Parametric CFD investigation of ALS technique on reduction in drag of bulk carrier

Development has been made in the field of Naval Architecture to enhance the fuel efficiency of ships by using techniques which reduces pressure drag at higher speeds. However, for slower moving vessels, the major concern is higher percentage of frictional drag. It is well-known fact that, frictional drag depends on the wetted surface area of a ship, viscosity and density of fluid flowing around it. Applications to change the viscosity and/or density and/or wetted surface area of the ship is need of an hour. In the Air lubrication system technique, alteration of above is possible by injecting air bubbles below the hull. In this study, numerical investigations into frictional drag reduction by injection of air bubbles were carried out in Star CCM+ for a 1:23 scaled model of a Bulk Carrier for two speeds and for different air injection rates using different diameters of series of injection holes.