圆柱壁面上液滴凝固相变对其运动行为的影响

采用CLSVOF耦合焓-多孔介质方法对单液滴撞击低温光滑圆柱壁面的现象进行数值模拟研究,揭示了壁面温度、壁面浸润性和液滴撞击速度等因素对液滴撞击低温光滑圆形壁面后动力学行为及相变特性的影响,研究中主要关注两个重要参数的变化规律：液膜高度变化和液滴对壁面的润湿特性。研究表明：提高壁面疏水性能可有效减小液滴碰撞圆柱的铺展润湿面积,从而减小冻结面积,降低结冰的危害程度;由于圆柱壁面的曲率作用,液滴撞击疏水圆柱壁面会出现液膜断裂,但在极低温度下,可抑制液膜在圆形壁面上的分裂,导致液膜在壁面上的铺展面积有所增加,防结冰性能下降。

Effect of cooled cylindrical surface on droplet dynamic behavior

The prevention and control of ice accumulation has important applications in aviation, building construction and power grid construction. A deep physical insight of the ice forming on the cylindrical surface would give an instruction to the ice-removal strategies for energy conversion devices. Simulations were performed using CLSVOF (coupled level-set and volume of fluid) to track the air-water interface and an enthalpy-porosity method to capture the phase transition. The effects of learning behavior and phase transition characteristics are mainly concerned with the variation of two important parameters: the change of liquid film height and the wetting characteristics of droplets on the wall. The results showed that improve the wall hydrophobicity performance, which could effectively reduce the spreading wetted area of the droplet impact cylinder, thereby reducing the frozen area and decreasing the damage degree of icing. Due to the curvature of the cylinder, the liquid film breaks when the droplet hits the hydrophobic cylindrical wall. However, at extremely low temperature, it can inhibit the splitting of the liquid film on the circular wall surface, resulting in an increase in the spreading area of the liquid film on the wall surface, and the icing phenomenon becomes more serious.