## 3 Calculation Results and Analysis
### Effect of Different Inflow Conditions on Water-Drop Collection on Airfoil Wall  
Under the same conditions, this paper compares and analyzes the calculated results of the water-drop collection coefficient with those calculated by FENSAP-ICE. In the solution of the airflow field, the turbulence model used by FENSAP-ICE and the k-\(\omega\) SST model adopted in this paper are different. The FENSAP plate of FENSAP-ICE adopts the Spalart-Allmaras model; this model is devised for aeronautical employment concerned with wall boundary fluidity. The principle of the water-drop impact on the wing calculated by the WATER-DROP3D plate of FENSAP-ICE is the same as that in this paper. They are all the Euler-Euler approach: water drops are regarded as a successive phase concerning the LWC of the water drop with the continuity equation and momentum equation of the water drop solved. In this study, the different influencing factors employed to compute the water-drop collection coefficient on the airfoil wall and the basis for their selection are shown in Table 3. \begin{table}
\begin{tabular}{c c c} \hline
**Inflow Condition** & **Value Selection** & **Select by** \\ \hline AOA of the wing (\({}^{\circ}\)) & 0, 3, 6, 12 & the AOA is greater than 0\({}^{\circ}\) to generate lift \\ \hline Incoming velocity (m/s) & 70, 84, 100 & Cruise speed of transport aircraft \\ \hline Water-drop diameter (\(\mu\)m) & 16, 25, 40 &
\begin{tabular}{c} Large supercooled water-drops are \\ not considered \\ \end{tabular} \\ \hline LWC (g/m\({}^{3}\)) & 0.2, 0.4, 0.6, 1 & Iced climatic conditions \\ \hline \end{tabular}
\end{table} 
Table 3: The basis for the numerical selection of different inflow conditions in this paper. Figure 7: NACA653-218 Airfoil grid generation. From the illustration, it is evident that the results obtained via both methodologies exhibit conformity. As the AOA escalates from 0\({}^{\circ}\) to 12\({}^{\circ}\), the overall trend of the collection coefficient of water drops is downward. Notably, the water-drop impact threshold on the lower surface of the airfoil increases gradually, while that on the upper surface decreases correspondingly. The upper surface water-drop impact limit moves downwards from position 0.03 m to position 0 m (displacement of 16.7% of the total airfoil height), and the lower surface moves downwards from position 0 m to position \(-\)0.05 m (27.8% of the airfoil height). This implies that the range of water-drop impact shifts towards the lower surface and the extent of downward movement is greater. Effect of incoming flow velocity on water-drop collection coefficient  
The maximal cruising speed of the C-212 transport aircraft is 100 m/s, and the economic cruising speed is 84 m/s. Therefore, the incoming flow speeds selected in this study are 70 m/s, 84 m/s, and 100 m/s. When other conditions are fixed, the value of \(y+\) on the wing wall is proportional to the incoming flow velocity. In this paper, the grid width of the first boundary layer on the wing wall is determined based on the flow velocity of 100 m/s. Therefore, the divided grid also conforms to the calculation conditions at 84 m/s and 70 m/s. Figure 9 illustrates the water-drop collection coefficients obtained from the present study and FENSAP-ICE software for various inlet velocities at an AOA of 6\({}^{\circ}\) and a water-drop diameter of 16 \(\upmu\)m. The results indicate that the maximum local water-drop collection coefficient and the water-drop impact threshold on the wing exhibit a gradual increase with the increase in incoming flow velocity. However, the magnitude of the increase is not significant. As the inflow velocity increases from 70 m/s to 100 m/s, the peak of water-drop collection coefficient only increases from 0.45 to 0.5 and the impact limit of the upper and lower surfaces expands very little. Figure 8: Effect of AOA on water-drop collection coefficient. 3.