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chemoleo
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Highest Theoretical VOD of Chemical Detonations
Well I wondered, what parameters limit the highest theoretical velocity of detonation (VoD):
For real explosives (check alt.engr.explosives) it's around 11000 m/s.
BUT - I am sure this can be exceeded.
Think of it that way:
VoD is limited by the density
VoD is limited by the temperature.
VoD is limited by the pressure surrounding the system.
Density can't ever be greater than that of the atoms concerned (low and high MW atoms) AND the distance between them. Hence, assuming a compound
with the shortest atomic distances possible (i.e. with covalent molecular bonds), plus high vapour pressures, plus maximum energy output upon
rearranging those bonds (i.e. the formation of CO2, N2 etc), this should represent the maximum VoD.
In idealised terms, if you heated a gas to the temperatures found at explosions (4000-6000K), while keeping it at pressures where atoms/molecules are
at bonding distances (i.e. between >1-2 angstrom), wouldnt this produce the maximum possible VoD, once this confinement was removed? I.e., the
speed at which gas atoms/molecules move *outward* from a confined container, and assuming zero pressure (vacuum) beyond that container, and assuming
that this is done at explosion temperatures (4-6k Kelvin), wouldnt that approximate the maximum theoretical VoD?
What are your thoughts on this?
[Edited on 16-12-2003 by chemoleo]
[Edited on 16-12-2003 by chemoleo]
Never Stop to Begin, and Never Begin to Stop...
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DDTea
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Not offering much well-thought out details here. But, if I'm not mistaken, Nuclear Weapons sport the highest VOD today. And, if i'm not
mistaken, the explosion is not caused so much by the release of gases, but by the expansion of atmospheric gases as a result of a massive
heat output.
Would it be possible to accomplish similar results by similar means? Rather than having explosive decomposition, just a compound that gives off
massive heat on decomposition to heat atmospheric gases?
But then, I suppose having a conventional HE would do the same thing... Only the energy from decomposition is put into the product gases as opposed
to atmospheric gases.
Alternately, could an initial explosion be used just prior to another detonation, where the first one's goal is to create a temporary vacuum
ahead of the second explosion-- so that the energy of the product gases is put to maximum efficiency by not having to compete with a high pressure
atmosphere?
Oh well; it's still fun to blow ants around with a hot soldering iron 
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Iv4
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FAE's
FAE's usually make a similer effect.
Once bored stupid a long time back I tried something similer with a bit of AP.A few plastc strws with arenged in a circle adn one in the middle set of
from its shock(had to run a small BP line since it didnt work).It was a little more powerfull but on even a small scale its not wort the extra effort
or the explosives needed.
Maybe its my extremely crapy testing.
Come to think of it though experements inside a vaccum might be a good way of testing the rough theory.
[Edited on 16-12-2003 by Iv4]
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Al Koholic
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I'll just say that using powdered aluminum is a great way of increasing the heat output of an oxygen rich detonation. I believe the BLU-52 used
this in the slurry it was composed of...generating a thermobaric effect similar to a nukes although on a much lower scale obviously.
Also, as far as detonation velocity is concerned, I was reading a pdf from the ftp the other day about electrically enhanced detonation. Aside from
being a very interesting read, it mentioned that the velocity, pressure, and some other parameters (brissance maybe? not sure...) could be enhanced by
passing a current through the developing shock front. The explosive was placed between a voltage source and as the detonation proceeded linearly
along the explosive slab, the conductivity of the shock front is actually pretty high due to plasma formation. This allowed current to flow through
the front hence increasing the amount of energy contained in the front and supposedly increasing the velocity of the shockwave. I don't know
much about the relationship between current, voltage, and the manifestation of the effects but I suppose there would be some limit to this
enhancement.
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chemoleo
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Ok, I thought it would be clear that I did NOT include nuclear explosions in the highest theoretical VoD!! Naturally, particles are accelerated to
close to the speed of light there, plus temperatures rise to several million Kelvin! The sheer photon generation there produces a massive shockwave by
itself! Needless to say, photon density (i.e. in the infrared/visible/UV range) is related to temperature (and secondary effects, i.e. adsorption and
release of lower energy photons produces more infrared, which we experience as heat).
Anyway, back to the highest possible VoD of *chemical* detonations:
Basically, I am postualating that a gas compressed to the density of a water, or lead, or uranium, plus heating this whole thing to the temperature to
the temperatures found at the core of the detonation (several thousand Kelvin) would produce a velocity of gas release (upon removal of the admittedly
very strong confinement) topping that of the highest VoDs found in todays chemical detonations.
