Time-resolved wave front measurements through a compressible free shear layer

Abstract

Time series of spatially resolved, aberrated wave fronts distorted by propagation through a compressible shear layer are presented. These wave fronts were measured using the small-aperture beam technique (SABT) applied to the compressible free shear layer facility at Arnold Engineering Development Center. Two viewing stations were investigated at the facility, the first directly downstream of the compressible shear layer's splitter plate and the second at a location 48.3 cm downstream of the first station. The first station was found to have optically active structures of approximately 2.5 cm in spatial extent, convecting at approximately 160 m/s, and inducing rms aberrations on the order of 0.06 waves. The second station had optically active structures approximately 5 cm in size, also convecting at approximately 160 m/s, and causing distortions on the order of 0.17 waves.