Study on Detonation Features of Low Powder Detonating Fuse in the Bending Condition

2011 ◽  
Vol 243-249 ◽  
pp. 5960-5963
Author(s):  
Qun Mei ◽  
Jun Feng Zhu ◽  
Zuo Liang Li
Keyword(s):  
Numerical Simulation ◽  
Detonation Wave ◽  
Detonation Velocity ◽  
Small Angle ◽  
Normal Velocity

Detonation of low powder detonating fuse is studied in numerical simulation and experiments in bending conditions using LS_DYNA3D. The results show that pressure of the explosion and detonation velocity are decreased in the same section areas after bending. In bending conditions, detonation wave is similar to small angle corner diffraction. So the detonation velocity is lower than normal velocity.

Gaseous detonation propagation in a bifurcated tube

2008 ◽  
Vol 599 ◽  
pp. 81-110 ◽  
Author(s):  
C. J. WANG ◽  
S. L. XU ◽  
C. M. GUO
Keyword(s):  
Numerical Simulation ◽  
Detonation Wave ◽  
Mach Reflection ◽  
Initial Pressure ◽  
Gaseous Detonation ◽  
Recirculation Region ◽  
Horizontal Branch ◽  
Regular Reflection ◽  
Detonation Propagation ◽  
Wall Geometry

Gaseous detonation propagation in a bifurcated tube was experimentally and numerically studied for stoichiometric hydrogen and oxygen mixtures diluted with argon. Pressure detection, smoked foil recording and schlieren visualization were used in the experiments. Numerical simulation was carried out at low initial pressure (8.00kPa), based on the reactive Navier–Stokes equations in conjunction with a detailed chemical reaction model. The results show that the detonation wave is strongly disturbed by the wall geometry of the bifurcated tube and undergoes a successive process of attenuation, failure, re-initiation and the transition from regular reflection to Mach reflection. Detonation failure is attributed to the rarefaction waves from the left-hand corner by decoupling leading shock and reaction zones. Re-initiation is induced by the inert leading shock reflection on the right-hand wall in the vertical branch. The branched wall geometry has only a local effect on the detonation propagation. In the horizontal branch, the disturbed detonation wave recovers to a self-sustaining one earlier than that in the vertical branch. A critical case was found in the experiments where the disturbed detonation wave can be recovered to be self-sustaining downstream of the horizontal branch, but fails in the vertical branch, as the initial pressure drops to 2.00kPa. Numerical simulation also shows that complex vortex structures can be observed during detonation diffraction. The reflected shock breaks the vortices into pieces and its interaction with the unreacted recirculation region induces an embedded jet. In the vertical branch, owing to the strength difference at any point and the effect of chemical reactions, the Mach stem cannot be approximated as an arc. This is different from the case in non-reactive steady flow. Generally, numerical simulation qualitatively reproduces detonation attenuation, failure, re-initiation and the transition from regular reflection to Mach reflection observed in experiments.

A numerical simulation of reflection processes of a detonation wave on a wedge

Shock Waves ◽  
2000 ◽  
Vol 10 (3) ◽  
pp. 185-190 ◽  
Author(s):  
S. Ohyagi ◽  
T. Obara ◽  
F. Nakata ◽  
S. Hoshi
Keyword(s):  
Numerical Simulation ◽  
Detonation Wave

scholarly journals An electrical method of determining the velocity of detonation of explosives

1924 ◽  
Vol 105 (731) ◽  
pp. 282-298 ◽  
Keyword(s):  
Detonation Wave ◽  
Detonation Velocity ◽  
Detonation Pressure ◽  
Electrical Method ◽  
Vapour Density ◽  
Velocity Of Detonation ◽  
Set Up

When a layer of molecules in a mass of explosive detonates, the change is transmitted throughout the mass, and the velocity with which the transmission takes place is called the rate of detonation. It has been shown that the pressure p set up in the front of a detonation wave can be written p = velocity of detonation × velocity of vapour × density, so that explosives with high rates of detonation will have correspondingly high detonation pressures and consequently high destructive properties. A glance at the accompanying table [ see Robertson: 'J. C. S.,' vol. 119, p. 1 (1923)], which includes also values for the heat produced during detonation, will show that this is the case:- The pressure developed by tetryl is more than six times that developed by gunpowder, but the number of calories liberated at detonation by 1 gm. is only 1·8 times as great. The detonation pressure therefore depends not only on the amount of energy liberated, but also on the rate at which it is liberated. Rate of detonation becomes therefore at once one of the most important constants in explosive technology.

