Publication Detail

Flapping Motion of a Three-Dimensional Foil for Propulsion and Maneuvering of Underwater Vehicles

Melissa Harness-Flores

Experiments were performed on a three-dimensional NACA 0015 foil with a 5.5 cm
average chord and 24.3 cm span performing a combined roll and pitch motion. The
trailing edge of the foil was tapered. The motion was produced by harmonically
rolling and pitching the foil near the root using two-axis control. Tests to determine
the mean thrust coefficient of the foil were conducted over a wide parametric space.
This parameter space included two roll amplitudes, with induced heave (at the 0.7
span) to chord ratio of h0:7=c = 1:00 and 1.50; respectively, with Strouhal numbers
ranging from 0.20 to 0.80; and maximum angle of attack varying between 15 and 50
degrees. The angle of attack and Strouhal number were also defined using the motion
at the 0.7 span. A planform area mean thrust coefficient of 2.07 was recorded for
40 degrees maximum angle of attack and h0:7=c = 1:50. Experiments to measure the
mean lift and thrust coefficient were performed after adding a static bias to the foil
pitch. Mean lift coefficients of near 4 were achieved in this manner. Further maneuvering
tests were accomplished by measuring the forces produced by an impulsively
starting foil in still water and at U = 0:4 m=s. Peak forces and impulse were measured
for pitch angles between 30 and 90 degrees and for three different roll velocities.
The highest propulsive impulse measured was 2.25 Newton-seconds at a maximum
roll amplitude of 1.28 m/s and pitch angle of 40 degrees.

type: Full theses / dissertations

Parent Project

Project No.: 2001-RT-2/RD-13
Title: Biomimetic Rigid Hull Vehicle with Flapping Foils for Enhanced Agility in the Surf Zone and Cluttered Environments