Skin Friction Measurement Technology for Underwater Applications
Small Business Information
2766 Indian Ripple Rd, Dayton, OH, -
AbstractThe measurement of skin friction on hydrodynamic surfaces at high Reynolds numbers is essential validation of computational models and design of advanced maneuvering systems. In this proposal we introduce an optical sensor for measurements of mean skin friction on large models that operates in water. This sensor is based on the diffusion of a fluorescent dye from a polymer film into the water, a mass transfer sensor. Mass transfer is determined by monitoring the rate of dye diffusion from the film and applying a numerical model to the transient mass transfer process. This technique has been demonstrated qualitatively by detecting flow separation and reattachment on an airfoil model in the 12-inch water tunnel at Penn State University. Quantitative measurements of skin friction were conducted on a turbulent boundary layer with a Reynolds number of over 7-million. These results indicated an absolute accuracy of the system was better that 8%. In the Phase II effort, a captive model data acquisition system will be designed and tested. The focus of the program is to deploy the system in the NSWC tow tanks for testing on large models.
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