Compressible Flow through a Nozzle/Diffuser
Compressible Flow through a Nozzle/Diffuser
This Demonstration models compressible flow through a reversible nozzle/diffuser. The inlet pressure , the exit velocity , and the exit temperature are calculated from mass and energy balances during air flow. Because it is reversible, the entropy change is zero. The air exits as a free jet at atmospheric pressure (=101.3kPa). Set the outlet diameter and inlet velocity with the sliders. When <, the device acts as a nozzle, with the inlet pressure higher than the exit pressure in order to provide the energy needed to accelerate the air through the nozzle. When >, the device operates as a diffuser, with the exit pressure higher than the inlet pressure . When "plots" is selected, the velocity or temperature is plotted as a function of outlet diameter for compressible air flow (blue) and incompressible air flow (green). Air is assumed to behave as an ideal gas and all flow is subsonic.
P
1
u
2
T
2
P
2
d
2
u
1
d
2
d
1
(>)
P
1
P
2
d
2
d
1
(<)
P
1
P
2