Includes bibliographical references (p. 102-105).

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

Thesis (Ph. D.)--Lehigh University, 1999. / Includes vita. Includes bibliographical references (leaves 118-124).

Thesis (M.S. in Electrical and Computer Engineering)--Naval Postgraduate School, December 1990. / Thesis Advisor(s): Janaswamy, R. Second Reader: Adler, Richard W. "December 1990." Description based on title screen as viewed on March 30, 2010. DTIC Descriptor(s): Linear systems, thickness, scattering, polarization, distribution, formulations, integrals, shape, structures, theses, electromagnetic wave propagation, reflection, surfaces, surface properties, wave propagation, cylindrical bodies, width, integral equations, frequency domain, plane waves, circular, truncation, concave bodies, convex bodies, radiation DTIC Identifier(s): Radar reflections, hollow cylinders, slit cylinders, OSRC (on surface radiation condition). Author(s) subject terms: Surface radiation conditions; transverse electric; circular cylinders; hollow cylinder slit cylinders Includes bibliographical references (p. 68-69 ). Also available in print.

Thesis--University of Wisconsin--Madison. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 165-168).

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 180-181). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1985. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 178-182).

Inertial and interceptive .impaction of spherical particles on circular cylinders was investigated theoretically. The particles were considered to be suspended in a fluid moving steadily through a random array of parallel cylinders. Fluid flowfields around the cylinders were obtained by numerically solving the Navier-Stokes Equation subject to Kuwabara's zero vorticity boundary condition. These solutions were subsequently utilized in calculating particle trajectories and impaction efficiencies. The latter are presented as functions of Reynolds number (0.2 ≤ Rec ≤ 40), particle inertial parameter (0 ≤ P ≤ 1000), particle to cylinder size ratio (0.001 ≤ K ≤ 1.) and cylinder concentration (10 ̄⁴ ≤ c ≤ 0.111). The impaction efficiencies and critical inertial parameters differ significantly from earlier theoretical predictions. The discrepancies are primarily attributable to the inaccurate flowfield representations used by previous authors. The agreement between Subramanyam and Kuloor's experimental work and present theory is satisfactory. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

The effect of vibration upon the rate of sublimation from horizontal circular cylinders has been studied previously in several investigations. However, no satisfactory overall correlation has been obtained up to the present time. In the present investigation, data have been obtained for mass transfer from naphthalene to air and phenol to air for horizontal cylinders vibrated vertically over a wide range of Reynolds number. It is shown that these data and the data of all previous investigations, including liquid systems, lie on or near a single smooth curve provided that an appropriate system of coordinates is selected. Further, for high Reynolds number and high Schmidt number, the data approach the theoretical equation of Jameson derived using boundary-layer theory. The author has found that the mass transfer coefficient for sublimation can be increased by a factor of 30 over that which prevails for the stationary (non-vibrating) case. For mass transfer to gaseous media only, the following correlation is proposed, having an average deviation of ±17 % : Sh = 0.261 Sc¹/³Revº•⁷¹⁷( H/d )º•²³³ This equation is believed to be valid over the following range of the variables: Diameter: 0.07 - 1.1 cm Frequency: 100 - 7000 RPM Amplitude (double): 0.05 - 4.0 cm Vibrational Reynolds number: 9 - 2000 Ratio of amplitude to diameter: 0.2 - 5.7 / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

The aerodynamics of a set of two-dimensional, stationary elliptic cylinders with eccentricity of 0.44, 0.92 and 0.98 is studied experimentally during the organised wake condition (R=2x10⁴-10⁵). The results indicate the effect of eccentricity and angle of attack on mean and unsteady pressure coefficients, Strouhal number and wake geometry, the three important parameters in the aeroelastic instability study. In conjunction with the available literature, the information presented here attempts at providing better understanding of the bluff body aerodynamics in the region between the two extreme cases of circular cylinder (e=0) and flat plate (e=∞) . The cylinder eccentricity and attitude has considerable effect on vortex shedding frequency, with variation of the Strouhal number in the range 0.037-0.274. Although basing Strouhal number on projected dimension or wake width reduces its dependence on angle of attack, the use of transverse distance between the separation points provides, in addition, a smoother transition even at higher eccentricities and smaller angles of attack. The measurement of fluctuating pressure in the narrow band around the Strouhal frequency showed substantial dependence on the Reynolds number at zero angle of attack, particularly for the ellipses of high eccentricity Considerable phase difference may exist between the pressure signals, however, it has negligible effect on the unsteady lift. The thesis also presents analytical results on the location of shear layer separation as obtained using Görtler's series in conjunction with mean pressure profile. The analytical data compared favourably with the results of flow visualisation through Schlieren technique. The high speed movie of the near wake region gave preliminary information about the location of the first vortex and the oscillations of the separating shear layers. The rise and decay of the unsteady pressure in the vortex formation region appeared to substantiate the visual observations. In general, the wake geometry ratio varied around the Kármán stability value of 0.281. The correlation of spanwise results clearly emphasized the three dimensional character of the unsteady aerodynamics. In general, the spanwise variation of fluctuating pressure is enhanced with increase in angle of attack. The phase data suggest inclination of the vortex line at the model to be ≲11°. Increase in angle of attack results in improved alignment of the vortex line with the cylinder axis. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate