Effect of oblique waves on jet turbulence

The paper describes experiments on acoustically excited axisymmetric turbulent jet flows. The investigation is based on the hypothesis that so called oblique transition may play a role in the breakdown to turbulence for an axisymmetric jet. For wall bounded flows oblique transition gives rise to steady streamwise streaks that break down to turbulence, as for instance documented by Elofsson & Alfredsson (J. Fluid Mech. 358). The scenario of oblique transition has so far not been considered for jet flows and the aim was to study the effect of two oblique modes on the transition scenario as well as on the flow dynamics. Even though it was not possible to detect the presence of streamwise streaks, for a certain range of the excitation frequencies, the turbulence intensity, at a fixed streamwise position, is found to be significantly reduced.