Jet Flow Rate Research Articles

Numerical modeling of three-dimensional flow field and two-dimensional coal combustion in a cylindrical combustor of co-flow jets with large velocity difference

The three-dimensional flow field and two-dimensional coal combustion in a cylindrical combustor of co-flow jets with large velocity difference are studied by numerical simulation. Prediction results show presence of a large central recirculation zone and its remarkable effect on rapid heating, devolatilization and ignition of coal particles, flame stabilization and combustion intensification. For optimum design of such combustors the effect of jet hole location and jet flow rate on sizes and reverse flow rate of this recirculation zone are also studied.

Cooling of the polymer jet in fibre spinning

The effect of various technological parameters (jet stretch ratio, temperature and flow rate of the polymer melt, temperature and velocity of the air which cools the melt, and rheological characteristics of the polymer) on the change in temperature and viscosity of the polymer jet along the length of the spinning zone has been investigated.

Forced capillary breakup of liquid jets

The characteristics of the forced capillary breakup (FCB) of liquid jets have been investigated over a broad range of variation of the breakup parameters: jet orifice diameter (34–527 μm), flow rate (10−5–1 cm3/sec), and excitation amplitude and frequency. The theory is compared with experiment.

Liquid Ink Jet Printing with MOD Inks for Hybrid Microcircuits

Application of the computer-controlled impulse ink jet with liquid metallo-organic decomposition (MOD) inks is demonstrated to be feasible in printing hybrid microcircuits. The advantages of ink jet printing over conventional screen printing are discussed. The hardware and software of the ink jet printing system have been developed. The MOD ink system suitable for the ink jet has been studied. Printing experiments with the ink jet have been conducted during the research. A theoretical model has been derived relating the ink jet flow rate to the primary spray control parameters. The ink jet system with silver neodecanoate MOD ink has been applied to metallize the grid pattern of silicon solar cells.

Bubble formation in a single-jet gas-solid fluidized bed

The jet instability and bubble frequencies in a single-orifice 2-D gas-solid fluidized bed were studied by flow visualization and measured by means of a high-sensitivity capacitance probe. The influence of a series of parameters, including particle size (0.105–0.590 mm), particle density (590–3990 kg/m 3), probe vertical location, jet flow rate ( 0.5 x 10 -4−35 x 10 -4 m 1/3 ) and background gas flow rate (0–4 times minimum fluidization velocity), on the bubble frequency was investigated. For the smallest particle size studied, the jet instability frequency was in good agreement with a 2-D version of a simple model due to Davidson and Harrison. The data show a systematic deviation from that model for increasing particle size. The model is then modified to account for the fact that with large particles, gas leakage from the forming bubble to the surrounding emulsion phase becomes important. The modified leakage model agrees well with the experimental data. Bubble coalescence at the tip of the jet was shown to result in bubble frequencies which are simple subharmonics of the basic pinching frequencies of the jet.

USE OF HIGH-PRESSURE WATER MIXING FOR SHIP-BASED OIL SPILL DISPERSING

ABSTRACT This paper discusses a project funded by Canada's Environmental Studies Revolving Fund to assess the potential of high-pressure water jets in assisting the chemical dispersion of oil at sea. Full-scale laboratory tests were conducted using 0.5-mm thick, fresh Alberta Sweet Mixed Blend crude oil treated with Corexit 9527 dispersant applied from an overhead spray boom at a dispersant-to-oil ratio of 1: 100. The effects on dispersion efficiency of mixing jet pressure, mixing jet flow rate, jet standoff distance, and vessel speed were evaluated. Based on the test results, specifications for a practical high-pressure water jet system have been suggested. The system would operate with a nozzle pressure of 7,000 kPa, a flow rate of 55 L/min per nozzle, and nozzles positioned about 0.6 m from the water surface. In laboratory tests such a system was capable of dispersing 80 to 100 percent of the surface slick, whereas similar tests with the well-known Warren Spring Laboratory breaker board system resulted in only a 10 percent dispersion.

A study on the control of the radial wall jet through two parallel disks. 3rd Report. Deflection of main jet and reattachment to a wall surface.

This paper presents the results of an experimental study on the control of the deflection and reattachment of a radial wall jet through comparatively wide spaced two parallel disks, with an additional control flow. The flow field may be considered as having properties including those of the deflected jet, reattached jet and wall jet. The effects of opposite wall height (distance of opposite wall surface from the nozzle center plane) and control flow rate (ratio of control flow rate to main jet flow rate) on the flow pattern near the nozzle outlet section were investigated. The velocity profile, shape and length of a jet potential core, and the deflection of a jet center axis depend mainly on the combination of the opposite wall height and the control flow rate.

A study on the deflection and reattachment of an axisymmetric radial wall jet. (Deflection of main jet near nozzle).

