American Institute of Aeronautics and Astronautics 1 Optimum Design of an Aircraft-Mounted Pod for Improved Aero-Optic Performance Grady Crahan, 1 Mark Rennie, 2 Eric J. Jumper, 3 Andrés Tovar, 4 Gilberto Mejía-Rodríguez, 5 and John E. Renaud 6 Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN, 46556 Aero-optic aberrations originating from the nearby flowfield of an aircraft can seriously limit the ability to focus on-board laser systems onto farfield targets. These aero-optic aberrations can be mitigated by using fences to control the flow around the outgoing beam aperture. The objective of this investigation is to attempt to determine the best shape for these fences using computational fluid dynamics in combination with optimization techniques. Future work will experimentally and computationally build on the solutions presented here. Nomenclature a j = parameters from fitting polynomial function C P = pressure coefficient C P0 = pressure coefficient in incompressible flow M = local Mach number M ∞ = freestream Mach number D = pod turret diameter h = height of the fence x = axial position x D = normalized axial position (x/D) x 1 = normalized position x D where the fence begins x 2 = normalized position x D to farthest point from the centerline to the fence y = radial transverse position y D = normalized radial transverse position (y/D) y 1 = normalized position y D where the fence begins y 2 = normalized position y D to farthest point from the centerline to the fence z = radial normal position  = lookback angle  r = ramp angle  = ratio of specific heats (air = 1.4) I. Introduction N aircraft traveling at compressible flow speeds is surrounded by optically-active regions which are formed by high density and associated index-of-refraction gradients. 1 These optically-active regions originate from localized compressible turbulent flowfields or inviscid flows such as shock waves. 2 The aberrations produced by these optically-active regions can have disastrous consequences for a traversing beam of light, and so can significantly restrict the effective field of regard of optical systems carried by the aircraft. A possible mitigation approach to aero-optic flows is to employ an adaptive-optic (AO) system 3 that places the conjugate waveform of the aberration onto the wavefront of the beam prior to its transmission through the aberrating 1 Graduate Research Assistant, Center for Flow Physics and Control, AIAA Student Member, gcrahan@nd.edu. 2 Research Assistant Professor, Center for Flow Physics and Control, AIAA Member, rrennie@nd.edu. 3 Professor, Center for Flow Physics and Control, AIAA Fellow, ejumper@nd.edu. 4 Research Assistant Professor, Design Automation Laboratory, AIAA Member, atovar@nd.edu. 5 Graduate Research Assistant, Design Automation Laboratory, AIAA Student Member, gmejiaro@nd.edu. 6 Professor, Design Automation Laboratory, AIAA Fellow, jrenaud@nd.edu. A