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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

LDV measurements and numerical modeling of the turbulent flow in a stirred mixer.

Wu, Howard Honezern. January 1988 (has links)
It is recognized that detailed knowledge of turbulence parameters, as well as velocities, can aid in understanding and modeling mixing rate-dominated phenomena in stirred vessels. Measurements using a laser-Doppler velocimeter and modeling using a k-ε turbulence model and FLUENT, a general-purpose fluid flow modeling program, have been conducted of the flow in a baffled, turbine-agitated vessel. The complex flow patterns and high turbulence intensities explain why flows in stirred vessels are difficult to attack experimentally or numerically. In the measurements, the necessary corrections for the periodic, nondissipative velocity fluctuations in the near-impeller region, which were caused by the periodic passage of the impeller blades, were made by an autocorrelation method. With the contributions of the periodic fluctuations removed, meaningful turbulence data including turbulence intensities, autocorrelation functions, turbulence energy spectra, turbulence scales, and turbulence energy dissipation rates were obtained. Integral scales and energy dissipation rates were a particular objective in this work because of their usefulness in modeling local mixing rates in turbulent flows. An energy balance around a region containing the impeller and the impeller stream showed that 60% of the energy transmitted into the vessel via the impeller was dissipated in the region, and 40% was dissipated in the rest of the vessel. An equation for calculating local energy dissipation rates ε from total turbulence energy and resultant integral scales, ε = A q³/² /L(res), appeared adequate with constant A = 0.85 (where q ≡ uᵢuᵢ/2, L(res) ≡√LᵢLᵢ, and uᵢ and Lᵢ are, respectively, the i-th component of fluctuation velocity and the turbulence integral scale measured in direction i). Both the k-ε model (two-dimensional) and FLUENT (which employed three-dimensional k-ε and Reynolds stress models) obtained mean velocity profiles fairly close to the experimental data, but both predicted k and ε significantly lower than the measured values. The reason for the underestimation of k and ε was not entirely clear, but may have been caused by use of only the random parts of velocities for computing k and ε at the impeller boundary. The objective of modeling complex turbulent flows in stirred vessels has been accomplished, a goal which until recently would have been considered beyond the possibility of computation.
42

Experimental study of thermosiphon performance

Sivanagere, Sumeeth S. January 2002 (has links)
Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains vii, 66 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 29).
43

Influence of the implant location on the hinge and leakage flow fields through bileaflet mechanical heart valves

Simon, Hélène A. January 2003 (has links) (PDF)
Thesis (M.S.)--Chemical Engineering, Georgia Institute of Technology, 2003. / Sambanis Athanassios, Committee Member ; Sotiropoulos Fotis, Committee Member ; Yoganathan Ajit, Committee Chair. Includes bibliographical references (leaves 239-243).
44

Influence of the implant location on the hinge and leakage flow fields through bileaflet mechanical heart valves

Simon, Helene A. January 2004 (has links)
Thesis (M.S.)--Chemical Engineering, Georgia Institute of Technology, 2004. / Sambanis Athanassios, Committee Member ; Sotiropoulos Fotis, Committee Member ; Yoganathan Ajit, Committee Chair. Includes bibliographical references (leaves 239-243).
45

An experimental investigation of flapping wing aerodynamics in micro air vehicles /

Bradshaw, Christopher John. January 2003 (has links) (PDF)
Thesis (M.S. in Aeronautical Engineering)--Naval Postgraduate School, June 2003. / Thesis advisor(s): Kevin D. Jones, Max F. Platzer. Includes bibliographical references (p. 89). Also available online.
46

DESIGN AND PERFORMANCE OF AN EXPERIMENTAL DUAL-FREQUENCY DOPPLER LIDAR FOR REMOTE MEASUREMENT OF WIND VELOCITY

Eberhard, Wynn Lowell, 1944- January 1979 (has links)
No description available.
47

An investigation on planar velocimetry by spatial cross correlation

Fawcett, Philip Andrew 12 1900 (has links)
No description available.
48

An improved system for measuring optically the surface dynamics of a sample

Moore, Andrew Clay 12 1900 (has links)
No description available.
49

An automated scanning laser doppler system for vibration measurements and wave-vector analysis of vibration of shells

Kil, Hyun-Gwon 08 1900 (has links)
No description available.
50

Development and analysis of a multiple beam laser system for measurement of surface vibrations

Yang, Ming 05 1900 (has links)
No description available.

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