Theoretical model for microbubble drag reduction technique applied to marine propellers

An increase in the propeller efficiency could result in a reduction of the contaminant emissions of ships. The reduction of drag by means of injecting microbubbles in the boundary layer of the blade of propeller is first studied in this article based on the fluid mechanics theory and the fundamental knowledge of this recent technique (that is usually applied to the hull of ships instead). A theoretical approach is proposed to evaluate the drag reduction due to the bubbles presence inside the boundary layer. This is a new application of bubbles dynamic to reduce the drag of the blades of the marine propellers, thus increasing their efficiency. • Microbubble drag reduction technique is first considered to be applied to propellers to increase its efficiency. • Literature background on the interaction of bubbles and marine propellers is presented. • A theoretical approach is proposed to evaluate the drag reduction due to bubbles presence inside boundary layer of a profile. • The final expression obtained for drag reduction is discussed including the pressure gradient effect.