I finally read this document that someone linked to about setting off
CH4 detonations, and they use this phrase:
"Blast shock waves decay to acoustic pressure waves at far field
distances from the COE"
So in at least one reference, "acoustic pressure wave" is used to
describe the thing we were discussing.
https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2018/intexpsafety/Bangham.pdf
On Fri, May 29, 2020 at 6:39 PM Ben Brockert <wikkit@xxxxxxxxx> wrote:
So technically (imagine me adjusting my nonexistent glasses) a
shockwave is supersonic. It's what makes a detonation a detonation: a
shockwave is traveling through the material at faster than the local
speed of sound. The longitudinal speed of sound in TNT is 1980 m/s,
the detonation speed is 6900 m/s, that it travels through faster than
the speed of sound is what makes it a detonation.
The spherical wave of pressure that comes out of a detonation is
generally called a shockwave, but once it's a little bit away from the
explosion, it is traveling at exactly the speed of sound because it is
basically just a loud sound. The same wave that comes out of a high
pressure burst or rapid deflagration is also called a shockwave, even
if there was no detonation. This "shockwave" can be seen as water
condensation from the sudden change in pressure, as movement of light
materials on the ground, or sometimes as a refraction from the change
in air density.
So, not meaning to pick on Henry V at all, because basically everyone
uses the word shockwave to describe that phenomenon including me, but
does that wave/sound/pressure spike have a technically accurate name?
Or is explodey science generally content with calling the two
different things shockwaves?
On Fri, May 29, 2020 at 5:37 PM Henry Vanderbilt
<hvanderbilt@xxxxxxxxxxxxxx> wrote:
Watch the start of the twitter vid
https://twitter.com/KXAN_News/status/1266470457873698817?s=09 closely. ;
Epicenter of the expanding shockwave hemisphere is not at the rocket - it's
at the flare vent downwind, visible a few rocket-widths to the right of the
actual rocket.
Mind, the shockwave's strength is not entirely symmetrical - it gets
stronger toward and left of the rocket, presumably because there was more
detonable mixture near the rocket where the fuel leak was. (Some of that
may be lighting effects also - more flame lighting things at the
(disintegrating) rocket itself.)
But the hemisphere is centered on the downwind flare vent. That's where
the detonation started.
Henry
On 5/29/2020 5:21 PM, roxanna Mason wrote:
Even more impressive, two miles away and set off car alarms.
On Fri, May 29, 2020 at 4:55 PM 1bcjolly <1bcjolly@xxxxxxxxxxxxx> wrote:
KXAN News (@KXAN_News) tweeted at 4:44 PM on Fri, May 29, 2020:
EXPLOSION: Watch the fiery blast at SpaceX South Texas facility that was
caught on camera this afternoon | STORY: https://t.co/DuzLHR0NJZ ;
https://t.co/RmPKBUAIij
(https://twitter.com/KXAN_News/status/1266470457873698817?s=09)
Get the official Twitter app at https://twitter.com/download?s=13
Sent from my Sprint Tablet.