Papamoschou, D., "Analysis of Partially-Mixed Supersonic Ejector," AIAA
Journal of Propulsion and Power, Vol. 12, No.4, 1996.
- Ejectors are devices used for noise suppression and thrust augmentation.
The ejector is a
- shroud placed around a jet exhaust. It absorbs sound and, under certain
increases thrust. However, in some cases it penalizes thrust,
especially if the flight Mach
number is high.
- Prevailing analyses assume complete gas mixing inside the shroud,
resulting in uniform exit flow.
- This is often not true, especially for supersonic engines. A new method
for analyzing ejectors
addresses their partially-mixed nature. It is uses a
simple, quasi-one dimensional model for each
stream of the ejector, with
friction and heat transfer occuring between the two streams. The
are in good agreement with experimental data in the literature.
- Below is one of the results, the thrust augmentation versus fligh Mach
number for several ejector
- geometries (A/S=axisymmetric, 2D=two-dimensional, L/b=length over radius).
It is seen that
the thrust benefit deterierates as the flight Mach number
Ma increases. For Ma>0.7, a thrust loss