• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.83-87
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• 2009

Ramjet engine is weak for low frequency combustion instability because of their long air flow passage. A model combustor which has fuel injector and V-gutter shaped flame holder was designed and fabricated in order to simulate a combustion mechanism of ramjet engine, and it could demonstrate combustion instability which might occur in ramjet combustor. The frequency of the instability was very similar to that of acoustic resonance frequency of combustor, and it proved that a typical combustion instability by thermo-acoustic coupling occurred.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.307-311
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• 2008

Ground test of model Scramjet engine was performed with T4 free-piston shock tunnel at University of Queensland, Australia. Test condition of free stream was Mach 7.6 at 31 km altitude. With this condition, variation effects of fuel equivalence ratio, cavity, cowl setting were investigated. In the results, supersonic combustion or thermal choking was observed depending on the amount of fuel. Cavity and W-shape cowl showed early ignition and enhanced mixing respectively.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.586-589
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• 2009

Scramjet engine combustor was tested with "RAMSYS" blow down wind tunnel in Kakuda Space Center, JAXA. As a result, installation of a cavity showed larger combustion pressure than the case without a cavity. Zigzag cavity applied for the first time in this experiment, showed the largest combustion pressure and is expected to contribute to the stable and economic operation of scramjet.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.7
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• pp.845-851
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• 2003

The purpose of this experimental study is to investigate the quantitative pollutants reduction by oxygen enrichment and induced air effect in venturi type after-burner. For this purpose, CO, $CO_2$, $O_2$. and HC concentrations were measured before and after the after-burner by changing the Oxygen flow rate and area ratio which is defined as the ratio of air inducing area divided by total area. As results of this study, when the area ratio were increased, the emission reduction effect was increased even less oxygen flow rate. In that case when oxygen was injected too little, the pollutants were increased.

• 한국전산유체공학회:학술대회논문집
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• 1998.05a
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• pp.128-137
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• 1998

In this numerical experiment, the preconditioned compressible Navier-Stokes equation is tested to analyze the laminar spray combustion. Sprayed flow field is formulated by Eulerian-Lagrangian system for the gas and liquid phases each. DSF(Deterministic Separated Flow) model was adopted for the sprays with the vortex model to describe transients of individual droplet heating. Simplified single global reaction model approximates methanol-air reaction with and without disk flame holder. The equation system is discretized by finite difference technique and time integrated by LU-SGS. Due to greatly simplified chemical reaction mechanism and the lack of experimental evidences, most of the efforts were devoted to show the applicability and robustness of preconditioned compressible flow calculation algorithm. Computation results in qualitatively reasonable combusting flow field, hence it is believed that further refinement are required to produce quantitatively accurate solutions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.449-452
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• 2004

“Flameless combustion” of lean to ultra lean mixtures, supported by high-temperature burned gas, can resolve the dilemma between complete combustion versus ultra-low NOx emissions in gas turbine combustors. The characteristics of NOx emissions and combustion in “lean-lean” two-stage combustion were investigated for fuel vapor and droplets / air mixture jets injected from the main injection tube that was placed perpendicular to the combustor wall into the primary hot burned gas prepared by combustion of lean mixtures on a perforated flame holder. The present results clearly show that the ultra-low NOx combustion supported by the reaction of lean mixtures well mixed with the hot burned gas from the primary stage is much more advantageous in achieving ultra-low NOx emissions while maintaining high combustion efficiency.

• Fire Science and Engineering
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• v.29 no.3
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• pp.1-5
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• 2015

The productivity and demand of porous material has been increasing by development of industry and increasing income. In particular, the fire caused by using wood flour risks wood processing industry and stock farm. The heat transfer of wood flour is carried into the depth direction by effect of oxidizer around flame, flame sometimes is progressed as smoldering. In the case of progressing as combustion fire, identifying the location of fire is difficult, and it leads to failing fire aid fire fighting. Therefore potential cause is acted as raising additional damage. This paper conducts experiments of downward deep seated fire of natural convection conditions. The samples is New Zealand wood flour that is demanded much in the domestic and oversea market. In this experiment, temperature of deep seated side is measure by changing wood flour density in holder The densities used in experiment are 3%, 5%, 10%, 15%. As a result, the tendency of temperature inside decreases as wood flour density increases. But, in the case of density which is above $0.2140g/cm^3$, the phenomenon, decreasing temperature, is not shown. The result of measurement show that average flame spread speed of wood flour is 0.249 mm/min.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.5
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• pp.13-20
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• 2020

The effect of the relative distance between two cavity flame holders on the performance of a supersonic combustor was experimentally investigated. A rectangular cross-sectional combustor model with one cavity flame holder on each of two facing walls was used, with two difference distances between cavities of 135 mm and 220 mm. The fuel equivalence ratio was varied as 0.16 and 0.38. A direct-connected type test facility was used to provide Mach 2 flow condition. The test results revealed that the combustion pressure was higher for the shorter cavity distance case. But fuel equivalence ratio did not have large effect on the combustion pressure. It was concluded that, to get higher combustor pressure, there needs to be further combustor configuration change such as smaller cavity distance or tandem cavity installation.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.5
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• pp.63-73
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• 2022

Investigation on operation of the test apparatus for the M4 semi-freejet tests with a full-scale vehicle model was carried out utilizing domestic facilities. An integrated design of the experimental apparatus and the vehicle model was obtained through iterative computational fluid dynamics (CFD) analysis. The test results showed that the M4 nozzle of the apparatus was fully expanded to provide required test conditions. It was also found that the intake of the vehicle model successfully started, and the corresponding shadowgraph images were recorded during the test. A variable nozzle of the model was set to adjust the back pressure of the model combustor, and wall-static pressures were measured to obtain the pressure distribution at the main locations of the model. The flame of torch ignitors and pilot fuel ignition were observed in a flame-holder of the combustor.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.5
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• pp.1-13
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• 2007

Scramjet engine is one of the most promising propulsion systems for future transport. For the ground test with T4 shock tunnel, model scramjet engine is designed. Design flight Mach number is 7.6 and flight altitude is 30km. Engine intake is designed by Levenberg-Marquardt optimization method and Korkegi relation. Furthermore, cowl cut out region is installed by the rule of Kantrowitz limit. Inside the combustor, cavity type flame holder is installed. Cavity is designed by Rayleigh line relation and PSR model. Numerical analysis is performed for the design confirm.