Unsteady Hydrodynamic Forces on a Lifting Body

Abstract

A simplified method described in the previous report, has been extended to calculate steady and unsteady lift of arbitrary three-dimensional body and wing configurations, in which the velocity potential is expressed by the doublet distribution over body, wing and the wake. The velocity potential on a thick body is simply obtained by subtracting the interior velocity potential defined inside the body from the solution of the doublet distribution for the translating oscillation. This method is applied to study hydrodynamic interactions between body and wing configurations in steady and unsteady lifting problems.Experiments for a body of revolution with and without a pair of low aspect ratio wing are carried out for steady lift with angle of attack and unsteady lift in heaving oscillation. Those results are compared graphically with the present theory, together with approximated calculations by equivalent wings.