Experimental Investigation of Non-Steady Forces on Hydrofoils Oscillating in Heave

摘要

Measurements of the unsteady forces on heaving delta wing hydrofoils hydrofoils having apex angles of 15 and 30 deg were carried out in fully wetted flow, planing at a free surface, and with forced ventilation. The fully wetted dynamic measurements were in good agreement with the results of lifting surface theory at small angles of attack. A slender body theory of planing due originally to Tulin is extended to account for non-steady motions. This theory generally underestimates the in-phase lift force; the quadrature unsteady lift is well predicted by the theory. Additional measurements of steady planing delta wings were carried out; for small apex angles and small angles of attack the theory is found to be adequate though it does appear to underestimate the lift somewhat. Some additional experiments on non-steady forces on two-dimensional fully wetted and fully cavitating hydrofoils were also carried out. (Author)