This is an compressed Air Amplifier. Compressed air flows through the inlet into an annular chamber. It is them throttled through a ring nozzle at high velocity. The airstream adheres to the Coanda profile which directs flow to the outlet. Low pressure area is created at the center creating a high volume flow of air into the primary airstream. The combination of primary and surrounding air exhausts create high volume and high velocity flow. (http://www.exair.com/en-US/Primary%20Navigation/Products/Air%20Amplifiers/Pages/Air%20Amplifiers%20How%20they%20work.aspx)