Accession Number : AD1013314


Title :   Control of Boundary Layers for Aero-optical Applications


Descriptive Note : Technical Report,15 Mar 2012,14 Mar 2015


Corporate Author : University of Notre Dame Notre Dame United States


Personal Author(s) : Gordeyev, Stanislav ; McKeon,Beverley


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/1013314.pdf


Report Date : 23 Jun 2015


Pagination or Media Count : 88


Abstract : This report presents results of systematic experimental studies of various passive mitigation techniques to reduce aero-optical effects caused be turbulent boundary layers. Parametric studies of Large-Eddy Break-Up devices showed that aero-optical distortions can be suppressed by 45 percent for several boundary layer thicknesses. It was shown that moderate cooling of the wall also reduces aero-optical distortions by 60 percent . A model to predict effects of non-adiabatic walls, both full and partial, over a range of subsonic and supersonic Mach numbers was developed and shown to correctly predict experimentally-observed reductions. Heating the wall allows extending the use of wavefront sensors into low subsonic speeds. Using this technique, aero-optical effects of boundary layers at low (1,700-8,000) Reynolds numbers, were investigated. Simultaneous velocity-optical measurements revealed that large-scale vortical structures are mostly responsible for aero-optical distortions and also indicated that the pressure fluctuations inside these vortical structures might be significant.


Descriptors :   TURBULENT BOUNDARY LAYER , EDDIES (FLUID MECHANICS) , large eddy , DISTORTION , REYNOLDS NUMBER , VORTICES


Subject Categories : Fluid Mechanics


Distribution Statement : APPROVED FOR PUBLIC RELEASE