Development of transonic and supersonic turret design methods for improved optical and aerodynamic performance

The development of airborne High-Energy Laser (HEL) systems is currently receiving a high level of research effort. There is growing evidence that spherical turrets are not ideal mounting platforms for HEL systems because they are highly susceptible to flows that produce strong optical aberrations such as shocks and separated-flow regions. The objective of the proposed research is to investigate innovative turret designs that mitigate or eliminate aero-optic effects over the maximum field of regard for the Mach number range 0.7 to 1.5. Subsonic turret design efforts will concentrate on methods to delay formation of shocks and separated flow regions around the exit pupil and will exploit Notre Dame"s past experience developing an aero-optic pod for the Navy. For supersonic Mach numbers, the investigation will begin by determining methods of anchoring the bow shock at a fixed location. All new turret concepts will be evaluated for susceptibility to aerodynamic jitter. New turret concepts will be analyzed using both Computational Fluid Dynamics (CFD) and wind-tunnel testing; however, the primary emphasis of the Phase I effort will be on CFD. The analysis approach will make use of Notre Dame"s established knowledge of aero-optic flows to more efficiently direct the investigation. BENEFIT: The Phase I research is expected to produce methods of maximizing the critical Mach number in subsonic flow, and maximizing the field of regard that is free of separated flow regions. The research is also expected to produce concepts for supersonic turret designs that minimize the number of shock waves in the field of regard, and anchor the shock waves at fixed locations. Preliminary aerodynamic force data as a function of beam-pointing angle at critical turret orientations will also be produced for the purpose of evaluating the possibility of jitter. Commercial applications include but not limited to securing laser communication systems.