The spatial structure of the flow in a supersonic underexpanded jet exhausting from a convergent nozzle with vortex generators (chevrons) at the exit is experimentally studied. Disturbances of two types are observed during interaction of a single chevron and the main jet. The stronger disturbance is caused by the presence of the wake component and by generation of two streamwise vortices. The weaker disturbance is manifested in the form of perturbations of the Mach wave type propagating in the supersonic part of the shear layer of the main jet. Interaction of the set of chevrons with the jet flow leads to transformation of the stationary jet structure and to formation of mushroom-shaped large-scale vortex structures. The experimental and numerical data are demonstrated to be in reasonable agreement.