Flow structure of the ridge integrated submerged inlet

Abstract

Control of the boundary layer upstream and in the region of the engine inlet is an important consideration for airplane designers. One important aspect of this problem can be seen in the performance analysis of submerged inlets for which the design is based on boundary layer ingestion. With a large offset between the flush entrance and the compressor face, these low drag concepts are suitable for stealth applications, but when the wetted area upstream of the inlet is long, the ingestion of thickened boundary layer results in flow separation at the bends, pressure recovery losses and finally reduction of thrust. In this paper, a ridge surface is used as a passive integration solution to prevent the upstream boundary layer from entering into the inlet. To investigate the new integration method, a submerged inlet with a triangular entrance is designed and its flow pattern is simulated numerically by ANSYS Fluent solver with and without the ridge configuration. The vortex structures, breakdowns, boundary layer transition and efficiency factors are determined by second order accuracy and use of two different structural mesh domains and flow solvers. Results indicate that the ridge surface improves the inlet efficiency significantly from low to high-subsonic flow regimes and a variety of sideslip angles.