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Previous studies have shown that in the subcritical regime, wavy circular cylinders exhibit less wind-induced drag than standard circular cylinders. However, the aerodynamic performance of wavy cylinders at higher Reynolds numbers is still unknown. Hence, a series of wind tunnel tests including measurement of the surface pressure, vortex-induced vibration (VIV) and dry galloping were conducted for a wavy cylinder and a corresponding standard cylinder at Re = 1.00 × 105-3.86 × 105. The results indicate that the aerodynamic characteristics, including the mean and fluctuating pressure distributions, mean and fluctuating aerodynamic force coefficients, Strouhal number, flow regime classification, and non-Gaussian characteristics, are significantly modified when shifting from the standard cylinder to the wavy cylinder. Furthermore, these modifications highly depend on the Reynolds number. Regarding the wavy cylinder, related parameters obviously vary along the spanwise direction, indicating three-dimensional aerodynamic characteristics. Moreover, the maximum VIV amplitude of the wavy cylinder is 40% lower than that of the standard cylinder. The velocity corresponding to the maximum amplitude is increased by 11% for the wavy cylinder. Additionally, the maximum dry galloping amplitude is reduced by 11%. • Wind tunnel tests were carried out to reveal the aerodynamics and vibrations of a specific sinusoidal wavy cylinder. • Aerodynamic coefficients, pressure distributions, and Strouhal numbers were obtained at subcritical and critical regimes. • Aerodynamics along the spanwise direction were determined to possess significant three-dimensional characteristics. • The vortex-induced vibration and dry galloping are weaker for the wavy cylinder than for the standard cylinder. [ABSTRACT FROM AUTHOR]

The rain-wind-induced vibration (RWIV) of stay cables has become a concern in bridge engineering over the past decades. Attaching helical fillets on the surface of stay cables is often used to suppress RWIV. In the critical Reynolds number range, stay cables also experience large amplitude vibration without rainfall, which is known as dry galloping. To investigate the optimal helical fillet parameters that can suppress RWIV and dry galloping, a series of wind tunnel tests were carried out. The results showed that a helical fillet can weaken the Reynolds number effect of the cable in the critical region, and the maximum C L and the decline value of C D are decreased. This effect gradually decreases with the decrease of helical fillet pitch, resulting in the decrease of the maximum C L in the critical region and the increase of C D in the supercritical region. The helical fillet has a good suppression effect on the dry galloping equilibrium position, and the suppression effect of the helical fillet on the dry galloping amplitude depends on the helical fillet parameters. A proper helical fillet setting can effectively suppress both RWIV and dry galloping. Compared with the helical fillet diameter, the suppression effect is more effective when changing its pitch. Finally, the drag coefficients in various Reynolds number regions are summarized to provide a reference for engineering design. • Wind tunnel tests were carried out to reveal the aerodynamics and vibrations for stay cables with helical fillets. • Aerodynamic force coefficients and Strouhal numbers of stay cables with helical fillets were obtained and compared. • The effects of wind speed, rain intensity, inclination, and yaw on the RWIV were studied. • The effects of the helical fillet diameter and distance on RWIV and dry galloping were analyzed. • The drag coefficients of cables at different Reynolds numbers were fitted to facilitate engineering applications. [ABSTRACT FROM AUTHOR]

Based on the statistical results of field investigations of stay cable shapes, the deformed cross-sections tend to be micro-elliptical. These deformations may significantly influence the aerodynamic forces and vibration characteristics of stay cables. Accordingly, the aerodynamic forces and wind-induced vibrations of stay cables with circular and various micro-elliptical sections are measured in wind tunnel tests. Furthermore, the influences of the Reynolds number, attack angle and major-minor axis ratio on wind-induced vibration are investigated. The aerodynamic damping is calculated based on the quasi-steady assumption to predict the observed vibrations. The results indicate that, compared with circular cables, cables with micro-elliptical sections generate larger-amplitude vibrations at certain Reynolds numbers and attack angles. Furthermore, large-amplitude vibrations occur mainly in the critical regime corresponding to Reynolds numbers of 2.5 ​× ​105–4.0 ​× ​105 and attack angles of α ​= ​10°–30° and α ​= ​60°–80°. However, the method based on the quasi-steady assumption is invalid for predicting wind-induced vibrations in the critical regime. • Wind tunnels tests were carried out to reveal the aerodynamics and vibrations for three micro-elliptical section cylinders. • Vibrations were observed of the micro-elliptical section cylinders in cribitcal and supercritical Reynolds number range. • Drag and lift coefficients were obtained from subcritical to super Reynolds number range. • The vibrations in critical and supercritical range are confirmed to be non-steady phenomenon. [ABSTRACT FROM AUTHOR]

During the rain-wind-induced vibration (RWIV) process, a water rivulet forms on the surface of stay cables, and the upper rivulet is considered to be an important factor in RWIV formation. The cables also exhibit galloping in the absence of rain. To reveal the effect of a rivulet on galloping and help explain the mechanism of RWIV, from the viewpoint of the Reynolds number effect, a cylinder with an artificial rivulet at multiple angles was tested in wind tunnel experiments. The results show that the rivulet has a significant effect on the aerodynamic force coefficients, and the increase in the rivulet position decreases the onset Reynolds number of TrBL0-1 transition. A large-angle rivulet limits reattachment on the upper surface of the model, and the vortex appears in TrBL1. Due to reattachment, bistability can be observed in the TrBL0-1 and TrBL1-2 transitions, and the wake vortex is suppressed. During the formation of a separation bubble, the aerodynamic forces change dramatically, which affects the aerodynamic damping of the cables and induces galloping instability in most cases. The condition of reattachment on the upper surface of cables may be an important reason for RWIV occurrences. • Wind tunnel tests were carried out to reveal the aerodynamics and vibrations for cables with rivulet positions. • Aerodynamic coefficients and Strouhal numbers of different Reynolds numbers are obtained and compared. • The vibration amplitude of cables with various rivulet positions is analyzed. • The mechanism of RWIV is discussed based on Reynolds number effect and aerodynamic damping. [ABSTRACT FROM AUTHOR]