Hydrodynamic Forces and Stability Boundaries of a Hyperventilated Hydrofoil in Calm Water and in Regular Waves.

摘要

Utilizing a submerged hydrofoil, a phenomenon of natural ventilation was experimentally investigated in both calm water and regular head waves. The phenomena, hereafter termed hyperventilation, is the development of a cavity extending several chords in length from the foil's leading edge. The cavity tail is open to the atmosphere with the result that the cavity pressure is equal to atmospheric pressure. In addition to measuring hydrodynamic forces exerted on the foil, an attempt was made to establish boundaries for stable hyperventilation. An expanded realm of stable hyperventilation was obtained by adding a wedge to each side of the streamlined strut aft of the midchord. Hyperventilation-triggering methods were also investigated. Results are presented showing the variation of mean and oscillatory components of lift and drag coefficients and lift/drag ratios to mean foil depth in calm water and in regular head waves at various foil angles and speeds. (Author)