SpudFiles

This technique of "double combustion chamber" increases twice (at least), the power of these weapons.
Actually shoot the gun 1X - 2X ?? ... no need to compress the air - fuel mixture previously.
In the first chamber "A", deflagration produces a pressure of about 3 -4 bar, as in any standard combustion weapon.
My idea was add a second combustion chamber "B", in which the products of combustion chamber "A", compress loaded in this chamber "B" mixture, thus achieving compression overcome atmospheric pressure, the resulting increase in pressure final shot. Not, is not a hybrid, but a common good power weapon combustion.
When gases accelerated by the transfer port is re-expand by increasing area in the chamber "B", there is a transfer of thermal energy, (due largely to the strong turbulence) from the chamber "A" . A chamber equivalent to the total volume of the two interconnected chambers, absolutely no energy increases to the trigger. I have tried this many times.
I relied to develop this method, in a study by Lars Rogstadkjernet entitled: "Combustion of Gas in Closed, Interconnected Vessels: Piling Pressure". Let down this excellent work in PDF, so that the interested reader can refer to.
In the case of this specific application, my gun, I touch the work of making various experiments, to give appropriate relationships with the necessary volumes of the chambers communicating hole diameter and effective method for mixing supply them both. If these relations, always for this application in particular, are not met, the power increase is not done, the gun behaving as if it had more than one camera ....
research on this topic is missing, but I think this is a first practical achievement, because without doubt my experimental gun pulls much stronger
Description:
1- Combustion chamber "A", 220 cm 3
2- Combustion chamber "B", 50 cm3
3- Manual air pump, 100 cm3 volumetric capacity, single action. It is activated 5 times, three to clean and two combustion chambers to inflate the exact amount of mixing.
4- sliding system for introducing ammunition (steel ball 3/16 "- 4,76mm).
5- liquid fuel tank (ethyl alcohol 95%) of 18 cm3
6- fuel line.
7- hose to avoid splashing.
8- gun barrel.

notes:
- The orifice intercommunication between the two chambers has a diameter of 5mm. The final output port, which overlooks the canyon is 4mm in diameter. This area ratio is the only one that seems to work well.
Actually it is unknown as the stoichiometric air mixture is compressed - fuel in chamber "B" because I do not have the necessary measurement tools, however, with an estimate "by eye and ear", and comparing penetration munitions at different targets, with and without the combustion chamber "B", I think about the mixture is compressed to about 1X - 2X, at least.
- This gun has also, a neodymium magnet retaining the ammunition strongly increasing retention combustion gases and adding more power to the shots.
This video shows the operation of this weapon combustion. Regards !

http://picasion.com/i/2kdl2
http://picasion.com/i/2kdku
http://picasion.com/i/2kdkE
http://picasion.com/i/2kdkJ
http://picasion.com/i/2kdkY

[youtube][/youtube]






“Combustion of Gas in Closed, Interconnected Vessels: Pressure Piling”
By Lars Rogstadkjernet

http://www.ub.uib.no/elpub/2004/h/40400 ... ppgave.pdf

It will fire whatever fits in the barrel

saulpaulo wrote:It will fire whatever fits in the barrel

In this particular case, the firing barrel has 4.8 mm, and shoots bb's of steel 3/16. "It is interesting to see the increase in energy that gives the second combustion chamber, being such a small ammunition With a single camera, "normal", it is impossible to drill a three-layer wood, 3 mm.With the second chamber, it does it without problems Logically, it is a low energy weapon, because it does not have the mixture compressed.

Don't bother Hector, it's just a spammer who is trying to promote the link in his signature.

uh ... I did not realize ...

jackssmirkingrevenge wrote:Don't bother Hector, it's just a spammer who is trying to promote the link in his signature.

New member finding his / her way through the forums...

I don't mind the spammer, it revived a thread I've been thinking about for awhile.
Is there any simple explanation for why having two chambers increases performance? And is there any way to calculate the ideal aperture for the hole connecting both chambers based on the volumes of each chamber?
I've been curious to see if a dual chamber system using oxy-hydrogen at low mixes could have decent enough performance to compare with a traditional burst disk propane hybrid.

Cthulhu wrote:I don't mind the spammer, it revived a thread I've been thinking about for awhile.
Is there any simple explanation for why having two chambers increases performance? And is there any way to calculate the ideal aperture for the hole connecting both chambers based on the volumes of each chamber?
I've been curious to see if a dual chamber system using oxy-hydrogen at low mixes could have decent enough performance to compare with a traditional burst disk propane hybrid.

I have checked with this small combustion weapon, and others that I have built, that yes, there is indeed a significant increase in energy. I do not have the knowledge to calculate all this numerically, but in the file that I attach, it's all, it's quite complex.
Basically, it is about using pa pressure generated in the primary chamber, and providing that energy to the second chamber. The mixture of the second combustion chamber, the small one, burns with more pressure than the atmospheric pressure, in this specific case of a combustion weapon. It is an experimental field that I have not yet experienced, I have only touched on the subject, with good results, independently of the size of the weapon. I calculate, based on my experience with small hybrids, and this type of bb 3/16 "steel ammunition, which shoots like a 2 or 3X hybrid, approximately.This is the article:

Thanks for the article Hectmarr, that was really interesting. Its interesting how hydrogen wasn't as effective of a fuel because of it's high speed of burning, I definitely will use this article in my testing to see if I can come up with a geometry that will cause optimal pressure piling for hydrogen. It's a shame there isn't a way of slowing down hydrogens flame front to allow it to pressure pile more effectively while keeping the benefit of being able to rapidly produce and burn it from electrolysis without metering.

