Polymer Actuated Variable Camber Foils

摘要

Conducting polymer actuators are employed to create actively shaped hydrodynamic foils. The active foils are designed to allow control over camber. Polymer actuator-driven control of camber, when applied to screws, promises to enable low cost blade shape optimization as a function of flow conditions. The design and fabrication of the active foils are presented, the forces are measured and operation is demonstrated both in still air and water. The foils have a span of 240 mm, and an average chord length of 70 mm. The trailing 30 mm of the foil is composed of a thin polypyrrole actuator that curls chordwise to achieve variable camber. The actuator consists of two 30μm thick sheets of hexafluorophosphate doped polypyrrole separated from each other by a gel electrolyte. A polymer layer encapsulates the entire structure. Potentials are applied between the polymer layers to induce reversible bending by approximately 35 degrees, generating forces of 0.15 N. A linear actuator driven foil has also been developed which relies on a dual cantilever mechanical amplification system to generate similar forces and displacements as are obtained with the bending system. Remaining challenges include increasing force, improving encapsulation, and demonstrating durability through water tunnel tests.