• Journal of Advanced Marine Engineering and Technology
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• v.33 no.4
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• pp.466-475
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• 2009

A numerical analysis of reactive flow in a liftoff flame is accomplished to elucidate the characteristics of flame propagation velocity and volume integral of reaction rate with the variation of fuel injection velocity at the fuel rich region, fuel lean region and diffusion flame region. The increase of fuel injection velocity enhances flame propagation velocity, but its effect on the flame propagation velocity is not much greater under 4%. The increase of fuel injection velocity affects directly and linearly on the flame surface area in the fuel rich region and so enhances volume integral of reaction rate to accommodate the increment of fuel.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.653-655
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• 1992

Longitudinal and transverse normal zone propagation in the superconducting coil are analyzed and propagation velocity is derived from the heat balance equations in the propagating boundary region. Transverse velocity is nearly $10^{-2}$ order of longitudinal velocity. Propagation velocity ie linearly proportional to the transport current. Increasing lamp current speeds up longitudinal velocity by 0.279 m/s under the applied field of 2T. Transient heat transfer has a significant effect on normal zone propagation velocity and it decreases longitudinal velocity by 4.2 m/s under the applied field of 2T as being compared to steady-state heat transfer.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.7
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• pp.1041-1049
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• 1994

Longitudimal and transverse normal zone propagations in the superconducting coil are analyzed and propagation velocity is derived from the heat balance equations in the propagating boundary region. The results of applying to the specific superconducting wire show that propagation velocity is linearly proportional to the transport current and increasing ramp current speeds up the longitudinal velocity by 1.22[m/s] under the applied field of 2T. Transient heat transfer has a significant effect on the normal zone propagation velocity and it decreases longitudinal velocity by 5.2[m/s] under the applied field of 2T as being compared to the steady-state heat transfer. Increasing ramp current speeds up the Z-axis transverse propagation velocity by 0.042[m/s] and transverse velocity of R and Z axis is costant regardless of the current flows.

• Journal of the Korean Institute of Gas
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• v.14 no.3
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• pp.46-52
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• 2010

Flame propagation velocity is the one of the main mechanism of the stabilization of triple flame. To quantity the triple flame propagation velocity, Bilger presents the triple flame propagation velocity, depending on the mixture fraction gradient, based on the laminar jet flow theory. However, in spite of these many analyses, there has not been any attempt to quantify the triple flame propagation velocity with the flame radius of curvature and scalar dissipation rate. In the present research, there was discussion about the radius of flame curvature and scalar dissipation rate, through the numerical study. As a result, we have known that the flame propagation velocity was linear with the nozzle exit velocity and scalar dissipation rate decreases nonlinearly with the flame propagation velocity and radius of curvature of flame increases linearly. Also radius of curvature of flame decreases non-linearly with the scalar dissipation rate. Therefore, we ascertained that there was corelation among the scalar dissipation rate, radius of flame curvature and flame propagation velocity.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.8
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• pp.1931-1939
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• 1993

The wave propagation characteristics of laminated composites subjected to a transverse high-velocity impact of a steel ball is investigated. For this purpose, high-velocity impact experiments were conducted to obtain the strain response histories, and a finite element analysis based on the higher-order shear deformation theory in conjunction with the static contact law is used. Test materials for investigation are glass/epoxy laminated composite materials with $[0^{\circ}/45^{\circ}/0^{\circ}/-45^{\circ}]_{2s}$ and $[90^{\circ}/-45^{\circ}/90^{\circ}-45^{\circ}/90^{\circ}]_{2s}$ stacking sequences. As a result, the strain responses obtained from the experiments represented the wave propagation characteristics in the transversely impact, also the wave propagation velocities obtained from high-velocity impact experiments and wave propagation theory agree well.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.77-78
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• 2015

Laminar burning velocities have been predicted by constant volume combustion chamber, counter flow burner and others. In this study, the measured flame propagation velocities in an assembled annular stepwise diverging tube were plotted with respect to equivalence ratio, length scale, and velocity scale. Three dimensional approach to understand the flame propagation velocity including laminar burning velocity is investigated, and the surface provides the correlation among quenching distance, propagation velocity, and equivalence ratio.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.2
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• pp.69-79
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• 1996

Dynamic stress intensity factors are derives when the crack is propagating with constant velocity under longitudinal shear stress in orthotropic disk plate. General stress fields of crack tip propagating with constant velocity and least square method are used to obtain the dynamic stress intensity factor. The dynamic stress intensity factors of GLV/GTV=1(=isotropic material or transversely isotropic material) which is obtained in out study nearly coincides with Chiang's results when mode Ⅲ stress is applied to boundary of isotropic disk. The D.S.I.F. of mode Ⅲ stress is greater when α(=angle of crack propagation direction with fiber direction) is 90° than that when α is 0°. In case of a/D(a:crack length, D:disk diameter)<0. 58, the faster crack propagation velocity, the less D.S.I.F. but when crack propagation velocity arrive on ghear stress wave velocity, the D.S.I.F. but when crack propagation velocity arrive on shear stress wave velocity, the D.S.I.F. unexpectedly increases and decreases to zero.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.13-18
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• 2007

When triple flames propagated in a diverging channel, the effects of fuel dilution on the lift-off characteristics of triple flames were investigated. A multi-slot burner was used to stabilize the lift-off flame especially at weak fuel concentration gradients. It was reported that there is a maximum propagation velocity at a critical concentration gradient in an open jet regardless of fuel dilution. The enhancement of a diffusion flame affected to increase the propagation velocity around critical concentration gradients. However, the influence of a confined channel on the structure of triple flames according to fuel dilution needs to be investigated compared with an open jet case. This study aimed to examine the effect of a confined channel on the structure and the propagation velocity of the triple flames according to fuel dilution. Lift-off height and propagation velocity of triple flames were investigated by employing three kinds of fuel compositions diluted by nitrogen (0%, 25%, 50% $N_2$), Fuel dilution reduced the propagation velocity of triple flame in a confined channel mainly due to the decrease of flame temperature in premixed branch. Despite the difference in fuel dilution, the propagation velocity has a maximum value at a specific fuel concentration gradient even though the critical concentration gradient increases with fuel dilution. And the critical concentration gradient in a confined channel is larger than that in an open jet due to enhancement of convective diffusion.

• Journal of the Korean Institute of Gas
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• v.15 no.2
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• pp.47-56
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• 2011

Flame propagation velocity is the one ofmainmechanismof the stabilization of triple flame. To quantify the triple flame propagation velocity, Bilger presents the triple flame propagation velocity depending on the mixture fraction gradient, based on the laminar jet flow theory. However, in spite of these many analyses, there was not presented any relation of these variables, triple flame propagation velocity, radius of flame curvature and scalar dissipation rate indirectly. In the present research, we have checked the results of numerical simulation with experiment and numerical analysis and verified the flame propagation velocity with a scalar dissipation rate proposed by Bilger through the numerical simulation. Also we have clarified that flame propagation velocity was depended on the radius of flame curvature and scalar dissipation rate.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.5
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• pp.947-951
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• 1989

It is well-known that the parameters of dynamic fracture mechanics depend not only on dimensions, loading and boundary conditions but also on the dynamic crack propagation velocity. Because the measurement of dynamic crack propagation velocity measuring device which can easily be expanded without modification is proposed in this report. it was found that the experimentally determined dynamic crack propagation velocity agreed well with those from other investigations in some polymers such as PMMA. Homalite-100 and Epoxy.