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Internal Fans in External Analysis

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Old   June 14, 2017, 14:16
Default Internal Fans in External Analysis
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Joseph
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Hi,

I'm trying to better understand how fans work in FloEFD. I have placed a fan inside of a box, and have qualified it as an internal fan with fluid entering on one side, and exiting on the other.

As I run the solver, I get a warning; 'Mass Flow is out of Fan curve's range.' When the solver finishes, and I try and view the flow trajectory, I get a very low fluid velocity through the fan (0.5 m/s or so).

Does anyone know what this error means, how I can remedy it, and how I can get a larger airflow through the fan?

Thanks
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Old   June 26, 2017, 15:24
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Boris Marovic
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Hi Joseph,

You can always go into the FloEFD help in the software and search for the error message. In this case it gives this information in the help:

"Mass flow is out of fan curve's range." - It means that the calculated mass flow rate value is out of the specified fan curve's range. This may happen when the specified mass (or volume) flow rate values do not cover the full range that the real fan operates. It is recommended to inspect the fan definition in Engineering Database and the project’s fan condition for possible errors. See Fans - Basic Information for details.

I cannot really tell what you did in your model so it is hard to tell what is wrong.

As for how fans work, this should help you:

I think the definition external inlet fan or external outlet fan etc. is self-explanatory.
Fans work just like they do in reality, they have a fan curve defined just like you can find in their data in the datasheet. The boundary condition checks on the pressure between the two sides of the fan which will be the delta Pressure in the curve and the flow rate applied is then taken out of the fan curve. Any flow pattern out of the fan depends on the other information in the fan database such as hub diameter RPM etc.
Again, you can find more information in the help. The fastest way to get to the right topic is either you click on help in the engineering database or in the fan curve boundary condition which will get you closer to the needed topic.

I hope this helps,
Boris
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Old   June 27, 2017, 18:18
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Joseph
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Thanks for taking the time to help me out, Boris. I really appreciate it.
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airflow simulation, cfd, fans, floefd, floefd pro 9

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