###### Abstract  
Submerged inlet has been widely used in UAVs and cruise missiles due to its good stealth characteristics, but it also brings the disadvantage of poor aerodynamic characteristics. Especially in large maneuvering flight, the flow field near the fuselage has a strong unsteady effect, and the total pressure recovery coefficient and distortion characteristics have deteriorated sharply. In order to investigate the steady and transient aerodynamic characteristics of the submerged inlet in large maneuver flight and improve its maneuver envelope, a design scheme of a distributed submerged inlet for large maneuver flight is proposed in this paper. Taking a cruise missile as the research object, the steady and transient analysis of the conventional submerged inlet and the distributed submerged inlet is carried out using CFD numerical method. The results show that the distributed submerged inlet can significantly improve the inlet performance and enhance the sideslip limit of the submerged inlet during large sideslip maneuver flight. When the sideslip angle is 30\({}^{\circ}\), compared with the conventional submerged inlet configuration, the outlet total pressure recovery coefficient of the distributed submerged inlet configuration is increased by 44.2%, and the total pressure distortion index is reduced by 66.3%. submerged inlet; large maneuver state; nested mesh; total pressure distortion index; distortion characteristics; hysteresis effect +
Footnote †: journal: Applied  
[PERSON] et al. used experimental and numerical simulation methods to study the influence of the high angle of attack maneuver flight on the aerodynamic characteristics of the inlet. The research results showed that the increase of the angle of attack from 10\({}^{\circ}\) to 60\({}^{\circ}\) would lead to an increase in the range of low-pressure area at the inner side of the inlet bottom and showed a more obvious pressure gradient on the engine inlet section [1]. In the F/A-18A project, [PERSON] et al. carried out a numerical simulation of an aircraft inlet under multiple working conditions in order to explore the difference in inlet aerodynamic characteristics between rapid maneuver flight and steady flight. The research results show that the static pressure in the numerical calculation results is in good agreement with the flight data [2]. In order to judge whether the results obtained under stable conditions are sufficient to describe the distortion level generated by the inlet during the rapid maneuver of the aircraft, [PERSON] used experimental means to study the aerodynamic characteristics of the inlet. The research results show that the transient high angle of attack maneuver conditions will not improve the distortion of the inlet [3]. [PERSON] compared the steady inlet data with the inlet data during the transient rapid maneuver, and the results showed that the total pressure recovery of the rapid maneuver inlet was very consistent with the total pressure recovery coefficient obtained under the equivalent stable angle of attack [4]. In order to explore whether the inlet can provide stable and uniform airflow for the engine during flight outside the normal maneuvering envelope, [PERSON] et al. used wind tunnel experiments to explore the inlet during maneuvering flight. In the experiments, engine surges were encountered in the process of nose left deviation and nose right deviation, while the total pressure distortion level did not exceed the maximum limit during the stable attitude experiment, which indicates that the aircraft's position. The rapid change of attitude may cause the increase of total pressure distortion in the inlet and even cause engine surge [5]. In order to predict the total pressure recovery and distortion at the engine inlet section, [PERSON] used the numerical simulation method to study the forebody/inlet model of F/a-18 at \(M_{e}=0.20\), \(\alpha=60^{\circ}\) and \(\beta=10^{\circ}\).