Submerged Inlet Performance Enhancement Using a Unique Bump-Shaped Vortex Generator

TLDR

The study introduces a low‑drag, bump‑shaped vortex generator that merges windward bump guidance with vortex sweeping to control the fuselage boundary layer for submerged inlets. Its performance was assessed through wind‑tunnel tests over a wide range of operating conditions. Results show the generator pushes the boundary layer away from the duct entrance, boosting total‑pressure recovery by up to 5 % at Mach 0.90 with only a 0.76 % drag penalty, and its optimal position moves toward the duct entrance as its height increases.

Abstract

By combining the guiding effects of the windward bump with the sweeping effects of the vortex pair on the fuselage boundary layer, a unique flow control device featuring low aerodynamic drag is developed for submerged inlets. Wind-tunnel tests are conducted over wide operating conditions to determine the performance improvement by the bump-shaped vortex generator. The results indicate that, with the aid of the unique vortex generator, the upstream fuselage boundary layer is effectively pushed away from the duct entrance, improving the entering flow quality and thereby the performance of the submerged inlet. Despite the 0.76% drag penalty of the aircraft at most, the unique vortex generator is observed to increase the total pressure recovery of the submerged inlet by as much as 3.7% at a freestream Mach number of 0.73 and 5% at a freestream Mach number of 0.90. A strong relation between the installation position and the height of the vortex generator is found such that, at the optimal installation position, the local boundary layer thickness is equivalent to the height of the vortex generator. As a result, the optimal location of the vortex generator moves toward the duct entrance with the increase of its height.