Centrifugal compressor

[Divya11]

Is it true that the first stage impeller of a centrifugal is always unshrouded while the other stages can have shrouded impellers? what is the reason for having an open first stage impeller?

 

[JJPellin]

No. Most centrifugal compressors have fully enclosed impellers in the first stage.

Johnny Pellin

 

[awhicker84]

The advantage of an open impeller is the reduction in stresses which helps increase the max tip speed. In other words, you could have a high head first stage.


To the others:
Are these open first stage impellers used mainly on high MW machines with high 1st stage flow coefficients?