Multi-directional freezing mechanisms of impact droplets on cold cylindrical surface

Ice formation on transmission lines in high-altitude cold regions poses serious risks to power networks, yet the freezing behaviors of water droplets impacting cold cylindrical surfaces remain poorly understood. Previous studies have focused on water droplets impacting flat or spherical surfaces, leaving a gap in understanding droplet impact dynamics and solidification on cylindrical surfaces under low temperatures. Addressing this, we investigate the freezing behaviors of water droplets impinging on cold circular tubes under various impact velocities and substrate temperatures. Here, we experimentally examine the coupling between droplet impact dynamics and solidification on cylindrical surfaces. Using a controlled setup, we study how impact velocity and substrate temperature influence freezing morphologies, including unique patterns such as unidirectional, bidirectional, single-ring, and double-ring freezing. We further explore the spreading dynamics and thermal balance through a theoretical model, correlating the axial and circumferential maximum spreading lengths. Our findings reveal that the complex interplay of impact dynamics and solidification results in diverse freezing morphologies, offering new insights into ice accretion mechanisms on cylindrical surfaces. These results not only contribute to the understanding of ice formation on power transmission lines but also provide a foundation for developing more effective anti-icing strategies for power infrastructure.