Control of Buffet Phenomenon on a Transonic Swept Wing

The control of the transonic buffet phenomenon over a half-model with a swept wing has been investigated in the S3Ch wind tunnel of the ONERA Meudon center in the framework of ONERA's joint research project BUFET'N Co. A fine description of the buffet characteristics in the uncontrolled configuration is first given as a reference. Various steady and unsteady measurement techniques on the model surface and into the flowfield are used to perform a detailed analysis of the buffet phenomenon. The flow separation between the shock foot and the wing trailing edge being the cause of buffet, mechanical, continuous, and pulsed fluidic vortex generators are located upstream of the shock foot to reduce the extent of this separated area. As far as fluidic actuators are concerned several momentum coefficients, spanwise spacing, and orientations of the jets have been tested, while the effect of the actuation frequency is studied for the pulsed jets. Fluidic actuators, as well as mechanical ones, have been proved to be very efficient to postpone the buffet onset.