Control of boundary layer separation by jet oscillation

Wake visualizations and wall pressure measurements have been conducted on a 2-D circular cylinder submitted to a zero-mass-flow oscillating jet, at Reynolds numbers about 10. Jets with relative momentum flux C^ of the order of 10' are efficient for a large range of azimuthal positions (up to 120°), both on natural laminar separation and tripped transitioned separation. Jets force the boundary layer transition, deviate the separating structures towards the wall, and, as a result, generate appreciable lift force. The drag is modified in a more complex way.