Roughness diagnostic tool

摘要

A roughness measuring tool wherein a pair of discs are mounted in spaced parallel relation for rotation by a motor about a common axis with a face of only one of the discs being exposed to a layer of fluid contacting a surface to be tested. A torsionally resilient coupling beteen the discs permits rotational displacement due to a difference in hydrodynamic drag thereon. The displacement is sensed as a phase difference between signals generated by rotation of the discs and a phase signal is applied to a function generator the output of which is displayed as a figure of merit of test surface condition.