Directed Energy Beam Improvement Using Binary Control for the Advanced Tactical Laser ( DEBI-BATL )

The effects of direct small-scale actuation on the aerodynamic and aerooptical characteristics of the flow over a hemisphere-on-cylinder turret model (D = 0.61 m) with a round 0.254 m diameter conformal optical window are investigated at M = 0.3 and ReD = 4.46·10 (with additional measurements at M = 0.4 and 0.5). Flow control is effected by arrays of piezoelectricallydriven synthetic jet modules. The cumulative effect of the actuation is manifested by concomitant delay of flow separation and active, dissipative suppression of turbulent motions downstream of separation. The effects of actuation on aero-optical distortions are assessed from the flow dynamics using surface oil visualization, static pressure distributions and hot-film measurements within the separated flow domain. In addition, the suppression of optical distortions across the separated flow is measured directly using a Malley probe over a range of elevation angles. These measurements show that for a fixed actuation level, the active suppression of spectral components of the optical distortion is about 30% within a resolved frequency band 0.5 < f < 25 kHz at M = 0.3.