Underwater Explosive Welding Using Detonating Code

2012 ◽  
Vol 706-709 ◽  
pp. 763-767 ◽  
Author(s):  
Akihisa Mori ◽  
Ayumu Fukushima ◽  
Kazumasa Shiramoto ◽  
Masahiro Fujita
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Sound Velocity ◽  
Detonation Velocity ◽  
Explosive Welding ◽  
Experimental Setup ◽  
Underwater Shock Wave ◽  
Welding Method ◽  
Metal Plates ◽  
Underwater Shock

Detonating code, which is a flexible code with an explosive core, is normally used to transmit the ignition of explosives with high detonation velocity 6 km/s. Therefore it is difficult to use detonating code for the explosive welding of common metals toward the detonating direction since the welding velocity exceeds the sound velocity of metals. Hence, an explosive welding method using underwater shock wave generated by the detonation of detonating code was tried. In the present investigation, the details of the experimental setup and results are reported. And the welding conditions are discussed through numerical simulation. From these results it is observed that the above technique is suitable to weld thin metal plates with relatively less explosives.

Direct numerical simulation of spatially developing turbulent boundary layers with uniform blowing or suction

2011 ◽  
Vol 681 ◽  
pp. 154-172 ◽  
Author(s):  
YUKINORI KAMETANI ◽  
KOJI FUKAGATA
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Direct Numerical Simulation ◽  
Drag Reduction ◽  
Skin Friction ◽  
Reduction Factor ◽  
Stream Velocity ◽  
Normal Velocity ◽  
Friction Drag ◽  
Local Skin

Direct numerical simulation (DNS) of spatially developing turbulent boundary layer with uniform blowing (UB) or uniform suction (US) is performed aiming at skin friction drag reduction. The Reynolds number based on the free stream velocity and the 99% boundary layer thickness at the inlet is set to be 3000. A constant wall-normal velocity is applied on the wall in the range, −0.01U∞ ≤ Vctr ≤ 0.01U∞. The DNS results show that UB reduces the skin friction drag, while US increases it. The turbulent fluctuations exhibit the opposite trend: UB enhances the turbulence, while US suppresses it. Dynamical decomposition of the local skin friction coefficient cf using the identity equation (FIK identity) (Fukagata, Iwamoto & Kasagi, Phys. Fluids, vol. 14, 2002, pp. L73–L76) reveals that the mean convection term in UB case works as a strong drag reduction factor, while that in US case works as a strong drag augmentation factor: in both cases, the contribution of mean convection on the friction drag overwhelms the turbulent contribution. It is also found that the control efficiency of UB is much higher than that of the advanced active control methods proposed for channel flows.

scholarly journals The EFP Formation and Penetration Capability of Double-Layer Shaped Charge with Wave Shaper

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4519
Author(s):  
Yakun Liu ◽  
Jianping Yin ◽  
Zhijun Wang ◽  
Xuepeng Zhang ◽  
Guangjian Bi
Keyword(s):  
Detonation Wave ◽  
Double Layer ◽  
Detonation Velocity ◽  
Incidence Angle ◽  
Shaped Charge ◽  
Experimental Simulation ◽  
Detonation Waves ◽  
Forming Process ◽  
Large Length ◽  
Overdriven Detonation

Detonation waves will bypass a wave shaper and propagate in the form of a horn wave in shaped charge. Horn waves can reduce the incidence angle of a detonation wave on a liner surface and collide with each other at the charge axis to form overdriven detonation. Detection electronic components of small-caliber terminal sensitive projectile that are limited by space are often placed inside a wave shaper, which will cause the wave shaper to no longer be uniform and dense, and weaken the ability to adjust detonation waves. In this article, we design a double-layer shaped charge (DLSC) with a high-detonation-velocity explosive in the outer layer and low-detonation-velocity explosive in the inner layer. Numerical and experimental simulation are combined to compare and analyze the forming process and penetration performance of explosively formed projectile (EFP) in DLSC and ordinary shaped charge (OSC). The results show that, compared with OSC, DLSC can also adjust and optimize the shape of the detonation wave when the wave shaper performance is poor. DLSC can obtain long rod EFPs with a large length-diameter ratio, which greatly improves the penetration performance of EFP.

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