In order to raise the stability margin of “X”-type inlet system with incoming Mach number range from 2 to 4 at a high angle of attack

an inverted two-dimensional inlet was designed and compared with the classical inlet layout. Results indicate that the inverted inlet layout has better overall performance at incoming Mach number 2.3 to 3.5 with angle of attack from 0° to 6°. There is no obvious phenomenon of shock/boundary layer interactions

allowing to meet the design requirements. When the same inlet design scheme is adopted

the terminal shock location and overall performance parameters have little differences between windward and leeward inlets of the inverted layout. The critical total pressure recovery coefficient of the inverted layout isalmost equal to classical layout when the angle of attack is 0°

2%-3% higher when the angle of attack is 4° and generally 19% higher when the angle of attack is 8°. The higher the incoming Mach number is

the more obvious the increase is. The total mass flow coefficient of the inverted layout is about 6% higher at angle of attack 8°. Moreover

the total drag force of inverted layout is lower than that of classical layout at low incoming Mach number

which is 1.7% lower when angle of attack is 4°. While at high incoming Mach number

the total drag force of inverted layout is higher than that of classical layout

which is 2.0% higher when angle of attack is 4°.