A fan with no blades?

[Professur]

http://www.dyson.co.uk/fans/

I suspect there's a conventional fan in the base, but interesting none the less.

 

[Luis G]

Up to 27 litres of air per second is drawn in by an energy-efficient, brushless motor.

Wonder if that brushless motor moves some blades.

 

[catocom]

could be like a pump...like the Wagner power sprayers.

 

[Altron]

Maybe there's a compressor or fan or something in the bottom, and it pressurizes the inside of the ring, and lets the air flow out at certain points along the ring, creating a venturi?