A numerical method is presented for determining the natural vibration frequencies, and the corresponding mode shapes, of a rotating cantilever beam which has a nonuniform, unsymmetrical cross section. Two coupled fourth-order differential equations of motion with variable coefficients are derived which govern the motion of such a beam having deformations in two directions. Through the development and utilization of the integrating matrix, the solution of the differential equations is obtained in the form of an eigenvalue problem. The solutions to the eigenvalue problem are determined by an iteration method based upon a special orthogonality relationship which is derived. Numerical examples, including an application to a twisted propeller blade, are presented with the results of the integrating matrix solutions being compared to exact solutions and experimental data. / Master of Science

Numerous hydrodynamic theories may be used to predict the performance of marine propellers. The goal of this thesis is to investigate and implement a lifting line theory as a program written in FORTRAN and to test its capabilities on some Wageningen B-Series propellers. Special attention is given to the validation of the routines involved in the implementation of the theory. Difficulties were experienced in obtaining results that accurately reflect the published experimental results, and some discussion is included regarding possibilities for the sources of these errors. Also discussed are the results of other lifting line codes and their respective differences from the current implementation.

The relationship between cross-flow at a waterjet inlet and delivered thrust is not fully understood. A direct thrust measurement system was designed for a waterjet propelled, free running USV. To induce sway velocity at the waterjet inlet, which was considered equivalent to the cross flow, circles of varying radii were performed at Reynolds Numbers between 3.48 x 106 and 8.7 x 106 and radii from 2.7 to 6.3 boat lengths. Sway velocities were less than twenty percent of mean forward speed with slip angles that were less than 20°. Thrust Loading Coefficients were compared to sway as a percent of forward speed. In small radius turns, no relationship was seen, while in larger radius turns, peaks of sway velocity corresponded with drops in thrust, but this was determined to be caused by reduced vehicle yaw in these intervals . Decoupling of thrust and yaw rate is recommended for future research. / Thesis (M.S.)--Florida Atlantic University, 2013.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2002. / Includes bibliographical references (leaves 116-118). / An analysis of current computational fluid dynamics capabilities in predicting mean lift forces for two dimensional foils is conducted. It is shown that both integral boundary layer theory and Reynolds Averaged Navier Stokes algorithms provide the same over-prediction of lift forces when properly converged. It is also shown that the over-prediction is insensitive to turbulence model details. Experimentation and computational fluid dynamics modeling show that discrete vortices are shed with significant sizes and distinct frequencies. These vortices are shown to result in significant cfd prediction errors when they are asymmetric in size or shape. Inaccuracies in flow predictions in the near wake appear to result in an effective change in the Kutta Condition due to pressure biasing associated with vortex asymmetry. The net result is a consistent overprediction of mean lift. Based on an analysis of over 1000 historical experiments an empirical model is developed to allow the error in predicted lift coefficient to be anticipated based on the local flow conditions at the trailing edge of the foil. A series of experiments are conducted and reported to test the accuracy of the empirical model. The result is a significant improvement in mean lift prediction and pressure profile for both RANS and IBLT. / by Randall S. Fairman. / Ph.D.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaf 29. / by Matthew S. Alves. / B.S.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 346-350. / by David Herbert Munro. / Ph.D.

Thesis (M.S.)--Mississippi State University. Department of Aerospace Engineering. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--Mississippi State University. Department of Computational Engineering. / Title from title screen. Includes bibliographical references.

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