This paper presents the results of an experimental study on the deflection and reattachment of an axisymmetric radial turbulent wall jet (main jet) discharged from a cylindrical nozzle onto an adjacent disk plate, in the presence of a lateral control flow from and annular slit. The main content of this report concerns the effect of various control flow rates (ratio of the control flow rate to the main jet flow rate) on the flow structure in the region near the nozzle exit. Mean and turbulent velocities were measured with a hot-wire anemometer, while static pressure was measured by means of a Pitot-static tube and a pressure pick-up of a strain gauge type. The velocity profile, shape and length of a jet potential core, and the deflection of the jet's center axis depend mainly on the control flow rate and the wall effect.

A study on the control of the radial wall jet through two parallel disks. 2nd report. Reattachment characteristics with a pressure field.

An experimental study has been made on the control of the reattachment of a radial turbulent wall jet through comparatively wide spaced two parallel disks, with an additional control flow. Static pressure distributions along the side wall and the opposite wall, and also across the jet flow were measured with half disk type and a disk type pressure holes. The effects of opposite wall height (distance of opposite wall surface from the nozzle center plane) and control flow rate (ratio of control flow rate to main jet flow rate) on the flow pattern through tow parallel disks were investigated. The position of reattachment to the side wall surface, and pressure at this depend mainly on the combination of the opposite wall height and the control flow rate.

The effect of a turbulent jet on gas transport during oscillatory flow.

Axial mass transport due to the combined effects of flow oscillation and a turbulent jet was studied both experimentally and with a simple theoretical model. The experiments show that the distance over which turbulence enhances transport is greatly increased by flow oscillation, and is particularly sensitive to tidal volume. The jet flow rate and jet configuration are relatively less important. To analyze the results, the region influenced by the jet is divided into two zones: a near field in which the time-mean flow velocities are larger than the turbulent fluctuations, and a far field where the time-mean flow is essentially zero. In the far field, axial mass transport is increased due to the turbulence which decays in strength away from the jet. When oscillatory flow is superimposed upon the steady jet flow, the turbulence in the far field interacts with the flow oscillations to augment the transport of turbulence energy and of mass. This transport enhancement is modeled by introducing an effective axial diffusivity analogous to that used in laminar oscillatory flow.

Liquid Jet Impingement Cooling of a Rotating Disk

Results are presented from an experimental study conducted to determine the average convective heat transfer coefficient for the side of a rotating disk, with an approximately uniform surface temperature, cooled by a single liquid jet of oil impinging normal to the surface. Tests were conducted over a range of jet flow rates, jet temperatures, jet radial positions, and disk angular velocities with various combinations of three jet nozzle and disk diameters. Correlations are presented that relate the average Nusselt number to rotational Reynolds number, jet Reynolds number, jet Prandtl number, and dimensionless jet radial position.

Heat Transfer Characteristics for Jet Array Impingement With Initial Crossflow

Two-dimensional arrays of circular air jets impinging on a heat transfer surface parallel to the jet orifice plate are considered. The jet flow, after impingement, is constrained to exit in a single direction along the channel formed by the jet orifice plate and the heat transfer surface. In addition to the crossflow that originates from the jets following impingement, an initial crossflow is present that approaches the array through an upstream extension of the channel. The configurations considered are intended to model the impingement cooled midchord region of gas turbine airfoils in cases where an initial crossflow is also present. A major objective is determination of the effect of initial crossflow air temperature relative to jet array air temperature on impingement surface heat fluxes. Dimensionless adiabatic wall temperatures and Nusselt numbers resolved to one streamwise jet hole spacing were experimentally determined for ratios of initial crossflow rate to total jet flow rate ranging from zero to unity. These results are presented and discussed relative to the flow and geometric parameters.

Design and Testing of a Water Tip Jet Propeller

This work was directed at the problem of developing a lightweight, low cost means of propelling a short run underwater vehicle. The system described occupies a position midway between the straight rocket and the geared turbine/propeller drive fed by a gas generator. It expands the propellant gases through a turbine, uses the turbine to direct drive a centrifugal sea water pump, and ejects the pumped water through jets at the blade tips of a specially designed propeller. Exhaust gas from the turbine is released from the propeller hub at the blade trailing edges. The reduction in turbine back pressure produced by the suction effect on the exhaust gas significantly increases turbine efficiency and reduces the system's sensitivity to operating depth. This paper covers the analytical design and sea testing of the water tip jet propeller and summarizes the test results. The test data, consisting of measurements of propulsive power vs tip jet flow rate and pressure at various vehicle speeds, indicate that the proposed system can provide specific power levels superior to those obtainable from any other underwater propulsion system for vehicles requiring a run time of about 3 s to 2 min. It has additional advantages of, relative insensitivity to depth, low cost, low self-noise, and absence of reaction torque.

