In order to improve the off-design aerodynamic performance of supersonic inlet

a two-dimensional variable geometry inlet with the free stream Mach number from 2.0-4.5 was designed. Numerical simulation was applied to investigate the inlet aerodynamic performance

and a superior scheme of variable geometry was acquired. The aerodynamic performance was compared between variable geometry inlets and fixed ones. The results indicate that the variable geometry technique could improve the inlet aerodynamic performance at the starting Mach number; Mach number at the throat of variable geometry inlet decreases with the increase of the inlet ramp angle and contraction ratio when the free stream Mach number ascends. The variable geometry inlet has better aerodynamic performance during a wide range of Mach number

its mass flow rate and total pressure recovery coefficient are 19.4% and 55.8% respectively higher than the fixed ones in some states.