Integrally geared centrifugal air compressor

[Divya11]

Hi All,

Attached is a performance curve for integrally geared centrifugal air compressor. Can anyone tell me the meaning of GVA specified on the left?
As far as I remember, the different curves are for different speeds of the compressor. Is that correct?

 

[georgeverghese]

GVA = Guide Vane Angle ?

The curves are drawn for various guide vane angles.