• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.3
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• pp.264-270
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• 2008

Most of burning rate models used in hybrid combustion depend solely on oxidizer flux. But this empirical relation can not represent well the important effect of the thermo-chemical properties of solid fuel and thereby requires different value of empirical exponent and constant for each fuel considered. In this study, a new burning rate correlation was proposed using the mass transfer number(B number) which encompasses the thermochemistry effect of solid fuel and the aerodynamic effect caused by the combustion on the solid fuel surface where the effect of aerodynamic property in the mass transfer number was studied. The PMMA, PP, and PE were chosen as fuel, and gas oxygen as oxidizer. The new empirical burning rate expression depending on both the oxidizer flux and the mass transfer number was able to predict the burning rate of each fuel with just a single exponent value and constant, and it was found that the aerodynamic effect on the blowing effect did show a minor effect on the burning rate correlation.

• Fire Science and Engineering
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• v.10 no.1
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• pp.44-48
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• 1996

Burning rate of immobilized methyl and ethyl alcohols on ceramic balls was studied. Experiments were performed by burning methyl, ethyl alcohols immobilized on sands (particle size 0.35mm) and ceramic balls (particle size 1-5mm) to measure mass burning rate, height burning rate and combustion temperature. The longer time from ignition to extinguishment was resulted from the larger particle size of ceramic balls and the smaller size of ceramic balls exhibited the higher mass burning rate. Of alcohols tested the relative magnitude of facilitation of combustion was methyl ＞ ethyl. Combustion temperature of alcohols, without regard to the types of alcohols, was not increased with smaller ceramic balls(up to 3mm of particle size). However, with larger ceramic balls, combustion temperatare of alcohols was increased by 40-50$^{\circ}$ and the highest combustion temperatare was obtained with sands (particle size 0.35mm).

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.70-75
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• 2012

In this paper, the regression rate of the End-Burning Hybrid Rocket with variation of swirl intensity was investigated experimentally with the variation of fuel diameter, injector shape and angle. When fuel grain diameter is large, fuel mass flow rate increases. And the injector diameter increase, fuel regression rate decrease. The impinging effect of oxidizer flow on fuel surface for fuel combustion efficiency is stronger than swril effect in this End-burning propulsion system. The relation between the regression rate, oxidizer mass flux and swirl intensity was obtained.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.228-231
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• 2006

In general, burning time is not considered with a factor of an empirical relation on the combustion characteristic in hybrid propulsion system. So, The effect of burning time on hybrid combustion characteristics and propulsion characteristics was studied. As results, regression rate is decrease with burning time, but fuel mass flux is maintained nearly constant with burning time at given oxidizer mass flux.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.323-326
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• 2005

In this study, experimental studies were performed the combustion characteristics of end- burning hybrid propulsion system. PMMA, PE were used as fuel and gas oxygen as oxidizer. The regression rate depend on oxidizer flow rate also on thermodynamic properties of fuel. as result, empirical formula for regression rate was deduces with oxidizer flow rate and mass transfer coefficient B number.

• Journal of the Korean Society of Safety
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• v.9 no.1
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• pp.76-82
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• 1994

Combustion phenomena(characteristics) of organic solvents including various alcohols Immobilized on ceramic balls were studied. Experiments were performed by burning methyl, ethyl, and propyl alcohol immobilized on sands (particle size 0.35mm) and coramic balls(particle size 1~5mm) to measure mass burning rate, height burning rate and combustion temperature. The longer time from ignition to extinguishment was resualted from the larger particle size of ceramic balls and the smaller size of ceramic balls exhibited the higher mass burning rate. Of alcohols tested the relative magnitude of facilitation of combustion was methyl >ethyl >propyl. Combustion temperatare of alcohols, without regard to the types of alcohols, was not increased with smaller ceramic balls(up to 3mm of particle size). However, with larger ceramic balls, combustion temperatare of alcohols was increased by 40~5$0^{\circ}C$ and the highest combustion temperatare was obtained with sands(particle size 0.35mm). Also, second rising was occurred at the combustion time of I5-20min. and this second rising time was increased with the smaller particle. These results will be able to be used for petrochemical industries using particles to evaluate the danger of fire and explosion.