In other words, isnt an explosive basically an extremely compressed heated gas, in it's final state? I am taking that thought to the extreme, as
you can see
On another note: Acceleration is a function of the mass, hence the velocity of a particle is greater the smaller the mass is. Probably it would then
make more sense to compress Hydrogen (!!) to the density of lead, heat it and release that baby from confinement! Voila! your maximum possible VoD,
right?
Anyway, I mentioned to use a *vacuum* so as to exclude any secondary effects etc.
It is well known that explosives are not as powerful in vacuum by the way, due to the lack of atmospheric compressions/vacuums etc.
[Edited on 16-12-2003 by chemoleo]
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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Microtek
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Neuron: That effect is indeed very interesting. When I read a patent on that subject ( the same you read I think, as the experiment was the same ) I
particularly noted the incredible detonation pressure which actually exceeds that of HNIW. Unfortunately, the Mach stem needs to build up for about 4
microseconds IIRC, so the minimum length of the charge would be about 40 mm at 8-9 Km/s.
Concerning the compressed gas, I think it would be difficult to define a VoD as such, simply because the entire volume of gas begins to expand at once
when the confinement is removed.
As you know, VoD is the speed of propagation of the reaction zone upon initiation and so doesn't have anything to do with the speed of the
released gases.
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Iv4
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I didnt mean a complte vaccum(assuming such a thing existed but you know)but partialy evacuated to test Mr.Samosa's idea.
I think the explosive jacket you describe is like what at BS is called 'proper detonation',/seting it of all at once(I dont say we because
I'm the sole person who uses reguler boosters).The idea there is that the shockwave from the initiater should be so stong st to set it of all at
once.
In this case I think that some of the explosive itself is being thrown forward and then detonated so it gets more power.
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tokat
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chain mechanics useing H and O , the VOD is set by the ammount of each substance.
I think explosive gases comprssed like chemoleo said would produce more VOD than solid, as Hydrogen burned in oyxgen has the highest isp in
rockets,per desinty or something.
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franklyn
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How powerful is it ?
Predicting the performance of new energetic materials from a given molecular structure
without real test measurements is very important for a chemist. Calculating detonation
properties of a notional energetic compound having desirable properties and recognized
to be cost effective , is a time saving determinant in the decision to whether it is worth
the effort to attempt a new or complex synthesis if an accurate assessment of the
proposed material is obtained without guess work or uncertainty.
A bit of a trick here , you must log in to references first , before you click this link
http://www.sciencemadness.org/talk/viewthread.php?tid=7518&a...
Publications available online
Comments on TNT Equivalence
http://www.osti.gov/bridge/servlets/purl/10168254-xKQZHg/nat...
Estimating Equivalency Of Explosives Through A Thermochemical Approach
http://www.llnl.gov/tid/lof/documents/pdf/241114.pdf
A Simple Method for Calculating Detonation Properties of C-H-N-O Explosives
http://stinet.dtic.mil/oai/oai?verb=getRecord&metadataPr...
Abstract:
Simple empirical equations are given which permit the calculation of the detonation pressures
and velocities of C-H-N-O explosives. The detonation pressures so derived correspond quite
closely to values predicted by the computer code RUBY
.
[Edited on 15-1-2008 by franklyn]
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12AX7
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| Quote: | Originally posted by chemoleo
Anyway, back to the highest possible VoD of *chemical* detonations:
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On that definition, then, would be quark-gluon plasma (an extremely hot phase of matter), neutronium (which is probably unstable at STP) somehow
explosively transforming to regular matter, or micromassive black holes (which are themselves probably stable, but naturally evaporate exponentially
by Hawking radiation and therefore can reach very high peak temperatures).
As chemicals go, the hottest things are the lightest things: hydrogen, carbon, nitrogen, oxygen, fluorine. Anything heavier has much more bulk around
its nucleus and therefore less ionization / electron affinity energy associated with its formation of bonds. Lead is quite dense, but also quite
inert; fusing it with an oxidizer releases little energy with respect to the thermal mass of the system. The only value of these elements is as
carriers of oxidizers (like BaO2, etc.) which are stable at STP. So, the only thing you can really do is play with assemblies of those light atoms.
Unfortunately, because they are light, substitution of them onto various skeletons of the others (like carbon) reduces density. You can make diamond,
a four-bonded polymer of carbon, but you can't add hydrogen or nitrate or other substituents without changing density, or form for that matter.
As far as adding things to increase VoD, you would have to examine the tradeoff of bulk energy vs. VoD and such.
