negative efficiency
 

hello everyone

I am reading "Fine turbo tutorial guide"
I've done the example for Hydraulic turbine-Francis , every thing is ok but the result for efficiency is negative value
I set the rotation speed= -500.0 as said in the tutorial
these are the results in the ".mf" file under "global performance" part :


Static_pressure_rise -56981.
Absolute_total_pressure_rise -55488.
Static_Head -5.8027 [m]
Absolute_total_Head -5.6506 [m]

Static_temperature_rise 0.53888E-02
Absolute_total_temperature_rise 0.57514E-02

Efficiency -0.86326 (based on total pressure rise and power)

Axial_thrust -11945. [N]
Torque -329.92 [N m]
Power 17275. [w]

I think the problem is in the definition that it uses for computing efficiency , but i don't know how to correct it
could anyone help me?

thanks