How to choose a fan for open circuit wind tunnel?

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SUMMARY

The discussion focuses on selecting a fan for an open circuit wind tunnel, specifically addressing the need for a fan capable of generating a volume flow rate of 5100 cfm against a pressure of -32 WC (or -8 kPa). The fan selection process involves creating a system friction loss curve and matching it with the fan performance curve to determine the operating point. It is confirmed that both axial and centrifugal fans can be considered, but the required static pressure of 32" necessitates a fan with at least 35 horsepower.

PREREQUISITES
  • Understanding of system friction loss curves in fluid dynamics
  • Familiarity with fan performance curves
  • Knowledge of airflow measurement units (cfm, WC, kPa)
  • Basic principles of Computational Fluid Dynamics (CFD) using ANSYS AIM
NEXT STEPS
  • Research fan selection criteria for high static pressure applications
  • Explore the differences between axial and centrifugal fans in high-pressure scenarios
  • Learn about horsepower requirements for fans in wind tunnel applications
  • Investigate advanced CFD techniques for optimizing wind tunnel designs
USEFUL FOR

Engineers and designers involved in wind tunnel construction, HVAC professionals, and anyone interested in fluid dynamics and fan selection for high-performance applications.

help_pls
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Hi all,

I am trying to design a open circuit wind tunnel, and I've got to the point where a fan should be selected. However, I am not familiar with fans at all, so I am wondering if you could help me!

My understanding is that the fan selection process is quite similar to the pump selection process; create a system friction loss curve (pressure vs flow rate) and match that curve with the fan performance curve (pressure vs flow rate), and then the intersection point will be the operating point. Is that correct?

So for my wind tunnel, CFD analysis using ansys aim tells me that with a desired volume flow rate of 5100 cfm, the total pressure difference between the inlet and right before the outlet is -8 kPa, or -32 WC. Does that mean that, doesn't matter if it is an axial fan or a centrifugal fan, or if it located upstream or downstream, I just need to look for a fan that can generate 5100 cfm against 32 WC of pressure?

Thank you
 
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help_pls said:
Hi all,

I am trying to design a open circuit wind tunnel, and I've got to the point where a fan should be selected. However, I am not familiar with fans at all, so I am wondering if you could help me!

My understanding is that the fan selection process is quite similar to the pump selection process; create a system friction loss curve (pressure vs flow rate) and match that curve with the fan performance curve (pressure vs flow rate), and then the intersection point will be the operating point. Is that correct?

So for my wind tunnel, CFD analysis using ansys aim tells me that with a desired volume flow rate of 5100 cfm, the total pressure difference between the inlet and right before the outlet is -8 kPa, or -32 WC. Does that mean that, doesn't matter if it is an axial fan or a centrifugal fan, or if it located upstream or downstream, I just need to look for a fan that can generate 5100 cfm against 32 WC of pressure?

Thank you
Yes, but 32" is a ton of static pressure. It isn't easy to find a fan for that and will require at least 35hp.
 
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russ_watters said:
Yes, but 32" is a ton of static pressure. It isn't easy to find a fan for that and will require at least 35hp.
Ok, thank you!
 
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