Leading-Edge Separation Control by Means of Pulsed Vortex Generator Jets

Abstract

DOI: 10.2514/1.26176 An airfoil was designed to stall with an abrupt turbulent leading-edge separation and equipped with a pneumatic system for active flow control. The system pulses compressed air through 45 deg skewed slots. Depending on the position of the slots, two very different behaviors were found. With the actuators positioned in the region of the separation line, the control system could not prevent separation. However, a very advantageous influence on the separation resulted with even higher normal forces than in prestall condition. The duty cycle was found to be the major control parameter for this kind of control. When the actuation was positioned well in front of the separation line the influence of the actuation system on the stall behavior changed completely. Here the system was able to prevent the leading-edge separation. The influence of the duty cycle becomes much weaker and maximum normal force scaled mainly with the mean ejected momentum, varied either by the duty cycle or the supply pressure.