Comparisons of boundary-layer transition measurement techniques in the Langley Unitary Plan wind tunnelFour different boundary-layer transition detection techniques, namely liquid crystals, very thin hot films, IR photography, and an optical interferometer, were compared using the same flat plate model for the same tunnel conditions. The comparisons, conducted at NASA-Langley, involved not only their sensitivity to transition but also their ease of use. The thin films, as expected, gave excellent quantitative information and were used as the standard for evaluating the other techniques. Both the liquid crystals and IR photography were able to detect transition before the boundary-layer intermittency factor had reached 50 percent. The optical interferometer was unsuccessful. Conditions sampled included a range of Mach numbers from 1.5 to 2.5 and unit Reynolds numbers from 1.0 to 4.0 million/foot.
Document ID
19890060293
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Hall, R. M. (NASA Langley Research Center Hampton, VA, United States)
Carraway, D. L. (NASA Langley Research Center Hampton, VA, United States)
Johnson, C. B. (NASA Langley Research Center Hampton, VA, United States)
Wright, R. E., Jr. (NASA Langley Research Center Hampton, VA, United States)
Obara, C. J. (Planning Research Corp. Hampton, VA, United States)