Effect of DBD Plasma Actuator Geometry and Excitation for Producing Transient Growth Modes in a Laminar Boundary Layer

摘要

This work is concerned with the response of a Blasius boundary layer to plasma actuators for the purpose of using these devices in bypass transition control. The structure of actuator-induced boundary layer streaks is measured using hot-wire anemometry over a streamwise distance of a approximately 100 boundary layer thicknesses, based on a thickness of 4 mm at the point of actuation. Spanwise power spectra of the streamwise disturbance velocity show that 90% of the actuator-induced disturbance energy is contained within a mode related to the spanwise spacing of the exposed actuator electrodes, and its first 3 harmonics. The modal content and corresponding streamwise growth characteristics are discussed for four plasma actuator geometries over multiple excitation voltages in the 3.5 - 5.5 kV_(pp) range. Actuator output was found to have a closer correlation to actuator power consumption than the excitation voltage. A common relationship between disturbance energy and power consumption was found among actuators of different dielectric thickness and similar electrode geometry. Degradation of the actuators was observed over the course of their running lifetime, causing test cases to diverge gradually from this relationship.