Experimental control of Tollmien-Schlichting waves using pressure sensors and plasma actuators

• This manuscript shows the successful application of the inverse feed-forwardcontrol (IFFC) technique for the cancellation of Tollmien–Schlichting (TS)waves. Active wave cancellation of two-dimensional broadband TS disturbancesis performed with a single dielectric barrier discharge (DBD) plasma actuator.The measurements required for the IFFC are performed with microphones,instead of hot wires most used for this task, in order to reduce the spaceoccupied by the sensors and assess the suitability of simpler and cheaperdevices. The experiments are conducted in an open-circuit wind-tunnel witha NACA0008 wing profile. An attenuation of the TS-wave amplitude of oneorder of magnitude is achieved. Direct numerical simulations (DNS) are alsoperformed, and compared to the outcome of the experiments. The modeling ofboth actuator and sensors in the DNS is not based on data from the presentexperiments. The plasma actuator used is a mapping of the force field inFabbiane et al., J. Fluid Mech. 2015, to the NACA0008 wing profile, whereasthe microphones are modeled as pressure probes. Despite these modellingchoices, a remarkable level of agreement between the DNS and the experimentsis achieved. However, the control performance is better in the DNS, withattenuations of three orders of magnitude of TS-wave amplitude. Furtheranalysis of experiments and simulations shows that the limiting factor in theexperiments is the ambient low-frequency acoustic waves in the wind tunnel,which are sensed by the microphones, acting as noise in the analysis of TS-waveevolution and thus leading to lower coherences between sensors and actuators.This in turn leads to a suboptimal control kernel in the experiment.179

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Strömningsmekanik och akustik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Fluid Mechanics and Acoustics (hsv//eng)

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