Russ wrote:
On Sun, 18 Dec 2005 12:39:09 -0800, Roy Lewallen
wrote:


Russ wrote:

Doesn't the delta P of a fuel-air bomb travel at greater than the
speed of sound?

No.

Roy Lewallen, W7EL


The definition of dentonation includes the flame front moving at
supersonic speeds.

http://www.globalsecurity.org/milita...itions/fae.htm

Yes, I can understand the flame front moving faster than sound, if it's
not a pressure wave. I don't know the mechanism, but presume it's
propagated by radiant heat. That is, a flame occurs, and its heat
radiates and superheats nearby material, causing it to flame. That would
be propagation by electromagnetic wave, i.e., infrared "light". The
radiation would travel at the speed of light, with the apparent speed of
the front being dictated by how fast the material is heated and ignited
by the radiated heat. Propagation by this mechanism and at this speed
would end as soon as the flame front reached the outside of the vapor
cloud, beyond which the resulting pressure wave would travel at the
speed of sound.

I'm not an expert at this, but I'm quite sure that the only way you can
get a mechanical wave to travel faster than sound is if the behavior of
the air becomes nonlinear at some compression level. That could
conceivably happen as a result of an explosion, but I don't think so. If
anyone has any references describing such nonlinear behavior, I'd love
to learn more about it.

Roy Lewallen, W7EL