StartingFlow by Repetitive Nanosecond Pulsed DBD Actuation at Microseconds and Millisecondsin Quiescent Air

The starting flow behavior of dielectric barrier discharge plasma driven by high-voltage (~17kV) nanosecond pulses of two different temporal scales (microseconds and milliseconds) is investigated experimentally in quiescent air. A laser schlieren light-source is used in the experiments of microsecond temporal scale to estimate the property and propagating speeds of compression wave. The schlieren technique with a halogen lamp and a two-velocity-component PIV system are used in the milliseconds experiment to demonstrate the start and steady period of flow under actuation. The averaged results in microseconds experiment indicate that the compression wave is propagating at a speed of 370m/s at early stage (6~16μs) after the single nanosecond pulse and quickly turns to the sonic level (338m/s). The speeds of compression wave do not vary with the change of voltage. The measurements in milliseconds test show that there are two starting vortices spread towards both direction in the starting stage. The vortex center on the encapsulated electrode side stays at 10mm point. The developing speed of the vortex on the exposed electrode side is related to the frequency of repetitive rate. When the induced flow become steady, one vortex flow structure on the encapsulated electrode side and a jet flow towards the exposed electrode side are found in presented test.