Sadly the source you quoted has 2 different experiments mixed up
During WWII there were at least 2 efforts in creating a "shock wave weapon" one uses a Vortex (an air ring, which are identical in principal to smoke rings some smokers can achieve to blow). Another Project used a spherical shaped reflector to redirect the shock wave of explosives to a single point.
The first project simply didn't had enough kick to be used as a weapon and the second was very expensive to make and didn't work at large distances (large being 20m away).
Here is a picture of me btw holding a rather large Vortex Cannon on my shoulder this one is not stron enough to effectivly stop a person, but it creates big havocs among loose piles of paper (like in some offices...)
The rings travel very slowly though, depending on how fast you can beat it, still it is significantly slower then speed of sound. Still a very nice toy. You can transfer gases with it over some distance though.