The proper name for the air cannon device is vortex generator. The blast of air that shoots out of the cannon is actually a flat vortex of air, similar to rings of smoke blown by a talented cigar smoker. Please note that this is not an endorsement of talented cigar smokers, nor should you ever take up smoking, but I think you know what I mean. Wow . . . I’ll think twice before ever mentioning talented cigar smokers again.
A vortex is generated because the air exiting the container at the center of the hole is traveling faster than the air exiting around the edge of the hole. Bernoulli’s principle states that the faster a flow of air is moving the lower its pressure. Since the air inside the vortex is moving faster than the outside air, the resulting inward pressure is the force that holds the smoke ring together. Eventually, air friction steals away all the energy stored in the vortex and the smoke ring drifts to a stop. Very cool!