Experimental detection of flow separation over a plain flap by wall shear stress analysis with and without steady blowing

The present article deals with the flow separation detection over a plain flap at a Reynolds number of 2{dot operator}10⁶ by the analysis of the wall shear stress fluctuations. Natural flow separation is first considered with the study of the evolution of wall shear stress fluctuations measured along the flap chord when the flap deflection angle is progressively increased. Then, steady blowing is applied and its effect on wall shear stress fluctuations is analysed. For both controlled and uncontrolled cases, flow separation criteria are defined, studied and compared.