TY - GEN
T1 - Using experimental optimization to tune the kinematics of a flexible propulsor
AU - Quinn, Daniel B.
AU - Lauder, George V.
AU - Smits, Alexander J.
N1 - Funding Information:
This work was supported by the Office of Naval Research under MURI grant number N00014-08-1-0642 (Pro- gramDirectorDr. BobBrizzolara),andtheNationalSci-ence Foundation under Grant DBI 1062052 (PI Lisa Fauci) and Grant EFRI-0938043 (PI George Lauder). The authors would also like to thank Patrick Thornycroft and Erik Anderson, who provided invaluableassistance in the automation of the experiment.
PY - 2015
Y1 - 2015
N2 - Gradient-based optimization is used to maximize the propulsive efficiency of a heaving and pitching flexible panel. Random initial conditions are sequentially improved until a minimum step size is reached, at which point the condition is considered locally optimal. Optimum pitch and heave motions are found to produce nearly twice the efficiencies of optimum heave-only motions. Particle Image Velocimetry (PIV) is used to investigate the flow structures at optimal conditions. Efficiency is globally optimized when (1) the Strouhal number is within an optimal range that varies weakly with amplitude and boundary conditions; (2) the panel is actuated at a resonant frequency of the fluidpanel system; (3) heave amplitude is tuned such that trailing edge amplitude is maximized while the flow along the body remains attached; and (4) the maximum pitch angle and phase lag are chosen so that the effective angle of attack is minimized. The multi-dimensionality and multimodality of the efficiency response demonstrate that experimental optimization appears to be well-suited for the design of flexible underwater propulsors.
AB - Gradient-based optimization is used to maximize the propulsive efficiency of a heaving and pitching flexible panel. Random initial conditions are sequentially improved until a minimum step size is reached, at which point the condition is considered locally optimal. Optimum pitch and heave motions are found to produce nearly twice the efficiencies of optimum heave-only motions. Particle Image Velocimetry (PIV) is used to investigate the flow structures at optimal conditions. Efficiency is globally optimized when (1) the Strouhal number is within an optimal range that varies weakly with amplitude and boundary conditions; (2) the panel is actuated at a resonant frequency of the fluidpanel system; (3) heave amplitude is tuned such that trailing edge amplitude is maximized while the flow along the body remains attached; and (4) the maximum pitch angle and phase lag are chosen so that the effective angle of attack is minimized. The multi-dimensionality and multimodality of the efficiency response demonstrate that experimental optimization appears to be well-suited for the design of flexible underwater propulsors.
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M3 - Conference contribution
AN - SCOPUS:85034417647
T3 - 9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015
BT - 9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015
PB - TSFP-9
T2 - 9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015
Y2 - 30 June 2015 through 3 July 2015
ER -