A stationary, spirally shaped passage that converts velocity head to pressure.
The purpose of a discharge volute is to recover the radial velocity head of the flow exiting the diffusor before exiting the compressor. A well-designed volute collects the flow while conserving the angular momentum of the flow. This is done by matching the area progression around the circumference of the volute according to the requirements of the discharge condition of the diffusor section. A volute that is oversized will incur losses due to over diffusion of the flow, and an undersized volute will fail to completely recover the dynamic pressure from the radial component of the flow entering the volute. In some cases, these losses can hurt not only your efficiency, but also flow stability.
