head of an axial turbine in two-phased analysis

amirbhr · June 8, 2020, 04:40

Hello all!
I am simulating an axial water turbine within an open channel. The simulation has been done using a free surface method for two phases water and air. In cfd-post, I have a problem with the efficiency computation while calculating the net hydraulic head. I cannot find any way to calculate the efficiency directly and I have to find the head to evaluate the efficiency. Would anyone help me in this regard?

amirbhr · June 16, 2020, 12:18

any help would be greatly appreciated

Opaque · June 16, 2020, 12:51

Are you using the existing macro in CFD-Post for efficiency? If yes, do those macros work for multiphase simulations?

What is the formula you expect should be used for those calculations? perhaps with such information, someone in the forum can help realize it via expressions.

amirbhr · June 24, 2020, 10:50

Thanks, Opaque!
Yes, I used Macro icon, but I encountered the error "no total pressure in stn. frame".
Besides, I tried to use the formula T(torque on shaft) * omega / (rho * g * Q(mass flow rate) * H (net head over the axial turbine) ). In this stage, the calculation of the hydraulic head (H) is my question.

June 8, 2020, 04:40	head of an axial turbine in two-phased analysis	#1
amirbhr New Member amirbhr Join Date: Jul 2019 Posts: 4 Rep Power: 7	Hello all! I am simulating an axial water turbine within an open channel. The simulation has been done using a free surface method for two phases water and air. In cfd-post, I have a problem with the efficiency computation while calculating the net hydraulic head. I cannot find any way to calculate the efficiency directly and I have to find the head to evaluate the efficiency. Would anyone help me in this regard?

June 16, 2020, 12:18	need for help	#2
amirbhr New Member amirbhr Join Date: Jul 2019 Posts: 4 Rep Power: 7	any help would be greatly appreciated

June 16, 2020, 12:51		#3
Opaque Senior Member Join Date: Jun 2009 Posts: 1,832 Rep Power: 33	Are you using the existing macro in CFD-Post for efficiency? If yes, do those macros work for multiphase simulations? What is the formula you expect should be used for those calculations? perhaps with such information, someone in the forum can help realize it via expressions. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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June 24, 2020, 10:50		#4
amirbhr New Member amirbhr Join Date: Jul 2019 Posts: 4 Rep Power: 7	Thanks, Opaque! Yes, I used Macro icon, but I encountered the error "no total pressure in stn. frame". Besides, I tried to use the formula T(torque on shaft) * omega / *(rho g * Q**(mass flow rate) * H (net head over the axial turbine) ). In this stage, the calculation of the hydraulic head (H) is my question.