Experimental and Numerical Investigation of a Fluidically Variable Hypersonic Inlet

A fluidically variable hypersonic inlet with fixed geometry is investigated in this paper by both experimental and numerical methods. The results show that the inlet maintains the shock-on-lip condition both at Mach 4.92 and 5.74 successfully. At Mach 4.92, the shock-on-lip condition is naturally obtained without any need of secondary flow injection. When the inlet operates at Mach 5.74, the fluidic control technique works to prevent the external ramp shocks from entering the duct, and the secondary flow ratio used to control the first and second ramp shocks is 1.03 and 0.67%, respectively. Compared with the fixed-geometry inlet under the same design constraints, the mass flow ratio and the total pressure recovery of the fluidically controlled inlet are improved by 23.8 and 3.95% at Mach 4.92, respectively. While operating at Mach 5.74, the total pressure recovery of the fluidically controlled inlet is slightly lower than the fixed-geometry one because the curved ramp shocks lead to additional total pressure loss. As a result, the fluidically controlled inlet has excellent performance at low operating Mach numbers, which is beneficial to the performance of hypersonic propulsion system at the acceleration stage.