Why Did the Total Head Increase in My Fluid Mechanics Experiment?

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SUMMARY

The discussion centers on an experiment involving a Venturi Rig where the total head unexpectedly increased at certain points despite expectations of a consistent total head. The primary factors identified include measurement uncertainty and turbulence levels affecting pressure readings. The participants concluded that turbulence can cause fluctuations in velocity, leading to higher readings on total pressure probes. This highlights the importance of precise measurement techniques in fluid mechanics experiments.

PREREQUISITES
  • Understanding of fluid mechanics principles, specifically the Venturi effect.
  • Familiarity with total head and pressure measurement techniques.
  • Knowledge of turbulence and its impact on fluid flow.
  • Experience with experimental design and measurement uncertainty analysis.
NEXT STEPS
  • Investigate the effects of turbulence on pressure measurements in fluid dynamics.
  • Learn about advanced measurement techniques for total head in fluid experiments.
  • Study the principles of the Venturi effect in greater detail.
  • Explore methods for reducing measurement uncertainty in fluid mechanics experiments.
USEFUL FOR

Fluid mechanics students, experimental physicists, and engineers involved in fluid dynamics research or applications will benefit from this discussion.

big_bird
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Hi

Recently performed a very basic fluid mechanics experiment with water flowing at different speeds through a Venturi Rig. Most of it went as expected, total head stayed roughly the same throughout but slightly decreased from flow loss due to resistant forces.

However, at certain random points the total head would increase further along the Venturi.

I know it is most probably imperfect experimentation technique. What could have caused this increase in the total head further along the pipe?? I'm a bit confused.

Thanks in advance for any light that can be shed on this.
 
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How much did it change? If it is a very small amount you should check it against the uncertainty in your measurement technique.

If the change is not small, does it correlate with anything like the flow speed?

A potential cause could be the turbulence level in your flow. Turbulent velocity fluctuations can cause a total pressure probe to read a pressure that is actually higher than the true mean total pressure.
 
thanks man, that helps
 

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