An NACA 631-012 airfoil section equipped with a single suction slot near the leading edge was investigated to determine whether or not the maximum lift coefficient could be increased by delaying the separation of flow at the leading edge characteristic of the basic section. The leading edge separation was delayed and the linear portion of the lift curve substantially extended until the turbulent boundary layer separated from the rear portion of the airfoil. The abruptness of the stall was thereby reduced. The maximum lift increased with increasing flow through the slot, rapidly at first, then at a diminishing rate. The effect on pitching moment was negligible. The profile drag was increased for low values of lift and reduced at high values of lift (for flow coefficients greater than 0.002) over the corresponding drag of the basic airfoil section. It was found that the slot location and width are important. Sixteen different slots were investigated without encountering the optimum, but the results indicated that the leading edge of the slot should be downstream of the point of separation of flow from the leading edge of the basic airfoil immediately prior to its stall.


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    Title :

    Experimental Investigation of an NACA 631-012 Airfoil Section With Leading-Edge Suction Slots


    Contributors:

    Publication date :

    1948


    Size :

    38 pages


    Type of media :

    Report


    Type of material :

    No indication


    Language :

    English