• Journal of the Korean Society of Safety
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• v.11 no.3
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• pp.137-142
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• 1996

Combustion characteristics of immobilized methyl, ethyl and propyl alcohols on sands were studied. Experiments were performed by burning methyl, ethyl and propyl alcohols Immobilized on sands (particle size 0.1~5mm) and ceramic balls(particle size 5mm) to measure mass burning rate, height burning rate and combustion temperature. It was concluded that the longer time from ignition to extinguishment was resulted from the larger particle size of sands and the smaller size of sands exhibited the higher mass burning rate. Of alcohols tested the relative magnitude of facilitation of combustion was methyl>ethyl>propyl alcohol. Combustion temperature of alcohols, without regard to the types of alcohols, was not increased with smaller sands. However, with larger sands, combustion temperatare of alcohols was increased with the larger particle.

• Journal of the Korean Society of Safety
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• v.22 no.6
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• pp.46-54
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• 2007

The purpose of this study was to examines the burning rate of fire retardant treated wood in the cone heater with a one-dimensional integral model. The wood samples used in this study were four species. The species of woods are Redwood, White oak, Douglas fir and Maple. Each sample was nominally 50mm thick and 100mm square. Samples were exposed to a range of incident heat fluxes 10 to $35kW/m^2$ using the cone heater. A one-dimension integral model has been used to predict burning rate, heat of gasification, flame heat fluxes, charring rate and char depth of samples. As a result measurement of mass loss rate, softwoods(Redwood and Douglas fir) has relatively low value than those for hardwoods(White oak and Maple). Average charring rate of woods in case of fire retardant treatment showed reduction effect of 41.29%, 50.00%, 48.18% and 60.82% for Redwood, Douglas fir, White fir and Maple, respectively. Almost all the predictions from integral model showed faster charring than those measured. Average difference between predictions and experimental data was 16%, 9.5% and 11.8% for N, F1 and F2 respectively. Water-soluble fire retardant used in this study find out more effect in hardwood than softwood from the result of measurement of mass loss rate and average charring rate.

• Journal of the Korean Society of Safety
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• v.19 no.3 s.67
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• pp.45-50
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• 2004

4-panel of 1m height and 45cm width were fixed on the $40cm{\times}40cm$ bottom plate and the opening of the panel comer was 5cm. Diameter of stainless vessel is loom and its height is 2cm and it located at the center of the bottom plate. 78mL liquid fuel was filled in the vessel and its depth was 1cm. Flame temperature was measured with K type thermocouple, and radiation heat of flame was measured with heat flux meter. Flame height and its behavior was visualized with video camera. and mass burning rate was measured by fuel combustion time. According to the development of fire, flame swirling was begin. From the experiment the mass burning rate was larger and the height of flame was higher than the usual pool fire flame. Flame temperature and heat flux also increased far more than the pool fire. Consequently the swirling air flow through the openings between the panel and thermal buoyance contribute to increase of heat release rate, flame length and mass burning rate.

• Journal of the Korean Society of Safety
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• v.23 no.6
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• pp.84-90
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• 2008

The mass loss rate and heat release rate of puzzle mats were analysed using variable external irradiation level. Five samples of puzzle mat were tested in this study : Type A, B, C, D and E. Type A, B and C are all general grades whereas Type D and E are both Flame retardant grades. Incident heat fluxs of $25kW/m^2$, $35kW/m^2$, $50kW/m^2$ and $70kW/m^2$ were selected for these experiments. All samples were tested in the horizontal orientation and were wrapped in a single layer of aluminum foil. Each sample was nominally 20mm thick and 100mm square. The combustion heat and mass loss rate were carried out from Oxygen bomb calorimeter and mass loss calorimeter according to ISO 5660-1 respectively. Heat release rates were calculated using the equation ${\dot{Q}}=A_f{\dot{m}}"_X{\Delta}H_c=0.75A_f{\dot{m}}"{\Delta}H_c$. where $A_f$ is the horizontal burning area of the sample, $\dot{m}"$ is mass loss rate per unit area, ${\Delta}H_c$ is complete heat of combustion and 0.75 is combustion efficiency.