Water accelerator

A water accelerator, said water accelerator comprising:

• a body,
• a channel extending along an axis X through said body from a water inlet to a water outlet,
• said channel comprising:
• an inlet section open to said water inlet, said inlet section having a first substantially constant diameter D1,
• said inlet section connects directly to an acceleration section,
• said acceleration section having diameter D2 decreasing in a flow direction from said water inlet to said water outlet,
• said acceleration section connecting directly or via a constant diameter section to an action section,
• said action section having a diameter D4 increasing in said flow direction,
• the increase of the diameter D4 of said action section starting gradually, and
• an air admission channel extending through said body from the exterior of said body to said action section and/or to a section of said channel subsequent to said action section in said flow direction, characterized in that an angle α between the inner surface of the action section and said axis X is 40° to 80°.