## 3 Reynolds Number Effects on Static Aerodynamic Characteristics
### RMS Values of the Wind Pressure Coefficients  
The RMS values of the wind pressure coefficients can reflect the intensity of pressure fluctuations. Figure 6 shows the distributions of the RMS values on the surface of the main beam at different Reynolds numbers.  
As shown in Figure 6a, the distribution curves of the RMS values on the upper surface at different Reynolds numbers are similar in shape. At \(D_{\text{d}}\) = 0.13, 0.87, and 0.92, \(C_{\text{p,rms}}\) reaches its maximum value, indicating that the turbulence induced by the railing enhances the pressure fluctuations. There are differences in the \(C_{\text{p,rms}}\) values at different Reynolds numbers. Except for the region where \(D_{\text{d}}\) = 0.10-0.17, the \(C_{\text{p,rms}}\) decreases with increasing Reynolds number. In the region where \(D_{\text{d}}\) = 0.10-0.17, \(C_{\text{p,rms}}\) decreases, increases, and then decreases again with increasing Reynolds numbers. The variation amplitude of \(C_{\text{p,rms}}\) differs across Reynolds number ranges. For 3.2 \(\times\) 10\({}^{4}\) < \(Re\) < 5.9 \(\times\) 10\({}^{4}\), the variation amplitude is large, reaching 60%, whereas for 5.9 \(\times\) 10\({}^{4}\) < \(Re\) < 1.2 \(\times\) 10\({}^{5}\), the fluctuation amplitude is smaller.  
As shown in Figure 6b, the RMS values on the lower surface exhibit a similar trend across different Reynolds numbers. A sharp variation in the RMS values occurs at the junction of the wind nozzle and the lower slanted belly plate. At \(D_{\text{d}}\) = 0.03, \(C_{\text{p,rms}}\) reaches its maximum value and then decreases. It stabilizes at approximately \(D_{\text{d}}\) = 0.08, indicating that the pressure fluctuation is stronger at this junction. There are noticeable differences in the values of \(C_{\text{p,rms}}\) in different Reynolds number tests, which decrease as the Reynolds number increases. For 3.2 \(\times\) 10\({}^{4}\) < \(Re\) < 5.9 \(\times\) 10\({}^{4}\), the \(C_{\text{p,rms}}\) changes significantly, with the  
Figure 6: Distribution characteristics of the RMS values of the wind pressure coefficients at different Reynolds numbers. (**a**) Upper surface. (**b**) Lower surface.  
largest decrease of approximately 37%. For 5.9 \(\times\) 10\({}^{4}\) < \(Re\) < 1.2 \(\times\) 10\({}^{5}\), the reduction in \(C_{\rm p,rms}\) is less pronounced.  
Overall, the mean values significantly vary along the surface, with different distribution trends for the upper and lower surfaces. Specifically, a sudden change in \(C_{\rm p,mean}\) is observed near the junction between the wind nozzle and the upper deck (\(D_{\rm d}\) = 0.05) on the upper surface, whereas a large negative pressure is observed near the two maintenance vehicle tracks (\(D_{\rm d}\) = 0.22 and 0.79) on the lower surface. The mean values show slight Reynolds number effects in some regions. As the Reynolds number increases, \(C_{\rm p,mean}\) in the \(D_{\rm d}\) = 0.07-0.33 range on the upper surface changes after a Reynolds number of 8.3 \(\times\) 10\({}^{4}\). For the lower surface, near the two maintenance vehicle tracks (\(D_{\rm d}\) = 0.22 and 0.79), \(C_{\rm p,mean}\) first decreases and then increases as the Reynolds number increases.  
In the regions near the side railings on the upper surface (\(D_{\rm d}\) = 0.13 and 0.87) and near the junction of the wind nozzle and the lower inclined web (\(D_{\rm d}\) = 0.03) on the lower surface, the RMS values of the wind pressure coefficients exhibit significant variation, with higher fluctuation levels. The effects of the Reynolds number on the RMS values are prominent on both the upper and lower surfaces of the main beam. As the Reynolds number increases, \(C_{\rm p,rms}\) generally decreases, with a significant reduction observed in the range of 3.2 \(\times\) 10\({}^{4}\) < \(Re\) < 5.9 \(\times\) 10\({}^{4}\), whereas the decrease is less pronounced in the range of 5.9 \(\times\) 10\({}^{4}\) < \(Re\) < 1.2 \(\times\) 10\({}^{5}\).