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Burner Design (swirl flow)
Posted 04.06.2012, 12:26 GMT-4 Fluid & Heat, Heat Transfer & Phase Change, Geometry 5 Replies
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My team is designing a burner for which we have to construct a cylindrical pipe within a cylindrical pipe (Concentric). Air flows inside the inner cylinder and Syn gas flows through the outer cylinder. After a certain height both the gases mix at the top inside the burner. I have completed modelling the burner as I wanted using COMSOL. For analyzing the velocity and temperature profiles of both the gases separately, I am not able to select the concentric pipes (inner and outer cylinders) in separate unions. Both are getting selected in same union. I have not had any formal training session of COMSOL. Can anyone please help me with this problem?
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5 Replies Last Post 18.06.2012, 14:02 GMT-4
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Posted:
1 decade ago
Any other voluntary suggestions related to this design will be hugely appreciated.
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Posted:
1 decade ago
Hi
its an impressive geometry you have mastered there, and all in COMSOL !
But still, I believe you will have to tweak it a bit further to avoid overlaps and silver edges, then you must use "assembly mode" to dedouble your boundaries, but previously you will need to do some grouping Unions) to minimise the pair creations
First you have your perforations 1,2,3,4: I would only keep 1 & 3 have them start at 0.2 and go for 0.4" all the way through, then disable Perforations 2&4 this removes some silver edges where you have the tube flush with the transverse perforations and the interiour boundaries will be removed by the union
Then you need to group the tubing into 3 objects by unions and differences try:
an union1 of ext10,13,14,15,16 (do not keep objects nor interiour boundaries)
then another union2 with mir2, cone2 ext7, 8, 9 and all the ext12(...) do not keep the objects nor interiour boundaris
then a last union3 with ext1,2 mir1 all ext3,5(...), do not keep objects nor ineriour boundaries
The last union3 has small faces that might need to be removed at the perforation outlets (to be considered)
make a difference1 between union 2 - union3 (keep input obkect no interiour boundaries,
then a difference2 between union1 - union3 (keep input objects, no interiour boundaries)
then a difference 3 between diff2-diff1 (keep input objects, no interiour boundaries)
The you need to remove the extra objects "Delete entities" union 1 & 2, and diff 2
Then use geometry assembly mode do not create pairs, keep imprints, it's in your case better to make the identity pairs manually.
If you move to the material section you should now have only 3 entities in the geometry selection list, for your 3 fluids inlets
You might want to keep certain internal boundaries to ease the meshing, such as at the cone tube sections caps, and you might want to further remove the small extra surfaces for the perforatiosn and get them flush with the tube
Then you need to make indentity selections for the regions where the fluids mix. For this I would suggest to use extensively the Definition - Selections first, and make 3 extra views where you add a delete entity and select 1,2,3 so in each view you have ONLY one geometrical domain then its easier to catch the common interface surfaces.
Once you have the selections, you can create youre Identity pairs too.
For the mesh start meshing the source identity pais and copy the mesh onto the destination of you identity pairs, then mesh the rest, you will need a lot of RAm as you need a dense mesh, because of the object ratios.
Do not forget to check the boundary meshings, asI'm not sure hoe these adapt to the "thin tubing" edge regions
Finally, I would suggest to start setting up the physics ona much simpler i.e. 2D-axi partial model, when your physics are all set up you can make the one for the large model as you then know better the different BC settings, also start in laminar, then only move to turbulent (even consider useing a stationary laminar flow as initial velocity conditions for the turbulent case)
do not forget you need 3 inlet BC and 1 outlet (I suppose) for the fluid part and 3 inlet temperatures and one outflow for the thermal part of NITF, plus whatever other BCs
Finally for the selection of several individual physics and one commo, the one common is quicker to set up, but might be trickier to get to solve, you will probably need to play with the order of the segregated solver
I hope these suggestions might help you on the way
--
Have fun Comsoling
Ivar
its an impressive geometry you have mastered there, and all in COMSOL !
But still, I believe you will have to tweak it a bit further to avoid overlaps and silver edges, then you must use "assembly mode" to dedouble your boundaries, but previously you will need to do some grouping Unions) to minimise the pair creations
First you have your perforations 1,2,3,4: I would only keep 1 & 3 have them start at 0.2 and go for 0.4" all the way through, then disable Perforations 2&4 this removes some silver edges where you have the tube flush with the transverse perforations and the interiour boundaries will be removed by the union
Then you need to group the tubing into 3 objects by unions and differences try:
an union1 of ext10,13,14,15,16 (do not keep objects nor interiour boundaries)
then another union2 with mir2, cone2 ext7, 8, 9 and all the ext12(...) do not keep the objects nor interiour boundaris
then a last union3 with ext1,2 mir1 all ext3,5(...), do not keep objects nor ineriour boundaries
The last union3 has small faces that might need to be removed at the perforation outlets (to be considered)
make a difference1 between union 2 - union3 (keep input obkect no interiour boundaries,
then a difference2 between union1 - union3 (keep input objects, no interiour boundaries)
then a difference 3 between diff2-diff1 (keep input objects, no interiour boundaries)
The you need to remove the extra objects "Delete entities" union 1 & 2, and diff 2
Then use geometry assembly mode do not create pairs, keep imprints, it's in your case better to make the identity pairs manually.
