# Structural Designing of Supersonic Swirling Devices Based on Computational Fluid Dynamics Theory
## 4 Structural Design Case and Analysis
### Swirler Design  
To design the swirler, we simulated and analyzed various combinations of the designs (Table 3). Through the analysis of the nozzle pressure distribution, Mach number distribution, and centripetal acceleration distribution, we developed a swirler design suitable for the desired operating conditions. Figure 7 shows the pressure distribution for various combinations of vanes and channel widths. It can be seen from Figure 7 that, from the perspective of the total pressure distribution, the pressure loss is the highest for the swirler design containing six vanes and an 8 mm wide channel and a nozzle, and the pressure loss is the lowest for the swirler design containing six vanes and a 6 mm wide channel and a nozzle. However, the difference in the pressure loss between the two designs was only 0.01 MPa. Therefore, it may be concluded that the combination of the number of vanes and channel widths has little effect on the pressure loss. Figure 8 shows the Mach number distribution for various combinations of number of vanes and channel widths. As shown in Figure 8, the combination of the number of vanes and channel widths has little effect on the Mach number distribution because it results in only a small pressure loss and a minor impact on the pressure at the inlet of the supersonic nozzle. For these nozzles, the Mach number of the nozzle outlet depended only on the geometric dimensions of the supersonic nozzle profile and the ratio of the back pressure at the outlet to the pressure at the inlet. Therefore, the combination of the number of vanes and the channel widths resulted in little variation in the Mach number of the entire nozzle. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Chemical Component** & **C1** & **C2** & **C3** & **iC4** & **nC4** & **iC5** & **nC5** & **N2** \\ \hline \hline \multicolumn{1}{c}{Mole fraction (\%)} & 91.8 & 8.1 & 0.1 & 0 & 0 & 0 & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Components of natural gas. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Design**} & **Number of** & **Channel** & **Swirler** & **Vane Arc** & **Swirler Outer** & **Vane Arc** \\  & **Vanes** & **Width** & **Height** (mm)** & **Radius (mm)** & **Diameter (mm)** & **Opening Angle (Degrees)** \\ \hline \hline \multirow{2}{*}{Design 1} & \multirow{2}{*}{4} & 6 & 52.00 & 58.39 & 135.00 & \multirow{2}{*}{90.00} \\ \cline{3-3} \cline{5-6}  & & 8 & 39.00 & 60.85 & 141.00 & \\ \hline \multirow{2}{*}{Design 2} & \multirow{2}{*}{6} & 6 & 34.00 & 71.04 & 145.00 & \multirow{2}{*}{60.00} \\ \cline{3-3} \cline{5-6}  & & 8 & 26.00 & 79.13 & 155.00 & \\ \hline \hline \multirow{2}{*}{Design 3} & \multirow{2}{*}{8} & 6 & 26.00 & 103.13 & 143.00 & 30.00 \\ \cline{3-3} \cline{5-6}  & & 8 & 20.00 & 140.60 & 155.00 & 25.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Design scheme of cyclone separator. Figure 8: Mach number distributions at different nozzle sections: (**a**) four vanes, 6 mm wide channel; (**b**) four vanes, 8 mm wide channel; (**c**) six vanes, 6 mm wide channel; (**d**) six vanes, 8 mm wide channel; (**e**) eight vanes, 6 mm wide channel; and (**f**) eight vanes, 8 mm wide channel. Figure 7: Pressure distribution at different nozzle sections: (**a**) four vanes, 6 mm wide channel; (**b**) four vanes, 8 mm wide channel; (**c**) six vanes, 6 mm wide channel; (**d**) six vanes, 8 mm wide channel; (**e**) eight vanes, 6 mm wide channel; and (**f**) eight vanes, 8 mm wide channel. The main purpose of identifying a suitable swirler design is to achieve gas-liquid separation by generating a centrifugal force. It can be observed from Figure 9 that the centripetal force distribution is mainly located in the annular space near the nozzle wall in Designs 1 and 2, and that the centripetal acceleration distribution is mainly located near the axis of the nozzle in Design 3. Therefore, it is expected that Design 3 may cause the formed droplets to mix with the gas flow; thus, it may not effectively achieve gas-liquid separation.