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ORCID
N/A
Access Type
Open Access Thesis
Document Type
thesis
Degree Program
Mechanical Engineering
Degree Type
Master of Science in Mechanical Engineering (M.S.M.E.)
Year Degree Awarded
2018
Month Degree Awarded
May
Abstract
The influence of symmetry breaking on the flow induced oscillations of bluff bodies in the steamwise direction is studied. First, a series of experiments is conducted on a one-degree-of-freedom circular cylinder allowed to exhibit pure translational motion in the streamwise direction over a range of reduced velocities, 1.4 < U* < 4.4, corresponding to a Reynolds number range of 970 < Re < 3370. Two distinct regions of displacements were observed in reduced velocity ranges of 1.6 < U* < 2.5 and 2.75 < U* < 3.85. Measured force coefficients in the drag and lift direction were examined, along with the wake visualization, through the range of reduced velocities, to infer the resulting wake modes. A new Alternating Symmetric (AS) mode was found. This transition from symmetric to AS shedding occurred near the end of the first region of response. Similar tests were run with a square prism in the parameter space of 2.4 < U* < 5.8 and 757 < Re < 1900 over angles of incidence of 0° ≤ α ≤ 45°. A distinct region of lock-in is observed for α = 0°, 2.5°, 5°, 7.5° over 3.2 < U* < 5.4 for α = 0°, and decreasing with increasing α. The wake structures were found to be roughly symmetric for α = 0°, but transitioned towards asymmetry with increasing α. For α = 0° and 2.5° a gradual increase in the asymmetry of the fluid forcing was observed with increasing U*, similar to the circular cylinder.
DOI
https://doi.org/10.7275/11936344
First Advisor
Yahya Modarres-Sadeghi
TDG_MS_CC_AltSymmetric.mp4 (13875 kB)
TDG_MS_CC_Competitive.mp4 (13861 kB)
TDG_MS_CC_Asymmetric.mp4 (11936 kB)
TDG_MS_SP_0deg.mp4 (13050 kB)
TDG_MS_SP_5deg.mp4 (17317 kB)
Recommended Citation
Gurian, Tyler, "Streamwise Flow-Induced Oscillations of Bluff Bodies - The Influence of Symmetry Breaking" (2018). Masters Theses. 646.
https://doi.org/10.7275/11936344
https://scholarworks.umass.edu/masters_theses_2/646
Included in
Acoustics, Dynamics, and Controls Commons, Fluid Dynamics Commons, Ocean Engineering Commons, Other Mechanical Engineering Commons