# An Experimental Study on Ice Accretion under Bridge Cable in Different Conditions
## 3 Results and Discussion  
### Formation of Ice on the Surface of the Cable  
At the experiment's beginning, the model's surface temperature was consistent with the ambient air temperature. The overcooled water droplets hitting the surface of the stay cable were entirely or partially frozen on the surface to form ice. Meanwhile, the latent heat released by freezing helped some water droplets form a flowing water layer to adhere to the top of the ice sheet, providing raw materials for accumulating the lower ice. The latent heat generated was transmitted to the surrounding air through the ice-water interface, also known as recondensation [20]. As the downstream distance increased, the surface of the stay cable became less efficient at collecting water and freezing, which kept the underside relatively cool. The discontinuity and randomness of ice accumulation caused by the nonuniform surface temperature and high water mobility led to the abnormal accumulation of local ice, contributing to the formation of ice ribs and ice ridges. Figure 4 shows the icing on the side of the stay cable under different temperatures and inclination angles. Under the condition of \(-5\,^{\circ}\mathrm{C}\), the arrangement of ice ribs formed at the bottom of the cable was more regular. At this time, the dominant icing path between the ice ribs was still forming, and the interval of the ice rib distribution was more uniform, the ice formed was small, and the number was relatively small. With the decrease in temperature, the icing on the lower part of the stay cable increased. The observation shows that the ice rib accumulation did not appear on the bottom surface of the stay cable until a certain period after the beginning of icing because the surface temperature of the stay cable was low at the beginning; water droplets can quickly solidify into ice after hitting the upper surface. The thickness of the ice accumulation on the stay cable surface increased with time, and the heat released in the freezing process caused the surface temperature of the stay cable to rise [21]. Some unfrozen droplets gathered on the surface and spread out to form a water film. The edge of the water film pushed further downstream, and in this process, the thickness of the water film decreased as it was transported downstream [22]. With the increase of the coverage of the water film, water droplets separated from the water film under the action of gravity, decomposed into multiple runoffs when flowing down the surface of the stay cable, and froze into ice further downstream. At this time, heat transfer with the air removed the remaining latent heat of melting in the water [23; 24] and then froze part of the runoff into a rib-like ice structure. This process prevented the ice thickness on the upper surface of the cable from increasing continuously. The formation of ribbed ice increased the surface of the ice structure, enhanced heat exchange with the air, and  
Figure 3: Spray nozzle. promoted the rapid growth of the side ice structure. At the same time, under the influence of gravity and surface friction, some large liquid droplets that were not entirely solidified, flowed downward along the cable surface in an elliptical path and gradually broke away from the cable surface to form ice edges. At the top of the ice edge was a thin layer of ice covered with liquid water, so the latent heat of melting released by the ice under the water film when it froze had to be removed from the ice-water boundary. Therefore, the temperature gradient from the ice surface to the environment controlled the ice growth rate [3]. Figure 5 shows the freezing condition of the bottom surface of the stay cable under different diameters and inclination angles after freezing for 60 min at the ambient temperature of \(-25\)\({}^{\circ}\)C. As can be clearly seen in Figure 5, the presence of spiral fillets changed the path of runoff on the cable surface.