[David Sauter]

Hello Everyone,

I have performed an unsteady simulation of a 2-stage axial steam turbine using an in-house solver. Now I am calculating the efficiency using actual enthalpy drop divided by isentropic enthalpy drop. The enthalpy values are given as circumferentially mass-averaged distributions at the inlet and outlet planes, i.e. as radial profiles. Therefore, also the calculated efficiency is in form of a radial profile.

My question is: If I want to calculate a global efficiency, how do I average it properly? Can I just integrate it in radial direction and then divide it by the blade height? Or do I have to use mass-averaging? If so, which mass flow do I use, inlet or outlet mass flow?

Thank you for your answers!