MIXING ENHANCEMENT USING AXIAL FLOW

What it is ...

Operating conditions

Applications

Round-jet experiments

2D-jet experiments

Twin-fluid atomization

Investigation of fundamental physics

Sponsorhip

Operating conditions

Two elements must be satisfied for the method to work:

Element 1:  Nozzle configuration
For JSE: an annular (or similar) convergent-divergent duct.  A critical parameter is the ratio of exit area to minimum area, Ae/Amin, of the duct. jse_nozzle.jpg (8017 bytes)
Fig. 1(a)  JSE nozzle geometry
For MESPI: a dual-stream nozzle with a convergent-divergent outer duct. A critical parameter  is the ratio of exit area to minimum area, Ae/Amin, of the outer duct.  The shape of the inner duct is arbitrary. mespi_nozzle.jpg (9294 bytes)
Fig. 1(b)  MESPI nozzle geometry
Element 2:  Nozzle pressure ratio

For both JSE and MESPI, the nozzle pressure ratio NPR (total pressure over ambient pressure) of the gas flow that promotes mixing must satisfy: (a) occurrence of sonic flow at Amin, and (b) generation of adverse pressure gradient in the vicinity of Ae.

The corresponding theoretical range of NPR is shown in Fig. 2 (green area). Experiments at Ae/Amin=1.25 have vaidated this prediction.

npr.jpg (13031 bytes)

Fig. 2  Nozzle pressure ratio for gas flow (green region).

Please download AIAA-2000-0093  (PDF) for more details on the operating conditions.
Also, see the
2D results for variations on the above nozzle arrangements.

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