Flow field characteristics and vibration response of ortho-hexagonal air-supported membrane structures

Abstract

The fluid-structure interaction (FSI) effects existing in air-supported membrane roofs subjected to wind loading are significant, which would result in the vortex-induced resonance. This study employs the particle image velocimetry (PIV) technique to systematically explore the FSI mechanism of open-typed hexagonal inflatable membrane structures, with different Reynolds numbers and angles of attack considered. The PIV system is utilized to visualize and capture the surrounding flow field characteristics, including vortex separation, turbulence intensity, and eddy structures. Simultaneously, the aeroelastic responses of the membrane structure are comprehensively analyzed in both time and frequency domains, such as the displacement statistic, vibration frequency, damping ratio, and vibration mode. By integrating the fluid spatiotemporal evolution and structural dynamics, it is indicated that the angle of attack plays a pivotal role in FSI effects. It is indicated that as the angle of attack increases, the position of vortex separation shifts from the trailing edge to the leading edge of the membrane surface. This trend would enhance the FSI effect and trigger the vortex-induced vibration (VIV). In the case of large angle of attack (20°) and Reynolds number (4.55 ×10⁵), the vortex structure develops more sufficiently, with its diameter enlarged and quantity increased significantly. The VIV phenomenon can be observed on the leeward side of the membrane when the reduced wind speed is close to 1.95, characterized by an obvious amplitude jump, a sharp reduction of damping ratios, and frequency lock-in.