Rotating cylinder for circulation control on an airfoil

The lift augmentation effect of a rotating cylinder located at the truncated trailing edge of a body is presented. A symmetrical airfoil model with a trailing-edge cylinder was tested in a low-speed wind tunnel, and the lift produced as a function of cylinder speed was determined for cylinder speeds up to three times the freestream velocity. Since the lift was attained at a 0ous geometric angle of attack, the lift- producing phenomenon is called circulation control, which results from the alteration of the wake region by the spinning cylinder. The lift coefficients was found to be a linear function of the ratio of cylinder speed to freestream velocity and reached a value of 1.20 at a speed ratio of 3.0. A comparison is made with a lone spinning cylinder in a crossflow (magnus effect) and the cylinder-forebody combination reported herein. The cylinder-forebody pair produces higher values of lift at a given cylinder speed and a linear response in contrast to the nonlinear response of the lone cylinder at low cylinder speeds.