Mitigation of Aero-Optic Distortions by Active Flow Control

"The goal of the proposed project is to develop and demonstrate an integrated flow control system to reduce aero-optic distortions via control of large-scale shear layer structures and manipulation of the turbulence spectrum in a compressible shear flow.Density fluctuations in a compressible shear layer can produce time-varying index of refraction across the shear layer. Optical systems that must operate in this aero-optic environment experience various types of degradations in performance due to therefractive index changes associated with these density variations. Recent work suggests that control of the compressible shear layer is possible such that an adaptive aero-optical system may be developed to alleviate many of these problems. Active flowcontrol strategies capable of virtually eliminating the large scale coherent structures in the compressible shear layer are addressed. Phase I will develop prototype actuators and demonstrate their impact on the aero-optic distortions in a small scaleexperimental test configuration. Phase II will refine the actuation and control strategy. Detailed experimental and computational investigations of the flow phenomena will guide the actuation/control work. Results from this project will improve theperformance of airborne optical systems. Non-military applications include optical data links for commercial aircraft. Reduced aero-optical distortions. Improved performance of airborne laser systems and directed energy weapons and optical data links forcommercial aircraft. Active suppression of oscillations in aircraft weapons bays."