Paper Presented at AIAA Conference (5/6/2006)
Dr. Sinha presented a paper entitled Drag Reduction of Natural Laminar Flow Airfoils with a Flexible Surface Deturbulator at the 3rd AIAA Flow Control Conference on June 5-8, 2006 in San Francisco, California. This paper gives an overview of Dr. Sinha's flight test results. The abstract reads:
A flexible composite surface deturbulator (FCSD) has been developed in order to stabilize large extents of thin separated flow over aerodynamic surfaces through passive interactions with a streamwise varying pressure gradient boundary layer flow. This accelerates the external flow since skin friction is mitigated, while attenuating turbulent dissipation in the separated region. In this study this effect has been used to reduce drag and increase lift of natural laminar flow airfoils at low Mach numbers with Reynolds numbers ranging from 3x105, which is typical of long endurance unmanned aerial vehicles, to 6x106 typical of many general aviation aircraft. Wing profile drag reduction of 10-20% was observed in high-Re flight tests with a NLF-0414F wing. Low-Re wind tunnel measurements on the NLF-0414F have shown a profile drag reduction of 60-80% including a 45% reduction in pressure drag, along with a 12% increase in section lift coefficient. This doubled the L/D from 12.5 to 25.7. A full-span upper surface FCSD treatment of an earlier generation Wortmann FX-S-02196 natural laminar flow wing indicated a 5-20% increase in total aircraft L/D over the range of flyable airspeeds.
For a PDF copy of the full paper, click AIAA-2006-3030-245.
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