Abstract
In the previous works, the present authors found that two types of longitudinal vortex shed periodically from crisscross circular cylinder system based on experiments using 320 mm wind tunnel and 200 mm water tunnel. The specific aim of this work is to confirm generality of this phenomenon by carrying out experiments with different diameter cylinder systems. The cylinders with diameter d = 127 mm was used in a large wind tunnel with measuring section of 1800 mm. The water tunnel was also used for smaller cylinders. The longitudinal vortex shedding from crisscross cylinders was visualized by the tuft grid method, and its frequency was counted directly, together with measurement by hot wire anemometer. These experiments show that the longitudinal vortex sheds from systems with d = 20~127 mm and that the trailing vortex sheds when gap-to-diameter ratio s/d is from 0 to 0.25, and the necklace vortex sheds when s/d is from 0.25 to 0.5. Their relationship between Strouhal number and Reynolds number is consistent qualitatively with former research works regardless of experimental conditions.
