4. Operational stages and amendments
Blast weapons could have been designed to fill a gap in capability; they are generally used for the attack of “soft” targets including personnel, both in the open and within protective structures. With the increased number and range of these weapons, it is likely that military forces will have widespread use of them in future conflicts.
Thermobaric explosives are generally fuel-rich compositions containing a nitramine (RDX, HMX, etc.), but they are characterized by the energy release occurring over a longer period of time than standard explosives, thereby creating a long-duration pressure. It is generally believed that the thermobaric explosives undergo the following stages upon detonation. In the first stage, an initial shock (or blast) wave from the explosive causes the nitramine to undergo anaerobic detonation (essentially a reduction reaction) occurring within hundreds of microseconds to disperse the fuel particles. The anaerobic combustion of fuel particles occurs in a second stage within hundreds of microseconds
[12]. The anaerobic combustion process happens along the detonation shock wave while consuming fuel particles in close proximity to the detonating nitramine. In the third stage (afterburning), the fuel-rich energetic material is subjected to aerobic combustion, which is initiated by the shock-wave-mixing with oxygen of the surrounding air and which lasts several microseconds. The nitramine residues are preferably present in the shock wave and undergoes anaerobic reaction with the fuel particles to propagate the shock wave and increase dispersion of the fuel particles
[12].
When the explosion takes place in an airtight environment, the energy release of the afterburning process can be subdivided into four types:
1)
Earlier reports and articles [13–15] suggest that the metal powder in TBXs absorbs heat but does not release energy on the detonation wave front. The reflection of metal powder with the detonation products causes the first kind of afterburning.
2)
The metal and the detonation products react with oxygen of condensed air. Because of the large density gradient, the R-T (Rayleigh–Taylor) instability turbulent flow is considered in order to explain this mixture and burning step
[16,17].
3)
The air detonation wave, reflected by the wall of the airtight environment, reacts with the high speed fireballs generated by the above process. Burning by the turbulent flow
[18–20] is increased and the boundary temperature of the fireball rises to reignite the mixture of the metal and the detonation products.
4)
The burning ball crashes to the barriers or the walls [13,17] and the kinetic energy of the medium in the ball is transferred into potential energy. The residual metal powder present may be ignited to form a new burning region. Of these four types, it is believed that the afterburning begins with the start of the detonation. It does not stop and even gets intense until the detonation processes finish. The fireball and the blast produced in the earlier stages are capable of reaching and turning corners and penetrate areas inaccessible to bomb fragments. Blast waves are intensified when reflected by walls and other surfaces, causing more intense damage effect of TBXs as compared to that of high explosives in confined conditions. The confined condition is important for TBXs. A limited space may be beneficial for the rising of temperature and pressure produced by the reactions. In contrast the temperature and pressure cannot be held or even reduced in the open environment, thus the result of damage decreases and may be inferior to the equally conventional high explosives.
My dear good mate.......... Just read again what I said at first.
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