The effect of fin and jet vortex generators on the crossflow separation of a 688 class submarine in a turning maneuver was studied. The vortex generators are located on the top and bottom centerline of the submarine. The intent of the vortex generators is to improve turning performance by changing the hydrodynamic forces incurred from crossflow separation. Performance of the jets and the fins are compared. Oil flow visualization and force and moment measurements were used as the primary diagnostics in determining the effectiveness of various vortex generator configurations. The fins were found to be very effective in delaying cross flow separation, while the jets were less effective. In addition, the oil flows revealed the importance of locating vortex generators near the bow and the critical role the sail plays in the fluid dynamics near the submarine. Overall, the fins were found to be viable as a concept for flow control, while the jets were less attractive. / Master of Science

This thesis analyses the behavior of an induction motor based on a mathematical model created for its simulation. The model describes the interaction of its several non linear differential equations to present a simulated output of induced torque and mechanical speed. Considering the applications to marine propulsion, it is also the goal of the project to design and test a control system for the speed of the motor by maintaining a specific cruse speed regardless the perturbations. / by Camilo Carlos Roa. / Thesis (M.S.C.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Ocean Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 148-151. / Ph.D.

Thesis. 1977. Ocean E.--Massachusetts Institute of Technology. Dept. of Ocean Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / Ocean E.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 124-126. / by Paul Sclavounos. / Ph.D.

Bibliography: leaves 70-72 / vi, 73 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Applied Mathematics, 1987

Recent developments in estimation of the survivability of a U.S. Navy transport barge in random seas are extended to improve accuracy. The single Degree-of-Freedom (DOF) model of a extreme roll response of a barge used in previous research is replaced by a 3-DOF roll-heave-sway model to include linear and nonlinear static and kinematic coupling between roll, sway and heave. The predominant nonlinearity in the model arises in an improved approximation of the roll righting moment and heave buoyant restoring force by coupling roll with heave. Kinematic coupling is introduced by allowing extreme displacements and rotations in the barge response. System coefficients in the 3-DOF roll-heave-sway model and a simpler 2-DOF roll-heave model are identified by comparing time domain simulations with measured physical model tests of barge motions. Predictions of the 3-DOF and 2-DOF models are compared to measured test data for the case of random waves. Monte Carlo simulations of the equations of motions are performed to predict the reliability of the barge in an operational sea state for a specified mission duration. Use of parallel computer processing is found to make this a viable option for stability estimations as we move into the next century. The stochastic nature of the ocean waves are modeled via filtered white noise. Estimations of the joint probability of the barge responses are presented after application of density estimation kernels. Both the 3-DOF roll-heave-sway model and 2-DOF roll-heave model are tested and compared. Last, examples are provided of some observed nonlinear behavior of the barge motions for variation in damping or ocean wave amplitude. Transient and intermittent chaotic responses are observed for deterministic input waves and quasiperiodic cases are illustrated. / Graduation date: 1996

Thesis: M.S., Massachusetts Institute of Technology, Department of Ocean Engineering, 1979 / Bibliography: leaves 65-66. / Wooi Tong Tan. / M.S. / M.S. Massachusetts Institute of Technology, Department of Ocean Engineering

A parametrically forced, single-degree-of-freedom equation modelling ship roll is investigated through the numerical study of invariant manifolds, Me1nikov's method, and transient basins. The calculation of the manifolds is facilitated through the development of a sophisticated algorithm for approximating the locations of the saddle points of the Poincaré map. For selected fixed values of the restoring-moment and damping parameters (the "base case"), the manifolds of the saddles of the Poincaré map are repeatedly computed for increasingly higher excitation amplitudes until homo clinic , heteroclinic, and mixed manifold intersections are observed. The critical amplitudes at which these tangles first occur are accurately predicted by Melnikov's method, verifying its viability as a tool for analyzing ship roll. Corresponding transient basins indicate that fractally mixed regions of stable and unstable initial conditions appear with the onset of transverse manifold intersections. For parametric forcing, the fractal areas are symmetric about the origin and do not significantly affect the integrity of the safe region near the origin. Test cases involving external or combined external-plus-parametric excitation result in asymmetric transient basins and, following the appearance of manifold tangling, a catastrophic reduction of the safe area. Lastly, Melnikov's method is used to perform a parameter study that indicates the effects of varying the restoring-moment and damping coefficients on the critical excitation level.</P. / Master of Science

A slender body theory method developed for a body moving parallel to a wall in shallow water is extended to include angular orientation of the body to the wall. The method satisfies only the zero normal velocity condition on the external boundaries but does not take into account the effect of induced flows on the body itself. A spheroid and a Series 60, block .80 hull were the bodies studied. The side force and yaw moment on each body were determined numerically for varying angular orientation with respect to either a single wall or canal bank. For both cases results for a range of depths and wall separation distances are presented. It is found that the method gives good qualitative side force predictions for a body moving parallel to a wall, but is unable to correctly predict the yaw moment or the side force due to angular orientation. This result dictates the need for a more complex mathematical model to properly represent the flow than the simple model and quasi'steady method used here. / Master of Science