Control of High Subsonic Cavity Flow Using Plasma Actuators

Abstract

Localized arc filament plasma actuators were used to control pressure fluctuations in a cavity with a depth of 12.7 mm and length-to-depth ratio of 4.86. The rear wall of the cavity is inclined 30 deg with respect to the upstream flow, and the cavity length is 61.7 mm. Five actuators were uniformly distributed along the span of the cavity, 1 mm upstream of the cavity leading edge. Experiments were conducted in a flow with a Mach number of 0.6 and a Reynolds number based on the cavity depth of 2 × 10 5. Forcing was conducted quasi-two-dimensionally (all actuators operated in phase) and threedimensionally (actuators operated out of phase). The objective of the research was twofold: first, to demonstrate that the peak tone as well as the broadband pressure fluctuations can be suppressed in a strongly resonating cavity, and second, the resonance can be re-established and the peak tone as well as the broadband pressure fluctuations can be amplified in a weakly resonating cavity. Time-resolved pressure and particle-image-velocimetry measurements were used to assess the effectiveness of the actuators and to explore the physics of the flow. Although both quasi-two-dimensional and threedimensional controls were successful in controlling the flow, the control was less sensitive to forcing frequency change in the latter in achieving the first objective. The results also showed that, although there are many forcing frequency options in achieving the first objective, the options are limited to frequencies near the dominant (even though weak) Rossiter modes in re-establishing the feedback in a weakly resonating cavity.

Controllable Shock Wave Generation by Near-Surface Electrical Discharge

“…Similar phenomena in different geometric arrangements have been depicted for a volumetric transversal arc discharge in a high-speed flow, explored by Shibkov et al [25]. Samimy et al [26,27,28] have employed localized arc filament plasma actuators (LAFPA) in a fundamentally unsteady manner to influence flow stability. The technique consists of an arc filament initiated between electrodes embedded on the surface to generate rapid (on the time scale of a few microseconds) local heating.…”

“…The control of cavity-based flow in a supersonic duct is of significant fundamental and technological interest for aerospace science and industry as currently the cavity appears to be a major element of a supersonic flameholding scheme, [1,2,3,4,5] and references herewith. The flow structure in cavities is sensitive to the geometrical configuration and main flow parameters, including the texture of the boundary layer upstream of the cavity and the presence of compression/expansion waves impinging on the cavity area.…”

“…In the last two decades the plasma-based technique was explored in terms of feasibility of steady or transient shock wave (SW) generation in supersonic flow and SW -boundary layer / separated flow interaction control [12,13,14,15,3,16,17,18,19,20]. A near-surface discharge between flush-mounted electrodes installed on a plane wall has been utilized in serial work on duct-driven flow control and for plasma-assisted supersonic combustion experiments [19,13,21,22,23,24].…”

Supersonic Cavity Flow Control for Scramjet Applications

“…They have proven to be able to significantly reduce peak tone and broadband pressure fluctuations in a high subsonic cavity as well as establish resonance in a non-resonating cavity. 12 These modifications of the resonance state theoretically modify the drag incurred by the cavity geometry. However, the drag of a naturally resonating cavity which has been controlled to suppress the resonance has not been measured and compared with that of a naturally nonresonating cavity.…”

Supersonic Cavity Control Using Plasma Actuators

“…1 The objective of this work is to demonstrate that the observed control authority of the LAFPAs extends to the supersonic regime, and to eventually show that the LAFPA/cavity system can provide a robust shock trap with minimal parasitic drag/power requirements.…”