Abstract
Flow induced vibrations of tube array occur in general heat exchangers and nuclear reactors. They cause the tube failures through fretting wear or fatigue. The experiments were conducted in cylinder bundles, 15 cylinders ( 3 rows and 5 columns) and 231 cylinders (21 rows and 11 columns) at various flow velocities. The two types of cylinders were made of piano wire and plastic optical fiber (POF ). In the case of 15 piano wire cylinders, the amplitude increases as flow velocity increases and cylinders move largely in transverse direction. For 15 POF cylinders, most cylinders vibrate greatly owing to their small flexibility with frequent collisions of cylinders. In a cylinder array of 231 cylinders, spatial behaviors of cylinders exhibit a pattern like a wave-like motion as flow velocity increases.
