Numerical Investigation of Geometrical Design Effect on the Submerged Inlet Aerodynamics Characteristics

Abstract

In the present study, turbulent flow at submerged inlets is numerically studied. Five different geometries including the standard inlet developed by National Advisory Committee for Aeronautics (NACA), divergent inlet, parallel inlet and two new proposed geometries are compared. The effects of the boundary layer thickness ratio (0.31, 0.8 and 2.56) defined as the ratio between the boundary layer thickness (\( \delta \)) and the entrance depth (d) and velocity ratio defined as the ratio between the flow velocity at the duct entrance and the free stream (0.2–1.6) on their performance are further investigated. Moreover, the \( \,K - \omega \; \) model is used to simulate the three-dimensional, incompressible and turbulent flow of interest. NACA inlet is validated with experimental data. Results showed that in all studied cases, increasing the boundary layer thickness has a negative effect on the Ram recovery ratio (or efficiency); however, the effect of the velocity ratio on the Ram recovery ratio was different with an initial increase followed by a decrease in the efficiency. It is shown that our two proposed inlets present the same efficiency as the NACA inlet, while the efficiency for the divergent and parallel inlets was lower. Interestingly, the proposed inlets show a lower drag force compared to the NACA inlet at the high velocity ratios.