Radial Turbine

alican9547 · March 8, 2014, 06:01

Hello dear friends,

I design a Francis Turbine in ANSYS. I used Bladegen. In CFX Solution Section, I see '' A wall has been placed at portion(s) of an OUTLET boundary condition (at 35.7% of the faces, 19.9% of the area) to prevent fluid from flowing into the domain.''

I did some searches and found a solution which is usage of opening type boundary condition in this forum and saw how to make opening boundary condition. I defined Total pressure for flow entering the opening and Static pressure for flow exiting the opening in setup section. But it did not solve and I don't still understand that how can I define my flow rate when I define this. There is no option to define flow rate at the opening boundary condition.

I calculated that the efficiency is approximately %98. How can I prevent the solution putting the wall there? Can the wall affect my results so much?

Thanks...

ghorrocks · March 9, 2014, 05:35

The "A wall has been placed..." message is a FAQ: http://www.cfd-online.com/Wiki/Ansys...f_an_OUTLET.22

First of all, note it is a warning, not an error. You may be accurate enough despite the warning. But to eliminate the problem (and it usually is a problem) you should move the outlet to somewhere no back flow exists. This usually means moving the outlet boundary further downstream.

March 8, 2014, 06:01	Radial Turbine	#1
alican9547 New Member Ali Can İspir Join Date: Nov 2013 Posts: 1 Rep Power: 0	Hello dear friends, I design a Francis Turbine in ANSYS. I used Bladegen. In CFX Solution Section, I see '' A wall has been placed at portion(s) of an OUTLET boundary condition (at 35.7% of the faces, 19.9% of the area) to prevent fluid from flowing into the domain.'' I did some searches and found a solution which is usage of opening type boundary condition in this forum and saw how to make opening boundary condition. I defined Total pressure for flow entering the opening and Static pressure for flow exiting the opening in setup section. But it did not solve and I don't still understand that how can I define my flow rate when I define this. There is no option to define flow rate at the opening boundary condition. I calculated that the efficiency is approximately %98. How can I prevent the solution putting the wall there? Can the wall affect my results so much? Thanks...

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March 9, 2014, 05:35		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	The "A wall has been placed..." message is a FAQ: http://www.cfd-online.com/Wiki/Ansys...f_an_OUTLET.22 First of all, note it is a warning, not an error. You may be accurate enough despite the warning. But to eliminate the problem (and it usually is a problem) you should move the outlet to somewhere no back flow exists. This usually means moving the outlet boundary further downstream.