Simulations and Experiments of a Dual-Stream Low-Boom Supersonic Inlet

Abstract

An axisymmetric supersonic inlet was designed to deliver high-quality subsonic flow to a turbofan engine, with a relaxed external compression centerbody to minimize the external overpressures. This study investigates the fluid dynamic performance and angle of attack, or pitch, sensitivity of two similar inlet geometries. The computations employ three-dimensional Reynolds-averaged Navier–Stokes simulations, while the experimental data were derived from the NASA Glenn Research Center at Lewis Field supersonic tunnel. Test conditions were based on a free-stream Mach number of 1.66 and pitch angles from to . Instrumentation includes stagnation pressure rakes in the core and bypass streams, as well as centerbody surface pressures. The two geometries were found to deliver high recovery flow to the engine face at zero pitch. At finite pitch angles, lower recovery flow was observed near the cowl, caused by the change in shock structure, but was successfully diverted to the bypass stream, and good levels of core stream recovery were maintained. The experiments showed a fuller boundary layer on the centerbody surface, while the outer core boundary layer was thinner than predicted. The measured core stream recovery at 5 deg pitch was 0.5–1.0% higher than in the simulations over a range of core flow rates.