Cthulhu wrote:Thanks for the article Hectmarr, that was really interesting. Its interesting how hydrogen wasn't as effective of a fuel because of it's high speed of burning, I definitely will use this article in my testing to see if I can come up with a geometry that will cause optimal pressure piling for hydrogen. It's a shame there isn't a way of slowing down hydrogens flame front to allow it to pressure pile more effectively while keeping the benefit of being able to rapidly produce and burn it from electrolysis without metering.

Keep me informed of your experiments, this is interesting and you have to analyze what possibilities you have for our weapons. a hybrid, it is not a very viable technique, because just by increasing the pressure of the mixture, equal results are obtained, without the complications of pressurizing two chambers. It's just my opinion, based on my ideas and not real experiences. If it seems to me that it is very useful, for combustion weapons, without pressurizing, because it does not complicate the weapon almost nothing, and the increase of energy in the shots can be important. I have tried several secondary combustion chamber volume, and several diameters of transfer holes, and this has been what I have in the small gun. In the future I will return to this topic, and the idea is to win two equal weapons, one with a single camera and another with two, to compare the results
 

hectmarr wrote:it is not a very viable technique, because just by increasing the pressure of the mixture, equal results are obtained, without the complications of pressurizing two chambers. It's just my opinion, based on my ideas and not real experiences. If it seems to me that it is very useful, for combustion weapons, without pressurizing, because it does not complicate the weapon almost nothing, and the increase of energy in the shots can be important.

I mostly see it as a possible alternative to high mixes, to achieve a high mix for more energy you have to have a compressor capable of reaching high pressures and you have to use a lot more fuel. However by utilizing pressure piling, even though the gun is more complex, it may offer the benefit of being able to have similar performance to a high mix hybrid at a lower mix level. This would conserve fuel and be faster and easier to fire. Of course, I'll make a real opinion on it after testing

[nevermind... hmmm... how does one delete a post with the new forum software?]

Yes, I found this topic a couple years late and it took me a bit to digest it....

...But I don't think there's much to the "piling" phenom. It allows you to boost pressure, yes, but for a significantly smaller available volume in the combustion chamber. The result would be higher pressures, but decreased mass flows to the barrel. This can be useful for a short barreled system (like the gun in the OP), but on a "ounce of fuel per ounce of fuel" comparison, I suspect you'd get better results by using a single combustion chamber of similar volume (meaning the same volume as the two combustion chambers combined) and a longer barrel. This way, all your energy and mass flow are available. How much better? That would depend on how well the dual chamber gun had tuned the port between the chambers, and matched them to the barrel length and projectile, of course.

A perfectly tuned system compared to a simple system with a perfectly sized barrel would result in very similar performance. Energy in = Energy Out - Losses, after all. If they've got the same amount of fuel and air, then the energy input would be identical. The dual system would suffer more turbulence and thermal losses, but hopefully it wouldn't be bad.

On the flip side, in a typical recreational system - where projectiles may vary and not a lot of work is put into the design? I suspect the differences could be dramatic. Not gonna test it myself (got better things to do), but the larger point is that I think this is a niche application at best.

D_Hall wrote: ↑

Fri Mar 06, 2020 4:29 pm

Yes, I found this topic a couple years late and it took me a bit to digest it....

...But I don't think there's much to the "piling" phenom. It allows you to boost pressure, yes, but for a significantly smaller available volume in the combustion chamber. The result would be higher pressures, but decreased mass flows to the barrel. This can be useful for a short barreled system (like the gun in the OP), but on a "ounce of fuel per ounce of fuel" comparison, I suspect you'd get better results by using a single combustion chamber of similar volume (meaning the same volume as the two combustion chambers combined) and a longer barrel. This way, all your energy and mass flow are available. How much better? That would depend on how well the dual chamber gun had tuned the port between the chambers, and matched them to the barrel length and projectile, of course.

A perfectly tuned system compared to a simple system with a perfectly sized barrel would result in very similar performance. Energy in = Energy Out - Losses, after all. If they've got the same amount of fuel and air, then the energy input would be identical. The dual system would suffer more turbulence and thermal losses, but hopefully it wouldn't be bad.

On the flip side, in a typical recreational system - where projectiles may vary and not a lot of work is put into the design? I suspect the differences could be dramatic. Not gonna test it myself (got better things to do), but the larger point is that I think this is a niche application at best.

I did some tests, but only with 4.76 mm steel bb in a small gun and in a longer gun, which burns ethyl alcohol.
I have not documented these experiments, because I also had at that time, and I have presently, better things to do.
The energy of the small bb with a single camera, is very poor, very little area in that caliber, and does not pass even a three-layer wood.
When using two cameras, as in the diagrams that are at the beginning of the post, the first thing that is heard is an important change in the sound of the combustion weapon, and it is seen with the naked eye, which drills a three-layer wood, without problems , the 3/16 "bb is definitely faster.
Actually I did not continue researching, I mean trying different volume relations between the cameras and shapes and areas of the holes that communicate it, because I like hybrids more, than logically, they have more energy with a little compressed mixture.
According to my estimates "by eye", the old gun, (which no longer exists), fires like a 2X hybrid, more or less.
It seemed appropriate to tell my experience here, and leave the information I used to guide me, always from the perspective of an amateur, who wants to try these interesting things.
The explosion of the smallest chamber, in one of the tests, really left me surprised and stunned, they make me think, a priori, and without pretending to have any scientific rigor in my apprehension, that the increase in speed of the bb, could be increased, playing with the volumes of both cameras, and the shape and surface of the holes that communicate them.
Maybe in the future I will try, but with a dual camera hybrid.

Can a "Dual Camera System" be made with a simple divider in a single camera? Basically, I have a propane tube, if I put a divider between both bottom and up parts with a 5mm hole, will it work the same?