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Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains xii, 93 p. : ill. (some col.). Includes abstract.

by Julian Guerra. / Thesis (M.S.C.S.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web. / This work seeks to understand water turbine noise generation and to make preliminary estimations of the noise levels. Any structure attached to a turbine upstream its blades will generate unsteady fluctuating loads on the blade's surface, which are proportional to the radiated acoustic pressure. The noise levels of a simplified turbine based on existing designs surpass the ambient noise levels of the ocean at low frequencies (< 20 Hz) by approximately 50 dB ref 1 μPa and stay under the ambient noise levels at higher frequencies for a blade-passing frequency of 0.83 Hz and point of observation (100 m, 45 degrees, 45 degrees) from the hub. Streamlining the cross-section of the upstream structure as well as reducing its width decrease the noise levels by approximately 40 dB ref 1 μPa, at low frequencies and moderately increase them at higher frequencies. Increasing the structure-rotor distance decreases the noise levels with increasing frequencies (> 30 Hz).

This work incorporates previous work done by Guerra and the application of fluid dynamics. The structure attached to the turbine will cause unsteady fluctuations in the flow, and ultimately affect the acoustic pressure. The work of Guerra is based on a lot of assumptions and simplifications to the geometry of the turbine and structure. This work takes the geometry of the actual turbine, and uses computational fluid dynamic software to numerically model the flow around the turbine structure. Varying the angle of the attack altered the results, and as the angle increased the noise levels along with the sound pulse, and unsteady loading increased. Increasing the number of blades and reducing the chord length both reduced the unsteady loading. / by Renee' Lippert. / Thesis (M.S.C.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

The finite element method is applied to an isolated and twisted wind turbine blade which is rotating in a vertical plane to determine its structural dynamic characteristics. The equations of motion are formulated for a rotating beam with flap and lead-lag degrees of freedom subjected to nonsymmetric bending. Using a variational approach, a blade finite clement is developed from these equations of motion. Additionally, expressions are formulated for the elastic strain energy and kinetic energy of a rotating wind turbine blade. Lagrange's equation is applied to these energy expressions and an isoparametric finite element based on three dimensional elasticity and quadratic interpolation functions is developed. Both sets of finite element equations are implemented in a general purpose computer program to solve the structural dynamics eigenvalue problem and results compare favorably with published data for the cases of a nontwisted cantilevered beam both at rest and while rotating. A blade finite element model of a 10KW horizontal axis wind turbine blade is presented and its lowest modes of vibration are calculated for the cases of the blade at rest and in operation at rotor speeds up to 250 RPM. / M.S.

A facility for the investigation of stall flutter in aircraft engine compressors and fans was designed. Stall flutter was achieved in the test fan and verified through sonic and photographic methods. The frequency components of the sonic output during flutter were determined using a real-time analyzer. This frequency analysis indicated a dominant peak within 7 percent of the theoretical torsional natural frequency of the blades. Photographs taken during stall flutter indicated the presence of an interblade phase angle. The effect of blade stagger angle, flow incidence angle and solidity on flutter speed was determined. / Master of Science