The CFD simulation of airflow characteristic and optimization design of dehumidification system of main cable in suspension bridge

This paper uses the computational fluid dynamics (CFD) method to calculate the actual resistance coefficient of the porous media model to investigate the airflow characteristics and design optimization of dehumidification system of main cable of the suspension bridge. According to the different stacking methods and gap sizes of steel wires, the main cable section is divided into tightened, gap, and loose regions. The purpose of the porous medium model is to investigate how the airflow characteristics within the main cable are affected by the ventilation mode, wire stacking mode, inlet velocity, intake clamp width and air supply distance. The results show that the airflow resistance of steel wire hexahedral stacking is significantly higher than that of steel wire square stacking. The section of main cable is anisotropic, as evidenced by the different airflow patterns along the horizontal and vertical directions when the steel wire is stacked in a hexagonal pattern. The "flow dead zone" is concentrated in the center of the main cable during external ventilation, whereas during internal ventilation, it is centered in the external area. The airflow characteristics inside the main cable are impacted by the porosity and stacking method of steel wires, and the air diffused more easily to the high porosity area. The airflow velocity inside the main cable increases with the increase of inlet velocity, and there exists a certain linear relationship. The ideal air clamp width for main cable dehumidification arises as the main cable diameter increased, which corresponds to the maximum rate of decreasing "flow dead zone" inside the main cable. The appropriate air supply distance for main cable of suspension bridge during dehumidification ranges from 50 to 150 m.