Fixed volumetric flow rate, pipe

Take a look at Table 48.2 to see the effect on Reynolds numbers of changing the diameter of smooth pipes for a fixed volumetric flow rate at ambient conditions. Low-viscosity fluids are often pumped in turbulent flow simply because it would require such a large diameter pipe to maintain laminar flow that the increased cost (caused by the larger diameter) would be more than the savings generated by lower frictional losses in laminar flow. 

Table 48.2 Effect on Reynolds Numbers of Changing Pipe Internal Diameter for a Fixed Volumetric Flow Rate at Ambient Conditions...

Consider flow through the pipe-work shown in Figure 1.3, in which the fluid occupies the whole cross section of the pipe. A mass balance can be written for the fixed section between planes 1 and 2, which are normal to the axis of the pipe. The mass flow rate across plane 1 into the section is equal to p Q and the mass flow rate across plane 2 out of the section is equal to P2Q.2, where p denotes the density of the fluid and Q the volumetric flow rate. 

Increasing the pipe size, downstream of the orifice (which offers a faster pressure recovery) is another option to intensify the cavitation effects but using pipes of larger size would mean handling higher volumetric flow rates (in order to carry out operation at the same cavitation number) and this may increase the fixed cost of the processing. 

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