable applicator nozzle for ultrasound wound therapy device

Abstract: A removable applicator nozzle for use in treating a wound is provided. The removable applicator nozzle includes a nozzle, a valve and a cup. The nozzle includes a proximal portion, a distal opening and a valve interface. The proximal portion of the nozzle is engagable with a portion of a transducer of an ultrasound wound therapy device. The distal opening of the nozzle allows at least a portion of a tip of the transducer to pass therethrough. The valve is engagable with the valve interface of the nozzle and the valve selectively allows fluid to flow therethrough. The cup includes an aperture and a puncturing device. The aperture is engagable with the valve and the puncturing device is able to puncture a bottle that is inserted on the cup. Fluid flows from the bottle, through the aperture and the valve and onto a tip of the transducer. The fluid is then moved to the distal opening of the nozzle by a vacuum effect.

Spray Characteristics of a Multi-hole Injector for Direct-Injection Gasoline Engines:

Abstract: The sprays from a high-pressure multi-hole nozzle injected into a constant-volume chamber have been visualized and quantified in terms of droplet velocity and diameter with a two-component phase Doppler anemometry (PDA) system at injection pressures up to 200 bar and chamber pressures varying from atmospheric to 12 bar. The flow characteristics within the injection system were quantified by means of a fuel injection equipment (FIE) one-dimensional model, providing the injection rate and the injection velocity in the presence of hole cavitation, by an in-house three-dimensional computational fluid dynamics (CFD) model providing the detailed flow distribution for various combinations of nozzle hole configurations, and by a fuel atomization model giving estimates of the droplet size very near to the nozzle exit. The overall spray angle relative to the axis of the injector was found to be almost independent of injection and chamber pressure, a significant advantage relative to swirl pressure atomizers. Temporal droplet velocities were found to increase sharply at the start of injection and then to remain unchanged during the main part of injection, before decreasing rapidly towards the end of injection. The spatial droplet velocity profiles were jet-like at all axial locations, with the local velocity maximum found at the centre of the jet. Within the measured range, the effect of injection pressure on droplet size was rather small while the increase in chamber pressure from atmospheric to 12 bar resulted in much smaller droplet velocities, by up to four-fold, and larger droplet sizes by up to 40 per cent.

Cold spray modeling and validation using an optical diagnostic method

Abstract: The Cold Gas Dynamic Spray process uses the kinetic energy of unmelted sprayed particles to produce coatings. The most important element of the cold spray system is the nozzle used to accelerate the particles. Consequently, the nozzle design optimisation is a key to improve the coating quality and reduce the spraying costs. In this study, an axi-symmetric two-dimensional mathematical model is presented and used to predict the flow inside a cold spray nozzle as well as the particle velocity in the vicinity of the nozzle exit. The model results are compared with those obtained using the one-dimensional isentropic theory and with particle velocity measurements made on a commercial cold spray system. The study shows that the particle exit velocity depends on the type, stagnation temperature, and pressure of the propellant gas. The comparisons show that the proposed model is more accurate than the one-dimensional theory. It allows predicting accurately the behavior of the particles in the cold spray jet even in the presence of shock waves. Following this work, the design of new nozzles for specific applications using this mathematical model can be considered.

Effects of some process parameters on the structure and properties of vortex spun yarn

Abstract: The effects of a number of process parameters, including the nozzle angle, nozzle pressure, spindle diameter, yarn delivery speed, and distance between the front roller and the spindle, on the stru...

Methods and apparatus for injecting fluids into a turbine engine

Abstract: A method facilitates operating a gas turbine engine (10). The method comprises supplying steam to a nozzle (50), supplying primary fuel to the nozzle, discharging the steam into a combustor (16) from a plurality of circumferentially-spaced steam outlets (106) defined in a tip (100) of the nozzle, and discharging the primary fuel into the combustor from at least one outlet (104) that is spaced circumferentially between the steam outlets.

Method and apparatus for promoting the complete transfer of liquid drops from a nozzle

Abstract: A printhead device for transferring liquid droplets from a nozzle includes a liquid source coupled to a nozzle via a microchannel. The nozzle is formed from an orifice having an inner circumferential surface, wherein at least a portion of the inner circumferential surface is serrated. Liquid droplets are transported from the source to the nozzle using a liquid droplet driver (e.g., employing a plurality of driving electrodes). Transfer of droplets to another surface can be accomplished by contacting a bulging droplet in the nozzle with a printing surface. The surface and/or nozzle are then moved relative to one another to effectuate complete transfer of the liquid drop from the nozzle.

