Particle image velocimetry (PIV) measurements were made on a highly loaded low-pressure turbine blade in a linear cascade. The Pack B blade has a design Zweifel coefficient of 1.15 and a peak at 63% axial chord on the suction surface. Data were taken at with 3% inlet freestream turbulence and a wake-passing flow coefficient of 0.8. Without unsteady wakes, a nonreattaching separation bubble exists on the suction surface of the blade beginning at 68% axial chord. The time-averaged separation zone is reduced in size by approximately 35% in the presence of unsteady wakes. Phase-locked hot-wire and PIV measurements were used to document the dynamics of this separation zone when subjected to synchronized, unsteady forcing from a spanwise row of vortex generator jets (VGJs) in addition to the unsteady wakes. The phase difference between VGJ actuation and the wake passing was optimized. Both steady state and phase-locked velocity measurements confirm that the optimal combination of wakes and jets yields the smallest separation.
Issue Section:
Research Papers
Keywords:
blades,
flow control,
flow instability,
flow measurement,
flow separation,
jets,
turbines,
turbulence,
velocity measurement,
wakes
1.
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, 2006, “Separated Flow Transition on an LP Turbine Blade With Pulsed Flow Control
,” ASME Paper No. GT2006-90754.Copyright © 2009
by American Society of Mechanical Engineers
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