Abstract
An analysis of the measurement of turbulent skin friction on smooth and rough plates using a hot wire anemometer, and surface Pitot tubes is here presented. Emphasis is placed on the use of a modified form of Stanton tube for use on rough surfaces. In addition various parameters such as: Roughness Reynolds number, centre line average roughness value, grit size etc., are correlated to the law of the wall, and boundary layer momentum thickness and shape factor. Further investigations are made into the relationship between turbulence intensity and roughness parameters. The effect of a blunt-edged flat plate on the skin friction results is also considered, and a drag law taking into account free stream turbulence is presented. The experimental results were obtained using plates mounted in a vertical plane in the test section of a low speed wind tunnel at velocities up to a maximum of 21 m/s with a plate Reynolds number of 750,000.