CFX: Transient sim with fluid-fluid domain interface

farzola · April 3, 2010, 12:44

Hello all,
I'm simulating a Kaplan hydraulic turbine. I got a good convergence in steady state, but I'm studying unsteady flows and of course is needed to carry out transient simulations.

I'm using a fifth part of runner subdomain and a complete draft tube geometry (the water conduit to the exit), this is equivalent to said a pitch angle for side one equal to 72 degrees and a pitch angle for side two equal to 360 degrees. Then I can see a very good behavior of oscillations due to blade passage frequency in the outlet of the runner but it didn't pass to the draft tube subdomain

. So, what's happens? From the draft tube point of view it's as the fifth part of runner is a total water passage way.

Someone can give me a recommendation to try to solve it.

ghorrocks · April 4, 2010, 08:34

Sorry, I don't understand your question.

brunoc · April 6, 2010, 13:05

Fidel,
Did you remember to check the pitch change on the rotor-draft tube interface? That seems to be the problem.

brunoc · April 6, 2010, 13:07

Fidel,
From what you said you have two domain interfaces. Did you check the pitch change on both of them?

farzola · April 7, 2010, 16:08

Quote:

Originally Posted by brunoc

Fidel,
Did you remember to check the pitch change on the rotor-draft tube interface? That seems to be the problem.

I'm setted a pitch change between rotor and draft tube equal to 72°/360° and a pitch change between distributor and rotor equal to 15°/72°. Is that correct?

April 3, 2010, 12:44	CFX: Transient sim with fluid-fluid domain interface	#1
farzola New Member Fidel Arzola Join Date: Mar 2010 Location: Venezuela Posts: 5 Rep Power: 16	Hello all, I'm simulating a Kaplan hydraulic turbine. I got a good convergence in steady state, but I'm studying unsteady flows and of course is needed to carry out transient simulations. I'm using a fifth part of runner subdomain and a complete draft tube geometry (the water conduit to the exit), this is equivalent to said a pitch angle for side one equal to 72 degrees and a pitch angle for side two equal to 360 degrees. Then I can see a very good behavior of oscillations due to blade passage frequency in the outlet of the runner but it didn't pass to the draft tube subdomain . So, what's happens? From the draft tube point of view it's as the fifth part of runner is a total water passage way. Someone can give me a recommendation to try to solve it. __________________ Thanks, Fidel

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April 4, 2010, 08:34		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,854 Rep Power: 144	Sorry, I don't understand your question.

April 6, 2010, 13:05		#3
brunoc Senior Member Bruno Join Date: Mar 2009 Location: Brazil Posts: 277 Rep Power: 21	Fidel, Did you remember to check the pitch change on the rotor-draft tube interface? That seems to be the problem.

April 6, 2010, 13:07		#4
brunoc Senior Member Bruno Join Date: Mar 2009 Location: Brazil Posts: 277 Rep Power: 21	Fidel, From what you said you have two domain interfaces. Did you check the pitch change on both of them?