• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.8
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• pp.1077-1085
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• 1997

The use of "clean fuels" such as butane, propane, and mixtures of these (LPG) is an attractive way to reduce exhaust emissions. In this study internal flow of the pintle type injector for LPG engine is studied. The breakup of liquid jet is the result of competing, unstable hydrodynamic forces acting on the liquid jet as it exits the nozzle. The nozzle geometry and up-stream injection conditions affect the characteristics of flow inside the nozzle, such as turbulence and cavitation bubbles. A set of calculations of the internal flow in a pintle type nozzle were performed using a two dimensional flow simulation under different nozzle geometry and upstream flow conditions. The calculation showed that the turbulent intensity and discharge coefficient are related to needle leading angle(.alpha.) and needle lift.edle lift.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.24.2-24.2
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• 2005

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.107-112
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• 2001

The effect of ambient gas (steam) condensation on swirl spray characteristics were studied experimentally for low subcooling condition of the liquid. The configuration of the liquid(water) sheet and the breakup modes were examined. Also variation of the discharge coefficient, breakup length, local and the cross-sectional area-averaged SMD of droplets with the liquid flow(injection) rate were obtained. The perforation breakup mode appears dominant with condensation while the aerodynamic wave breakup mode is dominant without condensation(in the air environment). The discharge coefficient, breakup length and the mean drop sizes decrease in a same manner with increasing of the liquid flow rate for both cases(with and without condensation). The condensation effects are insignificant with the discharge coefficient. However, the local and cross-sectional area-averaged SMD are larger and the breakup length becomes shorter in the steam environment. The spray angle predicted from the volumetric flux distribution along the radial direction of the sprays in the steam environment becomes larger with condensation.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.3
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• pp.275-284
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• 1998

Standard on the carbon dioxide extinguishing system was prepared by the committed of the national fire protection assocition(NFPA)in USA on 1980. And this code is also applied to the design of a marine fire extinguishing system The most important problem in design is the uniform discharge of $CO_2$ through each nozzle from the high pressure $CO_2$ storage facility. The purpose of this paper is to develop the computer software to design the marine fire protection piping system. By solving the continuity equation energy equation and Bernoulli's equation simulataneously the flowrate in branch pipelines and discharge nozzles can be calculated.

• Journal of ILASS-Korea
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• v.12 no.1
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• pp.58-64
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• 2007

The spray characteristics of the oxidizer-rich preburner are investigated. This system is generally operated at an oxidizerfuel mixture ratio of 50. The spray quality and mixing performance are very important for safe combustion. To know the spray characteristics of the oxidizer-rich preburner, we have designed various swirl injectors and measured droplet velocity and size by the PDPA system. The flow discharge coefficient of the fuel orifice is $0.12{\sim}0.21$, oxidizer orifice discharge coefficient is $0.16{\sim}0.28$. From the spray visualization, fuel nozzle spray angle is $15^{\circ}{\sim}25^{\circ}$, oxidizer nozzle spray angle is $65^{\circ}{\sim}85^{\circ}$ and combined spray angle is reduced $2^{\circ}{\sim}5^{\circ}$ compared to the oxidizer nozzle only case. From the PDPA measurement, droplet SMD is $175\;{\mu}m$ at 50 mm and $190\;{\mu}m$ at 100 mm of variant 1 combined case. The number concentration measurement revealed the reason of the droplet diameter increasement with distance. That is due to drop coalescence results from collision of drops which is occurred in dense sprays at a long distance from nozzle orifice exit.

• Journal of ILASS-Korea
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• v.7 no.4
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• pp.1-8
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• 2002

This paper investigates the spray angle and the outline shape of the liquid sheet discharged from a simplex swirl nozzle. A theoretical model was proposed and the corresponding experimental data were presented for comparison. Axial and tangential velocities and thickness of the liquid sheet at the nozzle exit were also predicted. The liquid sheet thickness at nozzle exit, as well as the discharge coefficient, turned out to be a sole function of the swirl Reynolds number. However, the axial and tangential velocities at nozzle exit and the spray angle could not be expressed only with the swirl Reynolds number. The predicted outline shape and spray angle of the liquid sheet agreed reasonably with the measured data.

• Journal of ILASS-Korea
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• v.18 no.1
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• pp.44-54
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• 2013

An experimental study was performed to investigate the liquid jet breakup of a circular nozzle and elliptical nozzles. Furthermore Numerical simulation was attempted to investigate the internal flow structure in the circular and elliptical nozzles. This study showed that the disintegration characteristics of the liquid jet of elliptical nozzles were much different from those of the circular nozzle. The liquid jet issued from the elliptical nozzles became more unstable at the same injection pressure. Surface breakup was observed at the jet issued from the elliptical nozzles with the increase of injection pressure. The disintegration of the liquid jet of elliptical nozzles was related with the internal flow structure which is revealed from the numerical simulation.

• Journal of Aerospace System Engineering
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• v.14 no.4
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• pp.1-9
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• 2020

The characteristics of an aerospike pintle nozzle system with excellent altitude compensation were analyzed using cold air testing. It was confirmed that reducing the stroke of the aerospike nozzle is effective in increasing the thrust. However, the results of additional numerical analysis indicated that the discharge coefficient factor was significantly lower at the maximum stroke. The Vena contracta due to the cowl reduction angle decreased the effective nozzle throat area at the maximum stroke and hindered expansion. Complementing the cowl design may thus increase the efficiency of a solid-propellant rocket engine that uses the aerospike pintle nozzle system.

• Journal of ILASS-Korea
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• v.1 no.1
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• pp.76-84
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• 1996

The nozzle geometry and up-stream inject ion condition affect the characteristics of flow inside the nozzle. such as turbulence and cavitation bubbles. Flow details in fuel nozzle orifice with sudden contraction of cross sectional area have been investigated both experimentally and numerically. The measurements of velocities of internal flow in a scaled-up nozzle with different length to diameter rat io(L/d) were made by laser Doppler velocimetry in order to clarify the effect of internal flow on the characteristics of fuel spray. Mean and fluctuating velocities and discharge coefficients were obtained at various Reynolds numbers. The turbulent intensity and turbulence kinetic energy in a sharp inlet nozzle were higher than that in a round inlet nozzle. Calculations were also performed for the same nozzles as scaled-up experimental nozzles using the SIMPLE algorithm. External spray behavior under different nozzle geometry and up-stream flow conditions using Doppler technique and visualization technique were also observed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.9
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• pp.1632-1637
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• 2010

A micro-water-nozzle, as one of a cooling means of micro-electronic devices, has been proposed and investigated. The I-V characteristics of the micro-water-nozzle and effect of applied voltage on the meniscus formation and deformation and ejection processes of de-ionized water on the micro-water-nozzle tip have been investigated. The water ejection processes, such as a drop formation, a drop deformation, a dripping, a cone jet, and an atomization, were taken place on the micro-water-nozzle tip by the electrohydrodynamic forces acted by the DC and AC high voltages applied on the meniscus of the micro-water-nozzle tip. The I-V characteristics of the micro-water-nozzle-to-plate electrode system were different from that of the same metal-point electrode system, due to the meniscus formation and water droplet ejection at the nozzle tip. The positive and negative DC and AC high voltages showed the water droplets ejection, the ejection rates of 1.8, 1.5 and 1.2 g/h respectively, which, however, showed that the proposed micro-water-nozzle-to-plate electrode system could be used as one of an effective pumping means.