Based on the conformal inlet of flying wing unmanned aerial vehicle (UAV) and the relevant engineering application

grilles with different grille hole spacing were designed. Research on the integrated design of aerodynamic and stealthy performance was carried out based on multilevel fast multipole method (MLFMM) and the numerical simulation with hybrid grid. Results indicated: (1) With the decrease of grille hole spacing

the electromagnetic shielding effectiveness increased gradually; at the frequency of 1GHz

the electromagnetic shielding effectiveness can reach to about 48.93% when the grille hole spacing was λ/3(λ represents wavelength)

and it would be shielded entirely while the grille hole spacing reached λ/6; (2) The conformal inlet grille generated a little influence on the fluid flow of wing surface of the flying wing UAV

but it had greater influence on the internal flow of inlet; (3) With the decrease of grille hole spacing

the lift/drag characteristic of flying wing UAV declined appreciably

while the total pressure recovery coefficient decreased and the distortion coefficient increased.