Suction and Pulsed-Blowing Flow Control Applied to an Axisymmetric Body

A flow-control study using steady suction and pulsed blowing in close proximity was conducted on an axisymmetric bluff body at length-based Reynolds numbers between 1.0 and 4.0×106. The study included a coupled incremental computational-fluid-dynamics and experimental approach. It began with computations of various model setup designs. Subsequently, flow-control experiments and computations were used to optimize steady suction alone. Finally, flow control was provided by a synchronized array of 28 suction and oscillatory blowing actuators, positioned slightly upstream of the baseline separation. Results show suction alone has a limited ability to delay separation and reduce drag on this geometry. Suction located far from the baseline separation is shown to actually increase drag. Addition of pulsed blowing enables separation delay to the trailing edge and drag to be nullified. Increased overall system efficiency, including estimated total actuator power invested, was found at low momentum input for optimally located steady suction and pulsed blowing. This was partially attributed to the particular geometry used because the active flow-control system shows a robust ability to delay separation. Not all measured trends were predicted by computation due to the complex nature of this configuration and the active flow-control system characteristics.