Aerodynamic Interference Mechanism of Rectangular Lamps Installed on Tandem Hangers Based on Fluid–Structure Interaction

After installing lamps on hangers, large amplitude vibrations are likely to occur. To explore the aerodynamic interference mechanism of lamps installed on tandem hangers, this study is based on computational fluid dynamics (CFD) and implements the fluid–structure interaction (FSI) numerical simulation of tandem hangers through user-defined functions (UDF). The variations in the aerodynamic forces and vibration responses of hangers under different wind attack angles are calculated and compared among three schemes: scheme 1 (no lamps), scheme 2 (lamps on the outer hanger), and scheme 3 (lamps on both hangers). The results show that installing rectangular lamps makes the aerodynamic forces of hangers extremely sensitive to changes in the wind attack angle. Moreover, the maximum crosswind and along-wind amplitudes of tandem hangers increase to 1.39 times and 2.24 times, respectively, compared with the hangers without lamps. After installing the lamps, the wake mode and pressure distribution of the hangers change. When the wake mode is the closely spaced alternating vortex shedding “2S” mode, aerodynamic interference is reduced, and the energy input decreases significantly, leading to a sharp drop in amplitude. The vortex shed from the upstream hanger attaches to the surface of the downstream hanger, forming a negative pressure zone that increases the crosswind amplitude. When the wake of the upstream hanger forms a parallel vortex street, both the crosswind and along-wind amplitudes increase.