The impact of speed-varying hydrodynamic coefficients of uuv maneuvering performance

The diameters of typical UUV´s range in size from 21 in to 5.5 ft. These vehicles typically operate over a speed range of 0 to 20 kts. For this vehicle size and speed range, the nonlinear hydrodynamic coefficients vary dramatically with speed due to the Reynolds number effects on crossf low drag. This Is unlike the behavior of torpedoes and submarines, where the crossfiow drag is relatively constant over their speed range. In this paper, the effects of speed on the hydrodynamic coefficients and the impact on vehicle maneuverability are discussed. Force and moment curves as a function of vehicle diameter, speed, and angle of attack are presented. Simulated maneuvering characteristics using constant hydrodynamic coefficients are compared with maneuvers using Reynolds number-varying coefficients. Implications on scale model testing results are also discussed.