Ventilated two-dimensional supercavitation behind a moving vertical flat plate in in a still fluid: Experiment and theory*

This study examines ventilated two-dimensional supercavity formation both in a deep-water condition and in a free-surface bounded environment where a vertical flat plate (h by b, h<<b) is in motion and the fluid is at rest. In the experiment, the vertical flat plate (with height h) horizontally moves with a constant speed (U) while two-dimensional compressed air is injected both in the upward and downward vertical directions with a volume flow rate (Q) behind the flat plate. Then, for a fixed geometry of the plate, depending on the Froude numbers (Fr=U/(gh)^1/2) and the air-entrainment coefficients (C_v=Q/Uhb), two-dimensional supercavites of various sizes are generated behind the moving plate both in deep water and near the free surface. The experimentally observed supercavity shapes are compared with those from a theoretical re-entrant jet model and they agree with each other very well. .