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First published online December 28, 2007
Journal of Experimental Biology 211, 274-279 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.012849
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Propulsive performance of biologically inspired flapping foils at high Reynolds numbers

Alexandra H. Techet

Massachusetts Institute of Technology, Department of Mechanical Engineering, Cambridge, MA 02139, USA


Figure 1
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  		Fig. 1. (A) Double canister flapping foil actuator design with the foil and the inline AMTI six-axis force sensor assembly between the pitch canister and the foil. The distance from center of roll axis to root of foil is indicated by r0; S is the foil span. (B) Foil motion coordinate system. The freestream flow is in the Yc direction and Zc is oriented in the opposite direction from gravity. Roll, {phi}(t), is constrained to the Xc–Zc plane and pitch, {theta}(t), is an angular motion about the foil shaft.

 

Figure 2
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  		Fig. 2. Vector diagram for velocity components relative to heaving and pitching motions and incoming fluid velocity.

 

Figure 3
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  		Fig. 3. Processed data recorded for St=0.2, h0.7/c=1.5, {alpha}max=20°. The horizontal axis is the time (in s). The lift and thrust are in the tunnel reference frame. The forces are calibrated using the AMTI sensitivity matrix.

 

Figure 4
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  		Fig. 4. Contour plots of thrust coefficient for h0/c=1.0 (A) and h0/c=1.5 (B); {alpha}max is given in degrees. Red circles represent location of each run performed; no data exist for the region shadowed in grey for h0/c=1.0.

 

Figure 5
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  		Fig. 5. Contour plots of thrust coefficient and efficiency for h0/c=1.0 (A) and h0/c=1.5 (B); {alpha}max is given in degrees. Blue diamonds represent location of each run targeted; no data exist for the region shadowed in grey for h0/c=1.0.

 




© The Company of Biologists Ltd 2008