Shear and Stress Sensitive Films for Near Wall Skin Friction Measurements

The measurement of skin friction on hydrodynamic surfaces at high Reynolds numbers is essential for the design of advanced Naval technology. Knowledge of the mean and fluctuating pressure distribution and wall skin friction is essential to the design of advanced propulsion systems and evaluation of drag reduction techniques. Unfortunately, the accurate measurement of wall skin friction on complex surfaces under high Reynolds number continues to be problematic. In this proposal we introduce a new sensor for measurements of skin friction and pressure that operates in water. This sensor is based an elastic polymer film which deforms under the action of the applied normal and tangential loads. Skin friction and pressure gradients are determined by monitoring these deformations and applying a finite element model to the elastic film. Preliminary tests using this sensor at low Reynolds numbers have proven promising and therefore, the development a skin friction sensor for use on seafaring vessels is recognized. In the Phase I effort, a series of sensors will be manufactured and tested on a flat plate in the Penn State University water tunnel at Reynolds numbers of up to 9-million. Skin friction results from the new sensor will be compared to established techniques.