[Norflow]

What is the proper formula (using CEL expressions) to calculate the "net head" of a hydraulic turbine in CFD-Post?

Would it be the difference in total pressure between the inlet (upstream of the turbine where the flow field is relatively stable) and the outlet (downstream of the turbine where the flow has a moderate swirl) divided by the density of water and gravity constant? See below...

Hnet = (massFlowAve(Total Pressure)@Inlet-massFlowAve(Total Pressure)@Outlet) / (p * g)

Assuming that I have properly set up the simulation using suitable BCs and appropriate solver models. This results in the proper units, but am I missing something?

[Opaque]

The formal energy change across the machine should be

Energy Change = massFlowAve(Stationary Frame Total Enthalpy)@Inlet-massFlowAve(Stationary Frame Total Enthalpy)@Outlet)

If you assume negligible change in temperature (for incompressible flows), the change of Stationary Frame Total Energy should reduce to the change of Stationary Frame Total Pressure, correct ?

h_tot_stn = h_stat + p / rho + V_stn^2 / 2

Hope the above helps,

[Norflow]

Thank you for your reply, Opaque.

I am modelling an axial flow turbine, through a straight horizontal pipe (with a reduced area at the throat of the turbine). I don't have any information regarding HWL and TWL elevations, so I cannot calculate static head at inlet or outlet.

Alternatively, I am trying to simulate different flows (Q - m^3/s) at certain turbine speeds (omega - rpm), to calculate the "experimental" net head through the turbine. Is this possible?

[Norflow]

Can anyone else shed some light on this subject?!