hello, while watching blitz street last night, i noticed that even with no confinement, tnt still created a large blast as opposed to the large woosh of flame like you get from black powder, what actualy causes this?

hello, while watching blitz street last night, i noticed that even with no confinement, tnt still created a large blast as opposed to the large woosh of flame like you get from black powder, what actualy causes this?

 

 

TNT, with a boost from a blasting cap detonates. That means that combustion proceeds along a front, at the (very high) local speed of sound due to adiabatic compression Pressures at the detonation front are extremey high and the wave is very fast, typically several kilometers per second. TNT detonation velocity is 6,940 m/s. The result is a very fast evolution of gas and a very strong blast wave.

 

Black powder deflagrates. This is a much slower process in which combustion is initiated by radiatuve heat transfer. The result is much slower gas evolution and a lesser blast.

 

http://en.wikipedia.org/wiki/Detonation (Note that this Wiki article concentrates on detonation in gasses. Detonation of solid and liquid explosives is a more violent process.)

 

http://en.wikipedia.org/wiki/Deflagration

ok then, that makes sense

Interestingly there was a program on the BBC in the last couple of days discussing this.

 

You should try taking a look at http://www.bbc.co.uk/iplayer/episode/b00v9kb3/Explosions_How_We_Shook_the_World/ as it discusses black powder in the mining industry and how it was replaced with TNT.