• Journal of the Korean Society for Aviation and Aeronautics
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• v.15 no.1
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• pp.1-10
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• 2007

When detonation is occurred, the working fluid is compressed itself, though there are no other devices that compress the fluid. As a result, an engine which uses detonation for a combustion process doesn't need moving parts so that the engine can be lighter than other engines ever exist, and such an engine is often referred to as a pulse detonation engine. Since using detonation has higher performance than using deflagration, many studies have been attempting to control and analyze the engines using detonation as combustion. The purpose of this study is to analyze the hybrid cycle which is consisted of Brayton and Pulse Detonation Engine cycle. At first, we set the theoretical basis of detonation analysis, and after that we consider two hybrid cycles; a turbojet hybrid cycle and a turbofan hybrid cycle. The more energy released, the higher detonation Mach number the detonation wave has. In general, a cycle which has a detonation process has higher performances but thermal efficiency of hybrid turbofan engine.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.2
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• pp.9-15
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• 2013

An effect of a spiral turbulent ring, so-called Shchelkin spiral, on a detonation performance was studied experimentally for acetylene and oxygen mixture. A couple of dynamic pressure transducers were used to calculate a detonation wave velocity by a time difference between two pressure peaks. In addition, impulse was measured by a load cell and the impulse was used to analyze the spiral effect on the detonation performance. A CFD analysis was adopted to calculate mass flow rates of the propellants and the minimum filling time. The maximum velocity and pressure were measured at the equivalence ratio of 2.4, and the measured values showed similar trend to C-J conditions calculated from CEA. For the shorter chamber with the short spiral, the maximum detonation velocity was appeared. In contrast, the longer chamber without the spiral showed the maximum thrust performance.

• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.1913-1918
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• 2012

The nitramine explosives with $-NH_2$ and -F groups were optimized to obtain their molecular geometries and electronic structures at DFT-B3LYP/6-31+G(d) level. The theoretical molecular density (${\rho}$), heat of formation (HOF), detonation velocity ($D$) and detonation pressure ($P$), estimated using Kamlet-Jacobs equations, showed that the detonation properties of these compounds were excellent. Based on the frequencies scaled by 0.96 and the principle of statistic thermodynamics, the thermodynamic properties were evaluated, which were respectively related with the temperature. The simulation results reveal that 1,3,5,7-tetranitro-1,3,5,7-tetrazocan-2-amine (molecule B1) performs similarly to the famous explosive HMX, and 2-fluoro-1,3,5-trinitro-1,3,5-triazinane (molecule C1) and 2-fluoro-1,3,5,7-tetranitro-1,3,5,7-tetrazocane (molecule D1) outperform HMX. According to the quantitative standard of energetics and stability as an HEDC (high energy density compound), molecules C1 and D1 essentially satisfy this requirement. These results provide basic information for molecular design of novel high energetic density compounds.

• Analytical Science and Technology
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• v.30 no.6
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• pp.405-410
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• 2017

High energetic materials (HEMs) have been used in fuels, civil engineering and architecture as well as military purposes such as explosives and propellants. The essential process for the development of new energetic compounds is to accurately calculate its detonation performances. The most typical equation for calculating the explosive performance is the Kamlet-Jacobs (K-J) equation. In the K-J equation, the parameter such as the number of moles of gaseous products at the explosion, the average molar mass of gas products, and the explosion heat greatly affect the explosion performance. These depend on the product composition for the detonation reaction. In this study, detonation products of 65 high energetic molecules (HEMs) were calculated from the various rules such as Kamlet-Jacobs, Kistiakowsky-Wilson, modified Kistiakowsky-Wilson, Springall-Roberts rules to calculate more accurate detonation velocity (Dv). In addition, they were applied to five kinds of detonation velocity equations proposed by K-J, Rothstein, Xiong, Stine and Keshavarz. The mean absolute error and root mean square error of HEMs were obtained from experimental and calculated velocity value for each method. The K-J and Xiong equation that is slightly complex showed a lower mean absolute error than the simple Rothstein and Keshavarz equation. When the mod-KW rule was applied to the Xiong equation, the detonation velocities were the most accurate. This study compared the various method of calculating the detonation velocity of HEMs to obtain accurate HEMs performance.

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2352-2358
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• 2012

A high-nitrogen energetic salt, 1-amino-1-hydrazino-2,2-dinitroethylene guanidine salt [G(AHDNE)], was synthesized by reacting of 1-amino-1-hydrazino-2,2-dinitroethylene (AHDNE) and guanidine hydrochloride in sodium hydroxide aqueous solution. The theoretical investigation on G(AHDNE) was carried out by B3LYP/$6-311+G^*$ method. The thermal behaviors of G(AHDNE) were studied with DSC and TG-DTG methods, and the result presents an intense exothermic decomposition process. The enthalpy, apparent activation energy and pre-exponential constant of the process are $-1060J\;g^{-1}$, $148.7kJ\;mol^{-1}$ and $10^{15.90}s^{-1}$, respectively. The critical temperature of thermal explosion of G(AHDNE) is $152.63^{\circ}C$. The specific heat capacity of G(AHDNE) was studied with micro-DSC method and theoretical calculation method, and the molar heat capacity is $314.69J\;mol^{-1}K^{-1}$ at 298.15 K. Adiabatic time-to-explosion of G(AHDNE) was calculated to be a certain value between 60-72 s. The detonation velocity and detonation pressure were also estimated. G(AHDNE) presents good performances.

• Explosives and Blasting
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• v.38 no.2
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• pp.13-21
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• 2020

The shaped charge was used in explosive demolition of a steel frame structure, but it was often not used because it was limited to use and impossible to supply at domestic and overseas. Existing linear shaped charge did not have sufficient cutting performance to cut steel frame structures with a huge scale and thick steel plate. To solve these problems, we produced a device that could generate metal jets using industrial explosives of high detonation velocity and pressure. In this study, we made a charging container of three types which applicable to explosive demolition of steel frame structures. The experiment of cutting performances was carried out to evaluate the effect of cutting of charging containers on the various thicknesses of the H-beam and steel plate. As a result of the experiment, sufficient cutting performance was confirmed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.2
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• pp.197-208
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• 2022

The existence of shallow bedrock and the desire to use underground space necessitate the use of blasting methods. The standard blasting method under water after drilling is associated with certain technical difficulties, including reduced detonation power, the use of a fixed charge per delay, and decoupling. However, there is no blasting method to replace the existing blasting method. In this paper, a dry hole charged with ANFO blasting is assessed while employing a dry hole pumping system to remove water from the drill borehole. Additional standard blasting is also utilized to compare the blasting performances of the two methods. The least-squares linear regression method is adopted to analyze the blasting vibration velocity quantitatively using the measured vibration velocity for each blasting method and the vibration velocity model as a function of the scaled distance. The results show that the dry hole charged with ANFO blasting will lead to greater damping of the blasting vibration, more energy dissipation to crush the surrounding rock, and closer distances for the allowable velocity of the blasting vibration. Also, standard blasting shows much longer influencing distances and a wider range of the blasting pattern. The pilot test confirms the blasting efficiency of dry hole charged with ANFO blasting.