So really, we're already about as good as it gets, which apparently is around 11km/s.
Tim
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Boomer
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On a side note, velocity of *detonation* is a completely different mechanism than expanding of compressed gasses.
In a C-J wave, at our beloved tangent point of hugonoit and rayleigh line, the unreacted matter gets compressed to a considerably higher density.
Taking HMX or HNIW at densities between 1.91 and 2.04, you get values of at least 2.5 g/ccm.
There is no way you can compress gasses to those densities, especially low-molecular-weight gasses. For hydrogen *gas* this probably exceeds critical
temp and pressure by an order of magnitude.
At those pressures, *all* matter behaves like a liquid. The VoD is the velocity of the shock front moving through it, while the particle velocity of
the shocked matter is something else entirely. You could calculate it from the hugonoit, but it is moot to compare it to particle speed of expanding
gasses.
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Mr. Wizard
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I'm not informed enough about quark-gluon plasmas, but I can speculate about some sort of gas or transparent mixture that can be started by a photon
of a certain energy. A beam of UV through a mixture of H2 and Cl2 for example. The initiation would take place as the beam traveled through the gas.
Wouldn't the wave front then be propagated at the speed of light in that medium? I realize that the propagation properties of the gas would change as
the reaction started, and block it, but perhaps the beam could be tuned to a certain wavelength that would do the job, yet not be blocked. Maybe the
gas could be set up with mirrors to get a laser effect inside and maximize certain wavelengths. If the reacting gas gave off the right wavelength of
light when it reacted, it might work even better.
Another idea would be to have mono atomic hydrogen kept with the atoms kept from flipping and joining to form H2 by an intense magnetic field or
some other method. When the field is turned off, the propagation would travel at the speed of light. H2 formation would give more energy per gram
than any other reaction I can think of.
Just thinking out loud.
[Edited on by Mr. Wizard]
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12AX7
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I don't think any of those count -- certainly, they entail external energy sources. In the case of photonic H2 + Cl2 reaction, that's the same as
sending a series of similar length fuses alongside a line of black powder. With the powder train ignited in many places (and, taken to its limit,
ignited uniformly by an infinity of infinnetessimal fuses), the apparent flame front is simply headed in a different direction.
It's like swinging a flashlight around. Sure, a billion miles from the axis of rotation, the light beam is moving back and forth (tangentially) at a
rate faster than the speed of light, but it still propagates at the speed of light.
Tim
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Mr. Wizard
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I agree they don't fit the parameters, as you outlined them. The only exception might be some kind of transparent mixture that reacted to the light
emitted from the reaction, and thus propagated itself at the speed of light in that medium. I'm not sure there are any examples of this, but you must
agree it is 'theoretically' possible.
I still think the fastest explosive would be H+H =H2 as the components are the lightest and the energy released the highest per gram. I didn't say it
would be the safest or easiest. 
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gregxy
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I have wonderd if you could consider an detonable explosive a "PHASER" Phonon amplification by stimulted emission of radiation. (Has a nice Star Trek
sound). The detonation wave causes new material to explode and the explosion strengthens the wave. I don't know if a shock wave in a solid or liquid
is still considered a phonon.
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12AX7
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Hmm. Well, it's a wave effect (as EM radiation), and can be figured accurately in quantum theoretical terms, otherwise known as phonons. You would
have to determine if a phonon of some energy / wavelength is capable of disrupting the structure. The interaction causes an irreversible exchange of
energy, but lasers do too; continuous lasers merely feed more "reagents" into the mix. A "continuous beam phaser", then, would be a device where the
shockwave is made to stand still by feeding a continuous supply of explosive into it. Perhaps the shockwave can be made into a transverse standing
wave inside a suitable chamber? Ah, but the chamber's dimensions would have to correspond to the phonon wavelength...
All very interesting thoughts... more theoretical (and more physics than I know) than practical, but could lead to interesting lab experiments I
suppose!
Tim
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gregxy
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Well Lasers require a "population inversion" that is that the
electrons be pumped into an quasi stable state where they are temporarly trapped at an energy above the preferrred lowest energy state. An energetic
material is also quasi stable material, that is the material is stable, but a more stable lower energy state exists.
One of the papers on sensitivity of explosives (i forget which
one) suggests that primaries transition from burning to detonation by the build up the strength of mechanical waves that run through the material.
I guess for a real "phonon effect" you would need an explosive made from a large single crystal material.
