How is exhaust flow different in a ducted fan turbine engine versus an unducted fan engine?

How is exhaust flow different in a ducted fan turbine engine versus an unducted fan engine?

• A. Ducted fan uses two separate nozzles; unducted uses a single nozzle.
• B. Ducted fan bypasses the core entirely.
• C. Unducted engines direct all flow through a single nozzle.
• D. Ducted fan uses a common exhaust nozzle for both fan and core; unducted has two nozzles.

Answer: (D)

Exhaust flow differences come from whether the bypass (fan) flow and the core flow share the same exit. In a ducted fan, there’s a bypass duct around the core, and the design often uses a single tailpipe where both the fan’s bypass air and the core exhaust mix and exit through one common nozzle. In contrast, an unducted fan has no bypass duct, so the bypass flow and the core flow stay separate and exit through two distinct nozzles. That’s why the statement about a common exhaust nozzle for both streams in a ducted fan, versus two nozzles in an unducted setup, is the correct way to describe the difference.

Exhaust flow differences come from whether the bypass (fan) flow and the core flow share the same exit. In a ducted fan, there’s a bypass duct around the core, and the design often uses a single tailpipe where both the fan’s bypass air and the core exhaust mix and exit through one common nozzle. In contrast, an unducted fan has no bypass duct, so the bypass flow and the core flow stay separate and exit through two distinct nozzles. That’s why the statement about a common exhaust nozzle for both streams in a ducted fan, versus two nozzles in an unducted setup, is the correct way to describe the difference.