Reflections on Fifty Years of Skin Friction Measurement

Abstract

*The purpose of this paper is to review early skin friction measurements in view of t heir relevance to current methods in prac tical use, both well -established older ones and those based on new technologies that have become recently available. In particular, the floating element measurements at Caltech in the 1950:s on flat surfaces up to hypersonic velocities, and the pressure g radient correction technique developed by Thomann’s group in Switzerland are di scussed in detail . The concluding remarks emphasize the importance of thorough understanding of the physical phenomena governing both the operation of the sensor instrument and the characteristics of the flow field where the measurements are made.