PROPELLER INDUCED SCOUR

This study examines the mechanics of propeller jet scour experimentally and identifies the key parameters for the scour process. Densimetric Froude Number and relative propeller distance from the bed surface are the two parameters investigated, which have significant effects on the scour. The scour regions can be divided into tangential scour hole, axial scour hole and deposition ridge. The scour hole is slightly skew to the left side of the jet axis if the propeller is rotated anticlockwise when viewed in the jetwise direction because of the tangential component of the jet flow. Equations of equilibrium scour dimensions are presented. A propeller jet scour is generally less than that of a corresponding circular jet. An upper bound estimate of a propeller jet scour is obtained.