Time frequency Coherences of Aerodynamic Loads on a Streamlined Bridge Girder in an Actively Controlled Wind Tunnel

Abstract:

Altogether 14 different two dimensional flow fields were simulated in an actively controlled wind tunnel by using multiple fans and vibration grids. Flow features and aerodynamic loads were measured simultaneously through the simultaneous acquisition facilities. Relationships between spatial coherences of aerodynamic loads and incident flow features were studied in both time and frequency domains. Spatial coherences of both incident flows and aerodynamic forces varied with each other. Spatial coherences of aerodynamic loads were affected by incident flow features. Shape of spatial coherence versus frequency did not always satisfy the exponential law, especially under large scale oncoming flow conditions. A new imperial model was proposed to reflect the influence of incident flow features on the spatial coherences of aerodynamic loads, and to reflect the differences between spatial coherences of aerodynamic loads and incident flows.