Learning Forum

[Abhi1311]

Greetings,

I am modelling a gas flow inside a chamber with an inlet and a outlet. I've given inlet pressure as 202650 Pascals and my inlet temperature of gas is 308.15 K. I've given the body temperature as 297.15 K in initialization window as well as patched the chamber with 101325 Pascal as shown in some random youtube tutorial video. When i run my case the pressure falls and then stays in between 200-300 Pascals although the temperature bar acts normal. Can anyone tell me where my case is going wrong, it is very urgent. Also, when i specify my mass flow rate at a certain value let's say 4L/min. The values keeps on fluctuating throughout the calculation and i desire it to stay constant throughout the calculation.

Regards,

Abhishek  

[Amine Ben Hadj Ali]

Please add screenshots of pressure inlet bc, initialization panel, operating condition and contour plot.

[Abhi1311]

Thank you for replying!

Please do let me know if you need anything else.

Yes sure I will attach files below.

[Amine Ben Hadj Ali]

Which values are you now expecting to see? By the way you are not now fixing the inlet total pressure as you mentioned in your post. You are using a mass flow inlet and this would lead to a variable total pressure to reach desired input mass flow.

[Abhi1311]

Yes i told you I'm giving inlet as 4l/min, the issue is that during the calculation the mass flow rate varies a lot and is not constant at all. I've attached a file for you to see what i mean. How can i rectify this issue?

Regards,

Abhishek

[Amine Ben Hadj Ali]

And this plot corresponds to what? Mass flow rate at outlet? I see you are using real gas this is prone to stability issues and convergence is not as easy as for constant material properties or ideal gas. So why real gas? Is this required here?

What is the material?

[Abhi1311]

a. This plot represents mass flow rate from inlet and i am using real gas as we later need to do the experiment in real life so i want to see and compare the results       in future.

b. Our input gas is Methane with properties changed to "Real Gas Peng Robinson" as on researching in the manual i found out this works best with fluids under     pressure and temperature change.

c. The material we are using is 316 Stainless Steel.

Please feel free to correct me wherever you feel like.

Regards,

Abhishek

[Amine Ben Hadj Ali]

Can you please check the flux report at inlet: what does the mass flow tell you there?

Doing experiments in real life is not an argument for using real gas EOS. If real gas EOS is not required I won't use it at all.

I recommend Aungier Kwong real gas EOS: but all EOS are pretty similar.

 

Stainless Steel for what? for the walls? If the walls are not resolved that does not play any role..

[Abhi1311]

Thank you for your time and consideration.

a. I will check the flux report at inlet soon,but what to do with the low pressure results i'm getting? 

 

b. Yes the whole body is made of Stainless steel and appropriate boundary conditions were applied on walls of the model.

Regards,

Abhishek

[Amine Ben Hadj Ali]

And by checking please reconsider how your domain is meshed: from parts of the screenshots the grid is not suitable at all. I would go for more cells across the gap between the two large walls..

[Rob]

If you calculate the inlet density based on temperature & pressure and compare it to the outlet density, how much change is there?  

[Abhi1311]

Thank you for you help, i will look into it

Regards

Abhishek

[Abhi1311]

I will look into your query soon and reply to you appropriately.

Regards 

Abhishek