Turbulence Amplification with Incidence at the Leading Edge of a Compressor Cascade
Hobson, Garth V.
Wakefield, Bryce E.
Roberts, William B.
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Detailed measurements, with a two-component laser-Doppler velocimeter and a thermal anemometer were made near the suction surface leading edge of controlled-diffusion airfoils in cascade. The Reynolds number was near 700,000, Mach number equal to 0.25, and freestream turbulence was at 1.5% ahead of the cascade. It was found that there was a localized region of high turbulence near the suction surface leading edge at high incidence. This turbulence amplification is thought to be due to the interaction of the free-shear layer with the freestream inlet turbulence. The presence of the local high turbulence affects the development of the short laminar separation bubble that forms very near the suction side leading edge of these blades. Calculations indicate that the local high levels of turbulence can cause rapid transition in the laminar bubble allowing it to reattach as a short "non-burst" type. The high turbulence, which can reach point values greater than 25% at high incidence, is the reason that leading edge laminar separation bubbles can reattach in the high pressure gradient regions near the leading edge. Two variations for inlet turbulence intensity were measured for this cascade. The first is the variation of maximum inlet turbulence with respect to inlet-Dow angle; and the second is the variation ofleading edge turbulence with respect to upstream distance from the leading edge of the blades.
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Hobson, Garth V.; Wakefield, Bryce E.; Roberts, William B. (1996-06);Detailed measurements, with a two-component laser- Doppler velocimeter and a thermal anemometer were made near the suction surface leading edge of Controlled-Diffusion airfoils in cascade. The Reynolds number was near ...
Im, Ju Hyun; Shin, Ju Hyun; Hobson, Garth V.; Song, Seung Jin; Millsaps, Knox T. (ASME, 2013-06);An experimental investigation has been conducted to characterize the influence of leading edge roughness and Reynolds number on compressor cascade profile loss. Tests have been conducted in a low-speed linear compressor ...
Inlet Turbulence Distortion and Viscous Flow Development in a Controlled-Diffusion Compressor Cascade at Very High Incidence Hobson, G.V.; Shreeve, R.P. (AIAA, 1993);Detailed two-component laser Doppler velocimeter (LDV) measurements of the flow through a controlled-diffusion (CD) compressor cascade at a Reynolds number of about 700,000 and at a low Mach number are reported in this ...