Karol Krizka

Check out Candle Cannon above that was created to celebrate Erber and Gerber’s Subs/Clubs’s 20th birthday. That is not as important to me as the fact that the Candle Cannon is the world’s largest air vortex cannon! The building team tested it out and found that the pressure ring that it sends out is still powerful enough to blow out the candles on the birthday cake over 180 feet (55 meters) away.

Sadly I am not able to find any information about the physics behind the cannon, apart from a image that shows how the air molecules move. But from what I see, I would guess that it has to do with the viscosity of the air, the resistance to flow. You can think of viscosity like friction, a force that tries to slow down the moving object. In this case the sides of the air pressure node created by pulling back and letting go the back cover of the cannon are “rubbing” against the sides of the cannon as they exit and thus slow down to move slower than the middle of the air node. This difference in speed of air creates a difference in pressures, with low pressure on the inside and high pressure on the outside. This means the outside air gets pulled in and some of the inner air gets pulled back out the replace it, ending up at some equilibrium shape in the shape of a ring.

That is at least how I think the air vortex cannon works from my knowledge of fluid dynamics and seeing the above animation. If you think I made a wrong assumption somewhere or know a good article that explains it, feel free to leave a comment below.