Numerical investigation of angle of attack profile on propulsion performance of an oscillating foil

Qing Xiao, Wei Liao

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

Effects of effective angle of attack (AOA) profile on an oscillating foil thrust performance are studied using a computational method. The foil is subject to a combined pitching/plunging motion with effective AOA satisfying a harmonic cosine function. To achieve this, either the pitching or plunging motion is modified from the conventional harmonic sinusoids. Investigations are performed over a series of Strouhal numbers (St), three maximum effective angles of attack and three different phase angles between pitching and plunging. It is shown that the degradation of thrust force and efficiency with sinusoidal pitching/plunging oscillation, at higher St, is effectively alleviated or removed when the AOA is imposed as a cosine profile. The improvement is more significant for the phase angle being different from 90degrees. A better performance is obtained with the imposed modification on pitching motion. The stronger reversed Von Karman
vortex wake associated with leading-edge vortex development is observed with the modified motions, which is believed to induce the improved thrust performance.
Original languageEnglish
Pages (from-to)1366–1380
Number of pages15
JournalComputers and Fluids
Volume39
Issue number8
Early online date22 Apr 2010
DOIs
Publication statusPublished - Sep 2010

Fingerprint

Angle of attack
Metal foil
Propulsion
Strouhal number
Computational methods
Vortex flow
Degradation

Keywords

  • pitching/plunging oscillation
  • propulsion performance
  • effective angle of attack
  • cosine profile
  • numerical investigation
  • angle of attack

Cite this

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abstract = "Effects of effective angle of attack (AOA) profile on an oscillating foil thrust performance are studied using a computational method. The foil is subject to a combined pitching/plunging motion with effective AOA satisfying a harmonic cosine function. To achieve this, either the pitching or plunging motion is modified from the conventional harmonic sinusoids. Investigations are performed over a series of Strouhal numbers (St), three maximum effective angles of attack and three different phase angles between pitching and plunging. It is shown that the degradation of thrust force and efficiency with sinusoidal pitching/plunging oscillation, at higher St, is effectively alleviated or removed when the AOA is imposed as a cosine profile. The improvement is more significant for the phase angle being different from 90degrees. A better performance is obtained with the imposed modification on pitching motion. The stronger reversed Von Karmanvortex wake associated with leading-edge vortex development is observed with the modified motions, which is believed to induce the improved thrust performance.",
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Numerical investigation of angle of attack profile on propulsion performance of an oscillating foil. / Xiao, Qing; Liao, Wei.

In: Computers and Fluids, Vol. 39, No. 8, 09.2010, p. 1366–1380.

Research output: Contribution to journalArticle

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