3 ms·
The design appears to have an exit nozzle area at least equal to that of the inlet. If so, this is sub-optimal from a propulsive efficiency point of view. The c
by mannykannot 4y ago
The design appears to have an exit nozzle area at least equal to that of the inlet. If so, this is sub-optimal from a propulsive efficiency point of view. The cross-sectional area inside is clearly less (mainly due to the engine nacelle), making this a convergent-divergent nozzle, which is desirable only when the flow goes supersonic. For subsonic conditions, a convergent nozzle, with its exit narrower than its intake, is better.
See de Piolenc, 'Ducted Fan Design vol. 1.', 2001
- aidenn0 4y agoGiven the era it was from, it also almost certainly did not have aerofoil-shaped blades; axial-flow compressors from this era were terribly inefficient.
- mannykannot 4y agoIt appears to be a conventional propeller, which had an airfoil cross-section and were fairly efficient by then, but current ducted fans for low-speed use typically have 6 or 8 broader and shorter blades.
- kqr 4y ago> used a prop to draw air through a venturi tube "Venturi" is your clue that it was convergent--divergent by design! Whether that's a good idea is a different question...