Hello,

Does anyone have any tips for getting a good approximation of the flexibility of a turbine's nozzles?

I'm trying to get the forces and moments on the nozzles as close as I can to the allowable loads. Currently have I'm using rigid elements to represent the base and nozzles of the turbine, with anchor restraints at the bottom (see attached picture).

Any better or additional ideas, tips or tricks?

Thanks,
Levi

I would recommend to get the flexibilities from Vendor or use FEM.

And another trick is at the 'edit static load cases' you can change elastic modulus from Ec to Eh which gives you slightly reduced nozzle load, but use it with a caution since code says Se shall be based on Ec, elastic modulus at room temperature. I'm using B31.1, so if you use B31.3 or others please take a look at your code.

Hi,
I would suggest to ask for the turbine displacement directly from vendor.
Since the temperature for those rigid elements will not be same as that of pipe. (what temperature you had used there?)
Also turbine there are different load cases.

Also for stiffness as rightly said in above post, FEA is a good option (provided you have all the inputs needed for FEA) or best way is to consult your vendor for the values.

Regards,
R.K.

Hi Levim,

I agree with RK that turbine nozzle displacement shall be taken from Vendor and incorporated in your calculation. We cannot treat nozzle movement the way we analyze static equipment or pumps.And turbine nozzle forces and moments shall be evaluated using 1.85 times of NEMA SM23 or as much as allowed by Vendor. Check NEMA SM23 on how the evaluation is being done.

Regards,
Ron