Study of thin film carbon nanotubes as thermo-acoustic transition control actuators

This experiment explored the feasibility of thin film carbon nanotubes (CNT) thermo-acoustic actuators as a way of active transition control of boundary layers on a flat plate. The device works by sending waves of heat and sound through the boundary layer at a specific frequency and phase with the goal of interacting with Tollmien-Schlichting (T-S) waves. A wind tunnel boundary layer plate experiment was designed that consists of a flat plate with an elliptical leading edge, adjustable trailing edge flap, and two sets of CNT actuators mounted on the surface. Actuators were located at two streamwise locations in the laminar region of the flat plate. The free-stream velocity was U = 16 m/s for comparison with other T-S wave results. Actuators were operated at 250Hz to specifically target the T-S wave instability at this flow velocity. A PIV system was used to detect and measure velocity fluctuations caused by the presence of T-S waves. Time and phase averaged PIV measurements were acquired at four downstream interrogation domains with the upstream actuator operating over a range of actuator power settings. The effectiveness of CNT actuators as T-S wave exciters was evaluated and will be discussed.