Velocity and momentum of vortex rings in relation to formation parameters

Abstract

Abstract The formation of ring vortices under water has been studied at orifices of diameter 2.54 to 6.35 cm and formation times from 0.04 to 0.68 s, with orifice Reynolds number between 3 × 10 4 and 3 × 10 5 . Ciné photographs of the formation process were taken, and the initial velocity of the vortices was found in general to be one half of the velocity of flow through the orifice. The translational momentum of the vortex rings was measured by a surge‐tube method. It was concluded that the formation process is most efficient when the length of the impulsive jet is not more than two orifice diameters.