Gases in the barrel go to liquid?

[W L Johnson]

Now I know this is a Naval Gun, I believe it's a 5in in the photo's, but does any of this apply to Small arms?

From http://www.eugeneleeslover.com/ENGINEERING/PICTURES-NO-1.html

THE COMPRESSION IN THE GUN IS SO HIGH THE GASES IN THE BARREL GO TO LIQUID. THE WHITE STUFF YOU SEE COMING OUT OF THE MUZZLE IS THE LIQUID GOING BACK TO THE GASEOUS STATE. THE LIQUID IS GOING BACK TO THE GASEOUS STATE AS FAST AS IT POSSIBLY CAN AND IT STICKS STRAIGHT OUT FROM THE BARREL ABOUT THE LENGTH OF THE BARREL AND THEN DISAPEARS AS INVISIBLE GAS.

YOU CAN SEE IT STICKING THROUGH THE BLACK SMOKE.

IT DOES HOWEVER HOLD TOGETHER RATHER IN A CIGAR SHAPE LONG ENOUGH TO PUSH THE PROJECTILE TO A HIGHER SPEED THAN WHEN IT LEFT THE MUZZLE AND DOES INCREASE THE PROJECTILE SPEED UP TO ABOUT 50 FEET FROM THE END OF THE MUZZLE.

 

[Navy_Guns]

Uh, no - it's not a liquid, that's total 10,000% BS.

 

[benEzra]

No, IIRC the white stuff is mostly particulates produced by the combustion process, primarily carbon. That's basically very hot, very highly compressed smoke shooting out of a tube at several thousand feet per second.

The pressures and temperatures are the same order of magnitude as an ordinary rifle (probably 50,000-65,000 psi and ~1000-1500 degrees fahrenheit), and the combustion gases (hydrogen, carbon monoxide, nitrogen) are still gases under those conditions.

 

[twofifty]

Yep as ben says, and the muzzle velocity is in the same range as most .30 caliber hunting loads.
A 16" naval rifle is akin to a scaled up 30-06.
Don't know about the twist rate though.

 

[W L Johnson]

A 16" naval rifle is akin to a scaled up 30-06.
Don't know about the twist rate though.

If you just want know the US 16" twist
USA
- 16"/50 (40.6 cm) Mark 7 RH 1 in 25
- 16"/45 (40.6 cm) Mark 6 Twist varied in individual guns of Mod 0, with some having a uniform RH 1 in 25 and others having a twist of increasing RH 1 in 50 to 1 in 32 at the muzzle. Mod 1 and Mod 2 guns were all uniform RH 1 in 25 twist.
- 16"/45 (40.6 cm) Mark 5 and Mark 8 Mark 5: Increasing RH 1 in 50 to 1 in 32 Mark 8: Uniform RH 1 in 25

 

[Comanche180]

I'm with the other guys. The quote is based on speculation, not science.

 

[highorder]

Liquid is the wrong term.

The high pressure gasses, and all gasses for that matter, behave as fluids under most circumstances.

 

[mrjohnston]

What everyone else said.. but man those pictures are always cool to look at.`

I didn't know that big guns like that had progresive twist barrels. That's cool.

Also, when you see it on that scale if kinda explains how muzzle breaks work. cool.

 

[ClayInTX]

All liquids have a critical temperature (TC) at which the liquid is indistinguishable from the gaseous state.

All gases have a critical pressure (PC) at which the state of gas is indistinguishable from the liquid state.

Both liquids and gases are called fluids for purposes of calculations. Actually, not just called fluids, these are fluids.

If the combustion gases, named herein, are hydrogen, carbon monoxide, and nitrogen then the critical pressures (PC) of all these are well below the pressures given herein, 50,000 to 65,000 psi. This indicates the gas should behave as a liquid.

The critical temperature, however, is well below the temperature given herein, 1000 to 1500 degrees Fahrenheit. This indicates the liquid should behave as a gas.

For those wanting to know these actual values, these may be found online. Search for Antoine’s Coefficients.

Consider water: Steam blowing from a nozzle is invisible as a gas for a short distance after leaving the nozzle; this length is dependant upon the pressure and temperature of the steam. Yes, the temperature is not absolutely fixed by pressure, steam can be superheated. It then becomes visible as a vapor, liquid water droplets, which then rapidly dissipates into the air as a gas and becomes invisible.

I have, then, a question: Are these gases from the naval guns actually behaving as liquids for some short time at the conditions given?

 

[eye5600]

The high pressure gasses, and all gasses for that matter, behave as fluids under most circumstances.

If I recall the phase separation diagram, the line between liquid and gas ends at some high temperature and pressure, so it's a case of either or both. Sort of gas compressed at such high pressure that it's indistinguishable from a liquid.

