Some Experiments and Considerations upon the Scale Effect on the Propeller and Self-propulsion Factors

Abstract

This paper deals with the scale effect on the propeller and self-propulsion factors. Propeller efficiency increases gradually with the increase of Reynolds number. Even if the propeller open tests were conducted over so-called critical Reynolds number, their results will not show the exact characteristics of the actual propeller. Wake fraction will be calculated from the followiog formula, Where, A and B are constants to be determined for a ship form. Thrust deduction coefficient will be calculated from the following formula, where, v is ship's speed, u the additional velocity imparted to the fluid by the propeller and k a constant depending on the hull form and speed of a ship.