Kelvin Wake Measurements Obtained on Five Surface Ship Models

摘要

Radar and optical images of ship wakes at sea have stirred an interest inobtaining model-scale Kelvin wake data. The distinctive Kelvin wave pattern consists of diverging and transverse waves. These wave systems, manifested as surface disturbances, have unique characteristics. The included angle between the two divergent wave arms is 39 deg. All components of the wave system parallel to the direction of travel of the ship have the same speed as the ship. Experimental measurements of the Kelvin wake were obtained for five surface ship models representing an assortment of naval combatants, including a cruiser, an aircraft carrier, and three destroyers. Measurements were performed in the Carriage I basin at DTRC (David Taylor Research Center) using capacitance wave probes, a newly developed laser-slope meter, and close-range photogrammetry techniques. Data obtained from these measurement systems resulted in single point time-histories of wave height and slope as well as a series of sequential stereo 'snap-shots' of the wave field generated by the towed model. All the models were tested without propulsion at a Froude number of 0.25. Similarities and differences in the wave patterns were documented and are discussed. In addition, Kelvin wake data were obtained for other conditions such as altered trim, speed variation, and with propulsion. The effect of these changes on the wave system is also discussed.