NONLINEAR STUDIES OF DYNAMIC STABILITY OF SUBMARINES IN THE DIVE PLANE

The problem of dynamic stability of submersible vehicles in the dive plane is examined utilizing linear and nonlinear methods. Local bifurcations are studied with the means of perturbation and linearization techniques. The primary mechanism of loss of stability is identified in the form of generic Hopf bifurcations to periodic solutions. Stability of the resulting limit cycles is established using centre manifold approximations and integral averaging. Particular emphasis is placed on analysing the effects of the quadratic drag forces due to their crucial role on stability of periodic solutions. The methods described could lead to techniques resulting in enlargement of the submerged operational envelope of a vehicle.