The development of optical techniques for the measurement of pressure and skin friction

A novel measurement approach is described which has been developed to allow both pressure and skin friction measurements at very low speeds in liquid or gaseous environments. This approach, surface stress-sensitive films, S 3 F, is based on the deformation of an elastic medium and the transformation of this deformation into surface loads (pressure and shear stresses). Measurements in both air and water flows have been made. A comparative analysis of the S 3 F and PSP techniques for a low-speed air-flow case is presented.