[Bhanu Swaroop]

Hi,

I am trying a design centrifugal compressor that runs with carbon dioxide as fluid. For this I have created an RGP file from NIST database following the instructions given in Fluent beta features manual( It was mentioned in the manual it works for CFx too). The issue is I know that the range of table is large enough but I am still getting "out of bounds error solving the issue by clipping, please try to increase the range of the table". The table is created for 220k-600k temperature and 2MPa to 20MPa pressure. My compressor was designed for pressure ratio of 2 with an initial pressure of 6.5 MPa at room temperature.

So is there anyway to solve this or is there any other method for constructing an RGP table?

[ghorrocks]

You can get this warning if your simulation is diverging. Are you sure your simulation is converging?

Also, as the flow goes through the device are you sure it stays within your table range? There will be a max and min of all variables and they may reach your table range.

[Opaque]

You are trying a use case that is not trivial, and you have not described your previous approach.

For example:
1 - have you run the model using CO as an ideal gas? How was the convergence? any issues to obtain a reasonable converged answer
2 - have you run the model using CO RGP Table under conditions where the gas remains ideal? does it converge similarly to attempt (1)? If not, why? Is it a problem in the RGP-provided data, or else?
3 - If your operating conditions include liquid CO2, and hopefully tiny amounts, have you started from a previously converged solution using CO2 as an ideal gas?

As your model becomes more complex, you NEED to have fixed points where you are 1000% certain there are no user errors, and you do not have to go back to re-check your work; therefore, you can focus on what was last changed.