• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.1
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• pp.47-59
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• 2022

Four swirl coaxial injectors with different recess lengths were manufactured using an additive manufacturing method. Single-injection and bi-injection cold-flow experiments were performed using water and air as simulated propellants in an atmospheric pressure environment. According to the recess length and propellant flow conditions, the injection pressure drop and discharge coefficient were investigated, and the breakup length and spray angle were measured using an image processing technique. In the bi-injection pressure drop and discharge coefficient results, the liquid-side injector was not affected by the recess. For the gas-side injector, however, the injection pressure drop increased and the discharge coefficient decreased as the recess length increased. The breakup length in the single-injection increased with the increase of the recess, but decreased in the bi-injection.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.13-18
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• 2010

This study aim to investigate the internal mixing flow characteristics by recess length of swirl coaxial injector for gas generator has propellant of Kerosene-LOx. Recess length is a very important element, have influence in spray stability and LOx post damage. The influence of recess length was analyzed by visualizing internal flow and measuring liquid film thickness and manifold pressures. Also, frequency characteristics were analyzed by liquid film thickness measurement with mixing time.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.29-33
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• 2010

This study aim to investigate the internal flow characteristics by recess length of swirl coaxial injector for gas generator has propellant of Kerosene-LOx. Recess length is a very important element, have influence in spray stability and LOx post damage. The influence of recess length was analyzed by visualizing internal flow and measuring liquid film thickness and manifold pressures. Also, each spray characteristic by recess length was investigated in internal or external injector.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.3
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• pp.9-17
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• 2006

The influences of recess length of a liquid/liquid swirl coaxial injector on spray characteristics were investigated. It was revealed that the internal impinging phenomenon played an important role in the spray characteristics, such as spray angle and breakup length. Also, as the recess length increased, the mean drop size increased due to the increase of effective film thickness and mixing efficiency increased, but in the case of very deep recess length, the mixing efficiency decreased.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.74-77
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• 2011

A mixing characteristics on recess length change of Gas-centered swirl coaxial injector using high-performance staged combustion rocket engine carry out study through CFD(Computational fluid dynamics). propellant phase that combined gas-liquid simulate gas-gas. In order to measure spreading angle, velocity distribution to injector exit and spray structure of propellant analyzed. Axial velocity increase by increasing recess length, but tangential velocity decrease. The result confirmed qualitative characteristics that the spreading angle decreases.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.217-220
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• 2009

This paper presents experimental results of Recess Characteristic of Swirl Coaxial Injector of fuel-rich gas generators. It was revealed that the internal impinging phenomenon played an important role in the spray characteristics, such as spray angle and breakup length.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.1
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• pp.24-33
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• 2020

In this study, model combustion tests were conducted to investigate the combustion instability characteristics of swirl coaxial injectors for a liquid rocket engine. To examine the effects of the combustion chamber resonant frequency and the injector mixing conditions, pressure fluctuations in the combustion chamber were measured by changing the combustion chamber length, injector recess length, and propellant mixture ratio. From the test results, the variation in the pressure fluctuations for each experimental condition was confirmed and the combustion stability was evaluated by stability mapping. It was found that the longitudinal mode and Kelvin-Helmholtz instabilities occurred due to the change in the combustion chamber and recess lengths.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.3
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• pp.17-24
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• 2016

The reacting flows of gaseous hydrogen/liquid oxygen 2D coaxial shear injector with varying recess length are numerically analyzed. The standard ${\kappa}-e$ model and laminar flamelet model are adopted for the steady turbulent combustion with the ideal and real gas equations. As the recess length increases, the recirculating region in the combustion chamber expands and the vorticity is intensified. Also, the variations of temperature, products, and pressure are strongly related to the recess length. The results show that an efficient combustor can be obtained by the introduction of the recessed injector.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.4
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• pp.70-80
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• 2019

Combustion tests using six bi-swirl coaxial injectors with different shapes and recess lengths were performed in a model combustion chamber capable of flame visualization. By utilizing gaseous methane and gaseous oxygen instead of actual propellants, the effects of injector design and experimental conditions on the flame structure and combustion stability were analyzed. It was found that not only the experimental conditions but also the injector geometry such as the recess length and orifice diameter had a considerable influence on the combustion stability. In addition, it was confirmed that the heat release pattern changed with the occurrence of combustion instability.

• 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.