The objective of this wind-tunnel test was to verify the predictions of the Eppler Airfoil Design and Analysis Code for a very thick airfoil having a high maximum lift coefficient c(sub 1,max) designed to be largely insensitive to leading edge roughness effects. The 24-percent-thick S814 airfoil was designed with these characteristics to accommodate aerodynamic and structural considerations for the root region of a wind-turbine blade. In addition, the airfoil's maximum lift-to-drag ratio was designed to occur it a high lift coefficient. To accomplish the objective, a two-dimensional wind-tunnel test of the S814 thick root airfog was conducted in January 1994 in the low-turbulence wind tunnel of the Delft University of Technology Low Speed Laboratory. Data were obtained for transition-free and transition-fixed conditions at Reynolds numbers of 0.7, 1.0, 1.5, 2.0, and 3.0 x 10(exp 6). For the design Reynolds numbers of 1.5 x l0(exp 6), the transition-free c(sub 1,max) is 1.3 which satisfies the design specification. However, this value is significantly lower than the predicted c(sub 1,max) of almost l.6. With transition-fixed at the is 1.2. The difference in c(sub 1,max) between the transition-free and transition-fixed conditions demonstrates the airfoil's minimal sensitivity to roughness effects. The S814 root airfoil was designed to complement existing NREL low c(sub 1,max) tip-region airfoils for rotor blades 10 to 15 meters in length.


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    Title :

    Wind-tunnel test of the S814 thick root airfoil


    Contributors:

    Publication date :

    1995


    Size :

    8 pages


    Type of media :

    Report


    Type of material :

    No indication


    Language :

    English