Hydroelastic Instability of Low Aspect Ratio Control Surfaces

Abstract

As the operational speeds of surface ships and submarines increase, so does the probability that unwanted vibrations caused by the hydroelastic instability (flutter) of the special class of hydrofoils called control surfaces. These include rudders and diving planes. By nature, these are thick symmetric hydrofoils having low aspect ratios. The 3-D tip effects become more pronounced as the aspect ratio decreases. In the present study, the added-mass and circulation terms of the 2-D flutter equations are modified to include three-dimensional effects. The modifications are performed by introducing quasi-steady coefficients to each term. The results predicted by the modified equations are found to compare well with experimental results on a towed rectangular foil having an aspect ratio of one.