Hysteresis of oscillatory airflow in a supersonic intake model

Supersonic airflow deceleration in a conventional mixed-compression intake is studied numerically. The simulation of turbulent two-dimensional flow is based on the Reynolds-averaged Navier–Stokes equations and the k-ω SST turbulence model. Numerical solutions are obtained with ANSYS-18.2 CFX finite-volume solver of second-order accuracy. The solutions reveal flow hysteresis with step-by-step changes in the free-stream Mach number M_∞. The hysteresis is caused by the instability of an interaction of a shock wave with the local region of flow acceleration formed near the throat of intake. Oscillations of the Mach number M_∞ in time are considered as well, and the existence of hysteresis is confirmed at small values of the amplitude A and period τ of the oscillations. The hysteresis shrinks with increasing amplitude A and eventually disappears at sufficiently large amplitudes. The dependence of shock wave oscillations on the period τ is also studied and transitions between different flow regimes are discussed.