Towing-tank experiments are performed for a surface combatant advancing in calm water as it undergoes static and dynamic planar motion mechanism (PMM) maneuvers. Data includes static drift and dynamic maneuvering forces and moments and motions, and phase-averaged local flow fields for dynamic maneuvers. The forces and moment measurements including UA are conducted in international collaborations with FORCE and INSEAN and the 24th-25th ITTC Maneuvering Committee.
Statistical convergence of data is evaluated by monitoring the convergence of confidence interval. Statistical convergence errors for forces and moment and motions data are usually less than 3%. For the SPIV measured flow field data, statistical convergence error is usually < 1% of UC for the phase-averaged velocity data and < 10% of the range value of turbulent kinetic energy for Reynolds stresses, respectively.
UA for SPIV measured phase-averaged flow data are following the ASME 2005 standards. Systematic uncertainty is estimated by calibrating the SPIV measured data to the open-water data. Random uncertainty is estimated end-to-end by repeating the tests. The relative expanded uncertainty is about 3 ~ 4% for U and about 10 ~ 30% for V and W velocities. The relative expanded uncertainty for Reynolds stresses are about 25 ~ 50% inside the boundary layer region.
Forces and moment data trends are as per predicted by the Abkowitz (1966) mathematic model. Hydrodynamic derivatives from the forces and moment data are evaluated by using the 'Multiple-Run (MR)' and 'Single-Run (SR)' methods. Evaluation results of the reconstruction error indicate that the MR method is more rigorous than the SR method, and the latter method is only suggested when the PMM motion is large enough. Hydrodynamic derivatives exhibit a trend with model size (or scale). In general, sway derivatives are nearly independent of model size, whereas yaw derivatives exhibit considerable dependency.
The effect of heave and pitch motions on forces and moment is considerable, typically 10 ~ 30% increase of forces and moment. The effect of roll motions on forces and moment is small or negligible. The effects of motions on hydrodynamic derivatives are small for linear derivatives whereas large for non-linear derivatives.
Phase-averaged flow field results indicate maneuvering-induced vortices and their interactions with the turbulent boundary layer.