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1	Receptivity of Laminar Boundary Layers to Spanwise-periodic Forcing by an Array of Plasma Actuators Osmokrovic, Luke 26 November 2012 (has links) This work is concerned with the response of a Blasius boundary layer to dielectric-barrier-discharge (DBD) plasma actuators for the purpose of using these devices in bypass transition control. The plasma actuators consist of a spanwise-periodic array of high voltage electrodes, which are oriented to produce streamwise vortex pairs. The structure of actuator-induced streaks is measured using hot-wire anemometry over a streamwise distance of approximately 100 boundary layer thicknesses, and is decomposed into 4 spanwise Fourier modes. The modal content and corresponding streamwise growth characteristics are discussed for ten plasma actuator geometries over multiple excitation voltages and freestream velocities. Actuator power consumption was found to control the streak amplitude, whereas freestream velocity affected both amplitude and streamwise extent of the streaks. A common relationship between disturbance energy and power consumption was found among actuators of different dielectric thickness and similar electrode geometry. plasma actuator transition transient growth laminar boundary layer streaks power consumption wind tunnel turbulence hot-wire anemometry disturbance velocity power spectrum nanofabrication data collapse electrode geometry 0538
2	Receptivity of Laminar Boundary Layers to Spanwise-periodic Forcing by an Array of Plasma Actuators Osmokrovic, Luke 26 November 2012 (has links) This work is concerned with the response of a Blasius boundary layer to dielectric-barrier-discharge (DBD) plasma actuators for the purpose of using these devices in bypass transition control. The plasma actuators consist of a spanwise-periodic array of high voltage electrodes, which are oriented to produce streamwise vortex pairs. The structure of actuator-induced streaks is measured using hot-wire anemometry over a streamwise distance of approximately 100 boundary layer thicknesses, and is decomposed into 4 spanwise Fourier modes. The modal content and corresponding streamwise growth characteristics are discussed for ten plasma actuator geometries over multiple excitation voltages and freestream velocities. Actuator power consumption was found to control the streak amplitude, whereas freestream velocity affected both amplitude and streamwise extent of the streaks. A common relationship between disturbance energy and power consumption was found among actuators of different dielectric thickness and similar electrode geometry. plasma actuator transition transient growth laminar boundary layer streaks power consumption wind tunnel turbulence hot-wire anemometry disturbance velocity power spectrum nanofabrication data collapse electrode geometry 0538

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Receptivity of Laminar Boundary Layers to Spanwise-periodic Forcing by an Array of Plasma Actuators

Receptivity of Laminar Boundary Layers to Spanwise-periodic Forcing by an Array of Plasma Actuators