Research Information System
41st Aerospace Sciences Meeting and Exhibit 2003, Reno, NV, United States Of America, 6 - 09 January 2003, (Full Text)
A separation control method by alternating tangential blowing/suction was proposed and the properties of the method were studied by applying it to the flow control of a NACA 0018 airfoil. Using alternating blowing/suction, in the blowing phase, the boundary layer velocity profiles downstream of the slot is made fuller and in the suction phase, the boundary layer velocity profiles upstream of the slot is made fuller. At a=25°, the flow separation is suppressed for Va = 2.5. Also change in frequency of blowing/suction did not affect the value of force coefficients (when Va is large enough to suppress separation). For NACA 0018 at a=25°, increasing the slot height resulted in larger values of time-averaged force coefficients. The control is more effective if the control is applied near the point of separation, which occurs for an uncontrolled case. During alternating blowing/suction (for value of Va is large enough to suppress separation), the global flow field did not vary too much; however the local flow near the slot had variation which caused the force coefficients to vary during the cycle. For attached flows the control was found to be ineffective. The number of slots required for suppressing the separation depended upon the extent of separation, which occurs for an uncontrolled case. © 2003 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.