• Tunnel and Underground Space
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• v.10 no.2
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• pp.218-226
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• 2000

In order to determine the performance of an explosive, various parameters such as the detonation pressure, detonation velocity, heat generation, and fume generation of the explosive should be accurately described. In this study, the pressure increase, volume expansion, temperature increase, and detonation velocity of high explosives were tried to determined theoretically based on thermochemical theories. From this study, a Fortran program for calculating the explosion parameters, which can influence on the performance of explosives, was developed and applied to the high-explosives, ANFO and NG.

• Explosives and Blasting
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• v.33 no.3
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• pp.21-28
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• 2015

The objective of this study is to develop a method for monitoring continuously the combustion propagation behavior of commercial thermite reaction mixtures using conventional continuous VOD (velocity of detonation) system. In order to monitor the combustion front propagation with elapsed time during thermite reaction, the VOD system employs two types of commercial VOD probes and one self-made probe: VOD PROBEROD-OS, VOD PROBEROD-HS and VOD PROBEROD-ES, respectively. Among the probes, the only self made VOD PROBEROD-ES successfully demonstrates the velocity of combustion propagation (VOC) with elapsed time. It was found that VOC of the thermite reaction mixture inside a steel tube has been reached around 200m/s within 100mm distance from the ignition and dramatically increased up to about twice the speed of sound in the range between 100mm and 300mm distance. Finally the VOC reached up to around 800m/s. This results imply that it is necessary to use over 300mm long cartridge of thermite reaction mixture in order to achieve normal VOC of the mixture.

• Explosives and Blasting
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• v.41 no.1
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• pp.32-45
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• 2023

Environmental regulations in Korea for blasting at industrial sites have conservative standards, which often result in reduced efficiency and cost-effectiveness due to the consideration of environmental regulations and public complaints. Therefore, there is a need for blasting methods that can reduce environmental damage while improving construction efficiency and cost-effectiveness. In this study, we analyzed the effects of the PA-Deck (Paraffin Air-Deck) blasting method, which is a kind of Air Decoupled Charge method in principle utilizing a paraffin-infused paper tube as an air gap, on reducing blasting hazards and improving blasting efficiency. The analysis also evaluated the effectiveness of newly applied equipment for collecting blasting vibration data, and derived the relationship between the explosion velocity and vibration velocity of explosives, and performed frequency analysis of the vertical component. The results of the blasting vibration velocity analysis showed that the Paraffin Waxed Paper Tube-based blasting method exhibited significantly lower vibration velocities compared to conventional blasting methods, and it was judged that more uniformly small-sized fragmented rocks were generated.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1423-1430
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• 1993

One of the most important parameters for explosive welding is flyer velocity $V_p$, which principally depends on momentum caused by detonation of explosive. And close dependency with other parameters such as detonation velocity $V_D$, dynamic angle $\beta$, charge ratio R, flyer thickness $t_f$ and stand-off distance d, should be taken accounts for welding design. This paper describes, as a result of experiment, an empirical equation related to relation between $V_p$/$V_D$ and R. The flyer velocity which is estimated by $V_{p}=0.284{\times}R^{0.593}$or $V_{p}=\sqrt[0.2]{2E_G}{\times}R^{0.593}$ can be used in ordinary experiments. And the calculated values of the flyer velocity exhibit better accuracy than those of other investigators.

• Explosives and Blasting
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• v.33 no.3
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• pp.1-13
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• 2015

Accidents related to gas explosion are frequently happened in foreign countries and in Korea. For the evaluation and the analysis of gas explosions, TNT equivalent methods are used. In this study, the influence of the selection of chemical equation in TNT explosion and the selection of enthalpy of the products on the explosion energy, detonation pressure, velocity of detonation, and temperature was calculated. Depending on the chemical equations, the maximum detonation pressure can be 2 times higher than the minimum. As an example for applying TNT equivalent method, an explosion of methane gas in a confined volume was assumed. With the TNT equivalent, it was possible to predict the variation of peak overpressure and impulse with the distance from the explosion location.

