Multiple Nozzles Research Articles

Pilot-scale development of cavitation-jet deinking

A new deinking method for paper recycling using a fluid-jet cavitation technique has been developed. An in-house, laboratory-scale device revealed that cavitation-jet treatment without deinking chemicals decreases ink and dirt content in deinked pulp. As the next step, a pilot-scale deinking device, 10 times larger than the laboratory device, was designed. The specifications of the pilot device were determined by experiments using the laboratory device. The pilot device was installed in a deinked pulp mill, and the effects of multijet nozzles within a reacting vessel, depending on consistencies of the deinked pulp, were investigated. The operation stability of the device was examined as well. The shape and size of an effective cavitation zone for ink detachment were changed by nozzle diameter and upstream pressure of the jet. The results from batch cavitation treatment of deinked pulp revealed that the device could treat the pulp with consistency up to 3.8% by weight and decrease attached ink, dirt specks, and macrostickies without addition of deinking chemicals. Hydrophobic colloidal materials, including microstickies after cavitation treatment, became more difficult to attach to hydrophobic surfaces. Continuous cavitation treatment gave similar results to those from batch treatment. Two types of multiple nozzle arrangements, parallel and cross-nozzle modes, decreased dirt specks to the same level as a mill disperser. On the other hand, the reductions of macrostickies by those modes were higher than with the disperser. Because treatment consistency increased more than 3%, treatment efficiency and device performance were significantly improved. This could be a big step toward practical use of cavitation treatment.

Compressible dynamic stall control using high momentum microjets

Control of the dynamic stall process of a NACA 0015 airfoil undergoing periodic pitching motion is investigated experimentally at the NASA Ames compressible dynamic stall facility. Multiple microjet nozzles distributed uniformly in the first 12 % chord from the airfoil’s leading edge are used for the dynamic stall control. Point diffraction interferometry technique is used to characterize the control effectiveness, both qualitatively and quantitatively. The microjet control has been found to be very effective in suppressing both the emergence of the dynamic stall vortex and the associated massive flow separation at the entire operating range of angles of attack. At the high Mach number (M = 0.4), the use of microjets appears to eliminate the shock structures that are responsible for triggering the shock-induced separation, establishing the fact that the use of microjets is effective in controlling dynamic stall with a strong compressibility effect. In general, microjet control has an overall positive effect in terms of maintaining leading edge suction pressure and preventing flow separation.

Experimental Study on the Cavitation Characteristics of an Oil Jet Pump With Multiple Nozzles for the Lubrication System in a Steam Turbine

Cavitation characteristics of oil jet pumps with multiple nozzles were studied using high frequency response pressure transducers with Mobile DTE Light Oil in experiment, which has an environment the same as that in the lubrication system of the steam turbine in a power plant. The influence of working oil pressure, pressure ratio, and area ratio on cavitation characteristics were studied with the area ratio ranging from 4 to 9, and the working oil pressure ranging from 1.8 to 2.8 MPa. Results show that the cavitation erosion on the throat surface is caused by the intense shear layer of high-speed jet in the throat, which leads to the collapse of vortex cavitation bubbles near the throat surface in an oil jet pump with multiple nozzles. What is more, the vortex cavitation is difficult to eradicate in an oil jet pump with multiple nozzles for the lubrication system of a steam turbine. However, there is a working point with low cavitation intensity, which is also the high efficiency point that ensures both relative safety and high efficiency. This study provides quantitative relation for the determination of working oil pressure, area ratio, and pressure ratio of an oil jet pump with multiple nozzles, which is significant for engineering.

An orthogonal analysis method for decoupling the nozzle geometrical parameters of microthrusters

This paper proposes an orthogonal analysis method for decoupling the multiple nozzle geometrical parameters of microthrusters, thus an reconfigured design can be implemented to generate a proper thrust. In this method, the effects of various nozzle geometrical parameters, including throat width Wt, half convergence angle ?in, half divergence angle ?out, exit-to-throat section ratio We/Wt and throat radius of the curvature Rt/Wt, on the performance of microthrusters are sorted by range analysis. Analysis results show that throat width seriously affects thrust because range value of 67.53 mN is extremely larger than the range value of other geometry parameters. For average specific impulse (ASI), the range value of exit-to-throat section ratio We/Wt and half divergence angle ?out are 4.82 s and 3.72 s, respectively. Half convergence angle with the range value of 0.39 s and throat radius with 0.32 s have less influence on ASI compared with exit-to-throat section ratio and half divergence angle. When increasing the half convergence angle from 10° to 40° and throat radius of the curvature from 3 to 9, average specific impulse initially decreases and then increases. A MEMS solid propellant thruster (MSPT) with the reconfigured geometrical parameters of nozzle is fabricated to verify the feasibility of the proposed method. The thrust of the microthruster can reach 25 mN. Power is estimated to be 0.84 W. This work provides design guideline to reasonably configure geometry parameters of microthruster.

