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Sonic flow for exhaust nozzle

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Old   May 10, 2012, 11:42
Default Sonic flow for exhaust nozzle
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Choon Yee
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Hi all,

I am doing a simulation for an convergent exhaust nozzle.

Can anyone provide me with advice on what to look out for during initialisation, if my simulation is likely to give me a sonic flow at the nozzle exit?

I am doing a compressible, turbulent flow analysis, with the pressure inlet used for nozzle inlet, and pressure outlet as nozzle outlet.

My previous attempts to run this simulation have kind of failed. I believe the nozzle inlet pressure is high, probably leading to sonic flow occuring at the nozzle exit. However, i believe my initialisation variables are not suitable to give me a sonic flow condition at the nozzle exit plane. Therefore, my simulation leads to divergence or poor convergence.

thank you!
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Old   May 10, 2012, 14:34
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1. The sonic flow for exhaust nozzles generally develops at after the nozzle and in the atmospheric.

2. You should apply the static pressure at the outlet according to your pressure ratio calculation.

3. create the large enclosure (at-least 20 lengths of nozzle) at the outlet plane and provide static pressure at the outlet of this enclosure. In this way the flow at the nozzle exit develops in a more natural way.

4. This is my personnel experience.
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