On the effects of Reynolds number on the aerodynamic characteristics of streamlined box girders

The streamlined box girder is widely used in long-span bridges, yet the impact of Reynolds number effects on its aerodynamic characteristics is still not fully understood. This study focused on the streamlined box girder of the Ningbo Xiangshan Harbor Bridge, using a 1:15 scale model tested in the 8 × 6 m wind tunnel in Mianyang, China, under various angles of attack and high-Reynolds numbers (up to Re = 1.09 × 106). The findings indicate that the mean aerodynamic force coefficient exhibits significant Reynolds number effects at positive angles of attack, with maximum variations reaching 84.00%. The fluctuating force coefficient shows a trend of initially decreasing and then increasing with the increase in Reynolds number across all angles of attack. As the angle of attack increases from 0° to 8°, the distribution of mean and fluctuating wind pressure changes significantly. The mean wind pressure coefficient on the upper surface of the upstream nozzle decreases significantly with increasing Reynolds number at positive angles, with the rate of decrease increasing with the angle of attack and reaching a maximum of 0.81, which explains the Reynolds number effect on the mean aerodynamic force coefficient. At the +5° angle of attack, the fluctuating wind pressure distribution decreases and then increases with Reynolds number; at other angles, it generally decreases with increasing Reynolds number. The wind pressure correlation between circumferential measurement points increases with Reynolds number. The spanwise correlations of the lift and moment coefficients exhibit the same trend, with maximum increases of 0.60 and 0.69, respectively.