Pulsed Vortex Generator Jets for Active Control of Flow Separation

A program for the development of a flow actuator for active control of flow separation on flight surfaces is proposed. The actuators will be used to modulate flow through discrete jets located on the aerodynamic surface. These jets (known as Vortex Generator Jets or VGJ's) produce streamwise and ring vortices which enhance boundary layer mixing and inhibit flow separation. This actuation technique lends itself to the development of a closed-loop active control system for flow separation control on aircraft flight surfaces because of the potential compactness of each actuator element and the simplicity of their operation. The ability to implement the control system only when necessary will allow improved aircraft performance over an extended flight envelope. In the proposed work plan, a flow visualization technique based on laser-induced fluorescence of a molecular flow tracer will be used to study the effects of this actuation technique on a separated flow surface. The influence of modulation frequency and amplitude on the effectiveness of this control scheme will be determined. The experimental results will be used as guidelines for the design of a Phase II prototype actuator for large-scale testing at flight conditions.