RÉSUMÉ

The flow separation induced by a flap of a two dimensional ramp has been characterized through a streamwise 2D2C PIV measurement at mid-span. The field of view follows the wall surface and its size is about 28.7 cm in height above the wall and the curvilinear length is about 94 cm, so that it contains all the separation bubble and a part of the flow upstream and downstream of it. Four 2k*2k cameras where used to keep a relatively good spatial resolution. The incoming boundary layer thickness upstream the separation is about 19 cm and it momentum Reynolds number about 10000. The separation border was detected with the backflow coefficient and it results that the separation length is about 61 cm and the maximum height about 3 cm. The Reynolds stresses and their main production terms were also determined. It results that a region of high turbulence intensity develops above the separation border for all the measured components. The production of u'² dominates the production for turbulent kinetic energy which imposes a redistribution from u'² to v'² to explain the increase of the last one. The production term u'² dU/dx drives the production of u'² in the first part of the flap which is not the case for zero pressure gradient boundary layers. Finally a high similarity is observed between v'² and u'v' as the production of the last one is dominated by v'² dU/dy.