Learning Forum

[Manula Yasas]

Hello,

Im try to simulate solid solid separtion in cyclone separator. I have two solids with different densities. I want to separate lower density particle from vortex finder and higher density particle from cyclone bottom. I have two questions.

1. How can I reduce the incomplete tracks in my simulation.
2. How can I put mixture of two density particles to my simulation. If anyone knows..Please help me

[Rob]

Assuming you're using DPM (the only model which can give an incomplete track) just create a second injection which uses a different material. You'll need to create the first injection to get anthracite in the materials list, copy it (don't overwrite) and adjust to suit. You can also copy the original injection and modify if you don't want to set up from scratch. 

Incomplete is a different issue.  The warning is triggered by particles remaining in the system for too long (read up on how it works). Look at the tracks (colour by residence time) to see where they're getting stuck. Then look at the flow field to see why. Post images for review/comment.

What mesh & turbulence model did you use?

[Manula Yasas]

 

 

Following are the setup I used for this. Those are only changes I done in the setup. Other settings are defaults. Can you please check those and give a comment about this application and used models. (Are they ok or not)

 

I didn’t understand the steps to give two injections and track those injections in results. Can you please explain it again. Following is the mesh i using for the simulation.

 

Please help me to reduce the incomplete particle trackings and inject two density particles to cyclone separator.

 

 

 

[Rob]

On the ash-solid panel, click "Change/Create" and put in another name & density. Then "OK". Do NOT overwrite, you now have two particle materials. Copy injection-0 and on the new injection use the new material, mass flow etc. 

You've used a size distribution. That's OK to add particles to the domain, but less simple to figure out what went where. By having multiple injections you can set particle size and material to suit. 

Depending on particle mass loading you may, or may not need to couple the particles the flow: look up how the model works. 

The mesh looks a little coarse, but it's difficult to judge without looking at the flow field. Similarly, where are the particles getting stuck? I assume you set the vortex finder as trap & bottom outlet as escape? 

[Manula Yasas]

Particles are stuck at the cylinder of the cyclone. They didnt go to cone atleast. Im not clear about the adding two materials. I think this is the panel you mentioned above as ash solid panel. In there, when i click the change/create option, nothing happens. Can you please explain the steps clearly.

 

[Rob]

Change the material name to "Boris" then hit change/create. Don't overwrite. Your new material is now Boris.  I'll refrain from making any comments about UK politics.... 

Stuck in the cylinder or at the cylinder/cone joint? Pictures will help. 

[Manula Yasas]

 

Thank You very much. Now I got the two injwctions with different densities. After calculations, Do I want to save the particle trackings separately…And import them separately to results…

My another question is, how I can reduce the  number of particle tracks. Is it affect to the incomplete trackings. Following is the incomplete particle track picture.

 

In our experiments, we use rotary airlock to bottom of the cyclone, we use filter to top of the vortex finder and we set the blower after the filter at top of the vortex finder. What are the DPM boundary conditions can we use.

 

[Rob]

I'd do all of the post processing in Fluent. DPM and CFD Post tend not to work so well; if you do want to try the particle tracks can be saved & exported via the File menu. 

Looking at the particle tracks I suspect your problem is mesh related. Some of those tracks look more like particles bouncing around the top section than following the rotating flow: look at the apparent kinks in the trajectory plot. 

You also now want to look at velocity vectors on planes, try with vectors "in plane" and see what the flow is doing. 

In terms of DPM boundaries. What do you want to happen? Then look at the options and suggest what you think you should use. 

[Manula Yasas]

Thank you very much to your support.