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tumadre
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| Quote: | Originally posted by Boomer
Taking HMX or HNIW at densities between 1.91 and 2.04, you get values of at least 2.5 g/ccm.
There is no way you can compress gasses to those densities, especially low-molecular-weight gasses. For hydrogen *gas* this probably exceeds critical
temp and pressure by an order of magnitude. |
So i can't make a slurry of frozen oxygen in liquid hydrogen,
and heat in a stainless steel pipe until detonation, and achieve a faster VOD?
liquid hydrogen 68 mg/cm^3
i think i'm confusing energy with VOD.
in which case liquid ozone with a hydrocarbon would be stronger.
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halogen
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I wouldn't try it if I were you.
On a similar note, I recall from somewhere that in their quest for a superbomb, the nazis created bombs in which the explosive was based on liquified
acetylene and ozone... One would think they were in seperate containers! But they had the unfortunate effect of exploding from the slightest
provocation (so they might have mixed em up first  ) but I hear liquid ozone is
a damn good explosive on its own. (And acetylene under pressure can polymerise explosively).
"There is no way you can compress gasses to those densities, especially low-molecular-weight gasses. For hydrogen *gas* this probably exceeds critical
temp and pressure by an order of magnitude."
ONLY under normal conditions. Metallic hydrogen does exist but it certainly takes some effort to create. Including single use apparates. Now that begs
the question of: If hydrogen can be compressed explosively to a metallic state, wouldn't its inevitable expansion produce an explosion of high
velocity? Now assuming a large enough explosive lense setup with accompanying LH resevoir, there would be two simultaneous detonations: one in which
the lenses explode, compacting the liquid hydrogen into a metallic state and two, the metallic hydrogen vapourises quite violently indeed... And
altogether the explosion is produced "chemically". In fact, it might even have a refrigirant effect, sort of like an "ice-bomb"... I think something
must be wrong with my reasoning.
F. de Lalande and M. Prud'homme showed that a mixture of boric oxide and sodium chloride is decomposed in a stream of dry air or oxygen at a red heat
with the evolution of chlorine.
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12AX7
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It would be compressed and heated. The hydrogen would be but a spring, delaying the expansion of the initial explosion, namely by splitting it into
two waves, the outer wave from the explosives followed by the reflection of the wave off the center of the hydrogen "pit".
Hmm, as the wave compresses the hydrogen, it would lose energy, and less would be reflected, no? The hydrogen turning around and expanding provides a
conservative effect, of course. Probably, the waves would be spread out into a few ripples.
Tim
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halogen
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Remember, the goal is velocity of detonation. The hydrogen has no real energy of its own. Its absorbing the energy from the explosive lenses (Like an
implosion nuke but with LH2 instead of Plutonium as a core.) Now, for a brief period of time, the hydrogen is supercompressed, in a very small volume
indeed. Now consider the incredible relative size of hydrogen; Does this not mean that one can fit more potentially into the same volume? And were
that pressure suddenly released, the speed of the "detonation" (which is what we're looking for, NOT efficiency. This is horribly inefficient) would
be tremendous.
And plus, I always liked the idea of an ice-bomb
The hydrogen would heat up from the pressure/decrease in volume, but think of a warm canister of CO2 liquid: When the pressure is released, it cools,
and voila - dry ice!
For a containment material (to encapsulate the liquid hydrogen) I imagine a lighter molecular weight material would prove advantageous. Lithium or
aluminum might be useable. Or a long chain hydrocarbon (mostly hydrogen and carbon).
F. de Lalande and M. Prud'homme showed that a mixture of boric oxide and sodium chloride is decomposed in a stream of dry air or oxygen at a red heat
with the evolution of chlorine.
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gregxy
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I don't know how you would make such a thing but how
about liquid flourine in glass microspheres mixed with powdered lithium? This should have the highest energy density of any chemical explosive.
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halogen
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Fluorine dissolves glass.
F. de Lalande and M. Prud'homme showed that a mixture of boric oxide and sodium chloride is decomposed in a stream of dry air or oxygen at a red heat
with the evolution of chlorine.
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12AX7
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Fluorine does not; hydroxyls on the glass, and moisture and HF in the fluorine, dissolve glass.
I would be more as concerned about the fluorine as the lithium. Lithium oxide / silicate is an excellent solvent for silica, and lithium silicide I'm
sure is none too pleasant for integrity either. Remember, the lithium has to be molten to get the stuff into it. (Well, I suppose you could squidge
it around, depending on the malleability of it...)
Tim
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tito-o-mac
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Can anyone explain to me how does one calculate the VOD of chemical detonations?
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