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Hi. As far as I know, Ross does not support mass coefficients in interconnections, e.g. the [M] and [m] in your equations above. I believe it is only stiffness and damping. And if I remember correctly, the cross-coupled mass-term [m] used to be small for the seals and for the impeller/diffuser interaction? So to use the current capabilities of Ross, I would suggest to model the mass [M] as a disk element, and the impeller/diffuser interaction as a bearing or seal in one node. I believe that the only difference between a bearing element and a seal element is how they are treated in the static analysis, e.g. the static bending line of the shaft line if it is horizontal + reaction forces. I would say this static bending line is not really of interest, since you would have to account for the seals during operation to get the correct bearing reaction forces? You are probably already aware of this, but the book "Turbomachinery Rotordynamics: Phenomena, Modeling, and Analysis" by Dara Childs is very comprehensive, especially for pumps. I believe it has several models with values for impeller / diffuser interactions, among other things. |
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Hello,
First, thank you for this software, it is great :D.
I am interested in pump rotordynamics and follow Corbo-1996.
My questions regard how to model the added effects special to hydraulic pumps with regards to pneumatic turbomachinery.
Following the paper from Corbo:
The following coefficients are defined for forces generated by the impeller. The coefficients are given (eq. (70) (71)).
Regarding Added mass eq (76), Stiffness reduction (78), cross-coupling (79), damping (82), mass coeff (83)
I am happy to provide a generic case if it helps solving the problem or once the problem is solved for future pump-struggling people :)
Thank you
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