Temperature and Specific Heat

General
1

Hello everyone,

I am working with the PyFR and need to understand how to set values in the config file that might have physical relevance. In particular, I am looking at the paper Iyer et al (2021) and I am adopting the geometry for a low-pressure turbine from http://www-g.eng.cam.ac.uk/whittle/T106/Start.html.

I anticipate that I am not an expert on turbines. My question is probably silly but I need to understand on what physical condition I may set CPT = 3.5 at the wall of the LPT. In other words, what values of the temperature T and of the specific heat cp I should consider in order to set this value for CPT? I know that the PyFR code is meant to work agnostically from the units but knowing how to set the aforementioned values might allow us to set the other parameters for BCs and ICs accordingly.

Thank you for all the hints you might give me.

Best,
Federico Cipolletta.

2

You can use SI units. An example of this can be seen in the Couette flow test case where:

cp = 1005.0
Uw = 70
H = 1.0
Pc = 100000.0
Tw = 300.0

where cp is the specific heat of air at 300 K, Uw is a velocity in metres per second, Pc is a pressure in Pascals, and Tw is the wall temperature in Kelvin.

Regards, Freddie.

3

Thank you, Freddie, for pointing this out. However, if I understand that correctly, here, H stands for the distance of the plates in the Couette Flow, as reported in Witherden et al (2014). Is that correct?

Why do you need to specify such value in the constants if you are not using that?

4

I presume it was included as a parameterisation for different height channels but it doesn’t seem to ever been used.

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