• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.245-248
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• 2005

SCRamjet is the key technology for hypersonic flight over mach number 6. It is characterized by very short residence time in combustor because its internal flow is supersonic. In this short time, the whole process of combustion must be done. Especially numerical study of combustor is important because air-fuel mixing rate influences the performance of combustor. Various methods of air-fuel mixing enhancement are proposed. Among these, cavity injection method is selected to study in this paper. The numerical study is conducted with the variation of the cavity length at the fixed height of unit and jet injection on the downstream of cavity.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.12
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• pp.3980-3990
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• 1996

When a moist air is rapidly expanded in a supersonic nozzle, nonequilibrium condensation occurs at a supersaturation state. Condensation shock wave appears in the nozzle flow if the releasing latent heat due to condensation goes beyond a critical value. It has been known that self-excited oscillations of the condensation shock wave generate in an air or a steam nozzle flow with a large humidity. In the present study, the passive control technique using porous wall with a cavity underneath was applied to the condensation shock wave. The effects of the passive control on the steady and self-excited condensation shock waves were experimentally investigated by Schlieren visualization and static pressure measurements. The result shows that the present passive control is a useful technique to suppress the self-excited oscillations of condensation shock wave.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.3
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• pp.9-14
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• 2013

Combustion tests were conducted for a hydrogen-fueled Mach 5 scramjet engine model using a blow-down facility. No fuel and two fuel flow rate cases were tested for two different model configurations. Time history of the wall static pressures inside the model and their time-averaged spatial distribution were used for the analysis of the flow and combustion characteristics. For shorter model, supersonic combustion was occurred for both of the fuel flow rate cases. For longer model, supersonic combustion was occurred for less fuel case, whereas thermal choking and subsonic combustion were occurred for more fuel case. Intake started even for this subsonic combustion case.

• 한국연소학회:학술대회논문집
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• 2003.12a
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• pp.159-165
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• 2003

This paper describes numerical efforts to characterize the flame-holding and air-fuel mixing process of model SCRamjet engine combustor, where a hydrogen jet injected into a supersonic cross flow and in a cavity. Combustion phenomena in a model SCRamjet engine, which has been experimentally studied at University of Queensland and Australian National University using a free-piston shock tunnel, was observed around separation region of upstream of the normal injector and inside of cavity. The results show that the separation region and cavity generates several recirculation zones, which increase the fuel-air mixing. Self ignition occurs in the separation-freestream and cavity-freestream interface.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.5
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• pp.19-26
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• 2011

In order to investigate the effect of fuel injection hole configuration within the scramjet combustor, experiment and quasi-one-dimensional analysis was performed. And the results were compared with experiment and analysis result which were performed in 2008 with same facility and test condition. Fuel injection hole size was decreased and quantity was increased. However the depth of fuel penetration and flow quantity of fuel were maintained. As a test result, combustion performance was increased significantly with no-cavity injector and slightly with plain-cavity. However, combustion performance with zigzag-cavity was decreased.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.423-431
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• 2010

In order to investigate the effect of fuel injection hole configuration within the scramjet combustor, experiment and quasi-one-dimensional analysis was performed. And the results were compared with experiment and analysis result which were performed in 2008 with same facility and test condition. Fuel injection hole size was decreased and quantity was increased. However the depth of fuel penetration and fuel flow were maintained. As a test result, combustion performance was increased significantly with no-cavity injector and slightly with plain-cavity. However, combustion performance with zigzag-cavity was decreased.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.4
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• pp.104-111
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• 2016

The flame stabilization is one of the topics which have to be solved for the airbreathing propulsion systems, using the entering air which is supersonic velocity as an oxygen sources. Making a recirculation zone with an eddy flow, installed the reducing velocity devices such as the bluff body, is the typical method of the flame stabilization. Recently using a cavity flame stabilization at the wall is an emerging technique as an effective method which extends the stabilization zone, and the related research papers have been published on the flow separation and reattachment, pressures and oscillations including length/depth ratios in the cavities. Even though, still there are lots of topics to study more in the cavity flame stabilization field as the preceding techniques, as well as the research and the development of the airbreathing propulsion system itself.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.2
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• pp.90-97
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• 2019

Sparkjet actuator, also known as plasma synthetic jet actuator (PSJA), is an active flow control device that has possibility of controling supersonic flow. This actuator utilizes arc plasma to deposit energy onto the gas inside the cavity to raise temperature and pressure. A change in the state of the fluid inside the cavity generates pressure waves and momentum jet, and they are exhausted through out the orifice exit and disturb external flow field. Since the cavity flow is affected by arc plasma, which is an equilibrium plasma and have generated equilibrium flow, the equilibrium state of air should be considered in order to analyze the flow of sparkjet actuator. In this study, numerical program for equilibrium flow was developed for the use of sparkjet actuator analysis. The developed program was validated by comparing the time - accurate jet front positions with the reference result. Then, impulse characteristics of the actuator in the atmospheric quiescent air were explained.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.1
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• pp.78-84
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• 2005

In the chemical laser system with a radial expansion nozzle array, the laser beam generation is achieved by mixing F atom from supersonic nozzle and $D_{2}$ molecule from holes of round-bended supply line. Based on that the fuel injection angle with main stream has a great influence of performance on supersonic combustor, the effects of $D_{2}$ injection angles with the main F flow on mixing enhancement are numerically investigated. The results are discussed by comparison with three cases of $D_{2}$ injection angles; $10^{o}$, $20^{o}$ and $40^{o}$ with the main flow direction. Major results reveal that as the $D_{2}$ injection angle increases, the maximum small signal gains and the static pressure in the laser cavity become higher. Consequently, the $D_{2}$ injection angle between $20^{o}$ and $40^{o}$ is recommended as an optimized geometric parameter in consideration of both of high gains and low cavity pressure.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.9
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• pp.2944-2952
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• 1996

In this paper the CSCM type upwind flux difference splitting Navier-Stokes method has been applied to study the ARL-SL19 transoni $c^ersonic compressor cascade flow. First, the general characteristics of baseline cascade flow were analyzed. At freestream Mach n.1.612 and exit/inlet pressure ratio 2.15, the results from current laminar flow were compared well in suction surface with the experiment; however, not well in pressure surface. Second, numerical study of the transoni $c^ersonic compressor cascade flow demonstrated the effectiveness of a passive control by the various size cavities. A cavity under the shock foot point at the suction surface of the blades was used as a passive control. The passive control of shock-boundary layer interaction by a cavity reduced total pressure losses. The effect of cavity length and depth was studied. The total pressure loss was reduced by about 10% and the isentropic efficiency was improved slightly. The effect of cavity depth in current study(d/l = 0.05, 0.02) was not found strong. Further adequate turbulence modeling and TVD schemes would help to capture the shock more accurately and increase the effectiveness of the current shock-boundary layer interaction study using upwind flux difference splitting computational methods.thods.