Aerodynamics of a low-pressure turbine airfoil at low Reynolds numbers-Part II: Blade-wake interaction

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Journal titleJournal of Turbomachinery
Article number11010
SubjectBlade-wake interactions; Flow coefficients; Freestream turbulence intensity; Linear cascade; Low-pressure turbines; Profile loss; Reduced frequency; Reynolds; Suction surfaces; Time varying; Turbine airfoils; Unsteady effects; Wake-induced transitions; Airfoils; Reynolds number; Turbines; Wakes; Aerodynamics
AbstractPart II of this two-part paper presents the aerodynamic behavior of a low-pressure high-lift turbine airfoil, PakB, under the influence of incoming wakes. The periodic unsteady effects of wakes from a single upstream blade-row were measured in a low-speed linear cascade facility at Reynolds numbers of 25,000, 50,000 and 100,000 and at two freestream turbulence intensity levels of 0.4% and 4%. In addition, eight reduced frequencies between 0.53 and 3.2, at three flow coefficients of 0.5, 0.7 and 1.0 were examined. The complex wake-induced transition, flow separation and reattachment on the suction surface boundary layer were determined from an array of closely-spaced surface hot-film sensors. The wake-induced transition caused the separated boundary layer to reattach to the suction surface at all conditions examined. The time-varying profile losses, measured downstream of the cascade, increased with decreasing Reynolds number. The influence of increased freestream turbulence intensity was only evident in between wake-passing events at low reduced frequencies. At higher values of reduced frequency, the losses increased slightly and, for the cases examined here, losses were slightly larger at lower flow coefficients. An optimum wake-passing frequency was observed at which the profile losses were a minimum. © 2013 American Society of Mechanical Engineers.
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AffiliationNational Research Council Canada (NRC-CNRC); Aerospace (AERO-AERO)
Peer reviewedYes
NPARC number21269527
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Record identifier5df3871c-a218-48e5-a5c2-a91151c88a4a
Record created2013-12-12
Record modified2016-05-09
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