## 4 The Flow Characteristics of Two Inlet Configurations under High Maneuver Condition
### Analysis of Steady Flow Characteristics  
During the steady state calculation, the attitude of the missile body and the incoming flow conditions remain unchanged. The total pressure recovery coefficient and total pressure distortion index on the outlet of the inlet section are shown in Figure 11. Configuration I represents the conventional submerged inlet, and configuration II represents the distributed inlet. It can be seen from Figure 11a,b that the \(\sigma\) of the two inlet configurations has a very similar trend with the \(\alpha\). In the range of \(-30^{\circ}\) to \(30^{\circ}\), \(\alpha\) first rises, then decreases, and then rises. \(\alpha\) is above 0.88. The total pressure distortion indices of the two inlet configurations are also very similar with the angle of attack, showing a trend of first rising and then declining in the range of \(-30^{\circ}\) to \(30^{\circ}\), and the total pressure distortion indices are below 0.2. The \(\sigma\) of the conventional submerged inlet is slightly higher than that of the distributed inlet, and \(D_{1}\) of the conventional submerged inlet is slightly lower than that of the distributed inlet. This is because there is a certain airflow mixing phenomenon at the intersection of the auxiliary inlet and the main inlet in the distributed submerged inlet configuration, which brings a certain energy loss. In addition, the auxiliary inlet located on both sides of the missile body in the distributed submerged inlet configuration will cause low-energy gas in the boundary layer on both sides of the missile body to flow into the inlet, which will also lead to a decrease in total pressure and an increase in total pressure distortion. It can be seen from Figure 11c,d that the limit of sideslip angle of conventional submerged inlet configuration is \(\pm 20^{\circ}\). When the absolute value of \(\beta\) is greater than \(20^{\circ}\), \(\sigma\) at the outlet drops sharply; when \(\beta\) reaches \(\pm\) 30\({}^{\circ}\), \(\sigma\) is less than 0.6. When \(\beta\) is within  
Figure 11: Steady State Calculation Results. (**a**) Total pressure recovery coefficient versus angle of attack, (**b**) Total pressure distortion index versus angle of attack, (**c**) Total pressure recovery coefficient versus angle of sideslip, (**d**) Total pressure distortion index versus angle of sideslip. \(\pm 20^{\circ}\), \(D_{1}\) of the conventional submerged inlet is about 0.22, and when the \(\beta\) reaches \(\pm 30^{\circ}\), the \(D_{1}\) suddenly increases to 0.7. This is because the submerged inlet mainly relies on the entrainment vortices generated by the side edges to drive the external airflow into the inlet. When the absolute value of the \(\beta\) is less than \(20^{\circ}\), the side edges on both sides of the inlet can generate the entrainment vortices that are beneficial to the inlet to drive the external airflow into the inlet. When the absolute value of the \(\beta\) is greater than \(20^{\circ}\), the side edge with the same direction as the incoming flow can no longer generate the entrainment vortices beneficial to the air inlet. Although the side ribs opposite to the incoming flow can still produce entrainment vortices that are conducive to the intake, the effect of driving the external airflow into the inlet is greatly weakened because the airflow changes the angle of the airflow through the side ribs during the flow around the body. When the \(\beta\) is greater than \(\pm 20^{\circ}\), the \(\sigma\) at the outlet of the distributed submerged inlet also decreases to some extent, but the decrease is small. When \(\beta\) reaches \(\pm 30^{\circ}\), the \(\sigma\) at the outlet of the distributed inlet is still greater than 0.80. \(D_{1}\) of the distributed inlet is always kept within 0.2. When \(\beta\) is \(\pm 10^{\circ}\), the \(D_{1}\) is about 0.12.