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Thesis--University of Minnesota. / Includes bibliographical references. Also issued in print.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Wanting leaf 133. Typescript. Vita. Includes bibliographical references (leaves 132-142). Also available on the Internet.

Thesis--University of Minnesota. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Wanting leaf 133. Typescript. Vita. Includes bibliographical references (leaves 132-142). Also available on the Internet.

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains xiii, 157 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 84-86).

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 126-129). Also available via the Internet.

Thesis (M. A.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Thesis (Ph.D.)--Drexel University, 2010. / Includes abstract and vita. Includes bibliographical references (leaves 126-137).

The thesis describes experimental techniques used and results obtained in the investigation of the pure tone components of sound radiation from a commercial 19 inch axial flow fan. The causes and extent of the discrete tone sources were investigated by several methods: cross-correlation of fan surface pressure fluctuations with far field sound, spectral analysis of surface pressure, and examination of surface pressure waveforms. A unique feature involved the design of an apparatus for detecting and transmitting fan-borne pressure fluctuations off the rotating blades. "Causality Correlations" with the on-axis far field sound rendered dipole source strength distribution functions over a span wise line at 15 per cent chord from the leading edge of the fan blade and around a circumferential ring on the motor support strut at a fan radius of 89 per cent. Results indicate that the on-axis discrete tones are a result of source mechanisms causing force fluctuations on the blades and struts which in turn lead to sound radiation which is dipole in nature and is most intense on the axis of the fan. These mechanisms include ingestion of a concentrated vortex, modulation of the clearance between the blade tips and the fan shroud, flow separation around the inlet bell mouth, and fluctuations in the inflow velocity due to the proximity of the fan to the wedged wall of the Anechoic chamber. Crude integral approximations of source strength distributions over the surfaces of the blades and the struts indicated that sound radiation at the blade passage frequency from these two contributors to the overall sound would be about equal, although more sound radiation is expected to originate at the rotor. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate