Experimental investigation on flow-induced vibrations of a circular cylinder with radial and longitudinal fins

Flow-induced vibration (FIV) of a heat exchanger tube may present both negative effects (e.g., causing fatigue damage of the tube) and positive effects (e.g., enhancing heat transfer efficiency). As a typical passive control approach, fins attached to the tube (or circular cylinder) present significant effects on its FIVs. This study carried out systematic wind tunnel tests to investigate the FIVs in the transverse direction (along with the drag forces) of a circular cylinder with various radial and longitudinal fins. For the radial group, 3 cases with spare, moderate, and dense fins were tested. For the longitudinal group, 24 cases with various fin numbers and arrangements were tested. For the longitudinal fin arrangement parallel to the flow direction (also known as a circular cylinder with single or dual splitter plates), various fin lengths were also tested. The experimental results showed that a radial finned cylinder always presents larger FIVs than a bare circular cylinder. The longitudinal fins may significantly increase or decrease the FIVs depending on the number and arrangement of attached fins. For example, a single splitter plate (placed either upstream or downstream of the circular cylinder) often increases the FIVs, while dual splitter plates with large lengths can effectively suppress the FIVs. The experimental results provide valuable guidance for selecting appropriate fin configurations to passively control the FIVs to a certain level that can enhance the heat transfer efficiency without introducing unacceptable fatigue damage.