Sonic flow for exhaust nozzle

beanlee999 · May 10, 2012, 12:42

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!

Far · May 10, 2012, 15:34

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.

May 10, 2012, 12:42	Sonic flow for exhaust nozzle	#1
beanlee999 New Member Choon Yee Join Date: May 2012 Posts: 13 Rep Power: 14	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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May 10, 2012, 15:34		#2
Far Senior Member Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,558 Blog Entries: 6 Rep Power: 54	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.