Learning Forum

[Barnaby_D]

Hi all,

Would anyone be able to advise on what I'm doing wrong/not doing? I'm trying to simulate a flat plate film cooling test using the Discrete Phase Model Injection method. I wanted to do this because it will be extended to represnt multiple film cooling holes on a turbine blade and it would save having to model/mesh all these individual holes. I've also already run and validated a fully modelled hole with the plate simulation so I know what I'm expecting to see.

In the Set Injection Properties box I've set it as a single injection type and set my coordinates, velocity vector, temperature and diameter. I can see the particle when I view it in the graphics window.

My problem is when I run my simulation there looks to be no influence on the temperature of the fluid i.e. my fluid has a 400K inlet and the coolant is 300K and the temperatures are all 400K.

Any help would be great!

[Rob]

Posting in Feedback for a CFD question isn't ideal, so will not speed up getting an answer. 

What are your particle track temperatures? Are you running coupled with the carrier phase? 

[Barnaby_D]

Hi Rob,

Thanks for the reply, sorry I didn't realise I was positing this in feedback, I've not used this forum before!

Since posting this I've managed to get the energy interaction between the particles to work after checking the Interaction with Continuous Phase box. However I'm not getting the correct temperatures i.e. i'm defining the injeciton at 300K but my lowest particle temperature is 374K.

 

Thanks

[Rob]

No worries, it's at the top of the thread. You'll want Fluids https://forum.ansys.com/forums/forum/discuss-simulation/fluids/ for this one. 

Can you post an image? I suspect the injection is added at 300K but the tracks/point data is after a small distance from the inlet so it's had time to warm up. How big are the particles?

 

[Barnaby_D]

Is there a way to transfer this post onto fluids?

My contours are below, I've set the particle diameter as 0.008m but this was because at first I thought this was the diameter of the injection outlet (since the hole I'm trying to simulate has a diameter of 8mm). Since I don't have any idea in particular what diameter I should, use is it best just to vary the diameter parametrically? I'm also using the default settings for DPM Iteration Interval (10) and Max number of steps (50000) 

Thanks

[Rob]

That's the carrier phase result, so makes sense that you'd not cool it to the DPM temperature.  There are some relationships for droplet diameter and hole size, you'll need material properties and speed too (I think). Plot the DPM tracks and see what the particle temperature is. 

We can't move threads at present, it's on the list of things we want. 

[Barnaby_D]

 

Thanks Rob,

So if I understand correctly, the reason my ‘starting’ particle temperatures are not the same as my inlet condition is because as soon as the mainstream flow interacts with the particles it increases the temperature of the particles and as you say, since the particle tracking is such a small distance the initial temperature for this steady simulation does as 374K not 300K.

EDIT** I realise I've been plotting just the static temperature so the temperature of the bulk flow, whereas I've been wanting the particle variable-> particle temperature instead.

 

Thanks Rob!

[Rob]

Yes, plot the particle temperature. It may still be marginally off the 300K but not by 74K. 

[Barnaby_D]

Yep, after plotting the particle temperature I get an inlet of 300K as I would expect.

Thanks