Mechanical input-forced extract

Mechanical input-forced extract. This arrangement is known as a plenum system. 

Figure 9.24 shows a typical plenum system of mechanical input and forced extract. The outlets in Fig. 9.24 may be subdivided into two categories ... 

For a forced vortex with spiral flow, energy is put into the fluid in the case of a pump and extracted from it in the case of a turbine. In the limiting case of zero flow, when all path lines become concentric circles, energy input from some external source is still necessary for any real fluid in order to maintain the rotation. Thus a forced vortex is characterized by a transfer of mechanical energy from an external source and a consequent variation of H as a function of the radius from the axis of rotation. 

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