Research Papers

Synchronizing Separation Flow Control With Unsteady Wakes in a Low-Pressure Turbine Cascade

[+] Author and Article Information
M. Bloxham, D. Reimann, K. Crapo, J. Pluim, J. P. Bons

Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602

J. Turbomach 131(2), 021019 (Feb 03, 2009) (9 pages) doi:10.1115/1.2952376 History: Received August 14, 2007; Revised August 29, 2007; Published February 03, 2009

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 Cp at 63% axial chord on the suction surface. Data were taken at Rec=20K 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 Cp and phase-locked velocity measurements confirm that the optimal combination of wakes and jets yields the smallest separation.

Copyright © 2009 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.



Grahic Jump Location
Figure 1

Three blade linear cascade

Grahic Jump Location
Figure 2

VGJ exit velocity profile and data acquisition locations (PIV). VGJ orientation and coordinate system.

Grahic Jump Location
Figure 3

CAD model of wake generator and test section of tunnel. Curved white arrows indicate direction of rotation. Straight arrow represents location of optical sensor.

Grahic Jump Location
Figure 4

(a) The primary PIV configuration depicting both data regions. (b) The coordinate system used to present the data. Also included are the merged camera view fields, the axial chord lines of the Pack B, and a representation of the separation bubble.

Grahic Jump Location
Figure 5

The in-plane PIV configuration. The green plane is a representation of the laser sheet.

Grahic Jump Location
Figure 6

Experimental Cp distributions for the Pack B compared to the VBI. Plot includes no control (no wakes or jets), wake only, VGJ only, and combined wakes/jets data.

Grahic Jump Location
Figure 7

Phase-locked isovelocity surfaces (U∕Uin=1.0) for wakes/jets (Case 6) configuration. The red arrows indicate approximate jet locations.

Grahic Jump Location
Figure 8

Streamwise vorticity comparison for VGJs only (Case 3). VGJ at x∕d=0 and z∕d=9 (hole center). Blowing ratio, Bmax=2.

Grahic Jump Location
Figure 9

Urms∕Uin plots of the wakes/jets (Case 6) configuration. The nondimensional time is labeled in the upper right corner of each plot.

Grahic Jump Location
Figure 10

Time history plots (Urms∕Uin) depicting wake/jet and wake only interaction with the separation bubble

Grahic Jump Location
Figure 11

Integrated isovelocity surfaces (Cases 6 and 2) at each data acquisition time. The data were normalized by the size of the no control separation bubble.



Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In