A Study on a Fixed Type Fin Stabilizer Exploiting the Coanda Effect

초록

A ship operating in rough sea may suffer from an undesirable motion which may severely affect the performance of the equipment onboard and make a person feel uncomfortable. Hence, considerable attention turned to roll Stabilization, and various devices such bilge keels, stabilizing fins, gyroscopic devices, tanks, rudders and flaps have been conceived and utilized for that purpose. The Coanda effect is evident when a jet of a fluid is applied tangentially to a curved surface of a hydrofoil since the jet then increases the circulation around the foil, and accordingly the lift. In the present study, model tests and numerical simulations have been conducted to examine the practicality of a fixed type fin stabilizer augmented by the Coanda jet. The results show that the lift coefficient of the modified Coanda fin at the angle of attack α=0° matches with that of the reference stabilizer fin at the maximum operating angle of attack α = 26° if the Coanda jet is supplied at the rate of the jet momentum coefficient Cj = 0.1. It is also concluded that fixed type fin stabilizers can be put to practical use for active motion control of ships and other mobile units by exploiting the Coanda effect.