On potential wake and thrust deduction

Abstract

In a recent study for the U.S. David Taylor Model Basin the existing wake and thrust-deduction formulae have been reviewed and a new approximate formula for deeply submerged bodies of revolution in ideal potential flow has been derived. It has been found that the effective wake can be expressed in terms of the nominal wake, its gradient in the axial direction, the velocity of advance, and the propeller strength. All these quantities can be measured by testing the model and the free-running propeller in a towing tank. The new thrust-deduction formula is based upon the theorems of classical hydrodynamics following the approach of H. Dickmann [1] and P. Weiss [2]. The assumptions made are within conventional limits. The results indicate that the effective wake may well be a multiple of the nominal wake as many previous tests have claimed.