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Problem in rotordynamic analysis

Posted 15 apr 2019, 14:05 GMT-4 Structural & Acoustics, Acoustics & Vibrations, Geometry 2 Replies

Partha Sarathi Kar
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Hi I am trying to find out critical speeds (eigen frequency in COMSOL) of a turboexpander. I am imporing the geometry file from SOLIDWORKS. I am unable to form an union so I have formed an assembly instead and now I am getting all wrong results. My eigen frequencies are coming in the order 10^-3 whereas they should be in order of 1000 Hz. In the mode shapes, I am getting deformation of a single part only as if the whole body is divided into a number of segments in stead of one whole body. If anybody has any solution or suggestion, I would be grateful if helped.

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2 Replies Last Post 16 apr 2019, 12:12 GMT-4
Prashant COMSOL Employee

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Posted: 5 years ago 16 apr 2019, 04:51 GMT-4

Dear Partha,

Reason you get the low frequencies is because the components are disconnected in the assembly state and under go rigid body motion. In order to get the correct results the geometry should be in union state. Because you mentioned that there is some problem while keeping it in union, can you write at support@comsol.com with the geometry file to investigate what is the problem in importing the geometry and keeping it in union state.

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Thanks and regards,
Prashant Srivastava
Dear Partha, Reason you get the low frequencies is because the components are disconnected in the assembly state and under go rigid body motion. In order to get the correct results the geometry should be in union state. Because you mentioned that there is some problem while keeping it in union, can you write at support@comsol.com with the geometry file to investigate what is the problem in importing the geometry and keeping it in union state.
Partha Sarathi Kar
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Posted: 5 years ago 16 apr 2019, 12:12 GMT-4

Dear Prashant, Thank you very much for your suggestion. I have added the question in support. I am also adding the geometry file here. Thanks again.

Dear Prashant, Thank you very much for your suggestion. I have added the question in support. I am also adding the geometry file here. Thanks again.

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