Experimental study of oscillating SD8020 foil for propulsion

Srigrarom, S., Chai, W. S. and Tan, H. T. (2007). Experimental study of oscillating SD8020 foil for propulsion. In: Peter Jacobs, Tim McIntyre, Matthew Cleary, David Buttsworth, David Mee, Rose Clements, Richard Morgan and Charles Lemckert, 16th Australasian Fluid Mechanics Conference (AFMC). 16th Australasian Fluid Mechanics Conference (AFMC), Gold Coast, Queensland, Australia, (1291-1294). 3-7 December, 2007.

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Author Srigrarom, S.
Chai, W. S.
Tan, H. T.
Title of paper Experimental study of oscillating SD8020 foil for propulsion
Conference name 16th Australasian Fluid Mechanics Conference (AFMC)
Conference location Gold Coast, Queensland, Australia
Conference dates 3-7 December, 2007
Proceedings title 16th Australasian Fluid Mechanics Conference (AFMC)
Place of Publication Brisbane, Australia
Publisher School of Engineering, The University of Queensland
Publication Year 2007
Year available 2007
Sub-type Fully published paper
ISBN 978-1-864998-94-8
Editor Peter Jacobs
Tim McIntyre
Matthew Cleary
David Buttsworth
David Mee
Rose Clements
Richard Morgan
Charles Lemckert
Start page 1291
End page 1294
Total pages 4
Collection year 2007
Language eng
Abstract/Summary The thrust producing performance and efficiency of an SD8020 oscillating foil with a symmetrical saw-tooth angle of attack pitching profile was studied through force and torque measurements, as well as dye flow visualization, in the water tunnel at low Reynolds number of 13,000-16,000. The propulsive efficiency and thrust coefficient of the pitching foil were determined as a function of the Strouhal number, pitch amplitude and angular frequency. A propulsive efficiency of 30% was obtained experimentally at low Strouhal numbers. The flow visualization has revealed different wake patterns at various Strouhal numbers and can be classified into three regimes – a drag wake, a transition wake and a thrust wake. The drag wake consists of a combination of a regular Kármán street and an array of ‘primary’ stop-start vortices, whereas the thrust wake consists of a reverse Kármán vortex street, commonly observed in swimming fish. The transition wake regime, which occurs at approximately 0.2 < St < 0.5, is interpreted as a momentum balanced wake, where the thrust developed by the foil approximately balances its produced drag. This wake was observed to either consist of an inclined vortex street, or a paired vortex pattern. Based on the force and efficiency data collected, increasing pitch amplitude and angular frequency was associated with a decrease in propulsive efficiency and an increase in thrust forces produced. A high efficiency value of 0.3, accompanied by a thrust coefficient of order one is found at a low pitch amplitude of 10°, angular frequency of 0.79 rad/s and Strouhal number of 0.05. This presented the best conditions for thrust production observed at low Strouhal and Reynolds numbers.
Subjects 290201 Aerodynamics
290501 Mechanical Engineering
Q-Index Code E1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Conference Paper
Collection: 16th Australasian Fluid Mechanics Conference
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Created: Wed, 19 Dec 2007, 15:20:45 EST by Laura McTaggart on behalf of School of Engineering