Aero-Optical Environment Around a Conformal-Window Turret

This paper presents the aero-optical environment around a generic conformal-window turret formed from a hemisphere on a short cylindrical base. A suite of optical instruments consisting of a Malley probe, a conventional two-dimensional Shack-Hartmann wave-front sensor, and a new high-bandwidth, lower-resolution Hartmann wave-front sensor were used to measure the aberrations on the wave front of a laser beam emanating from the turret at various angles in both the forward and aft direction in the turret's zenith plane. The measurements were made over a range of Mach numbers from 0.35 to 0.45. Complementary steady- and unsteady-pressure measurements over a slightly larger range of Mach numbers were also made, along with a surface-flow-visualization study of the complex flowfield over and around the turret. The use of the suite of sensors allowed for the recognition and separation of the aberrating optical environment into components associated with stationary disturbances and convecting disturbances at the frequency of the turret's separated wake and at order-of-magnitude-higher frequencies associated with structures that form in the separated shear layers, respectively. The optical data separated in this way are valuable because of the implications for adaptive optics.