How to define the custom characteristic line while setting attribute for compressor?

[ronitd07]

Hello,

I am trying to use custom characteristic curve for offdesign calculation of my compressor. I have followed the documentation given at https://tespy.readthedocs.io/en/dev/advanced_features/characteristics.html . But I dont understand how can i define at compressor set attribute to use my defined characteristic line

from tespy.tools.characteristics import CharLine
from tespy.tools.characteristics import load_custom_char

gen_char = load_custom_char('eta_s_test', CharLine)
self.cp1.set_attr(eta_s=self.eta_compressor, design=['eta_s'], offdesign = ['eta_s_test'])

but i ger error - ValueError: Available parameters for (off-)design specification of component compressor1 are: P, pr, dp, eta_s, eta_s_char, igva, char_map_eta_s, char_map_eta_s_group, char_map_pr, char_map_pr_group.

in char_lines.json i have below entry

   {
    "eta_s_test": {
            "x": [0, 0.5, 1, 1.5, 2],
            "y": [0.8, 0.9, 1, 1.1, 1.2]
                }
    }           

[fwitte]

Hi @ronitd07,

have a look at this section: https://tespy.readthedocs.io/en/main/building_blocks/components.html#component-characteristics, specifically the second block of code for the Turbine eta_s_char. You do not rename the characteristic, but you pass to the component the changed data:

line = CharLine(
    x=[0.1, 0.3, 0.5, 0.7, 0.9, 1, 1.1],
    y=np.array([0.6, 0.65, 0.75, 0.82, 0.85, 0.855, 0.79]) / eta_s_design
)
t.set_attr(eta_s_char={'char_func': line})