Active control of crossflow-induced transition by means of in-line pneumatic actuator orifices

Abstract

The possibility of a pneumatic actuator system for controlling the crossflow vortex induced laminar breakdown is investigated by means of hot-wire measurements. Steady blowing or suction through a spanwise row of periodically arranged orifices initiates a system of longitudinal vortices which reduces the amplitude of the most amplified stationary crossflow vortices. Thus the onset of high frequency secondary instability and the following laminar-turbulent transition was shifted farther downstream. All experiments were conducted at the redesigned DLR swept-flat-plate experiment in the open test section of the 1m wind tunnel at the DLR in Göttingen.