Evaluation of the ISSI S3F Film for Distributed Measurements of Pressure Gradient and Wall-Shear in Water at High Reynolds Number

This report documents the results of an assessment study of a new technology for distributed measurements of wall-pressure and wall-shear stress in a hydrodynamic application. The objective of the investigation was to evaluate the ISSI Inc. S3F technology under a range of controlled, laboratory hydrodynamic flow conditions representative of wall shear observed in Naval applications, moderate to high Reynolds number liquid flows. The active element for this sensor is a thin film made of an elastomer with known thickness and shear modulus. The measurement is accomplished by monitoring the surface normal and tangential deformations of the film and then converting these deformation fields into pressure gradient and wall-shear stress. The ability of these films to operate in a liquid boundary layer at high shear load was tested in the twelve-inch water tunnel at the Applied Research LaboratoryPenn State University. Quantitative and qualitative measurements of 2-D pressure gradient and wall-shear stress distributions were obtained behind a vortex generator, around two strut end-wall junction models, and in a 2-D canonical turbulent boundary layer.