Author(s): Galla Ravi Kishore; Subhasish Dey

Linked Author(s): Subhasish Dey

Keywords: Offset jet; Coanda effect; Rough bed; Recirculation region; Open channel flow; Boundary layer

Abstract: This study presents an experimental investigation of hydraulic characteristics of submerged offset jets. The instantaneous velocity was captured by an acoustic Doppler velocimeter (ADV). A total of 20 runs were carried out by varying different parameters: Reynolds number (28475−80730), offset ratio (3.16−6.2), jet Froude number (1.9−3), submergence parameter (0.65−2.82) and sluice gate openings (3, 3.5, 4, 4.5 and 5 cm). It is observed that the length of the reattachment depends on the relative offset height and the tail water depth. A mathematical formulation is developed for the submerged offset jet assuming a submerged jump in a drop structure to find the back-up depth and subcritical sequent depth by applying the momentum and continuity equations at the inlet and at tail water depth respectively. A mathematical equation is also developed for the back-up depth at the efflux section, which is experimentally verified for the range of supercritical Froude numbers from 1.1 to 10 and submergence factor. The jet trajectories (lower layer of jet, upper layer of jet and maximum jet velocity layer) are also derived applying the boundary conditions. The computed jet trajectories of the submerged offset jet show a satisfactory agreement with the experimental data.

DOI: https://doi.org/10.15142/T3550628160853

Year: 2016