NASA says the first-ever largt scale wind-tunnel tests of robust fan capable of operatin in turbulent flow have proved success ful, marking an early step on the pat to a new generation of highly efficier airliners designed to take advantage ( boundary layer ingestion (BLI). Researchers theorize that transport aircraft with embedded engines, or an aft-mounted propulsor, could see double-digit improvements in fuel-burn efficiency over tube-and-wing, podded engine designs. Up to 8% of the improvement could come just from ingesting the boundary layer. This is because the flow velocity into the fan from the boundary layer is slower than the free stream and-as there is no excess kinetic energy if the fan is ingesting the slower layer-less energy needs to be added to reach the same thrust.
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