Axial Velocity Distribution at the Efflux of a Stationary Unconfined Ship’s Propeller Jet

Abstract

This paper is aimed at presenting an up-to-date investigation of the hydrodynamics of the jet (wake) of a stationary, unconfined ship’s propeller. The velocity field of a ship’s propeller jet is of particular interest for the researchers investigating the jet induced damage on a seabed as documented in previous studies. This paper discusses the time-averaged velocity field at the efflux, which is the immediate exit of the downstream propeller jet. The propeller jet is a rotating flow, which has axial, tangential and radial components of velocity. The axial component of velocity is the main contributor to the total velocity magnitude. Researchers are more interested in the axial velocity field within the ship’s propeller jet, due to the large contribution made by the axial velocity to the jet. The axial velocities at the efflux plane were obtained using joint experimental and numerical approaches. The results confirmed the two-peaked ridges axial velocity profile and disagreed with the 0.707Dp contraction suggested by Blaauw & van de Kaa (1978), Verhey (1983) and Robakiewicz (1987) at efflux of a ship’s propeller jet.