Comparison on aerodynamic and stealthy performance of flying wing unmanned aerial vehicle with three conformal intake inlets

Based on stealth and structural loading requirements of flying wing unmanned aerial vehicle (UVA), three dorsal S-shaped inlets with three conformal intakes were designed. According to the ratio of the upper and bottom of the sectional projection shape of the intake, three inlets, i. e. : triangular, trapezoidal and rectangular inlets, were named. The coupled numerical simulation was carried out on the inflow/outflow integrated for flying wing UAV, and the simulation method based on shooting and bouncing ray (SBR) was also performed to study the electromagnetic scattering of inlet. Then the aerodynamic and stealthy performance of flying wing UAV with three conformal inlets was obtained. Results indicate: (1) The lift/drag and the longitudinal moment characteristic of the model with rectangular inlet are the best. (2) As the three inlet models are arranged in previous order, the total pressure recovery coefficient increases gradually, and the distortion coefficient decreases; moreover, the airflow along the inlet becomes smooth gradually, and then, of course, the internal flow characteristic of the model with rectangular inlet shows the best. (3) At the attack angle 0° the mean value of the three inlet models radar cross-section (RCS) increases first and then decreases basically. The stealthy performance of the model with rectangular inlet is the best with the terminator open, but the model with triangular inlet shows better when the terminator is short-circuited.