Aero-Optical Environment Around a Cylindrical Turret with a Flat Window

Optical aberrations over a cylindrical turret with a flat window were measured using a two-dimensional wavefront sensor and a Malley probe, as a function of laser beam elevation angle. Topology of the flow around the cylinder was extensively studied using hot wires. It was found that, depending on the window elevation angle, the flow either had a weak separation bubble followed by a reattached boundary layer or a strong separation with a large recirculation region behind the cylindrical turret. Optical aberrations were shown to be consistent with flow topology. It was found that optical aberrations were high around an elevation angle of 100 deg and at large lookback elevation angles.