Nozzle loss coefficient that increases with Reynolds number?

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SUMMARY

The discussion centers on the behavior of the drag coefficient (Cd) of a sphere at high Reynolds numbers, specifically the phenomenon where Cd initially drops due to boundary layer separation and then increases with further increases in Reynolds number, referred to as "post critical separated flow." The user inquires about the possibility of a similar effect occurring in internal flows, particularly in an inlet flow nozzle, while dealing with incompressible flow at Reynolds numbers around 1e5. The conversation highlights the complexities of fluid dynamics in inlet flows and suggests that the increasing loss coefficient may occur after the nozzle throat.

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  • Understanding of Reynolds number and its significance in fluid dynamics.
  • Familiarity with drag coefficients and boundary layer theory.
  • Knowledge of incompressible flow principles.
  • Basic concepts of nozzle design and flow characteristics.
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  • Explore the behavior of loss coefficients in various nozzle designs, particularly after the throat.
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bemortu
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TL;DR
Is it possible to design an inlet nozzle (subsonic, turbulent) with a loss coefficient that increases with Reynolds number?
Hi,
I started to think about the drag coefficient of a sphere. At high Reynolds number Cd drops of suddenly when the boundary layer separates. If the Reynolds number is increased further, Cd increases with increasing Re. (I'm thinking about what is referred to as "post critical separated flow").

Does anybody know if something similar can be achieved for internal flows? Specifically in an inlet flow nozzle. I would like to have an increasing loss coefficient of the nozzle when Reynolds number increases. I'm dealing with incompressible flow (i.e. subsonic). Reynolds number around 1e5 (order of magnitude).
 
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I would think that, if something like this happened, it would occur after the throat of the nozzle, rather than before.
 
cavitating venturi?
 
Search term orifice coefficient vs reynolds number found many good hits. Here's a graph from one of them for square edge orifices:
Orifice.jpg

You are up against the fluid dynamics of inlet flows. Smooth rounded inlets have much different curves.
 

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