Shock detection on airfoils by means of piezo foil- and hot film arrays

The authors describe comparative investigations concerning the detection of shock positions on a transonic airfoil model. A piezo foil array consisting of 24 separate sensors and a hot film array consisting of 8 separate sensors were used. While the piezo sensors detect increasing unsteady fluctuations of pressure, wall shear stress, and temperature in the region of a shock, the hot film sensors only register shear stress fluctuations qualitatively and, if calibrated, the mean wall shear stress too. Owing to their low total height, the two sensor arrays can be mounted on the airfoil model without causing disturbances, and they allow reliable detection of shock positions