Burner, gas turbine combustor, burner cooling method, and burner modifying method

Abstract: In a burner for injecting mixed gas fuel containing at least one of hydrogen and carbon monoxide into a combustion chamber of a gas turbine combustor, the burner includes a fuel nozzle for startup from which liquid fuel is injected into the combustion chamber, and a mixed fuel nozzle disposed around the fuel nozzle for injecting the mixed gas fuel. An air swirler is disposed at a downstream end of the mixed fuel nozzle and has a plurality of flow passages from which compressed air is injected into the combustion chamber, and the mixed fuel nozzle has injection ports disposed in the inner peripheral side of the flow passages of the air swirler. Cooling holes formed in the nozzle surface and positioned to face the combustion chamber introduce a part of the mixed gas fuel injected from the mixed fuel nozzle into the combustion chamber.

Toilet bowl cleaning and/or deodorizing device

Abstract: A device for spraying an inner surface of a toilet bowl with a cleaning and/or deodorizing chemical is disclosed. The device includes a container for the chemical, a spray nozzle through which the chemical can be sprayed laterally around a perimeter of the nozzle, a conduit in fluid communication with the container and the spray nozzle, fluid delivery means for delivering chemical from the container through the conduit and to the spray nozzle, and means for attaching the spray nozzle near a rim of the toilet bowl. The spray nozzle of the automatic or manual toilet bowl cleaning device can operate such that the chemical is applied to the entire circumference of the inner surface of the toilet bowl whereby the entire toilet bowl is cleaned around the inner circumference of the toilet bowl.

Method and apparatus for actively controlling fuel flow to a mixer assembly of a gas turbine engine combustor

Abstract: An apparatus for actively controlling fuel flow from a fuel pump to a mixer assembly of a gas turbine engine combustor, where the mixer assembly includes a pilot mixer and a main mixer. The pilot mixer further includes an annular pilot housing having a hollow interior, a primary fuel injector mounted in the pilot housing and adapted for dispensing droplets of fuel to the hollow interior of the pilot housing, a plurality of axial swirlers positioned upstream from the primary fuel injector. The fuel flow control apparatus further includes: at least one sensor for detecting dynamic pressure in the combustor; a fuel nozzle; and, a system for controlling fuel flow supplied by the fuel nozzle through the valves. The fuel nozzle includes: a feed strip with a plurality of circuits for providing fuel to the pilot mixer and the main mixer; and, a plurality of valves associated with the fuel nozzle and in flow communication with the feed strip thereof. The control system activates the valves in accordance with signals received from the pressure sensor.

Combustion turbine engine and methods of assembly

Abstract: A method of assembling a combustion turbine engine in provided. The method includes coupling at least one fuel nozzle inner atomized air tube to a combustor end cover plate body. The method also includes assembling a fuel nozzle insert sub-assembly by inserting at least one flow control apparatus into a fuel nozzle insert sub-assembly body. The method further includes inserting at least one seal between the combustor end cover plate body and the fuel nozzle insert sub-assembly body as well as inserting at least one seal between the combustor end cover plate body and the fuel nozzle insert sub-assembly body. The method also includes coupling the fuel nozzle insert sub-assembly to the combustor end cover plate body. The method further includes inserting at least one bellows onto a bellows support fitting and inserting the bellows support fitting onto a fuel nozzle insert sub-assembly body support surface. The method also includes assembling a fuel nozzle sub-assembly. The method further includes assembling a fuel nozzle assembly by coupling the fuel nozzle sub-assembly to the combustor end cover plate body.

Tri-body variable area fan nozzle and thrust reverser

Abstract: A gas turbine engine system includes a fan (14), a housing (28) arranged about the fan, a gas turbine engine core having a compressor (16) at least partially within the housing, and a fan bypass passage (30) downstream of the fan for conveying a bypass airflow (D) between the housing and the gas turbine engine core. A nozzle (40) associated with the fan bypass passage includes a first nozzle section (54a) that is operative to move in a generally axial direction to influence the bypass airflow, and a second nozzle section that is operative to also move in a generally axial direction between a stowed position and a thrust reverse position that diverts the bypass airflow in a thrust reversing direction. An actuator (42) selectively moves the first nozzle section and the second nozzle section to influence the bypass airflow and provide thrust reversal.

The Investigation of Gravity-Driven Metal Powder Flow in Coaxial Nozzle for Laser-Aided Direct Metal Deposition Process

Abstract: The quality and efficiency of laser-aided direct metal deposition largely depends on the powder stream structure below the nozzle. Numerical modeling of the powder concentration distribution is complex due to the complex phenomena involved in the two-phase turbulence flow. In this paper, the gravity-driven powder flow is studied along with powder properties, nozzle geometries, and shielding gas settings. A 3-D numerical model is introduced to quantitatively predict the powder stream concentration variation in order to facilitate coaxial nozzle design optimizations. Effects of outer shielding gas directions, inner/outer shielding gas flow rate, powder passage directions, and opening width on the structure of the powder stream are systematically studied. An experimental setup is designed to quantitatively measure the particle concentration directly for this process. The numerical simulation results are compared with the experimental data using prototyped coaxial nozzles. The results are found to match and then validate the simulation. This study shows that the particle concentration mode is influenced significantly by nozzle geometries and gas settings.