Multi-material, multi-technology FDM: exploring build process variations

Purpose – The purpose of this paper is to investigate a build process variation for fused deposition modeling (FDM) in which contours and rasters (also referred to as internal fill patterns) are built using different layer thicknesses and road widths. In particular, the paper examines the effect of the build process variation on surface roughness, production times and mechanical properties. Additionally, a unique FDM process was developed that enabled the deposition of discrete multiple materials at different layers and regions within layers. Design/methodology/approach – A multi-material, multi-technology FDM system was developed and constructed to enable the production of parts using either discrete multi-materials or the build process variation (variable layer thickness and road width). Two legacy FDM machines were modified and installed onto a single manufacturing system to allow the strategic, spatially controlled thermoplastic deposition with multiple extrusion nozzles of multiple materials during the same build. This automated process was enabled by the use of a build platform attached to a pneumatic slide that moved the platform between the two FDM systems, an overall control system, a central PC and a custom-made program (FDMotion) and graphic user interface. The term multi-technology FDM system used here implies the two FDM systems and the integration of these systems into a single manufacturing environment using the movable platform and associated hardware and software. Future work will integrate additional technologies within this system. Parts produced using the build process variation utilized internal roads with 1,524 μm road width and 508 μm layer height, while the contours used 254 μm road width and 127 μm layer height. Measurements were performed and compared to standard FDM parts that included surface roughness of planes at different inclinations, tensile testing and fabrication times. Findings – Results showed that when compared to the standard FDM process, the parts produced using the build process variation exhibited the same tensile properties as determined by a student's t-test (p-values > 0.05, μ1-μ2 = 0, n = 5). Surface roughness measurements revealed that the process variation resulted in surface roughness (Ra) improvements of 55, 43, 44 and 38 per cent for respective planes inclined at 10, 15, 30 and 45° from vertical. In addition, for a 50.8 × 50.8 mm square section (25.4 mm tall), the build process variation required a minimum of 2.8 hours to build, while the standard FDM process required 6.0 hours constituting a 53 per cent reduction in build time. Finally, several manufacturing demonstrations were performed including the fabrication of a discrete PC-ABS sandwich structure containing tetragonal truss core elements. Originality/value – This paper demonstrates a build strategy that varies contour and raster widths and layer thicknesses for FDM that can be used to improve surface roughness – a characteristic that has historically been in need of improvement – and reduce fabrication time while retaining mechanical properties.

Kenneth McKechnie Eldred—A distinguished noise control engineer II

Ken's accomplishments in noise control engineering cover the spectrum from basic engineering research to recommendations for noise control in six areas: measurement of industrial noise; measurement and reduction of structural vibration in space vehicles; noise radiation from jet flow; noise reduction of jets by multiple nozzles and turbofans; vibroacoustic environmental simulation for aerospace vehicles; and community and transportation noise control. Some of these areas are discussed in consulting reports, and others in papers published in the open literature. He was a consultant at Bolt Beranek and Newman from 1973 until 1982 when he formed Ken Eldred Engineering. His publications appeared in the journal NOISE Control, several NOISE-CON and INTER-NOISE Proceedings, Noise Control Engineering Journal, and the Journal of the Acoustical Society of America. Representative samples of his accomplishments taken from the above sources will be presented.

Simulation of a novel intermittent ventilation system for underground mines

With increase of energy costs and implementation of carbon tax in many countries, a cost-effective mine ventilation system has become highly desirable in underground mine operations. In this study, a novel intermittent airflow ventilation system is proposed and evaluated via simulation with the goal of reducing the energy cost whilst maintaining methane level in the mining face below the allowable level. Parametric studies are conducted to investigate the effects of various factors influencing the effectiveness and performance of this novel intermittent ventilation system, in particular the effect of intermittency period, air velocity, and application of multiple outlet nozzles with intermittent on-off flapper valves for air flow control. Significant energy savings and air handling requirements are shown to be possible through the scheme proposed.

