When air is blown from a slot directly upstream of a flap, the flow over the flap can bear large adverse pressure gradients without separation. This effect is used to design high-lift airfoils with low momentum coefficients of blowing. For experimental assessment of these airfoils a rectangular wing with an aspect ratio of 4.3 was built. The flow around the model in a low speed wind tunnel is analysed using pressure measurements and long distance microscopic particle image velocimetry. To measure the velocity in the vicinity of the slot and next to the surface of the flap the jet is seeded with particles. For Reynolds numbers of about Re = 1 · 106 the dimensionless momentum coefficient of the jet and the angle of attack of the airfoil are varied. Numerical simulations of the three-dimensional flow around the circulation control airfoil in the wind tunnel are compared to the experimental data. Good agreement is observed in terms of pressure distributions and velocity profiles. 顯微粒子成像測速系統(tǒng)(Micro PIV)