Efficiency curve versus velocity ratio

Figure 4-110 depicts an efficiency curve versus velocity ratio for a reaction-type expander. The optimum efficiency will occur at a velocity ratio of. 63. For a velocity ratio considerable greater or less than. 63 a significant efficiency penalty can be expected. Considering the effects on the parameters mentioned above, it is easy to see the importance the velocity ratio has on the performance of the expander. 

Figure 12-461, Part 3. Stage performance of a compressor is usually represented in a pressure coefficient, n, or M, and efficiency, t), versus Q/N (capacity vs. speed). A given impeller stage design will have a different characteristic depending on the relationship of its operating speed to the inlet sonic velocity of the gas. For higher ratios of speed to sonic velocity, N/A , the head or pressure coefficient curve will be steeper at flows higher than the design. (Used by permission Bui. 423, 1992. Dresser-Rand Company.)...

When the outlet maximum velocity (after eight turns) at a meandering ratio of 4 is plotted versus Re, a curve similar to the dependence of the mixing efficiency on Re is yielded [59], At Re 80, the outlet maximum velocity increases considerably, whereas at low Re it remains nearly constant. 

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See also in sourсe #XX -- [ ]

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