Development of Digital Flow Control System for Multi-Channel Variable-Rate Sprayers

Abstract. Precision modulation of nozzle flow rates is a critical step for variable-rate spray applications in orchards and ornamental nurseries. An automatic flow rate control system activated with microprocessors and pulse width modulation (PWM) controlled solenoid valves was developed to control flow rates of multi-channel nozzles independently for variable-rate sprayers. The system consists of a data acquisition module, a data processing module, and a flow rate control module. An embedded computer along with a touch screen was used to process control algorithms and allowed communication between the sprayer operator and the control system. The flow rate control module was designed with multi-channel driver circuits for activating the solenoid valves and driver protection circuits for avoiding surge voltages due to frequent on/off actions of the solenoid valves. Laboratory tests were conducted to verify the accuracy of the control system with three nozzles (0.530 to 1.703 L min -1 ) at four different operating pressures (138 to 345 kPa) and ten duty cycles (10% to 100%). The microcontroller-controlled circuit precisely produced PWM signals with desired pulse widths to match the duty cycles, and linear spray outputs were achieved accurately with the duty cycles of the PWM-controlled solenoid valves. With the protection circuit for the solenoid valve drivers, the longevity of the solenoid valves increased from 350 to 2,426 h. The system offers flexibility in choosing the number of connection channels needed for the number of nozzles individually or in a group on sprayers. Accordingly, together with canopy structures and travel speeds from laser scanning or other sensors, this compact control system is capable of performing variable flow rate functions for multiple nozzles separately.

Evaluation of a solid stream radial nozzle on fixed-wing aircraft, for penetration of spray within a soybean canopy

Abstract Experiments were conducted to evaluate the Accu-Flo multiple orifice nozzle for penetration of spray into a soybean (Glycine max L.) canopy by comparing results to those from a popular straight stream nozzle and rotary atomizer. A mixture of water + Induce® adjuvant was applied at three different spray release heights in a random sequence, using an Air Tractor 402-B agricultural aircraft. Sampler stands were placed at twenty-four locations in the field. Water sensitive paper (WSP) cards were clipped onto rigid stands just above the canopy and 30 cm off the ground within the canopy. Weather data were recorded using two different stations on-site. Wind was predominantly from the west and parallel to the direction of the spray runs. The spray delivery systems compared were the Accu-Flo nozzles, (64 needle 0.020 opening), CP®-09 straight stream with 5 degree deflection, and Micronair® AU5000 atomisers (14 mesh screen) at a low volume spray rate of 18.7 l/ha. A total of 54 spray runs were made over three days, and heights were varied at 3.7 m, 4.9 m and 6.1 m. Water sensitive papers were scanned and analysed for coverage per unit card area using an image analysis system. Altitude and [Nozzle X Altitude] interaction were significant effects on coverage at the 0.01 and 0.07 significance levels, respectively, for the top cards. Nozzle type was not a significant effect on coverage for the top cards, but was significant at the 0.01 level for the bottom cards. Altitude alone had no obvious effect on coverage for the bottom cards, although it had an effect for the top cards. The highest percentage area of spray coverage was observed from the Accu-Flo nozzles, especially for the bottom cards. Average spray coverage from the Accu-Flo nozzles was 1.7 times higher than coverage from the CP® nozzles or Micronair® atomisers in the lower portion of the canopy.

Representation of a small-scale nozzle for gas–liquid injections into a fluidized bed on a large-scale grid

A novel method for efficient computations of a fluidized bed reactor with liquid injections is developed. It allows economical simulations for a reactor that contains multiple nozzles using a relatively coarse grid, while still accounting for the influence of particular features of individual nozzles. The method relies on patching variables in the near nozzle area obtained on the fine nozzle-scale grid onto the coarse reactor-scale grid followed by the solution of the flow equations elsewhere in the coarse grid domain. The procedure is tested for a small fluidized bed that permits both fine and coarse grid solutions. It was found that the developed procedure represents the flow adequately and allows for the distinction of different nozzle geometries.

