Is My Flow Laminar or Turbulent at Re= 200,000?

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SUMMARY

The discussion centers on calculating the Reynolds number for an automotive AC suction line, which is approximately 200,000. This value indicates turbulent flow, as it exceeds the threshold of 10,000. Despite initial assumptions of laminar flow, the presence of vibrations in automotive applications can lead to turbulence. The conversation highlights the importance of considering dynamic viscosity and the characteristics of the flow, particularly in short tubes where high Reynolds numbers may not immediately result in turbulent flow.

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  • Understanding of Reynolds number calculations
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  • Experience with automotive HVAC systems
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  • Research the effects of vibrations on fluid flow in automotive applications
  • Study the implications of short tube lengths on flow stability
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Automotive engineers, fluid dynamics researchers, and HVAC system designers will benefit from this discussion, particularly those focused on flow characteristics in automotive applications.

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I am calculating Reynolds number for a automotive ac suction line with 16mm Id 300kpa and 10 deg C and 230 kg/hr. I am getting around 200,000. I think I got laminar flow, but the equation says turbulent. greater than 10,000. dynamic viscosity is my most questionable variable. i checked and double checked all my SI units. Anybody know if this Reynolds number is in the reasonable range?
 
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Sometimes when you are working with cars, although the flow might be theoretically laminar, we have to account for the vibrations that will most likely make it turbulent.

You can still use the Reynolds number you obtained but with the turbulent equation.
 
What makes you think your flow is laminar?

At any rate, for pipe flow, the diameter Reynolds numbers typically quoted for the onset of turbulent don't mean that the flow is instantly turbulent. It merely means the flow is unstable and will eventually become turbulent. If your tube is quite short, you could have extraordinarily high diameter Reynolds numbers and still be laminar for at least a short distance downstream.
 

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