Conceptual redesign of the B-1B bomber inlets for improved supersonic performance

This paper presents a conceptual study of two alternative inlet concepts for the United States Air Force B-1B bomber to provide for improved supersonic performance with expansion of capabilities to high-altitude, high-speed flight at Mach 2.0. The two inlet concepts are two-dimensional, variable-ramp inlet systems designed to replace the current fixed-geometry, pitot inlets of the B-1B. One inlet incorporates a two-ramp system, while a second inlet incorporates a two-ramp system containing an isentropic contour. The entire inlet system including the supersonic diffuser, throat, cowl lip, and subsonic diffuser sections was designed to maximize the total pressure recovery at the engine fan face to achieve maximum thrust by the engine at Mach 2.0 conditions. Analytic methods implemented into the MATLAB and the NASA SUPIN codes are used to design and analyze the two-dimensional inlet concepts. In addition, WIND-US computational fluid dynamics simulations were used to check and improve the results of the analytic design methods. The results suggest that at Mach 2.0, the total pressure recovery of the inlets could increase from 0.70 to 0.94. The inlet capture area and cowl drag increased; however, the overall improvements resulted in a 98% thrust increase over the existing inlet at the design point.