Nodal diameter, harmonic index and mode

  • Last Post 5 days ago
Sheida posted this 19 January 2018


I have an impeller with 6 main blades and 6 splitter blades. I want to have modal analysis including the nodal diameter (for SAFE diagram) and frequency. Is there any way that I can have nodal diameters in a table?

I expected to have maximum up to 3 nodal diameters and 3 harmonic indices. When it's selected to find 100 modes or 200 modes, at the end it displayed 2 harmonic indices. How can I have all harmonic indices as output results? Thanks.




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yousefmech posted this 04 February 2018

Hi Sheida 

you can select the number of desired modes but normally modes of interest are the blades bending modes 

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  • Sheida
Sheida posted this 5 days ago

Hi Yousef,

I ran a cyclic symmetry model with 14 blades. There are 3 harmonic indexes. I asked for 20 modes. Thus for each harmonic index, I have 20 modes. I don`t have mechanical engineering background. I should draw the diagram (Freq. vs. ND). I don`t know from these different mode shapes, which one is related to each ND. Would you please let me know how I can find first blade bending modes? Thank you.

Mode shapes

#structural-Dynamic; #Modal