Study on the Time Domain Calculation of Hydrodynamic Forces of Oscillating Foils
Date Issued
2004
Date
2004
Author(s)
Wu, Chang-Cheng
DOI
zh-TW
Abstract
Based on the steady panel method, this study explores the mechanism of caudal fin and further explains oscillation foils under two dimensional unsteady flow field. The validity of the presented study method is compared with the theoretical analysis of the two-dimensional flat plate foil from Theodorson, and with the experimental results from Triantafyllou by examining the thrust coefficient, power coefficient, and propulsive efficiency of a two-dimensional foil under heaving and pitching motion. A series of calculation suggests that the smaller the nominal attack angle, the greater the propulsive efficiency. In addition, the results indicate that the best efficiency is yielded when Strouhal number equals approximately 0.15, which agrees to the results from Triantagyllou’s experiment where no leading edge vortex was assumed.
Nevertheless, under large heave amplitude and large attack angle, the propulsive efficiency from the presented study method differs significantly from that of Triantafyllou’s experiment. This is due to the lack of consideration of the leading edge vortex in the wake model presented.
Subjects
史徹赫數
推進效率
尾鰭
振動翼
小板法
panel method
oscillation foils
caudal fin
Strouhal number
propulsive efficiency
Type
thesis
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