Optical Aberrations Caused by Coherent Structures in a Subsonic, Compressible, Turbulent Boundary Layer

by Jacob Allen Cress The relationship between optical aberrations and coherent structures in the turbulent boundary layer is investigated in a series of experiments. A statistical model is derived using the “extended” Strong Reynolds Analogy that allows the total temperature to vary and also presumes pressure fluctuations in the boundary layer are negligible compared to temperature fluctuations. This model is compared to experimental results taken of a moderately heated and cooled boundary layer. The effect of elevation angle on the amount of optical aberration is also investigated and discussed in relation to coherent structures. Two-dimensional wavefronts through a single boundary layer are presented along with average correlation length results. The distribution in time of the optical aberrations is analyzed and considered in terms of communication applications. This work concludes with a discussion of coherent vortical structures and how they are related to optical aberrations, and the relative contribution of pressure and temperature fluctuations to wavefront distortions.