• Explosives and Blasting
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• v.23 no.3
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• pp.43-56
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• 2005

The defoliation velocity is tile rate of propagation of a detonation in an explosive. An explosive's velocity of defoliation(VOD) can be used to indicate a number of important characteristics regarding the product's performance under specific field and test conditions. Also, it is useful quality monitoring technique and call be measured accurately and easily at borehole and testing sites. This paper discusses the relevance of the detonation velocity of explosives in blasting. Attempts were made to classify detonation velocities and offer an interpretation of blasting process which will be useful to blasting engineers. But it was found that there is not necessarily a direct relationship between defoliation velocity and explosive quality or efficiency.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.6
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• pp.525-538
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• 2014

Safety of reactive systems is one of the most important research areas in the field of weapon development. A NoGo response or at least a low-order explosion should be ensured to prevent unexpected accidents when the reactive system is impacted by high-velocity projectile. We investigated the shock-induced detonation of cased reactive systems subject to a normal projectile impact to the cylindrical surface based on two-dimensional hydrodynamic simulations using the I&G chemical rate law. Two types of energetic materials, namely LX-17 and AP-based solid propellant, were considered to compare the dynamic responses of the reactive system when subjected to the threshold impact velocity. It was found that shock-to-detonation transition phenomena occurred in the cased LX-17, whereas no full reaction occurred in the propellant.

• Explosives and Blasting
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• v.30 no.2
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• pp.29-42
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• 2012

Variables influencing the free face movement due to rock blasting include the physical and mechanical properties, in particular the discontinuity characteristics, explosive type, charge weight, burden, blast-hole spacing, delay time between blast-holes or rows, stemming conditions. These variables also affects the blast vibration, air blast and size of fragmentation. For the design of surface blasting, the priority is given to the safety of nearby buildings. Therefore, blast vibration has to be controlled by analyzing the free face movement at the surface blasting sites and also blasting operation needs to be optimized to improve the fragmentation size. High-speed digital image analysis enables the analyses of the initial movement of free face of rock, stemming optimality, fragment trajectory, face movement direction and velocity as well as the optimal detonator initiation system. Even though The high-speed image analysis technique has been widely used in foreign countries, its applications can hardly be found in Korea. This thesis aims at carrying out a fundamental study for optimizing the blast design and evaluation using the high-speed digital image analysis. A series of experimentation were performed at two large surface blasting sites with the rock type of shale and granite, respectively. Emulsion and ANFO were the explosives used for the study. Based on the digital images analysis, displacement and velocity of the free face were scrutinized along with the analysis fragment size distribution. In addition, AUTODYN, 2-D FEM model, was applied to simulate detonation pressure, detonation velocity, response time for the initiation of the free face movement and face movement shape. The result show that regardless of the rock type, due to the displacement and the movement velocity have the maximum near the center of charged section the free face becomes curved like a bow. Compared with ANFO, the cases with Emulsion result in larger detonation pressure and velocity and faster reaction for the displacement initiation.

• Journal of the Korean Institute of Gas
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• v.16 no.1
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• pp.8-14
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• 2012

Hydrogen is considered to be the most important future energy carrier in many applications reducing significantly greenhouse gas emissions, but the explosion safety issues associated with hydrogen applications need to be investigated and fully understood to be applicable as the carrier. The risk associated with a explosion depends on an understanding of the impacts of the explosion, particularly the pressure-time history during the explosion. This work provides the effects of explosion parameters, such as specific heat ratio of burned and unburned gas, equilibrium maximum explosion pressure, and burning velocity, on the pressure-time history with flame growth model. The pressure-time history is dominantly depending on the burning velocity and equilibrium maximum explosion pressure of hydrogen-air mixture. The pressure rise rate increase with the burning velocity and equilibrium maximum explosion pressure. The specific heat ratio of unburned gas has more effect on the final explosion pressure increase rate than initial explosion pressure increase rate. However, the specific heat ratio of burned gas has more influence on initial explosion pressure increase rate. The flame speeds are obtained by fitting the experimental data sets. The flame speeds for hydrogen in air based on our experimental data is very low, making a transition from deflagration to detonation in a confined space unlikely under these conditions.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.5
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• pp.47-57
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• 2012

A modified ignition and growth(I&G) model which is necessary to simulate the combustion phenomena of energetic materials and an analytical model determining the unknown parameters of the reaction rate equation are proposed. The modified I&G model sustains important physical implications with overcoming some problems of previous rate equations. This rate model consists of ignition term which represents the formation of the hotspot due to void collapse and growth term which means the shock to detonation transition phenomena. Also, the theoretical model is used to investigate the combustion characteristics of certain energetic materials before running Hydrocode by pre-determination of unknown parameter, $b,\;G,\;x,\;I$. The analytical model provides efficient and highly accurate results rather than previous method which simulated the unconfined-rate-stick via the numerical means.