numerical investigation of back pressure and free-stream effects on a mixed compression inlet performance

Inlet performance has an important role in the operation of airbreathing propulsion systems. in this study, performance of a supersonic axisymmetric mixedcompression inlet in the supercritical operating condition is numerically studied. the effects of freestream mach number and engineface pressure on performance parameters, including mass flow ratio, drag coefficient, total pressure recovery, and flow distortion are investigated. to this sake, a multiblock densitybased finite volume cfd code is developed and reynoldsaveraged navier-stokes equations with spalart-allmaras one-equation turbulence model is employed. the code is validated by comparing numerical results against other computational results and experimental data for two test cases of inviscid flow in a two-dimensional mixed-compression inlet and flow in an external compression inlet. finally, the code is utilized for investigation of a specific supersonic mixed-compression inlet with the design mach number of 2.0 and length to diameter ratio of 3.4. results revealed that the increment of freestream mach number leads to decrease in total pressure recovery and drag coefficient, while mass flow ratio and flow distortion increase. the effects of engineface pressure on performance parameters showed that by increasing the engineface pressure, mass flow ratio and drag coefficient remain constant while total pressure recovery increases and flow distortion decreases.