Aperture effects on the aerooptical distortions produced by a compressible shear layer

作者：Fitzgerald EJ^*; Jumper EJ

来源：AIAA Journal, 2002, 40(2): 267-275.

DOI：10.2514/2.1668

A recent paper presented time-series measurements of optical wave front distortions produced by a weakly compressible shear layer using the small-aperture beam technique (SABT). These researchers used a posttest, high-pass, digital filter to remove vibrational noise from their beam-jitter signals, choosing a corner-frequency compatible with their 5-cm test aperture. A reexamination of their raw data is documented, and the proper corner-frequency selection for vibration-corruption removal is systematically treated. The resulting SABT wave front reconstructions recaptured the structures previously reported, but now reveal large-amplitude, time-varying, tilt aberrations not previously of interest to 5-cm-aperture optical-system applications. These tilt aberrations are indicative of large-scale flow structures with a spatial scale larger than the test aperture. This conclusion is supported by the results of a recently published numerical simulation. Experimental evidence is presented that suggests that the measured small-scale distortions may have been caused by temperature discontinuities in the splitter-plate boundary layer that fed into the shear layer.

• 出版日期2002-2