Control of crossflow instability over a swept wing using dielectric-barrier-discharge plasma actuators

This paper investigates the potential use of dielectric-barrier-discharge (DBD) plasma actuators to control the crossflow instability of the boundary layer on a 45° swept NLF-0415 airfoil at −4∘ angle of attack.The disturbance evolution is resolved using nonlinear parabolized stability equations (NPSEs). Actuators are mounted near the leading edge and generate an electric wind perpendicular to the crossflow vortex axes. The spanwise distance between neighboring actuators is first set to be the fundamental wavelength of the unstable mode. This harmonic actuation reduces the disturbance energy only when the induced body force and the disturbance velocity have reverse sign. At certain different locations, the actuators can actually increase the disturbance energy. The robustness in laminar flow control is improved when two actuators per fundamental wavelength are used. This subharmonic actuation leads to reduction in the energy of the primary unstable mode independent of the actuator locations. Finally, the simulation without baseflow forcing reveals that harmonic modes play important roles in this subharmonic control.