Aerodynamic flow control using synthetic jet technology

Abstract

The manipulation of global aerodynamic forces on bluff bodies using surface fluidic actuators based on synthetic jets technology is demonstrated in wind tunnel experiments using a 2-D cylinder model. Because synthetic jets are zero-mass-flux and are synthesized from the working fluid in the flow system in which they are embedded, their interaction with a cross flow results in formation of closed recirculation regions and in an apparent modification of the surface shape (and thus of surface pressure) with important consequences to flow separation. In the present experiments, the cylinder is instrumented with a pair of spanwise jet actuators and can be rotated about its centerline so that the angle between the jets and the direction of the free stream can be continuously varied. Azimuthal distributions of surface pressure measurements at Re D up to 131,000 over a range of jet angles demonstrate that the jets effect substantial increase in lift and reduction in drag. Velocity measurements in the near wake show that as a result of the actuation, the cross stream extent of the wake, its velocity deficit and all turbulent quantities are reduced. The response of the lift force and of the wake flow to a transient change in the control input are also investigated using pulsed amplitude modulation.