Wind-Tunnel Investigations of Blunt-Body Drag Reduction Using Forebody Surface Roughness

Whitmore, Stephen A. and Sprague, Stephanie and Naughton, Jonathan W. (2001) Wind-Tunnel Investigations of Blunt-Body Drag Reduction Using Forebody Surface Roughness. Technical Report NASA/TM-2001-210390, Research Engineering, NASA Dryden Flight Research Center.

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Abstract

This paper presents results of wind-tunnel tests that demonstrate a novel drag reduction technique for blunt-based vehicles. For these tests, the forebody roughness of a blunt-based model was modified using micromachined surface overlays. As forebody roughness increases, boundary layer at the model aft thickens and reduces the shearing effect of external flow on the separated flow behind the base region, resulting in reduced base drag. For vehicle configurations with large base drag, existing data predict that a small increment in forebody friction drag will result in a relatively large decrease in base drag. If the added increment in forebody skin drag is optimized with respect to base drag, reducing the total drag of the configuration is possible. The wind-tunnel tests results conclusively demonstrate the existence of a forebody drag-base drag optimal point. The data demonstrate that the base drag coefficient corresponding to the drag minimum lies between 0.225 and 0.275, referenced to the base area. Most importantly, the data show a drag reduction of approximately 15 percent when the drag optimum is reached. When this drag reduction is scaled to the X-33 base area, drag savings approaching 45,000 N (10,000 lbf ) can be realized.

EPrint Type:	NASA Technical Memorandum
Keywords:	Base drag, Drag reduction, Reusable launch vehicle, Skin friction, Wind tunnel
Subjects:	Aircraft/Project: M2-F1 (01 - 09) Aeronautics: (05) Aircraft Design, Testing And Performance Aircraft/Project: LASRE Aircraft/Project: X-33
ID Code:	52
Deposited On:	01 June 2004
Additional Information:	33 pages. Presented at 39th AIAA Aerospace Sciences Meeting and Exhibit, Reno, Nevada, January 8–11, 2001, AIAA-2001-0252. Stephanie Sprague, University of Kansas. Jonathan W. Naughton, University of Wyoming.