This is going to sound a little off topic but bare with me and you see where I'm going with this.
*We had four engineering professors (one a fluid-dynamics specialist) overseeing our work*
So, just before the last semester rolled to an end me and my first year engineering team built a little project... and enhanced vacuum cannon. The local news did a bad job of reporting it even though we were the ones who did the foot work to even get them to show up (our PR department sucks.)
Anyways, the system works like this... two 5 foot lengths of PVC, one Schedule 8 (3 inch) the second schedule 40 (1 1/2 inch.) Between the two is a Converging-Diverging nozzle that reduces the three inch pipe down to roughly a half inch then opens back up to an inch and a half. Between the nozzle and the 3 inch pipe is a screw connection that holds a membrane (3mil laminate with two layers of duct tape.) We then drop a ping pong ball down the smaller pipe before sealing the front end with a piece of laminate. Using a vacuum pump, we reduced the pressure inside the pipe as far as we could before slowly increasing the pressure in the larger pipe. At around 40 psi the membrane would burst. The air would then rush through the CD nozzle, experience a simultaneous drop in pressure and increase in velocity (as well as an incredible yet immeasurable drop in in temperature) and accelerated a ping pong ball to roughly mach 1.2 (let's see the Chinese return that serve.) About 2/3 of the way down the barrel air would leak around the ball, pressure would exceed 1 atmosphere and our seal would fly off. By the time the Ping pong ball left the barrel it was going between mach 0.9 and 0.7. within six inches it drops to mach 0.5. This is still fast enough to do impressive damage.
When we turned half an apple into mist (not sauce, mist... the rest was mash wrapped in skin) I thought "what could we do with a real gun?" After a few weeks mulling it over I've come to discount it's practical use as a means of acceleration (mostly the result of an evacuated barrel rather than the C-D nozzle.) However a variation of the design can be used to drag outside air or water through the nozzle. So believe it could be used in place of a flash suppressor as a means of cooling the barrel and gasses prior to atmospheric release. The main issue is that this system benefits from scale, the bigger you go the better it works.
Has anyone tried this or know of anyone who has?
*We had four engineering professors (one a fluid-dynamics specialist) overseeing our work*
So, just before the last semester rolled to an end me and my first year engineering team built a little project... and enhanced vacuum cannon. The local news did a bad job of reporting it even though we were the ones who did the foot work to even get them to show up (our PR department sucks.)
Anyways, the system works like this... two 5 foot lengths of PVC, one Schedule 8 (3 inch) the second schedule 40 (1 1/2 inch.) Between the two is a Converging-Diverging nozzle that reduces the three inch pipe down to roughly a half inch then opens back up to an inch and a half. Between the nozzle and the 3 inch pipe is a screw connection that holds a membrane (3mil laminate with two layers of duct tape.) We then drop a ping pong ball down the smaller pipe before sealing the front end with a piece of laminate. Using a vacuum pump, we reduced the pressure inside the pipe as far as we could before slowly increasing the pressure in the larger pipe. At around 40 psi the membrane would burst. The air would then rush through the CD nozzle, experience a simultaneous drop in pressure and increase in velocity (as well as an incredible yet immeasurable drop in in temperature) and accelerated a ping pong ball to roughly mach 1.2 (let's see the Chinese return that serve.) About 2/3 of the way down the barrel air would leak around the ball, pressure would exceed 1 atmosphere and our seal would fly off. By the time the Ping pong ball left the barrel it was going between mach 0.9 and 0.7. within six inches it drops to mach 0.5. This is still fast enough to do impressive damage.
When we turned half an apple into mist (not sauce, mist... the rest was mash wrapped in skin) I thought "what could we do with a real gun?" After a few weeks mulling it over I've come to discount it's practical use as a means of acceleration (mostly the result of an evacuated barrel rather than the C-D nozzle.) However a variation of the design can be used to drag outside air or water through the nozzle. So believe it could be used in place of a flash suppressor as a means of cooling the barrel and gasses prior to atmospheric release. The main issue is that this system benefits from scale, the bigger you go the better it works.
Has anyone tried this or know of anyone who has?
