ABSTRACT

Figure 2 taken from Blevins (1984) shows experimental data of the decay in centre-line axial velocity along a submerged water jet versus is axial distance.

Based on this and similar data which confirms the relationship, the authors have adopted a model of velocity ratio V/V◦ versus normalized distance d/D◦ from nozzle, where V is the jet velocity at distance d

from a nozzle of diameter D◦, and V◦ is the jet exit velocity at the nozzle. V is assumed constant up to six diameters from the nozzle, and then decreases with distance according to:

where d > 6 D◦. Figure 1 shows a divergent fully developed jet angle forming a conical shaped cavity. The authors have found from experience that this angle is typically about 14 degrees. However the angle does seem to vary somewhat according to different authors although experience suggests that this typical value works well with the range of nozzle types normally used.