• Journal of the Korean Institute of Gas
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• v.7 no.4 s.21
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• pp.24-29
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• 2003

Numerical analysis was conducted to predict the damage of indoor gas explosion for the propagation of explosion flame. Indoor gas diffusion distribution due to gas leakage was obtained by diffusion equation that adopted initial conditions from reference. Enthalpy of each gas-mixture ratio and reduced mechanism was applied to calculate flame temperature, and laminar combustion velocities with the variant of each gas concentration from reference were applied to the gas mixture. Turbulent combustion velocity was modeled by coupling of turbulent energy and laminar combustion velocity in k-$\epsilon$ model. For the analysis of flame propagation cartesian and cylindrical coordinate were used to indoor position and flame propagation respectively. The study analyzes the cause of pressure rising with the variation of flame propagation by glass damage, and the result shows that indoor pressure rising with ignition position varies window dimension.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.9
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• pp.829-836
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• 2013

The combustion characteristics with variations in synthetic natural gas (SNG) compositions were studied in a lab-scale combustor. The objective of the current study is to investigate the flame stabilization, flame structure, and spectrometry in a non-premixed SNG flame with varying fuel compositions. For the analysis of light emission in SNG flames, we used a spectrometer. As experimental conditions, the fuel jet velocity at the nozzle exit $u_F$ was varied from 5 to 40 m/s and the coaxial air velocity $u_A$ was varies from 0 to 0.43 m/s. The experiments showed that the flame stability increased with the hydrogen component in SNG.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.6
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• pp.625-632
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• 2011

The ignition characteristics of a $CH_4$/hot air counterflow diffusion flame were investigated numerically using a flame-controlling continuation method. For the chemical reactions, the GRI-v1.2 reaction mechanism was used in the simulation. The maximum flame temperature was presented in the space of the inverse global strain rate, and showed S-curve-type behavior. The flame temperatures and velocities of the upper and middle branches were compared for different global strain rates. In addition, the global strain rate was compared with the local strain rates defined at the flame surface and the boundaries of the fuel and oxidizer sides of the fuel/air mixing layer. These local strain rates correlated well with the global strain rate.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.77-82
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• 2000

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.77-82
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• 2000

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.6
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• pp.1669-1678
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• 1990

The annular and coaxial swirl flows between which LPG is supplied was selected to study the swirling flames in double co-swirl flows. The objective of this study is to research into the effects of double co-swirl flow conditions on the stability limit, the reverse flow boundary, and the time mean temperature distributions of the swirling flames. The increase of swirl intensity of axial flow makes the stability limit decrease, but the annular swirl flow (SM>0.5) makes stability and swirl intensity of axial flow increase, And the existence of axial swirl flow makes flame intensive and small in size, and this may be applicable to the design of high power compact combustor.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.4
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• pp.352-356
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• 2008

In this study of lifted hydrogen jet with coaxial air, we have experimentally studied the characteristics of stabilization point in turbulent diffusion flames. The objectives are to present the phenomenon of a liftoff height decreasing as increasing fuel velocity and to analyse the flame structure and behavior including liftoff mechanisms. The fuel jet exit velocity was changed from 100 up to 300 m/s and a coaxial air velocity was fixed at 16 m/s with a coflow air less than 0.1 m/s. For the simultaneous measurement of velocity field and reaction zone, PIV and OH PLIF technique was used with two Nd:Yag lasers and CCD cameras. It has been suggested that the stabilization of lifted hydrogen diffusion flames was correlated with a turbulent intensity, $S_t{\sim}u^{\prime}$, and jet Reynolds number, $S_t{\sim}Re^{0.017}_{jet}$.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.780-787
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• 2019

As a carbon-free, green growth alternative, internal and external interest in hydrogen energy and technology is growing. Hydrogen was added to co-axial methane, methane-propane, and methane-propane-ethane diffusion flames, which are the main ingredients of LNG, to evaluate its effect on flame formation and combustion products. The variation in combustion products produced by adding hydrogen gradually to diffusion pyrolysis at room temperature and normal pressure conditions was observed experimentally by using a gas analyzer, and the shape of diffusion pyrolysis was observed step by step using a digital camera. The experimental results showed that the production volume of nitrogen oxides tended to increase and became close to linear as hydrogen was added to the diffusion pyrotechnic. This is because the relatively high temperature of heat insulation and fast combustion speed of hydrogen facilitated the production of thermal NOx. On the other hand, CO2 production tended to decrease as hydrogen was added to reduce the overall carbon ratio contained in the mixed diffusion flame of methane, methane-propane, and methane-ethane-propane. This means that the mixed fuel use of LNG-hydrogen in ships may potentially reduce emissions of CO2, a greenhouse gas.

• Journal of the Korean Institute of Gas
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• v.16 no.4
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• pp.32-37
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• 2012

The aim of this study is to evaluate the characteristics of explosion and flame velocity that can be utilized to factories where Mg-Al alloy metal powders are handled in the form of raw materials, products or by-product for similar dust explosion prevention and mitigation. Because the strength of the blast pressure is the result due to flame propagation, flame velocity in dust explosion can be utilized as a valuable information for damage prediction. An experimental investigation was carried out on the influences of content ratio of Mg-Al alloy (mean particle size distribution of 151 to 161 ${\mu}m$). And a model of flame propagation velocity based on the time to peak pressure and flame arrival time in dust explosion pressure, assuming the constant burning velocity, leads to a representation of flame velocity during dust explosion. As the results, the maximum flame velocity of Mg-Al(60:40 wt%), Mg-Al(50:50 wt%) and Mg-Al(40:60 wt%) was estimated 15.5, 18 and 15.2 m/s respectively, and also tend to change with content ratio of Mg-Al.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.2
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• pp.64-76
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• 2009

Experimental and numerical studies are conducted on the characteristics of flame extinction and edge flame oscillation in counterflow diffusion flames. The characteristics of flame extinction and edge flame oscillation are well described varying burner diameter, separation distance between two burners, global strain rate, and velocity ratio. It is verified numerically and experimentally that radial conduction heat loss significantly contributes to flame extinction and edge flame oscillation at low strain rate flames in zero- and micro-gravity. It is also shown that for appropriately small burner diameters flame extinction modes are grouped into four and these are significantly attributed to excessive radial conduction heat loss. The edge flame oscillation can be characterized well by one curve with Strouhal number and Peclet number.