The flow field in an experimentally tested supersonic inlet operating at off-design conditions was investigated numerically, with particular attention to the near-critical and subcritical regimes. Simulations were performed exploiting a research CFD code based on an unstructured finite volumes discretisation scheme and on the Unsteady-RANS equations approach. The Spalart-Allmaras turbulence model was used for closure. The computed results were validated against the experimental findings and compared with other numerical solutions available in the literature.