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Type of Document	Dissertation
Author	Ringuette, Matthew James
URN	etd-05292004-183807
Persistent URL	http://resolver.caltech.edu/CaltechETD:etd-05292004-183807
Title	Vortex formation and drag on low aspect ratio, normal flat plates
Degree	PhD
Option	Aeronautics
Advisory Committee	Advisor Name Title Prof. Morteza Gharib Committee Chair Prof. Anthony Leonard Committee Member Prof. Joel Burdick Committee Member Prof. Michael Dickinson Committee Member
Keywords	drag vortex formation flat plate aspect ratio
Date of Defense	2004-05-21
Availability	unrestricted
Abstract Experiments were done to investigate the role of vortex formation in the drag force generation of low aspect ratio, normal flat plates starting from rest. This very simplified case is a first, fundamental step toward understanding the more complicated flow of hovering flight, which relies primarily on drag for propulsion. The relative importance of the plate’s free end, or tip, with varying aspect ratio was also studied. Identifying the relationship among aspect ratio, vortex formation, and drag force can provide insight into the wing aspect ratios and kinematics found nature, with the eventual goal of designing man-made flapping wing micro air vehicles. The experiments were carried out using flat plate models in a towing tank at a moderate Reynolds number of 3000. Two aspect ratios, 6 and 2, were considered, the latter in order to have a highly tip-dominated case. A force balance measured the time-varying drag, and multiple, perpendicular sections of the flow velocity were measured quantitatively using digital particle image velocimetry. Vorticity fields were calculated from the velocity data, and features in the drag force for different aspect ratios were related to the vortex dynamics. Finally, since the flow is highly three-dimensional, dye flow visualization was done to characterize its structure and to augment the two-dimensional digital particle image velocimetry data.
Files	Filename       Size       Approximate Download Time (Hours:Minutes:Seconds)     28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access    Thesis.pdf 3.32 Mb 00:15:21 00:07:53 00:06:54 00:03:27 00:00:17