Influence of the inlet relative Mach number on ram-rotor flow field and performance

The three dimensional Reynolds-averaged Navier-Stokes equations and the Spalart-Allmaras turbulent model are adopted to simulate numerically the flow field of the three dimensional flow-path of a ram-rotor with different inlet relative Mach numbers (Ma
₀
= 2.1~2.5) and two kinds of throat length-height ratio. It has been found that the flow fields are different with the changing of the throat length-height ratio. When the throat length-height ratio is 1, with the increasing of the inlet relative Mach number, the separation zone moves from near the top wall to the bottom wall; and it is contrary when the length-height ratio is 2. With Ma
₀
increases, the incident angle and the reflection angle of shock wave decrease. The shock loss, the interaction of the shock wave and boundary layer, and the boundary layer separation are the main factors of the flow loss. The averaged flow angle at the exit with the throat length-height ratio 2 is larger than that with the throat length-height ratio 1. The Mach number, the total pressure and the pressure ratio at the exit increase and the adiabatic efficiency decreases with the increasing of Ma
₀
. Under the same Ma
₀
, the ram-rotor with the throat length-height ratio 2 has higher total pressure, the pressure ratio and the adiabatic efficiency.