or shrouded", "with splitters" (every other inducer removed), and "w/o splitters" (all full blades). Figures 0.1, 1.2.1, and 1.3 show three different open full inducer rotors with alternating full blades/vanes and shorter length splitter blades/vanes. Generally, the accepted mathematical nomenclature refers to the leading edge of the impeller with subscript 1. Correspondingly, the trailing edge of the impeller is referred to as subscript 2. As working-gas/flow passes through the impeller from stations 1 to 2, the kinetic and potential energy increase. This is identical to an axial compressor with the exception that the gases can reach higher energy levels through the impeller's increasing radius. In many modern high-efficiency centrifugal compressors the gas exiting the impeller is traveling near the speed of sound. Most modern high-efficiency impellers use "backsweep" in the blade shape. A derivation of the general Euler equations (fluid dynamics) is Euler's pump and turbine equation, which plays an important role in understanding impeller performance. This equation can be written in the form: Equation-1.2 (see Figures 1.2.2 and 1.2.3 illustrating impeller velocity triangles) where: subscript 1 is the impeller leading edge (inlet), station 1 subscript 2 is the impeller trailing edge (discharge), station 2 is the energy added to the fluid is the acceleration due to gravity is the impeller's circumferencal velocity, units velocity is the velocity of flow relative to the impeller, units velocity is the absolute velocity of flow relative to stationary, units velocity Diffuser The next component, downstream of the impeller within a simple centrifugal compressor may the diffuser. The diffuser converts the flow's kinetic energy (high velocity) into increased potential energy (static pressure) by gradually slowing (diffusing) the gas velocity. Diffusers can be vaneless, vaned, or an alternating combination. High-efficiency vaned diffusers are also designed over a wide range of solidities from less than 1 to over 4. Hybrid versions of vaned diffusers include wedge (see Figure 1.3), channel, and pipe diffusers. Some turbochargers have no diffuser. Generally accepted nomenclature might refer to the diffuser's lead edge as station 3 and the trailing edge as station 4. Bernoulli's fluid dynamic principle plays an important role in understanding diffuser performance. In engineering situations assuming adiatice flow, this equation can be written in the form: Equation-1.3 where: is the inlet of the diffuser, station 2 is the discharge of the diffuser, station 4 (see inlet above.) Collector The collector of a centrifugal compressor can take many shapes