• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1999.10a
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• pp.1-1
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• 1999

2유체 동축인젝터(coaxial twin fluid injector)는 액체산소와 액체수소를 추진제로 사용하는 SSME(Space Shuttle Main Engine)이나 유럽의 Arian 5 Vulcain 엔진과 같은 저온추진제 엔진에 널리 사용되고 있다. 추진제를 미립화 시키는 장치로서 사용하는 다른 여러 형태의 인젝터에 비교할 때 저속의 액체산화제 주위에 고속의 가스연료가 분사됨으로서 발생되는 전단력에 의해 추진제가 미립화되는 특징을 가지며, 이러한 메카니즘은 매우 복잡하여 아직까지 정확히 규명되지 못하고 있는 실정이다.

• Journal of the KSME
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• v.23 no.4
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• pp.288-294
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• 1983

고속기류에 의한 수표면의 유통은 호수나 강에서 흔히 볼 수 있는 물리적인 현상으로서 기류의 속도가 증가함에 따라서 수표면에서 액적이 발생하게 되는 이른바 액체미립화 현상(atomization )이 일어나게 된다. 이러한 액체의 미립화는 내연기관에서의 분무연소에서 부터 가정에서 습도를 유지하는 가습기 및 살충제분무기에 이르기까지 그 운용도가 매우 광범위하며 최근에 이르러 액체미립화가 유체역학의 한 부분을 차지하는 단계에까지 이르러 매년 각국에서 미립화에 대한 심포지움이 개최되고 있으며 연구실적면에서는 미국보다도 오히려 가까운 일본에서 미립화에 대한 연구가 더 활발히 진행되고 있는 반면 아직 우리나라에서는 이렇다할 연구가 없으며 미립 화에 관한 논문도 불과 한두 편에 이르는 실정이다. 이러한 중요한 물리적인 현상에 대해 좀더 자세한 이해를 위해서는 액체와 기체의 상호접촉면에서의 정량적인 특성에 대한 연구가 필요하며 이러한 정량적 인자에는 (1) 액막의 평균두께 (2) 액막내의 속도분포, (3) 액막표면의 파고, 파장의 파면구조, (4)기체중의 속도분포 등이 있다.

• Journal of the Korean Society of Propulsion Engineers
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• v.6 no.2
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• pp.37-44
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• 2002

A theoretical study of spray and combustion characteristics due to coaxial twin-fluid injection is conducted to investigate the effects of liquid jet property, droplet size, contact length and liquid jet velocity. Model is properly validated with measurements and shows good agreement. Prediction of jet contact length, droplet size, liquid jet velocity reflects genuine features of coaxial injection in physical and practical aspects. Both the jet contact length and tile droplet size are reduced in a linear manner with an increase of injector diameter. Cross sectional area of liquid intact core is reduced with augmented jet splitting rate, thus the jet is accelerated to maintain the mass continuity and with an assistant of momentum diffusion by burnt gas.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.1
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• pp.132-139
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• 1997

Spray characteristics of external mixing sonic twin-fluid atomization nozzles are investigated experimentally. Particle sizes are measured by the Fraunhofer diffraction method using the Malvern particle analyzer, and their radial distributions are obtained using the tomographical transformation technique. The spatial distribution of SMD shows that the drop size increases in the radial direction at a fixed liquid flow rate, and the distribution is getting uniform rapidly as the atomizing gas pressure increases. The SMD decreases as the liquid flow rate increases at a fixed GLR. It is found that the atomization efficiency of the flush type sonic nozzle is superior to that of protrusion type. The effect of laser beam diameter of the particle analyzer on the spatial SMD distribution is minor at present experimental conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.11
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• pp.1552-1560
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• 2001

This paper presents the experimental results of a study undertaken to develop an electrostatic spray system for a combustion application. The characteristics of the liquid atomization and the droplet dispersion in the electrostatic spray of twin fluids were investigated by the optical measurement techniques. The processes associated with the break-up of charged jets were also observed using the laser sheet visualization. The diameter and velocity of droplets were simultaneously measured using the phase Doppler measurement technique. The electrostatic atomization of the liquid fuel depended primarily on the charging voltage and the flow rate, but the dispersion of droplets depended significantly on the aerodynamic flow. Aerodynamic influences on the liquid atomization decreased with an increase of the charging voltage. Consequently, the liquid atomization and the droplet dispersion could be independently controlled using the electrostatic and aerodynamic mechanisms.

• Journal of ILASS-Korea
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• v.3 no.4
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• pp.50-57
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• 1998

The utilization of resonance should be considered to get the maximum effect of ultrasonic to atomize liquid. The ultrasonic generator, transducer, horn, and all attached parts are used to produce the resonance, and specially the characteristics of liquids such as liquid load, property, and etc., for the liquid atomization affinity are considered. In this study, the variable device of liquid load was made and distilled water and city water selected as experimental liquids were sprayed by a twin-fluid spray method and their diameters, distributions, and spray quantum of spray droplets were measured by the light scattering system. And all data were observed, compared and considered relatively. In results, a lot of phenomena of liquid atomization affinity by ultrasonic appeared in accordance with liquid loads, namely head h.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.8
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• pp.1056-1067
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• 1997

Present study visualized flow pattern and investigated spray characteristics of twin-fluid atomization with converging-diverging nozzles. Particle sizes were measured by using the Malvern particle analyzer, and the radial size distributions were evaluated by using the tomographic transform technique. The results show that the SMD generally increases in the radial direction at a prescribed liquid flow rate and the increasing rate in the SMD becomes gradual as atomizing gas pressure increases. The SMD decreases as the liquid flow rate increases at a fixed GLR (gas/liquid mass ratio). The atomization performance of the protrusion-type nozzle turned out to be superior to that of the flush-type. However, in the case of the protrusion-type, flow separation occurs outside the liquid delivery tube when the pressure at the gas nozzle chamber is high enough, which may deteriorate the atomization performance.

• Journal of the korean Society of Automotive Engineers
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• v.10 no.5
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• pp.24-32
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• 1988

본 고에서는 일점연료분사시스템의 문제점을 해결하는 방안 및 장래 유망하다고 보여지는 희박혼합기상태에서 연소상태의 개선을 목적으로, 연료분사밸브로서 미립화특성이 좋은 2유체 분사밸브를 사용하기 위하여 기술하고자 한다.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.2
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• pp.24-29
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• 1998

An experimental study was carried out to investigate the characteristics of spray pattern such as discharge coefficient, spray angle, and mass distribution for two-fluid airblast swirl injector, within the range of fluid supply pressure 0~13kg/$\textrm{cm}^2$. In general atomization is promoted with increasing total gas mass flow and performance of the splay pattern was more stable when radial mass flow was greater than axial mass flow, radial swirler was better than Axial swirler for atomization. Equivalent spray angle did not change with water mass flow except for the condition of 3kg/$\textrm{cm}^2$ and showed the same for the gas mass flow. Mass distribution from the patternator shows that maximum value of the distribution were lowered but distributed larger area when gas flow rate increased. Center of mass position did not change with increasing water mass flow.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.104-105
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• 2012

The design of coaxial porous injector was suggested to improve the mixing and atomizing performance at the center region of the conventional 2-phase flow coaxial shear injector spray. Several cold flow tests of 2-dimensional injectors was performed, and the gas injection area was varied to determine the effect of the magnitude of gas radial momentum.