Semi-confined explosions

The overpressure developed in semi-confined explosions depends on the following key parameters ... 

Explosion - A rapid increase in pressure in a confined space or semi-confined space. 

TNT (CONWEP) between 6 and 12 m distance, whereas semi-confined MTV in the stainless steel cans yield 20-33% TNT. A peculiarity of MTV detonation is the increasing equivalency with increasing distance, an effect observed with many non-ideal explosive showing high-temperature after-burn reactions. 

Due to the low density of H2, an accidental hydrogen emission creates a high probability of forming highly explosive volumes in the upper part of a confined or semi-confined space. A characteristic of the near-ceiling HAM volumes is a free region in the combustible bay basement and, probably, along the sides of a gas-polluted space. 

However, confining surfaces increase the danger resulting in a hydrogen+air cloud explosion. It has been shown in [6] that when a H2 + air mixture is ignited in a U-shaped semi-open duct of 90 m volume, the combustion velocity can reach 80 m/ s and compression wave overpressure AP = 2 10" Pa. The turbulence artificially generated in U-shaped duct may cause transition of deflagration to detonation. 

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