## 3 Calculation Results and Analysis
### Effect of Different Inflow Conditions on Water-Drop Collection on Airfoil Wall
Effect of water-drop diameter on water-drop collection coefficient  
The diameter of water drops in the cloud is generally between 2 \(\upmu\)m and 50 \(\upmu\)m. A water drop with an average diameter of less than 15 \(\upmu\)m can easily bypass the airfoil wall, and the amount of icing caused by it can be ignored for the icing of the whole wing. In addition, this paper doesn't consider the splash of large supercooled water drops with a diameter of more than 50 \(\upmu\)m [41], so the diameters of water drops selected in this paper are 16 \(\upmu\)m, 25 \(\upmu\)m, and 40 \(\upmu\)m.  
As depicted in Figure 10, when subjected to specific conditions (i.e., an AOA of 6\({}^{\circ}\) and an inlet velocity of 84 m/s), an increase in water-drop diameter leads to an escalation in the maximal local water-drop collection coefficient, accompanied by an expansion in the range of water-drop impact. This phenomenon arises due to the heightened mass and inertia of water-drops, rendering it increasingly challenging to deviate from their motion trajectory. By comparing the results with those illustrated in Figure 9, it can be inferred that, within a certain range, the water-drop diameter exerts a more significant impact on water-drop collection on the wing wall than the inlet velocity. As the diameter of water-drops increases from 16 \(\upmu\)m to 40 \(\upmu\)m, the impact limit on the upper surface of the airfoil extends from position 0.01 m to position 0.025 m (with a movement distance of approximately 8.3% of the total height of the airfoil), and the impact limit on the lower surface extends from position \(-\)0.045 m to position \(-\)0.075 m (with an increase of approximately 16.7%). The impact range of water drops increased from 0.055 m to 0.1 m, increasing by 81.8%. It can be seen that the influence of supercooled water droplets with large diameter in the upper air on the icing of airfoil leading edge is far greater than the speed of the aircraft. Therefore, based on the preliminary research in this paper, the accurate measurement of supercooled water drops is a research topic that needs to be focused on in the future aircraft anti icing and deicing. Figure 10: Effect of water-drop diameter on water-drop collection coefficient. Figure 9: Effect of incoming flow velocity on water-drop collection coefficient. (d) Effect of LWC on water-drop collection coefficient  
Because most of the frozen LWC is less than 1 g/m\({}^{3}\), when the average LWC exceeds 0.12 g/m\({}^{3}\) and the diameter of water drops in stratiform clouds is 14 \(\upmu\)m, the aircraft will produce slight icing, so the LWCs selected in this calculation are 0.2 g/m\({}^{3}\), 0.4 g/m\({}^{3}\), 0.6 g/m\({}^{3}\), and 1 g/m\({}^{3}\). According to Figure 11, it can be observed that the local water-drop collection coefficient remains consistent despite variations in LWC, when the AOA is fixed at 6\({}^{\circ}\), inflow velocity is at 84 m/s, and the diameter of the water-drop is 16 \(\upmu\)m. Therefore, it can be inferred that wall water-drop collection is not influenced by LWC.