Method of and device for determining propeller efficiency on board of a ship

摘要

There is proposed a method of and a device for determining propeller efficiency η on board of a ship. The propeller efficiency η is calculated based on angular velocity n of the propeller, thrust T produced by the propeller, torque Q, and advance velocity ua of the water entering the propeller plane. The advance velocity ua is determined as a global quantity using measurement data produced by inducing harmonic excitation in the ship propulsion system when the ship is assumed to sail under a steady state. The propeller efficiency η is useful for optimizing propulsion efficiency or overall economical efficiency of the ship, scheduling ship maintenance, or designing propellers.