Hot-Wire Measurements Around a Controlled Diffusion Airfoil in an Open-Jet Anechoic Wind Tunnel

The aeroacoustic measurements in the large anechoic wind tunnel of Ecole Centrale de Lyon, which previously focused on the wall pressure distribution and the far-field acoustic pressure, are extended to velocity measurements by hot-wire probes in the nozzle jet and in the vicinity of a Controlled Diffusion airfoil. The present work focuses on the flow conditions corresponding to a Reynolds number based on the airfoil chord length $Rec=1.6×105$ and a geometric angle of attack $αg$ of 8°. Midspan measurements were achieved at the exit plane of the wind tunnel nozzle upstream of the test airfoil and in a large eddy simulation domain that was embedded in the potential core around the airfoil mockup. The inlet measurements by a single hot-wire probe provided insight into the free-stream turbulence intensity upstream of the profile. The $X$-probe measurements on the upper and lower computational boundaries show the overall deflection of the jet potential core by the cambered airfoil. These are compared to previous Reynolds averaged Navier-Stokes predictions. The $X$-probe measurements in the airfoil wake provide information on the development of the airfoil boundary layer and the resulting wake after separation. The measured wake velocity defect has been compared with both numerical predictions.