The present experiments are performed within the framework of research of laminar-turbulent transition processes in a boundary layer at the enhanced free stream turbulence level. The investigations were carried out in the subsonic wind tunnel MT-324 ITAM SB RAS at low (Tu = 0.18%U
?) and enhanced (Tu = 0.79%U
?) free stream turbulence levels. The tested model was a straight wing. Reynolds numbers was 61800 < Rec1 < 97000. The longitudinal localized structures arising in the boundary layer under the influence of high free stream turbulence level, were modeled artificially by means of localized suction through the slot on a model surface. The focus of the paper is on wave packets (forerunners) occurring in the regions preceding a drastic change of flow velocity inside the boundary layer at the localized disturbances fronts. It is found, that the high free stream turbulence level accelerates the development of wave packets-forerunners and their transformation to the turbulent spots.
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