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Hi, I am currently working on vibration issues on a vertical axis machine, and I would like to model the rotor dynamics to understand what is going wrong. I've just discovered the ROSS library and it seems to be exactly what I am looking for! However, I do not find in the documentation how to model a vertical axis. I think I could overcome this limitation by modeling my vertical rotor as horizontal and set gravity to zero. So how could I model a vertical rotor using ROSS? Thank you |
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Replies: 2 comments
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Hi. I believe that the orientation of the axis only comes into play when calculating static load. For the dynamics, e.g. natural frequencies and damping, I do not believe that gravity is involved at all. So I think a starting point is to disregard static forces (e.g. solve them separately if needed), and use ross for the natural frequencies. In most of my calculation, the rotors are vertical. The tricky part is to estimate the bearing forces in these machines (in my case hydropower units), which may range from very low to quite high. |
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Hi LeifParr, Many thanks for your reply. I dug into the code and I eventually found how to set gravity to zero. So I set Edit: I marked the discussion as "Answered" |
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Hi. I believe that the orientation of the axis only comes into play when calculating static load. For the dynamics, e.g. natural frequencies and damping, I do not believe that gravity is involved at all. So I think a starting point is to disregard static forces (e.g. solve them separately if needed), and use ross for the natural frequencies.
In most of my calculation, the rotors are vertical. The tricky part is to estimate the bearing forces in these machines (in my case hydropower units), which may range from very low to quite high.