Boundary layer trips on airfoils at low reynolds numbers

Three categories of boundary layer trips (single 2-D plain, multiple 2-D plain, and 3-D trips) were tested on the M06-13-128, E374, and SD7037 airfoils over the Reynolds numbers of 100,000 to 300,000. Flow visualization and drag data were acquired for a number of trip heights and locations. To facilitate comparisons between airfoils, trips were located relative to untripped laminar separation locations. Drag data showed dramatic drag reductions for relatively thin trips, with thicker trips having slightly better performance. The trip location proved to be of little significance for trips located upstream of laminar separation. Little advantage was seen in utilizing multiple 2-D trips or complex 3-D trips over single 2-D trips. Finally, through the application of trips, it was not possible to improve the performance of an airfoil exhibiting large laminar separation bubbles over that of an untripped airfoil with small bubbles.

[1]  Robert J. McGhee,et al.  Correlation of theory to wind-tunnel data at Reynolds numbers below 500,000 , 1989 .

[2]  M. Selig.  Summary of low speed airfoil data , 1995 .

[3]  W. A. Timmer,et al.  Experimental aerodynamic characteristics of the airfoils LA 5055 and DU 86-084/18 at low Reynolds numbers , 1989 .

[4]  J. E. Carter,et al.  Analysis of airfoil transitional separation bubbles , 1984 .

[5]  Dan M. Somers,et al.  Subsonic Natural-Laminar-Flow Airfoils , 1992 .

[6]  M. F. Platzer,et al.  Transition Modeling Effects on Viscous/Inviscid Interaction Analysis of Low Reynolds Number Airfoil Flows Involving Laminar Separation Bubbles , 1988 .

[7]  B. Carmichael,et al.  Low Reynolds number airfoil survey, volume 1 , 1981 .

[8]  Michael S. Selig,et al.  Spanwise variations in profile drag for airfoils at low Reynolds numbers , 1995 .

[9]  M. Drela.  XFOIL: An Analysis and Design System for Low Reynolds Number Airfoils , 1989 .

[10]  William H. Rae,et al.  Low-Speed Wind Tunnel Testing , 1966 .

[11]  Werner Pfenninger,et al.  Investigations on reductions of friction on wings, in particular by means of boundary layer suction , 1947 .

[12]  S. M. Batill,et al.  Experimental studies of the laminar separation bubble on a two-dimensional airfoil at low Reynolds numbers , 1980 .

[13]  T. Mueller,et al.  Effects of distributed grit roughness on separation and transition on an airfoil at low Reynolds numbers , 1986 .

[14]  Ali H. Nayfeh,et al.  Effect of roughness on the stability of boundary layers , 1986 .

[15]  Andy P. Broeren,et al.  Summary of Low-Speed Airfoil Data - Vol. 3 , 1996 .

[16]  Laura L. Pauley,et al.  Low-Reynolds-number separation on an airfoil , 1996 .

[17]  F. X. Wortmann.  PROGRESS IN THE DESIGN OF LOW DRAG AEROFOILS , 1961 .

[18]  R. Pletcher,et al.  Prediction of Incompressible Separated Boundary Layers Including Viscous-Inviscid Interaction , 1979 .

[19]  W. Pfenninger,et al.  Wind-tunnel tests on a high performance low-Reynolds number airfoil , 1984 .

[20]  Mark D. Maughmer,et al.  Design and experimental results for a high-altitude, long-endurance airfoil , 1989 .