Fluidic Control of a Turret Wake, Part I: Aerodynamic Effects

The effects of direct small-scale actuation on the aerodynamic and aero-optical characteristics of the flow over a round 0.254 m diameter conformal optical window built into the hemispherical cap of a cylinder turret model (D = 0.61 m) are investigated at M = 0.3 and ReD = 4.46·10 6 (with additional measurements at M = 0.4 and 0.5). Flow control is effected by arrays of piezoelectrically-driven 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 estimated from Malley probe measurements over a range of elevation angles. These measurements show that for a fixed actuation level the suppression of spectral components of the optical distortion within the Malley probes’s resolvable frequency band 0.5 < f < 25 kHz at M = 0.3 is about 30%.