Tow tests have been performed on flexible circular cylinders, with and without short helical strakes, towed in a basin at critical and supercritical Reynolds numbers. The tests were conducted at the Naval Surface Warfare Center’s David Taylor Model Basin in Carderock, Maryland. Measurements were made of both the drag and acceleration (due to vortex-induced vibration) of the cylinder. A 3-1/2 inch diameter ABS pipe was used to achieve Reynolds numbers ranging from about 2×105 to 5×105, and a 5-9/16-inch diameter PVC pipe was used to achieve Reynolds numbers ranging from about 7×105 to 1.5×106. Tests were also conducted with aluminum inserts (strong-backs), made to fit just inside the test cylinders, in order to obtain stationary (rigid) cylinder drag measurements for comparison purposes. The test results for cylinders fitted with triple-start helical strakes are presented in this paper.

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