REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188
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4. TITLE AND SUBTITLE
Calculation of Unsteady Transonic Flows With Mild Separation by Viscous-Inviscid Interaction

6. AUTHOR(S)
James T. Howlett

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) NASA Langley Research Center
Hampton, VA 23665-5225

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

5. FUNDING NUMBERS

WU 509-10-02-03

8. PERFORMING ORGANIZATION
REPORT NUMBER

L-16996

10. SPONSORING/MONITORING
AGENCY REPORT NUMBER
NASA TP-3197

11. SUPPLEMENTARY NOTES

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

Unclassified{Unlimited

Subject Category 02

13. ABSTRACT (Maximum 200 words)
This paper presents a method for calculating viscous effects in two- and three-dimensional unsteady transonic flow fields. An integral boundary-layer method for turbulent viscous flow is coupled with the transonic smalldisturbance potential equation in a quasi-steady manner. The viscous effects are modeled with Green's lag-entrainment equations for attached flow and an inverse boundary-layer method for flows that involve mild separation. The boundary-layer method is used stripwise to approximate three-dimensional effects. Applications are given for two-dimensional airfoils, aileron buzz, and a wing planform. Comparisons with inviscid calculations, other viscous calculation methods, and experimental data are presented. The results demonstrate that the present technique can economically and accurately calculate unsteady transonic flow fields that have viscous-inviscid interactions with mild flow separation.

14. SUBJECT TERMS 15. NUMBER OF PAGES Viscous-inviscid interaction; Transonic unsteady aerodynamics; Aileron buzz; Boundary layer
37
16. PRICE CODE
A03
17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF REPORT OF THIS PAGE OF ABSTRACT OF ABSTRACT Unclassified Unclassified
NSN 7540-01-280-5500 Standard Form 298(Rev. 2-89) Prescribed by ANSI Std. Z39-18
298-102 NASA-Langley, 1992