水中揚力体に加わる非定常流体力について : 第1報翼単独の場合

概要

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A numerical method has developed to analyze unsteady hydrodynamic forces of 3D Iifting surfaces of arbitrary planform, in which velocity potential is expressed by the doublet distribution over wing surface and the wake. The wing surface is divided into a number of meshes and the strength of the doublet on each mesh is assumed to be constant which makes numerical calculation simple. The wake is also divided into strips of semi-infinite length and the strength of the velocity potential within the strip is assumed to vary with x downstream. Velocity potential on wing surface is obtained by the solution of a set of simultaneous equations. Comparison of lift coefficients with existing theories show good agreement in steady and unsteady problems. Experiments for some rectangular and triangular wings were carried out, where the steady lift with angle of attack and unsteady lift in heaving oscillation were measured. Triangular wing of aspect-ratio of 2 shows good lift characteristics in wide range of angle of attack. Unsteady lifts for whole wings generally show good agreements with linear theories within present experiments, but some nonlinear effects due to dependence of the velocity of uniform flow appeared in added-mass coefficients at low reduced frequency.
社団法人日本船舶海洋工学会の論文