Drag Reduction in Water

To achieve design objectives of affordability and stealth, simultaneously with higher speed, there is a need to reduce energy requirements traditionally associated with high-speed performance of underwater vehicles. The specific objective of the overall effort is to develop and demonstrate a class of viscoelastic materials that will reduce friction drag without the requirement of additional energy or consumable additives. The approach is to complete development of theory and to validate it with experiments. Under previous efforts, Cortana outlined a theoretical approach suitable for choosing appropriate physical parameters and structure of such materials, and for estimating turbulent friction drag reduction under given flow conditions. In the Phase I period, Cortana updated theory and numerical calculations for use with axisymmetric bodies, and for prediction of results for actual experimental configurations. In the Phase II base period, we will conduct proof-of-concept experiments for coated flat plates in a 12-inch water tunnel test facility, with significant effort devoted to molding quality control and coating structural design for minimization of edge effects. The Phase II option will focus on out-year experimental design and molding techniques for axisymmetric bodies, with the potential for limited experiments in the 12-inch tunnel.