Study of Secondary Deposits in Multiple Round Nozzle Impactors

Inertial impactors are devices that consist of one or more particle-laden jets impinging onto a surface. Many modern impactors consist of impaction stages that have hundreds of closely spaced jets that, under certain conditions, can influence each other. The objectives of this study were to experimentally quantify the effect of jet interactions on particle collection efficiency, and to determine the underlying collection mechanism. From this testing, three types of secondary deposits were found, defined as midline, nozzle, and halo. The magnitude of these deposits varied widely depending on nozzle spacing, Reynolds number, and particle Stokes number. It was found that midline deposition occurs on a line halfway between adjacent nozzles on the impaction plate, and contains up to 8% of particles entering the nozzle. Midline deposition occurs due to a recirculation zone at the intersection of the two jets. Nozzle plate deposition was found to be minimal, comprising less than 3% of particles entering the nozz...

Enhanced Mass Transfer of Deuterium Extracted from Falling Liquid Pb-17Li Droplets

Release of deuterium from falling droplets of Pb-17Li in vacuum is experimentally studied. By comparing different diameter nozzle data each other, the effect of ambiguous solution is eliminated, and reliable result is attained. The amount of deuterium that is dissolved into Pb-17Li, followed by the release from the liquid droplets in vacuum, is measured with four different diameter nozzles ranging from 0.4 mm-1.0 mm under an initial velocity of 3.0 m/s and four temperatures between 375 °C and 450 °C. The resultant mass transport, represented by quasi-dispersion-coefficient is 3.4 × 10-7 [m2/s], which is approximately two orders of magnitude faster than previous studies under static condition. It also revealed different temperature dependency. Cyclic deformation of the sphere shape is observed with a high speed movie camera. These results show the falling droplets of liquid Pb-17Li in vacuum follow the mass transfer mechanism under convection prior domain by self-excited oscillation. This result suggests that the tritium recovery method from a breeding liquid Pb-17Li blanket is viable when using multiple nozzles in vacuum for the extraction.

Efficient Thrust Distribution with Adaptive Pressure Control for Multinozzle Solid Propulsion System

An integrated approach for chamber pressure control and thrust distribution for multiple nozzles of a solid propulsion system is presented. In this study, a solid propulsion system with variable nozzle throat area controlled by a pintle actuator is considered. To keep the hardware configuration simple and lightweight, multiple nozzles share a combustion chamber. Consequently, changing the throat area of one nozzle results in an unintended change of chamber pressure and thrust from other nozzles. Therefore, pressure stabilization and thrust distribution for multiple nozzles should be conducted simultaneously to achieve the desired performance. For the inner control loop, an adaptive sliding mode controller with feedback linearization is used for pressure stabilization. With the pressure control loop working properly, a thrust distribution algorithm into 10 nozzles for translation and attitude maneuver is developed as an outer control loop.

Advances in Electrospun Functional Nanofibers

Advances in Electrospun Functional Nanofibers

A Numerical Study of Both Internal and External Two-Phase Flows of a Rotating Disk Atomizer

In this paper, a numerical study has been carried out to model and simulate the air-liquid two-phase flows both inside and around a rotating disk atomizer, which is fitted with multiple spray nozzles. The physical problem was simulated with an Eulerian multiphase model in a single computational domain. The realizable two-equation turbulence model was used for the turbulent flow. The governing equations were solved with a finite-volume-based numerical method. The rotary frame method was used for the spinning disk. Numerical simulation was conducted in a rotational disk speed range of 1000 to 10000 rpm and a liquid feed flow rate range of 100 to 175 gpm for the liquid feeder. Both uniform and non-uniform liquid distribution conditions were considered. Detailed results about flow velocity and volume fraction fields inside and outside of the atomizer are presented and discussed. It was found that when liquid is nonuniformly distributed through the distributors, some of the nozzles could reach flooding conditions at lower rotational disk speeds and liquid feed volume flow rates, as compared to uniform distribution cases.

Performance studies of energy consumption for single and multiple nozzle systems under impinging air jets

Impinging air jets of various shapes, sizes and configurations are commonly used in heating, cooling and drying industrial processes. An analytical study has been carried out to optimise the thermal performance of single and multiple nozzle systems using impinging air jets. The optimisation of the nozzle array was given for practical purposes. The results show that within practical limits, a narrower nozzle size results in a greater heat and mass transfer coefficient. An economical analysis of the drying processes is also given for slot nozzles.

