The scaling behavior of high-order structure functions for a turbulent jet induced by a rotating propeller

The traditional marine propulsion system used to move a ship is constituted by an electric motor turning a propeller. The device produces a turbulent jet that impacts the seabed and banks of harbour basins or navigation channels up to a distance of several propeller diameters from them. This causes the formation of a scour hole and a deposition mound. The present work aims at investigating, for the first time, the scaling behavior of the high-order structure functions for this turbulent jet, by discussing the experimental results in light of monofractal or multifractal models. This latter would explain the possible existence of intermittency. To this end, an experimental campaign was performed in the “Laboratorio Grandi Modelli Idraulici” (GMI) of the University of Calabria, in an 18 m long, 0.985 m wide and 0.7 m deep horizontal flume with rectangular cross-section. The test was performed in still water condition with a fixed water depth, using a propulsion system constituted of an electric motor turning a propeller with four blades. The propeller diameter was equal to 8.2 cm. The flow field was measured with an Acoustic Doppler Velocimeter (ADV). Specifically, the longitudinal structure functions were studied in this work using Taylor’s hypothesis.