Determine a numerical value of 〈Z〉

Real-gas behavior for turbomachinery is sometimes empirically accommodated

through the expression W

∙

=  〈Z〉W

∙ ig, where W

∙ ig is the ideal-gas mechanical power

and 〈Z〉 is some suitably defined average value of the compressibility factor.

(a) Rationalize this expression.

(b) Devise a turbine example incorporating real-gas behavior via residual properties,

and determine a numerical value of 〈Z〉 for the example.