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CIVINS / CIVINS

Growing world-wide commitments and potential naval threats in the future will challenge the U.S. maritime forces to become more integrated and interoperable. The Total Fleet Concept calls for a maritime force for the nation that essentially combines the assets and unique capabilities of each maritime agency available to the U.S. government and forms a scalable force that can be employed around the globe to accomplish missions in the national interest. The U.S. Navy is the preeminent maritime power in the world. However, it has concentrated almost exclusively on maintaining its capability at the Blue-water level of operations. In light of the emerging asymmetrical threat from non-peer competitor forces, the Navy has embarked on a stated program of building up its littoral and lowlevel regional capability in order to engage these adversaries in their own environment. This thesis studies the Navy's budget requests of the Future Years Defense Program. It also examines whether these budget requests and the long-range 30-year shipbuilding plan is leading to the transformational Fleet that is envisioned by the Total Fleet Concept, or is a continuation of the predominantly Blue-water operations focused Fleet and the assets that accompany that strategy. / US Navy (USN) author.

Approved for public release; distribution is unlimited / An evaluation was conducted of the various propulsion motors being considered for electric ship propulsion. The benefit of such an evaluation is that all of the propulsion options being considered by the U.S. Navy have been described in one document. The AC induction motor, AC synchronous motor, High Temperature Superconducting (HTS) motor and Superconducting DC Homopolar Motor (SDCHM) are examined. The properties, advantages, and disadvantages of each motor are discussed and compared. The power converters used to control large propulsion motors are also discussed. The Navy’s IPS program is discussed and the results of concept testing are presented. Podded propulsion is introduced and the benefits are discussed. The final chapter presents the simulation results of a volts/Hertz controlled 30 MW induction motor. The evaluation revealed that the permanent magnet motor is the best propulsion motor when considering mature technology, power density, and acoustic performance. HTS motors offer significant volume reductions and improved acoustic performance as compared to conventional motors. This includes both AC and DC HTS motors. The main obstacle for the SDCHM remains the unavailability of high current capacity brushes. / Ensign, United States Navy

Thesis (M.A.)--Boston University

Thesis. 1975. M.S.--Massachusetts Institute of Technology. Dept. of Ocean Engineering. / Bibliography: leaves 234-235. / by John G. Lundblad. / M.S.

Two major areas were studied in this research to achieve more efficient and optimised method for the prediction of ship motion, and this research has two aims. The first aim was to improve an algorithm of the oscillatory problems for strip theory by means of reducing numerical integration using the desingularised method. A new way of distributing point sources was developed by the author in order to solve the boundary problem on the source distribution. Results showed that desingularsation can be utilised on rounded hull shapes. Although the desingularsation process reduces the computational time, the conventional method is more robust and stable due to the simple source panel distribution. The second aim was an investigation of viscous roll damping of ship motion with the influence of forward velocity, and several numerical simulations were developed in order to support wind-tunnel experimentation. The wind tunnel experimentation was conducted by using a 1.2 m NACA6521 modified cylindrical-bulb model to investigate the viscous effect on the rolling motion of the ship. Since viscous damping was very small under restrictions from the experimental condition, a normal method of collecting data of roll motion, in which a device is physically attached on the bulb model, was not suitable. As a solution, remote sensing was utilised to capture the motion picture by a digital video camera. A visual analysis was then conducted to obtain data of the roll motion of the bulb model inside the wind-tunnel test section. Two different numerical simulations were developed under the hypothesis that the forward velocity influences the boundary layer generation to cause viscous roll damping on the ship model hull. The first numerical simulation uses the energy method to produce damping coefficients, and the second numerical simulation requires solving the motion of equation numerically. It was discovered that the increase of forward velocity results in a linear increase of the viscous damping coefficient. The numerical simulation and experimental data agree closely. Therefore, the theory used to predict the viscous roll damping was shown to be reasonably accurate.

University of Macau / Faculty of Science and Technology / Department of Electromechanical Engineering