Abstract
Plasma actuators have attracted interest for use as active flow control devices due to their many benefits; they have no moving parts and are lightweight, can be flush mounted, and require low power. In this study, the performance of plasma actuators are experimentally characterized with dielectric material, dielectric thickness, and operating frequency for surface and channel actuator geometries. The channel height, changing the effective dielectric constant, is also varied. Induced velocities were measured using a pitot tube and PIV, and power consumption levels were recorded. For the surface plasma actuator, PTFE and GRE dielectric materials show similar performance, with Kapton producing the highest induced velocity jet. Higher plasma ionization tends to occur with operating frequencies of 5 and 10 kHz, with a minimum at 7 kHz – possibly related to a change to streamer discharge from corona discharge. Power consumption was also higher at frequencies of 5 and 10 kHz. Thinner dielectric materials outperformed thicker ones for a given high voltage input. GRE, which has the highest dielectric constant of the tested materials, resulted in higher induced velocities than PTFE and Kapton for the same dielectric thickness. For the channel actuator, the smallest air gap corresponding to the lowest permittivity generated the highest peak induced velocity at 12 kHz. Different air gap heights do not seem to affect the induced velocities for frequencies above 14 kHz. A high gradient of velocity reduction with streamwise distance from the exposed electrode of the channel actuators was also observed.
Highlights
Plasma actuators (PA) have been studied extensively for a number of years, advancing the understanding of the underlying physics and showcasing their potential as flow control devices in many applications
Plasma actuator performance was characterized with induced velocity data acquired via a traversable pitot tube connected to a FC012 micromanometer from Furness Controls and particle image velocimetry (PIV) flow field measurements, see Fig. 5
Induced velocities from pitot tube and PIV measurements are presented for both the surface and channel PA cases
Summary
Plasma actuators (PA) have been studied extensively for a number of years, advancing the understanding of the underlying physics and showcasing their potential as flow control devices in many applications. The DBD plasma is formed when a high, AC or ns, voltage is supplied across electrodes, ionizing the surrounding gas In this region, it is known that DBD actuators partially ionize the fluid with the resulting electric field giving a body force to the ionized particles during DBD annihilation [15,16]. The dielectric area needed to store charge can be too small to take full advantage of the applied voltage This is known as the self-limiting factor of acDBD plasma actuators with the highest recorded induced velocities reaching 10 ms−1 [29,30,31]. A lower dielectric constant corresponds to a smaller capacitance value which scales with r /t3, where t3 is the dielectric thickness This decreases the local concentration of the electric field strength allowing higher voltage input before saturation is reached [14].
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