If you move to the material section you should now have only 3 entities in the geometry selection list, for your 3 fluids inlets
You might want to keep certain internal boundaries to ease the meshing, such as at the cone tube sections caps, and you might want to further remove the small extra surfaces for the perforatiosn and get them flush with the tube
Then you need to make indentity selections for the regions where the fluids mix. For this I would suggest to use extensively the Definition - Selections first, and make 3 extra views where you add a delete entity and select 1,2,3 so in each view you have ONLY one geometrical domain then its easier to catch the common interface surfaces.
Once you have the selections, you can create youre Identity pairs too.
For the mesh start meshing the source identity pais and copy the mesh onto the destination of you identity pairs, then mesh the rest, you will need a lot of RAm as you need a dense mesh, because of the object ratios.
Do not forget to check the boundary meshings, asI'm not sure hoe these adapt to the "thin tubing" edge regions
Finally, I would suggest to start setting up the physics ona much simpler i.e. 2D-axi partial model, when your physics are all set up you can make the one for the large model as you then know better the different BC settings, also start in laminar, then only move to turbulent (even consider useing a stationary laminar flow as initial velocity conditions for the turbulent case)
do not forget you need 3 inlet BC and 1 outlet (I suppose) for the fluid part and 3 inlet temperatures and one outflow for the thermal part of NITF, plus whatever other BCs
Finally for the selection of several individual physics and one commo, the one common is quicker to set up, but might be trickier to get to solve, you will probably need to play with the order of the segregated solver
I hope these suggestions might help you on the way
--
Have fun Comsoling
Ivar
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Posted:
1 decade ago
Hi Mr. Kjelberg,
Thanks a lot for spending time to read my question and giving your suggestion. I will implement the ideas you gave us and come back to you for more ideas.
Thanks a lot for spending time to read my question and giving your suggestion. I will implement the ideas you gave us and come back to you for more ideas.
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Is it possible to run the model assuming a multi-phase flow??
If yes, can you give us some ideas based on this? That'd be very helpful for us
Thank you.
If yes, can you give us some ideas based on this? That'd be very helpful for us
Thank you.
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi
its an impressive geometry you have mastered there, and all in COMSOL !
But still, I believe you will have to tweak it a bit further to avoid overlaps and silver edges, then you must use "assembly mode" to dedouble your boundaries, but previously you will need to do some grouping Unions) to minimise the pair creations
First you have your perforations 1,2,3,4: I would only keep 1 & 3 have them start at 0.2 and go for 0.4" all the way through, then disable Perforations 2&4 this removes some silver edges where you have the tube flush with the transverse perforations and the interiour boundaries will be removed by the union
Then you need to group the tubing into 3 objects by unions and differences try:
an union1 of ext10,13,14,15,16 (do not keep objects nor interiour boundaries)
then another union2 with mir2, cone2 ext7, 8, 9 and all the ext12(...) do not keep the objects nor interiour boundaris
then a last union3 with ext1,2 mir1 all ext3,5(...), do not keep objects nor ineriour boundaries
The last union3 has small faces that might need to be removed at the perforation outlets (to be considered)
make a difference1 between union 2 - union3 (keep input obkect no interiour boundaries,
then a difference2 between union1 - union3 (keep input objects, no interiour boundaries)
then a difference 3 between diff2-diff1 (keep input objects, no interiour boundaries)
The you need to remove the extra objects "Delete entities" union 1 & 2, and diff 2
Then use geometry assembly mode do not create pairs, keep imprints, it's in your case better to make the identity pairs manually.
If you move to the material section you should now have only 3 entities in the geometry selection list, for your 3 fluids inlets
You might want to keep certain internal boundaries to ease the meshing, such as at the cone tube sections caps, and you might want to further remove the small extra surfaces for the perforatiosn and get them flush with the tube
Then you need to make indentity selections for the regions where the fluids mix. For this I would suggest to use extensively the Definition - Selections first, and make 3 extra views where you add a delete entity and select 1,2,3 so in each view you have ONLY one geometrical domain then its easier to catch the common interface surfaces.
Once you have the selections, you can create youre Identity pairs too.
For the mesh start meshing the source identity pais and copy the mesh onto the destination of you identity pairs, then mesh the rest, you will need a lot of RAm as you need a dense mesh, because of the object ratios.
Do not forget to check the boundary meshings, asI'm not sure hoe these adapt to the "thin tubing" edge regions
Finally, I would suggest to start setting up the physics ona much simpler i.e. 2D-axi partial model, when your physics are all set up you can make the one for the large model as you then know better the different BC settings, also start in laminar, then only move to turbulent (even consider useing a stationary laminar flow as initial velocity conditions for the turbulent case)
do not forget you need 3 inlet BC and 1 outlet (I suppose) for the fluid part and 3 inlet temperatures and one outflow for the thermal part of NITF, plus whatever other BCs
Finally for the selection of several individual physics and one commo, the one common is quicker to set up, but might be trickier to get to solve, you will probably need to play with the order of the segregated solver
I hope these suggestions might help you on the way
--
Have fun Comsoling
Ivar
Is it possible to run the model assuming a multi-phase flow??
If yes, can you give us some ideas based on this? That'd be very helpful for us
Thank you.