Block microfibrils prepared by quasi-steady state electrospinning and their chromosome-like structures

Materials science research has focused primarily on isometric structures rather than anisometric structures. This is typically driven by the associated levels of processing complexity rather than importance. Pulsating instability is not recognized as a useful phenomenon in electrospinning, while it has been systematically examined in electrospraying. We prepared anisometric block microfibrils for the first time by using pulsating instability of electrospinning. A low frequency pulsating mode which represents a quasi-steady state was achieved using systems consisting of multiple inner nozzles in conjunction with an outer nozzle. A fully-electrospinnable viscous sheath solution confines the pulsating inner flows, generating uniform fibers of separate core blocks. The blocks inside a sheath can be extracted by selective dissolution, and the resulting diblock or triblock microfibrils have amphiphilic surface activity and are self-assembled into chromosome-like structures. Flow rate and solution conductivity were able to control block length, which was explained by the low frequency pulsating mechanism and the driving fluid concept of electrohydrodynamic jetting. This pulsating mode processing of block microfibrils has the potential to open up a new area of anisometric fibers for emerging applications.

Large area impingement spray cooling from multiple normal and inclined spray nozzles

An inclined spray chamber with four multiple nozzles to cool a 1 kW 6U electronic test card has been designed and tested in this study. The multiple inclined sprays can cover the same heated surface area as that with the multiple normal sprays but halve the volume of the spray chamber. The spray cooling system used R134a as a working fluid in a modified refrigeration cycle. It is observed that increasing mass flow rate and pressure drop across the nozzles improved the heat transfer coefficient with a maximum enhancement of 117 %, and reduced the maximum temperature difference at the heated surface from 13.8 to 8.4 C in the inclined spray chamber with a heat flux of 5.25 W/cm 2 , while the heat transfer coefficient of the normal spray increased with a maximum enhance- ment of 215 % and the maximum temperature difference decreased from 10.8 to 5.4 C under similar operating conditions. We conclude that the multiple inclined sprays could produce a higher heat transfer coefficient but with an increase in non-uniformity of the surface temperature compared with the multiple normal sprays. List of symbols A Area of the heated surface (m 2 ) _ Q Heater plate power input (Watt) h Heat transfer coefficient (W/m 2 K) Tw_max Maximum temperature value on the heated surface (C)

Research on Flow Divider of High Pressure Water-Jet Target Material Detection Device

In order to identify target material and physical dimension quickly and effectively by utilizing high pressure water-jet, the equal eigenvalues of reflected sound signal is required when high pressure water-jet impulse the same target through array nozzles. It is necessary to research the reasonable structure for flow divider to ensure that pressure and flow of every nozzle are identical. According to the device structure size, basic structure of flow divider and pipeline connection request, structure parameters of flow divider were acquired and introduced in this paper. The required initial parameters were calculated on demand, and the inside fluid state of flow divider was also judged. The governing equations are developed by combining incompressible viscous fluid continuity equation with N-S equation and standard k-ε turbulence model. Structure parameters were optimized by combining fluent with the orthogonal experiment. Through the comparison of pressure and flow data acquired in the analysis of the inside flow field of the flow divider, maximum relative pressure deviation of nine channels that based on the optimal size is 0.0243% and maximum relative deviation of the mass flow is 0.0000187%. The requirements of pressure and flow uniformity for identifying target material by using high pressure water-jet and multiple nozzles can be met perfectively.

Effect of Print Masks on the Functional Performance of Inkjet Printed Pd Hexadecanethiolate in Toluene

For more than a decade studies have shown that print masks can be designed to alleviate print artifacts in inkjet printed images by using the ability to independently address multiple nozzles within a print-head. With the increase in applications of inkjet functional printing in recent years, the higher throughput associated with multiple nozzle arrays is necessary for large scale production. This provides the motivation for designing print masks that can maximize the quality of inkjet printed devices rather than minimize the number of print artifacts detectable by the human eye. Four separate print masks are selected and employed for printing a rectangle onto Silicon and a six-contact bridge-type pattern onto oxidized Silicon using a Pd ink. The resulting printed rectangles are compared via image quality metrics while the sixcontact bridge-type patterns were characterized electrically and compared via sheet resistance. The results show a clear trend. The print masks showing better performance via image quality metrics also showed better performance in terms of sheet resistance.