Transient Blade Row two adjacent rotating domains

istratik · February 22, 2022, 15:07

Dear all,
I would like to ask you if i could utilize transient blade row to simulate two adjacent contra rotating blade rows.
Current runs with Profile Transformation diverge and i wonder if this is due to a modelling error or transient blade row cannot simply solve two rotating domains.

Best regards,
Giannis

Opaque · February 22, 2022, 15:54

Your description is too generic.

Which kind of machine are you modeling? Axial, Radial, mixed? What is your blade/passage count? Any pitch change for the transient model?

What timestep are you using measured with respect to the 1 rev, or blade passing?

istratik · February 23, 2022, 03:43

Quote:

Originally Posted by Opaque

Your description is too generic.

Which kind of machine are you modeling? Axial, Radial, mixed? What is your blade/passage count? Any pitch change for the transient model?

What timestep are you using measured with respect to the 1 rev, or blade passing?

The machince consints of two axial fans. The front fan has 12 blades and the rear 8.
I think the question in its essecence is more generic, since it relates to whether CFX Transient Blade Row can solve two adjacent rotating blade rows. In the manual it is not stated clearly and the Frame Change option is Transient Rotor Stator, so it has me thinking

Opaque · February 23, 2022, 11:56

More than likely you have a setup error.

You have not shown how it is diverging, nor explained your approach to make it converge. Signs you need to read the sticky at the top of the forum, and the link about convergence Glenn usually refers to (I do not recall it)

ghorrocks · February 23, 2022, 17:48

Here is the divergence FAQ: https://www.cfd-online.com/Wiki/Ansy...do_about_it.3F

istratik · February 24, 2022, 04:39

Hey I might not be so clear, so I will restate my question which does not relate to divergion.
The question is whether transient blade row can be applied to two adjacent rotating bladerows (no stator inbetween).

Thank you for your answers and i will definetly look into divergence faq.
Giannis

Opaque · February 24, 2022, 10:45

It is supposed to work. If it does not you will need to prove (convince yourself) the feature is broken based on a proper setup; otherwise, there is a setup errror.

istratik · February 27, 2022, 14:51

Quote:

Originally Posted by Opaque

It is supposed to work. If it does not you will need to prove (convince yourself) the feature is broken based on a proper setup; otherwise, there is a setup errror.

Simulating the same configuration (Transient Blade Row/Profile Transformation) with the rear rotating domain set as stator, converged without any issues.

February 22, 2022, 15:07	Transient Blade Row two adjacent rotating domains	#1
istratik New Member Ioannis Stratikis Join Date: Jan 2022 Location: Thessaloniki Greece Posts: 6 Rep Power: 4	Dear all, I would like to ask you if i could utilize transient blade row to simulate two adjacent contra rotating blade rows. Current runs with Profile Transformation diverge and i wonder if this is due to a modelling error or transient blade row cannot simply solve two rotating domains. Best regards, Giannis

February 22, 2022, 15:54		#2
Opaque Senior Member Join Date: Jun 2009 Posts: 1,880 Rep Power: 33	Your description is too generic. Which kind of machine are you modeling? Axial, Radial, mixed? What is your blade/passage count? Any pitch change for the transient model? What timestep are you using measured with respect to the 1 rev, or blade passing? __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

February 23, 2022, 11:56		#4
Opaque Senior Member Join Date: Jun 2009 Posts: 1,880 Rep Power: 33	More than likely you have a setup error. You have not shown how it is diverging, nor explained your approach to make it converge. Signs you need to read the sticky at the top of the forum, and the link about convergence Glenn usually refers to (I do not recall it) __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

February 23, 2022, 17:48		#5
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,872 Rep Power: 144	Here is the divergence FAQ: https://www.cfd-online.com/Wiki/Ansy...do_about_it.3F __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

February 24, 2022, 10:45		#7
Opaque Senior Member Join Date: Jun 2009 Posts: 1,880 Rep Power: 33	It is supposed to work. If it does not you will need to prove (convince yourself) the feature is broken based on a proper setup; otherwise, there is a setup errror. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

February 24, 2022, 04:39		#6
istratik New Member Ioannis Stratikis Join Date: Jan 2022 Location: Thessaloniki Greece Posts: 6 Rep Power: 4	Hey I might not be so clear, so I will restate my question which does not relate to divergion. The question is whether transient blade row can be applied to two adjacent rotating bladerows (no stator inbetween). Thank you for your answers and i will definetly look into divergence faq. Giannis

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