| Popis: |
Phase-locked PIV has been used to investigate the time-dependent behaviour of a Dielectric Barrier Discharge (DBD) plasma actuator, excited by a sine-wave signal with peakto-peak amplitudes between 7.2 kV and 10 kV, and frequencies of 2.5 kHz and 4 kHz. The results indicate that the maximum induced velocity and body force occur during the negative half-cycle of the excitation signal, with a phase lag relative to the excitation signal that grows when excitation voltage or frequency is increased. A smaller, secondary peak is observed in the induced body force, occurring during the positive half-cycle of the excitation signal. The results suggest that this peak is due to formation of a secondary high-velocity region due to local discharges near the grounded electrode. Analysis of the induced body force, estimated using momentum balance in a control volume surrounding the actuator, indicates the significant role of the shear force acting on the actuator surface for the present configuration. The variability in the results of different methods for determining the shear force, and the difference observed in certain conditions between the estimated body forces and those measured directly using a balance highlight the need for further improving the methodology for body force prediction based on PIV measurements. |
