About a Centrifugal compressor

Centrifugal compressors sometimes called vane compressors or radial compressors, are a subclass of dynamic axisymmetric work-absorbing turbines.They achieve pressure rise by adding energy to the continuous fluid flow through the rotor/impeller.The equations in the next section show this specific energy input.A large portion of this energy is kinetic energy, which is converted to increased potential energy/static pressure by slowing down the flow through the diffuser.The static pressure rise in the impeller may be roughly equal to the rise in the diffuser.

Components of a simple centrifugal compressor

A simple centrifugal compressor stage has four components (listed in flow order): inlet, impeller/rotor, diffuser, and collector, each component of the flow path, with the gas flow (working gas) entering the centrifugal impeller axially from left to right.This turbine shaft (or turboprop) impeller rotates counterclockwise when looking downstream at the compressor. Airflow will pass through the compressor from left to right.

Turbomachinery similarities 

Centrifugal compressors are similar to other turbomachinery in many respects, compare and contrast as follows

Similarities to Axial Compressors:

Centrifugal compressors are similar to axial compressors in that they are based on rotating airfoils.Both are shown in adjacent photographs of an engine with a 5-stage axial compressor and a one-stage centrifugal compressor.The first part of the centrifugal impeller looks very similar to an axial compressor.The first part of the centrifugal impeller is also called the inducer.Centrifugal compressors differ from axial compressors in that they use a significant change in impeller inlet to outlet radius to generate a larger pressure rise than a single stage (e.g. 8 in the Pratt & Whitney Canada PW200 series helicopter engines to make an axial phase.The German Heinkel HeS 011 experimental engine of the 1940s was the first aviation turbojet with a compressor stage where the radial flow diversion was between none axial and 90 degrees centrifugal.It's called a hybrid/diagonal flow compressor.The Pratt & Whitney Canada PW600 series of small turbofan engines feature a diagonal stage.

Centrifugal fan

Centrifugal compressors are also similar to centrifugal fans of the type shown in the adjacent figure in that they both increase the energy of the flow by increasing the radius.Compressors run at higher speeds to create a greater pressure rise than centrifugal fans. In many cases, the engineering methods used to design centrifugal fans are the same as those used to design centrifugal compressors, so they look very similar.For purposes of generalization and definition, it can be said that the density increase in centrifugal compressors is typically greater than 5%.Furthermore, when the working fluid is air or nitrogen, their relative fluid velocities usually exceed Mach number 0.3.In comparison, a fan or blower is generally considered to increase density by less than 5%, with peak relative fluid velocities below Mach 0.3.