More info here:http://en.wikipedia.org/wiki/Phase_(matter)

Now whether that's the case in a gun barrel, I have no idea.

 

[deadin]

I don't know where this guy got his information, but he's full of BS.
The Navy had to wait until the 1990s before they got roll compensators for their big guns????? Geez, I wonder what I was seeing back in the '60s on ships built in the '40s that did a pretty good job of compensating for pitch, yaw and roll when firing their big guns.

 

[rustycrusty]

Actually that IS liquid coming out the muzzle. I don't know where he got those photos but he's going to be in deep dung when the USN finds out that he has exposed their new, highly secret 5" 54caliber water gun!

 

[docsleepy]

ClayInTx -- THANKS for that info. I teach physics, am just about to that point in the text, and that will make for some additional interesting facts to pass along in the chapter on materials science.

 

[Sunray]

"...didn't know that big guns..." If you ever get to Buffalo, NY, visit their Naval Park. Aside from the Fletcher Class destroyer(The Sullivans), the guided missle cruiser(Little Rock) and the submarine(Croaker) you can tour, they have a hunk of a 16" gun barrel you can pet.
"...did a pretty good job of compensating for..." Using mechanical computers too.
"...scaled up 30-06..." Using a 14 million grain bullet without a cartridge. snicker.

 

[Double Naught Spy]

For some reason, I had it in my mind that the differences in smoke color stems from the completeness of combustion. The outer dark ring represents the gasses that bypassed the projectile and hence preceded it out of the barrel. These gasses contain particles that were exposed to less duration and amount of heat and pressure and combusted less than the gasses following the projectile.

In other words, the dark ring/cloud preceding the projectile is composed of a much greater relative quantity of charred particles and the whiter gasses are composed mainly of calcined particles.

Notice in the following video that you have the initial dark gasses/smoke, following by the white gasses/smoke, and then a couple of seconds later another puff of white gasses/smoke.

http://www.youtube.com/watch?v=nsNlmiLJGIw

If the white gasses were liquids being converted back into gass as quickly as possible as claimed on the site cited in the OP, then there should be no secondary puff of white gasses. The heat and pressure are both dissipated long before that secondary puff. That secondary puff occurs when the breech is opened after firing.

 

[twofifty]

kindo OT, but the fact that the crews were able to work out firing solutions that often landed hits at 20,000+ yards by the 2nd or third salvo is very impressive to me.

 

[Ric]

As an old Field Artillery Chief I have to call BS on that one. But the pics are impressive.

 

[m00t]

As has been stated, some of the gases in the barrel behind the projectile are far, far above the critical pressure/temperature and the distinction between being a liquid or a gas is rather blurry. As the supercritical liquid/gas exits, it's going to both cool and drop in pressure rapidly... the rate of both processes will determine what side of the critical point the state falls on, and whether or not liquid particles are observed...



Basically, it would have to cool to the point of being just on the liquid side of the critical point, before the pressure dropped to the gas side of the critical point in order for true liquid to be observed. As a guess, I'd say it's possible, but not probable. What we're likely seeing is just supercritical gas/liquid dropping in pressure to plain ol' gas. And, you know... smoke.

Calculating what conditions would produce a visible liquid may be entertaining, though... it's definitely possible if heat can be removed from the gas quickly enough before it loses pressure.

 

[rust collector]

Yeah, fun pix but further down in the text he indicates that projectile weight wasn't known until recently. That's a little hard to swallow. Scales aren't high tech, and manufacturing tolerances are not a bold new concept.

 

[Averageman]

Hmmm.
As an old Tanker I often found condensation in the bore evacuator. I know thats not a Naval gun, but the liquid in the B.E. smelled of ammonia. It could be a very powerful odor at times, other times much weaker.
I often though this was due to the heating and cooling of the gun during the firing and residue left in the moisture.

 

[rcmodel]

It was condensation.

There is no gunpowder turning to heated gas, turning to liquid, then back to gas, and so on.

Total BS!!

IN A CIGAR SHAPE LONG ENOUGH TO PUSH THE PROJECTILE TO A HIGHER SPEED THAN WHEN IT LEFT THE MUZZLE

Even deeper BS!
Any projectile begins slowing down the instant it leaves the bore of the gun.
The only way a projectile can gain speed in the adsence of bore pressure is if it has a rocket motor attached to it.

rc

 

[twofifty]

IF a fluid was 'pushing' or 'accelerating' the back of the round after it leaves the barrel's support, this would surely induce extreme yaw and lead to huge variability in the hits.

 

[jimmyraythomason]

"this would surely induce extreme yaw and lead to huge variability in the hits."...uh...does this mean they missed?

 

[twofifty]

That be right - sorry for the big words.

 

[BruM]

Now these are big guns.