Measurements, made with laser Doppler velocimetry, about a double-circular-arc compressor blade in cascade are presented for −1.5 and −8.5 deg incidence angles and a chord Reynolds number near 500,000. Comparisons between the results of the current study and those of our earlier work at a 5.0 deg incidence are made. It is found that in spite of the relative sophistication of the measurement techniques, transition on the pressure surface at the −1.5 deg incidence is dominated by a separation “bubble” too small to be detected by the laser Doppler velocimeter. The development of the boundary layers at −1.5 and 5.0 deg is found to be similar. In contrast to the flow at these two incidence angles, the leading edge separation bubble is on the pressure surface for the −8.5 deg incidence. Here, all of the measured boundary layers on the pressure surface are turbulent—but extremely thin—while on the suction surface, a laminar separation/turbulent reattachment bubble lies between roughly 35 percent and 60 percent chord. This bubble is quite thin, and some problems in interpreting the backflow data are discussed.
The Measurement of Boundary Layers on a Compressor Blade in Cascade: Part 4—Flow Fields for Incidence Angles of −1.5 and −8.5 Degrees
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Zierke, W. C., and Deutsch, S. (April 1, 1990). "The Measurement of Boundary Layers on a Compressor Blade in Cascade: Part 4—Flow Fields for Incidence Angles of −1.5 and −8.5 Degrees." ASME. J. Turbomach. April 1990; 112(2): 241–255. https://doi.org/10.1115/1.2927638
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