Discrete Phase Modeling (DPM) for Liquid Fuel Combustion

anu4anusai · March 30, 2020, 00:35

Hi all,

I am trying to simulate hot flow in swirl stabilised combustor.

Atomiser model used : pressure swirl.

When i run, the residuals are not converging.

Also the dpm plots such as mass in domain, mass evaporated etc is also fluctuating cyclically. I am also getting a warning message : Atomization model is not valid under the conditions (every 700th iteration).

How do we check convergence in this case? Hereby attaching the plots.

Screenshot from 2020-03-30 09-00-27.png

Screenshot from 2020-03-30 09-00-06.png

Screenshot from 2020-03-30 08-59-46.png

Screenshot from 2020-03-30 09-00-49.png

vinerm · March 30, 2020, 10:49

If you are getting a Warning that the model is not valid, then certainly there are some conditions that are not matching with those for the pressure-swirl atomizer to work. LISA model, on which this model is based, requires few checks to be done. If the field parameters do not pass those checks, Fluent gives this warning. It could be that flow is not enough to cause instability that is required for the breakup and won't cause any droplets to form.

As far as the simulation is concerned, residuals look alright. The jumps in the monitors are due to injection of particles. The residuals and source values change whenever the particles are injected and those are not injected at all time-steps. So, you need to have a re-look at the setup and the conditions.

anu4anusai · March 31, 2020, 05:53

Thank you for your reply. So in this case, what are conditions i need to check?

And how to evaluate the convergence of the solution?

vinerm · March 31, 2020, 06:05

I'd recommend you to go through the relevant paper

https://www.researchgate.net/publica...the_Near_Field

Rajasekar_K · February 20, 2021, 06:26

Discrete Phase Modeling (DPM) for Liquid Fuel Combustion

Hi i am also encountering same problem in my simulation, did you find any solution for that if it is shared it would be helpful for me

March 30, 2020, 00:35	gas turbine spray combustion using dpm	#21
anu4anusai New Member Anusai Ramankutty Join Date: Dec 2019 Posts: 9 Rep Power: 6	Hi all, I am trying to simulate hot flow in swirl stabilised combustor. Atomiser model used : pressure swirl. When i run, the residuals are not converging. Also the dpm plots such as mass in domain, mass evaporated etc is also fluctuating cyclically. I am also getting a warning message : Atomization model is not valid under the conditions (every 700th iteration). How do we check convergence in this case? Hereby attaching the plots. Screenshot from 2020-03-30 09-00-27.png Screenshot from 2020-03-30 09-00-06.png Screenshot from 2020-03-30 08-59-46.png Screenshot from 2020-03-30 09-00-49.png

March 30, 2020, 10:49	Warning and Conditions	#22
vinerm Senior Member Vinerm Join Date: Jun 2009 Location: Nederland Posts: 2,946 Blog Entries: 1 Rep Power: 36	If you are getting a Warning that the model is not valid, then certainly there are some conditions that are not matching with those for the pressure-swirl atomizer to work. LISA model, on which this model is based, requires few checks to be done. If the field parameters do not pass those checks, Fluent gives this warning. It could be that flow is not enough to cause instability that is required for the breakup and won't cause any droplets to form. As far as the simulation is concerned, residuals look alright. The jumps in the monitors are due to injection of particles. The residuals and source values change whenever the particles are injected and those are not injected at all time-steps. So, you need to have a re-look at the setup and the conditions. __________________ Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority.

March 31, 2020, 06:05	Lisa	#24
vinerm Senior Member Vinerm Join Date: Jun 2009 Location: Nederland Posts: 2,946 Blog Entries: 1 Rep Power: 36	I'd recommend you to go through the relevant paper https://www.researchgate.net/publica...the_Near_Field __________________ Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority.

February 20, 2021, 06:26	Lisa	#25
Rajasekar_K New Member Rajasekar Join Date: Nov 2019 Posts: 4 Rep Power: 6	Discrete Phase Modeling (DPM) for Liquid Fuel Combustion Hi i am also encountering same problem in my simulation, did you find any solution for that if it is shared it would be helpful for me

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March 31, 2020, 05:53		#23
anu4anusai New Member Anusai Ramankutty Join Date: Dec 2019 Posts: 9 Rep Power: 6	Thank you for your reply. So in this case, what are conditions i need to check? And how to evaluate the convergence of the solution?