Peculiar Behavior of Disc Drag during Force Measurements for Supercavitating Hydrofoils

摘要

In order to make precise force measurements for Supercavitating hydrofoils, behavior of the disc drag as well as the effects of the gap between the test foil and the facing side-wall are carefully investigated for three typical Supercavitating hydrofoils whose nose shapes are slightly modified, in a wider range of cavitation number σ, for various incidences α_i and gap distances h. Unexpectedly from Numachi's disc-drag experiments, the disc drag significantly decreases within the transient region from the subcavitating region to the Supercavitating region. It is also very sensitive to foil shapes as well as incidences.