thumb| centrifugal impeller with a highly polished surface likely to improve performance  thumb|inlet velocity triangles for centrifugal compressor impeller thumb|exit velocity triangles for centrifugal compressor impeller thumb|figure 1.1 â aero-thermo domain of turbomachinery thumb|figure 1.2 â physical domain of turbomachinery centrifugal compressors, sometimes termed radial compressors, are a sub-class of dynamic axisymmetric work-absorbing turbomachinery. the idealized compressive dynamic turbo-machine achieves a pressure rise by adding kinetic energy/velocity to a continuous flow of fluid through the rotor or impeller. this kinetic energy is then converted to an increase in potential energy/static pressure by slowing the flow through a diffuser. the pressure rise in impeller is in most cases almost equal to the rise in the diffuser section. == theory of operation == in the case of where flow simply passes through a straight pipe to enter a centrifugal compressor; the flow is straight, uniform and has no vorticity. as illustrated below Î±1=0 deg. as the flow continues to pass into and through the centrifugal impeller, the impeller forces the flow to spin faster and faster. according to a form of euler's fluid dynamics equation, known as "pump and turbine equation," the energy input to the fluid is proportional to the flow's local spinning velocity multiplied by the local impeller tangential velocity. in many cases the flow leaving centrifugal impeller is near the speed of sound (340 metres/second). the flow then typically flows through a stationary compressor causing it to decelerate. these stationary compressors are actually static guide vanes where energy transformation takes place. as described in bernoulli's principle, this reduction in velocity causes the pressure to rise leading to a compressed fluid. == historical contributions, the pioneers == over the past 100 years, applied scientists including stodola (1903, 1927â1945),  pfleiderer (1952), hawthorne (1964),  shepard (1956), {{cite book|author=shepard, dennis g. |title=principles of turbomachin
Compressors