• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.577-580
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• 2010

Coaxial injectors using GCH4/LOx as propellants was designed with shear(gas)/shear(liquid) type and shear(gas)/swirl(liquid) type. Spray characteristics were investigated by cold flow test. Spray patterns of the shear/shear and the shear/swirl type injectors were like a spout of water and hollow cone, respectively. Atomization efficiency of the shear/swirl type injector was better than atomization efficiency of the shear/shear type injector.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.322-326
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• 2005

The spray and acoustic characteristics of a swirl coaxial injector are studied experimentally. The spray and acoustic characteristics of a swirl coaxial injector are investigated according to the injection conditions, such as the pressure drop of the liquid and gas phase, and injector geometries, such as recess length and gap size between the inner and outer injector.

• Journal of the Korean Society of Propulsion Engineers
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• v.27 no.1
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• pp.27-36
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• 2023

To understand the atomization performance in gas-liquid swirl-coaxial injector applied to a small rocket engine, a cold-flow test was performed by varying the design parameters and supply condition of propellants. As the swirl-chamber diameter and the angle of the convergent section, which are design parameters of injector increased, the spray performance of the injector improved by increasing the swirl strength. In addition, as the gas-liquid momentum-flux ratio increased, the gas flow separated some of the droplets from the liquid film, and a gas-droplet mixture core was formed in the center of the spray sheet.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.20-23
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• 2011

The spray and atomization characteristics of swirl coaxial injectors which use gas methane and LOx as propellants are investigated experimentally with a recess length variation. Mass distribution and spray angle are measured by a patternator and droplet size to find atomization characteristics are measured by GSV(Global Size and Velocity) system. As a result, when the liquid sprayed, the spray angle decreased and the atomization characteristic was improved with the recess length increase. When the gas and liquid injected simultaneously, the spray angle was decreased and the atomization characteristic was improved comparing to only the liquid injection.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.1
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• pp.54-61
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• 2005

Characteristics of sprays injected by gas/liquid coaxial atomizers operated at atmospheric pressure are studied using shadowgraph, mechanical patternator and PDPA. The gas-to- liquid momentum flux ratio(M) and the liquid Reynolds number(Re) are selected as key parameters in characteristics of gas/liquid coaxial sprays from the dimensional analysis. The properties of shear coaxial sprays are compared with those of swirl coaxial sprays through the macroscopic and microscopic analysis. Macroscopic similarities between shear and swirl coaxial sprays are revealed under flow conditions of high momentum flux ratio. Also, empirical correlations between the mean drop diameters(D32) and operating conditions of coaxial sprays are proposed in this paper.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.168-172
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• 2003

The effects of injection conditions on the droplet sizes resulting from the disintegration of a liquid jet by a fast annular gas stream have been investigated using PDPA. The gas/liquid momentum ratio M = $\rho$$_{g}$ $U_{g}$$^2$/$\rho$$_1$ $U_1$$^2$ and Weber number We = $\rho$$_{g}$ $g^2$ $D_1$/$\sigma$ are selected as key parameters in atomization of shear coaxial spray from the fluid mechanics standpoint. It is revealed that SMD( $D_{32}$) varies inversely with gas/liquid momentum ratio(M), whereas Weber number(We) has little effect on the droplet sizes as gas velocities increase. It is found that gas/liquid momentum ratio is more dominant factor controlling the breakup and atomization process of shear coaxial spray. Finally, an empirical correlation between SMD and injection conditions(i.e. gas/liquid momentum ratio M and Weber number We) is proposed based on the experimental results.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.4
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• pp.68-76
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• 2016

This research is carried out for the performance evaluation of the injector that is one of the critical components of bipropellant-rocket-engine. Spray characteristics are investigated in detail according to the recess length and injection pressure on the swirl-coaxial-injector using gaseous methane and liquid oxygen as propellants. A visualization is conducted by the Schlieren photography that is composed of a light source, concave mirrors, knife, and high-speed-camera. A hollow-cone-shape is identified in the liquid spray that is spread only by inner injector and the spray angle is decreased due to the diminution of swirl strength in accordance with the increase of the length of injector orifice. When the injector sprays the liquid through the inner injector with the aid of gas through the outer injector, the spray angle in external mixing region tends to increase with rise of the recess length, while in internal mixing region, it is decreased. It is also confirmed that the same tendency of the spray angle with recess length appears irrespective of the injection pressure of liquid spray.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.82-85
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• 2009

In the development of Liquid Rocket Engine(LRE) systems, it is essential to understand the spray characteristics which influence mainly the performance and the stability of combustion. The injectors for this study have a recessed Liquid-swirl/Gas-centered jet coaxial type. For the similarity with actual conditions, the experimental conditions are calculated by using the momentum ratio as a matching parameter, and the stimulants of fuel and oxidizer are gaseous nitrogen and water respectively. The spray fields were measured by means of a photographic technique. Moreover, an effect of the momentum ratio has been investigated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.877-880
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• 2011

A coaxial swirl/shear injector using GCH4/LOx as propellants was degisned and manufactured. Flow analysis by Fluent was performed to decide the number of orifice and the rear shapes of inlet orifice etc. Flow rate of the injector was measured according to differential pressure and uniformity of injector's spray pattern was confirmed by a patternator. The results showed that the difference of flow rate was around 10% and the spray angle of oxidizer was $66^{\circ}$.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.658-661
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• 2011

A coaxial swirl/shear injector using GCH4/LOx as propellants was degisned and manufactured. Flow analysis by Fluent was performed to decide the number of orifice and the rear shapes of inlet orifice etc. Flow rate of the injector was measured according to differential pressure and uniformity of injector's spray pattern was confirmed by a patternator. The results showed that the difference of flow rate was around 10% and the spray angle of oxidizer was $66^{\circ}$.