Learning Forum

[Dario De Domenico]

Good afternoon all,

I designed a cryogenic centrifugal pump for liquid hydrogen and I simulated it in CFX 22.2 trying to account for density variation throughout the impeller. In particular, density is a function of both temperature and pressure. Therefore, instead of inserting a mathematical expression in a polynomial form, I created a table in Excel in the .csv format where the first two columns contain the values of temperature and pressure and the last column the values of density corresponding to a specific couple of temperature and pressure values. I managed to import the table in CFX by right-clicking on User Functions > Insert > Table Function > Import..., but when I edit the density under the material's properties, the software requires to specify an index between brackets. If I type T,p (to make the software understand that density varies with temperature and pressure) I get the following error:

Does anyone know how to sort out this problem?

I tried to type just T or p but doing so I am afraid the software is interpreting density as a function of only one variable.

Thanks in advance for your help!

Kind Regards,
Dario De Domenico

[DrAmine]

Ansys CFX as the error clearly tells is expecting a single arugment table.

What you require is probably to create your own Real Gas Property Table.

[Dario De Domenico]

Many thanks for your reply, Dr Amine!

Could you please tell me where to find a guide for the creation of my own Real Gas Property Table?

Kind Regards,

Dario

[DrAmine]

What is the fluid in your pump?

[Dario De Domenico]

It's liquid hydrogen (in detail, normal hydrogen, a mixture of parahydrogen and orthohydrogen)

[DrAmine]

Refer to Fluent beta Features to learn how to generate RGP Tables for materials which are already available from REFPROP (like H2). The tables can be then used in Ansys CFX. So you do not need to go through manually creating the tables which is challenging.

[Dario De Domenico]

Ok, I'll have a look at Fluent beta Features. Thank you very much for your help!

If I have further doubts about this topic, may I submit my questions here?

[DrAmine]

I think better to create a new thread. Please in Ansys CFX turn on beta features to be able to use subcooled liquid properties.

[Dario De Domenico]

All right, thank you very much!