Similarities and Differences in Aero-Optical Structure over Cylindrical and Hemispherical Turrets with a Flat Window

This paper discusses similarities and differences for aft-looking angles of the aerooptical environment over flat windows on a three-dimensional hemispherical turret and two-dimensional cylindrical turret. Both fluid-mechanic and aero-optical data for the baseline flows over the turrets and with two types of passive flow devices are presented and discussed for relatively-high, subsonic Mach numbers. Although the flow around the hemispherical turret was found to be far-more complex than over the cylindrical turret, the flow physics over the windows themselves were shown to be very similar; this similarity afforded an opportunity to study the flow over the window in more detail for the cylindrical turret and to easily examine a range of flow devices for improving its aero-optical environment, selecting two devices, presented here, for further study on the hemispherical turret. For both turret configurations the most aberrating flow environments were cased by separated flows. For small aft-looking angles the separated flows reattach over the windows and the devices were shown to be effective in preventing the separation altogether and greatly improving the aero-optical environment. Once fully separated, neither device improved the environment.