V∞ V∞ VExhaust VWake V∞ V∞ VWake + VExhaust Engine Boundary layer develops Aircraft VWake V∞ V∞ Boundary layer develops Engine Aircraft VWake + VExhaust

V∞ V∞ V∞ V∞ Aircraft wake (drag) Turbofan exhaust (thrust) BLI propulsor Turbofan exhaust (thrust) The turbofan has to generate enough thrust to overcome the aircraft’s drag (top). A boundary-layer ingesting propulsor could accelerate the slower moving air in the aircraft wake (bottom). The turbofans could then be downsized, since they have to generate less thrust, which leads to weight savings and drag reductions, increasing the overall efficiency.