Performance of a Propeller in a Wake and the Interaction of Propeller and Hull

Relations are developed which describe the propeller-hull interaction and the efficiency of the wake-operating propeller in the practical case where both potential and viscous effects are important. Momentum equations and the actuator disk representation of the propeller are used. Thrust deduction and efficiency are found to be functions of both the local and the ultimate wake velocity which are, in turn, expressible as functions of the static and total pressures in the propeller plane. The two velocity ratios have opposite effects on the thrust deduction, hence a potential-flow model simulating the velocity at the propeller plane and ignoring the ultimate wake-velocity deficiency arising from viscosity is inadequate.