Study of Cross-Sectional Air Flow Characteristics of Main Cables of Suspension Bridge Based on a Fixed-Grid Porous Model
This study analyzes the cross-sectional air flow characteristics of tightened steel wire bundles during the dehumidification process of main cables of suspension bridge.A fixed-grid model was established based on the Lingdingyang Bridge,which is an accurate porous model that considers the compactness of steel wire bundles and suits the suspension bridge well.The influences of multiple factors on the air flow characteristics were analyzed,including the compactness of steel wire bundles,air flow direction,resistance coefficient calculation method and layers of steel wire bundles.As per the analysis,when the air was injected from different directions,the accurate porous model revealed the unevenness of the cross-sectional flow velocities inside the main cables and the inhomogeneity of the flow resistance.At a designated air flow velocity,the air flew faster at the clearance than inside the steel bundles when the air was flowing vertically.The air flow velocities at the horizontal clearance increased when the air was flowing horizontally,and there existed a 11.29％pressure difference between the injection and exhaust points.The comparison of the resistance coefficient model calculated by the Ergun equation and the fitted model demonstrates that the pressure difference between the injection and exhaust points gradually increases as the air flow velocity decreases.When the air was injected at a speed of 0.031 25 m/s,the pressure differences between the injection and exhaust points reached 89.5％(horizontal direction)and 95.6％(vertical direction).The differences in viscous resistance coefficients and in the inertial resistance coefficient under different steel wire bundle layers were less than 1％and 2％,respectively,indicating that the resistance coefficient is approximately independent of the number of layers.
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