GLTRS--Glenn
TITLE AND SUBTITLE:
Transient Growth Theory Prediction of Optimal Placing of Passive and Active Flow Control Devices for Separation Delay in LPT Airfoils

AUTHOR(S):
Anatoli Tumin and David E. Ashpis

REPORT DATE:
May 2003

FUNDING NUMBERS:
WBS-22-274-00-0206

PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
John H. Glenn Research Center at Lewis Field
Cleveland, Ohio 44135-3191

PERFORMING ORGANIZATION REPORT NUMBER:
E-13848

SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
Washington, DC 20546-0001

REPORT TYPE AND DATES COVERED:
Technical Memorandum

SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA TM-2003-212228

SUPPLEMENTARY NOTES:
Anatoli Tumin, University of Arizona, Tucson, Arizona 85721 (work funded under NCC3-991); David E. Ashpis, NASA Glenn Research Center. Responsible person, David E. Ashpis, organization code 5820, 216-433-8317.

ABSTRACT:
An analysis of the non-modal growth of perturbations in a boundary layer in the presence of a streamwise pressure gradient is presented. The analysis is based on PSE equations for an incompressible fluid. Examples with Falkner-Skan profiles indicate that a favorable pressure gradient decreases the non-modal growth while an unfavorable pressure gradient leads to an increase of the amplification. It is suggested that the transient growth mechanism be utilized to choose optimal parameters of tripping elements on a low-pressure turbine (LPT) airfoil. As an example, a boundary-layer flow with a streamwise pressure gradient corresponding to the pressure distribution over a LPT airfoil is considered. It is shown that there is an optimal spacing of the tripping elements and that the transient growth effect depends on the starting point. At very low Reynolds numbers, there is a possibility to enhance the transient energy growth by means of wall cooling.

SUBJECT TERMS:
Hydrodynamic stability; Vortex generators; Flow control; Turbulence; Transition; Turbomachinery; Turbines; Separation

NUMBER OF PAGES:
25

PDF AVAILABLE FROM URL:
2003/TM-2003-212228.pdf ( 354 KB )
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