• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.531-535
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• 2008

Present study examines the detonation wave propagation characteristics in annular channel. A normalized value of channel width to the annular radius was considered as a geometric parameter. Numerical approaches used in the previous studies of detonation wave propagation were extended to the present study with OpenMP parallelization for multicore SMP machines. The major effect of the curved geometry on the detonation wave propagation seems to be a flow compression effect, regardless of the detonation regimes. The flow compression behind the detonation wave by the curved geometry of the circular channel pushes the detonation wave front and results in the overdriven detonation waves with increased detonation speed beyond the Chapmann-Jouguet speed. This effect gets stronger as the normalized radius smaller, as expected. The effect seems to be negligible beyond the normalized radius of 10.

• Journal of the Korean Society of Safety
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• v.11 no.4
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• pp.64-71
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• 1996

Detonation phenomena of $C_2H_2$were invesgated using the various shock tube. To study the detonation characteristics according to the composition of $C_2H_2-0_2$$_2$ and $C_2H_2$-air mixtures, the composition were varied from 5 to 90% and 5 to 50% of acetylene each other. A spiral ring was installed in the shock tube to study the effect of obstacles in DDT phenomena. Detonation velocities were measured using the photodiode, and the DDT phenomena was visualized using the high speed schlieren photograph. From the experimental result, it was found that the detonation velocity was most high near the 1. 8times the stoichiometric ratio of acetylene. And from the visualization of DDT phenomena, it was found that the detonation wave was strengthened throuth the pile up of small compression wave of burned gas. And the obstacles in shock tube accelerate the detonation reaction by turblent effect of flammable gas mixture.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.367-370
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• 2007

Present study examines detonation wave propagation characteristics in annular channel. A normalized value of channel width to the annular radius was considered as a geometric parameter. A parametric study was carried out for a various regimes of detonation waves from weakly unstable to highly unstable detonation waves. Numerical approaches that used in the previous study of numerical requirements of the simulation of detonation wave propagations in 2D and 3D channel were used also for the present study with OpenMP parallization for multi-core SMP machines. The major effect of the curved geometry on the detonation wave propagation seems to be a flow compression effect, regardless of the detonation regimes. The flow compression behind the detonation wave by the curved geometry of the circular channel pushes the detonation wave front and results in the overdriven detonation waves with increased detonation speed beyond the Chapmann-Jouguet speed. This effect gets stronger as the normalized radius smaller, as expected. The effect seems to be negligible beyond the normalized radius of 10.

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.275-278
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• 2012

We investigate the interaction between the propagation of detonation and inserted gaps in the high explosive. The Eulerian-based multi-material simulation code validated through comparison with experimental results was used. A series of gap materials is used to understand the detonation propagation characteristic in the presence of multiple gaps.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.4
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• pp.57-64
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• 2011

It has been suggested that turbulent effect should be considered for the study of highly unstable detonation of hydrocarbon fuels, as in the case of pulse detonation engine (PDE). A series of numerical study are carried out to understand the characteristics of the highly unstable detonation by considering viscosity, turbulence model and turbulence-combustion interaction model. Through studies of the different levels of modeling, it is understood that the viscosity and turbulence have negligible effects on low frequency characteristics, but tend to enhance the high frequency characteristics. It is also considered that the turbulence-chemistry interaction model should be taken the influence of the activation energy into account for detonation studies.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.5
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• pp.121-134
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• 1994

Shock tube investigation of ethylene oxide-$0_{2}-N_{2}$ mixture have been performed to reveal detonation characteristics of the mixture in terms of detonation pressure and speed. Theoretical calculation of thermodynamic parameters at the Chapmann-Jouguet detonation of the mixture has been also performed. A comparision of the observed results with the calculated ones can lead us to predict the detonation parameters of ethylene oxide in an artificial air. In addition, we have observed ignition delay times of ethylene oxide mixtures. The best fit of the observed delay times to Arrhenius gas kinetic relation gives : ${\tau}=10^{-144}{e{xp}}(E_a/RT)[C_{2}H_{4}O]^{-4.8}[O_{2}]^{-12.4}[N_{2}]^{-14.1}$ $E_a=3.67kcal/mole$ The observed activation energy is markedly reduced, compared with the case of ethylene oxide diluted in Ar. It could be due to the factor that $N_2$ play a role as detonation promoter yielding very reactive NOx radicals.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.686-690
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• 2017

In this study, we numerically investigate the detonation characteristics (detonation velocity and pressure) of a hybrid ethylene-air and RDX mixture using two-phase model. Compared with detonation of pure ethylene-air mixture, the detonation of the hybrid ethylene-air and RDX mixture has higher pressure and stronger impulse because the hybrid mixture has additional chemical heat release of RDX particles. To validate the numerical results using two-phase model, we compare the experimental data which show changes of detonation pressure and velocity according to concentration of RDX particles.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.2
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• pp.66-73
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• 2008

Present study examines the detonation wave propagation characteristics in annular channels. Numerical approaches used in the previous studies were extended with marching windows technique. Parametric study has been carried out using a radius of curvature normalized by the channel width considered as unique geometric parameter. In the channels of small radius of curvature, detonation wave is unstable and the regular cell structure is not observed. There is a critical radius of curvature where cell structure can be sustained. The effect of curvature makes the pressure difference on inner and outer surfaces where the detonation wave is overdriven. The results converge to that of straight channel as the radius of curvature gets larger, as expected.

• Journal of the Korean Society of Safety
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• v.6 no.2
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• pp.31-36
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• 1991

Quenching effects of acetylene and hydrogen into oxygen detonation by using detonation arrester ［DA］are studied in this paper. The experiments were carried out in cylinderical shock tube. 5m long, 30mm dia., with stolchlometric ratio ［SR］of each gas and 10-l20$\mu$ Cell Size of brass and Stainless Steel of DAs were installed in it To clarify arresting ability correlation with initial pressure, Pi, critical thickness, Tct, and shapes of supporting panel of DA are also investigated It is found that ­detonation velocities has most dependency on Pi, it shows notable changes around 0.5kgf/$\textrm{cm}^2$ for hydrogen, 0.15kgf/$\textrm{cm}^2$ for acetylen respectively, ­DA can be safety device able to arrest shock wave of detonation, ­over Tct flame transmission might be only the factor has to be considered, ­acetylene seems to be much more stronger detonation characteristics than hydrogen because of reaction heat.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.624-628
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• 2011

To develop a pulse detonation engine, it needs to understand the mechanism of a detonation initiation, and establish the methods for measuring and analyzing the detonation phenomenon. In this study, DDT tube, which use oxygen-acetylene propellant mixture, were designed and manufactured, and the effect of equivalent ratio and Schelkin spiral on the characteristics of the detonation initiation were discussed.