Numerical Simulation of Near-Critical and Unsteady, Subcritical Inlet Flow

The unsteady, Reynolds-averaged Navier-Stokes equations were solved for the flow about an experimentally tested external compression axisymmetric inlet operating in the near-critical and unsteady subcritical flow regimes. The near-critical solution reached a stable steady state, while the subcritical solution attained an unstable, bounded oscillatory state characterized by large-amplitude pressure oscillations and traveling shock waves. The self-sustained oscillations, known as inlet buzz, result from a shear layer instability combined with a closed-loop feedback of reflected disturbances. Solutions are compared with experimental results.