On the Development of a Harmonic Pitching and Heaving System with Real-Time Control and Optimization Capabilities

Previous computational and experimental efforts have shown that bioinspired oscillating foils can be highly efficient propulsors. However, preceding laboratory implementations of oscillating foil systems have primarily focused on characterizing propulsive performance via parametric studies involving simple harmonic motions. Here, we describe the development of an oscillating pitching and heaving system for hydrofoils that is capable of generating arbitrary periodic motions as well as real-time control and optimization. The heaving and pitching motions are driven by two precision stepper motors, with built-in encoders for determining the linear and angular position of the system. Real-time measurements of hydrodynamic forces are made concurrently with a six-axis force transducer. For validation of this system, we measure the forces and torques generated by a NACA 0012 hydrofoil undergoing sinusoidal pitching and heaving motion in a free surface water channel facility, and we compare the measured thrust coefficients and propulsive efficiencies to previous studies. Ongoing work makes use of this platform for parameter space exploration and optimization of foil kinematics.