Flow Distributions and Discharge Coefficient Effects for Jet Array Impingement With Initial Crossflow

Two-dimensional arrays of circular air jets impinging on a surface parallel to the jet orifice plate are considered. The jet flow, after impingement is constrained to exit in a single direction along the channel formed by the jet orifice plate and the impingement surface. In addition to the crossflow which originates from the jets following impingement, an initial (independent) crossflow is present which approaches the array through an upstream extension of the channel. The configurations considered are intended to model the impingement cooled midchord region of gas turbine airfoils in cases where an initial crossflow is also present. Experimentally determined row-by-row streamwise distributions of the jet and crossflow velocities are presented for ratios of the initial crossflow rate to the total jet flow rate ranging from zero to unity. Comparisons are drawn between the measured flow distributions and a theoretical model which is presented. Effects of crossflow velocity and impingement surface proximity on jet hole discharge coefficients are also presented and discussed.

Jet Cooling at the Rim of a Rotating Disk

Results are presented from an experimental study conducted to measure heat transfer rates at the rim of a rotating disk convectively cooled by impinging jets. The disk face contour radially inward from the rim is varied to simulate the geometric conditions found on gas turbine engine rotors. Heat transfer rates are found to be relatively unaffected by impingement for jet flowrates less than the order of one-tenth the disk pumping flow. Disk pumping flows are evaluated through the use of an analysis which accounts for the presence of the disk hub. At larger jet flowrates, heat transfer rates increase strongly with increasing jet flow, reaching two to three times the no-impingement values at jet flowrates approximately equal to the pumped flow. All the heat transfer results, both with and without jet impingement, are essentially unaffected by changes in the disk face contour.

Variable-cut particle-size classification by opposing jets.

A new technique of aerodynamic particle-size classification has been developed utilizing axisymmetrically-opposed air jets. For a fixed geometry the cut size can be varied from 0.8 to 3.6 micrometer by changing the jet flow rates. Future designs are expected to extend the useful particle-size range. Particles remain airborne after size separation, permitting the use of continuous, automated methods for analyzing the particle concentration and chemical compositon.

Heat Transfer Between an Impinging Jet and a Rotating Disk

An experimental study of the flow interaction and heat transfer between a single impinging jet and a rotating disk is presented. Tests were conducted over a range of jet flowrates, impingement radii, and disk rotational speeds with various combinations of three jet and three disk sizes. Flow visualization using smoke addition to the jet flow reveals the presence of a flow regime transition which is correlated in terms of the rotationally induced disk pumping flow acting as a cross-flow influence on the jet. Higher rotational speeds, larger impingement radii, and smaller jet flowrates favor a rotationally dominated flow interaction whereas the opposite trends favor an impingement dominated interaction. Heat transfer rates are essentially independent of jet flowrate in the rotationally dominated regime, but increase, strongly with increasing flowrate in the impingement dominated regime.

Liquid—liquid mass transfer in systems agitated by submerged jets

Mass transfer across a plane interface has been investigated for liquid—liquid systems, with the liquid phases agitated by vertically opposed, submerged jets, one in each phase. Mass transfer coefficients were determined for the systems ethyl acetate—water and butanol—water, and for the transfer of dissolved helium between water and toluene, and toluene between toluene and water. The latter two solutes provided a wide range of molecular diffusion coefficients. When turbulent eddies penetrated to the interface the mass transfer coefficients were found to be proportional to D 0.5, and could be represented by the Levich-Davies mass transfer model for mass transfer between turbulent liquids. The characteristic turbulence velocities in this model were related to the velocities of the liquids from the jet nozzles, and to the equipment dimensions (e.g. the distances of the jets from the interface, the radius of the vessel and the diameters of the jet nozzles) by an expression based on the hydrodynamic behaviour of jets. For the low interfacial tension system butanol—water, a flat disc had to be placed in the interface at the region of jet impingement, to prevent disruption of the interface, but, even so, only a limited range of jet flow rates could be used. Only at the highest flow rates were turbulent conditions obtained, and most of the experimental mass transfer coefficients for this system were between the values predicted by the Levich-Davies model and the Levich “three-zone” model for boundary layer flow.

ON THE RELATION BETWEEN POWER INPUT AND IMPELLER JET FLOW RATE

Based on the flow pattern in impeller region and on the angular momentum balance over the potential flow region, a relationship between impeller jet flow rate and power input is derived in which the impeller jet flow rate is proportional to the root of power input. The correlation equations based on this result are well in agreement with the experimental results for baffled and non-baffled agitated vessels with different type impellers.

ジェット流法によるニッケルメッキ

Nickel was electroplated by using a jet flow device. For the normal Watts bath (containing 240g/l of nickel sulfate, 45g/l of nickel chloride, and 30g/l of boric acid at pH=4), the maximum available current density (im) was found to be 90Amp/dm2 at 45°C or 180Amp/dm2 at 60°C when the electrolyte was supplied at a jet flow rate of 200cm/sec. (average value in nozzle).At higher current densities, deposition of nickel was perfectly restrained.The deposition rate attained to its maximum value (not limiting current value) at Ep (about -1.5V vs SCE), followed by a marked decrease at less noble potentials.The effects of pH, flow rate, and nickel concentration on im were discussed with respect to codeposition rate of hydrogen and the resultant increase of pH in the diffusion layer around the cathode.No remarkable difference in im was observed between the Watts bath and sulfamate bath, both of which were of the same concentration of nickel.