Proportional Opposition Control of Turbulence

Proportional opposition control of sweep events in a turbulent boundary layer has been carried out using a wall-normal jet. Changes to the turbulence structure in the region closer to the wall have been examined using hot-wire anemometry. Control of each detected sweep event has been obtained by using multiple injections whose number is proportional to the duration of the event. Differently from the more conventional opposition control technique with a single injection of a longer duration, the proposed technique with multiple injections allows to control the sweep event over its whole duration without changing the working parameters of the jet actuator.