Supercavitating Foils With Flaps Beneath a Free Surface

Abstract

Linearized airfoil theory—in conjunction with a mapping technique—is applied to the calculation of the forces and moments acting on supercavitating hydrofoils operating near a free surface at very large Froude numbers and zero cavitation number. Only the effects of angle of attack and flap deflection are considered. The results—intended for engineering use—are presented primarily in the form of curves of flap effectiveness, lift curve slope, pitching and hinge moment coefficient, and flap loading versus flap-chord ratio, depth being introduced as a parameter. Lift-drag ratio and hinge moment coefficient as functions of lift coefficient are presented for typical operating conditions.