Rather, improvements have been achieved through understanding and applying incremental pieces of knowledge discovered by many individuals.įigure 1.1 represents the aero- thermo domain of turbomachinery. Improvements in centrifugal compressors have not been achieved through large discoveries. Figures 1.1 and 1.2 illustrate the domain of turbomachinery with labels showing centrifugal compressors. This relationship is the reason advances in turbines and axial compressors often find their way into other turbomachinery including centrifugal compressors. These understandings apply to all dynamic, continuous-flow, axisymmetric pumps, fans, blowers, and compressors in axial, mixed-flow and radial/centrifugal configurations. Over the past 100 years, applied scientists including Stodola (1903, 1927–1945), Pfleiderer (1952), Hawthorne (1964), Shepard (1956), Lakshminarayana (1996), and Japikse (many texts including citations), have educated young engineers in the fundamentals of turbomachinery. As described in Bernoulli's principle, the reduction in velocity causes the pressure to rise. If the flow has to be turned in a rearward direction to enter the next part of the machine, eg another impeller or a combustor, flow losses can be reduced by directing the flow with stationary turning vanes or individual turning pipes (pipe diffusers). The stationary compressor is ducting with increasing flow-area where energy transformation takes place. It then flows through a stationary compressor causing it to decelerate. In many cases, the flow leaving the centrifugal impeller is travelling near the speed of sound. According to a form of Euler's fluid dynamics equation, known as the 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. As the flow passes through the centrifugal impeller, the impeller forces the flow to spin faster as it gets further from the rotational axis. In the case where flow passes through a straight pipe to enter a centrifugal compressor the flow is straight, uniform and has no vorticity, ie swirling motion, so the swirl angle α 1 = 0° as illustrated. 10 Structural mechanics, manufacture and design compromise.4 Components of a simple centrifugal compressor.3.5 Turbomachinery using centrifugal compressors. 2 Historical contributions, the pioneers.
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