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"Mass flow is out of fan curve's range" warning message

Question asked by James Lee on Jun 23, 2018
Latest reply on Jul 11, 2018 by Siavash Khajehhasani

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Hi Guys,

I was doing an internal flow analysis when I encountered the "Mass flow is out of fan curve's range" warning message. My analysis involved an electronic enclosure with several electronic components and 3 internal fans. The warning is showing on 1 of the fan.

I was not able to add more fan curve point as I have added what is stated in the fan specification. I still can proceed with the simulation but the temperature fluctuates rather than stabilizing to a constant value. I want to know whether I can still trust the value or should I treat the internal fan as external fan when the cover of the enclosure is taken off.

Hope to hear from you soon.

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Jon Dahlgren Jun 25, 2018 3:11 AM

I've had simular problems with the fan tool. In the end I found a working point close enough to the fan curve and satisfied there, even though the warning was still there.

Following your thread to see if any solution appears.

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Siavash Khajehhasani Jul 5, 2018 7:26 PM

If you fan operating in stall region, it affects the stability of fan and accordingly the outcome. You could stay away from that region by modifying your boundary condition. On the other hand, you could also add some extra points to fan cure in a way following the curve trend (a reasonable estimation) to see if the issue is this.

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Tg R2 @ Siavash Khajehhasani on Jul 11, 2018 12:33 AM

Hi Siavash

Could you be more specific about "You could stay away from that region by modifying your boundary condition" - you meant extending the comp domain or something else. Because after extending beyond the enclosure the analysis becomes external, and the domain has to be quite big not to encounter the other issue - the vortexes.

I encountered the above problem a couple of times and could tell you that adding points to the fan curve never helped

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Siavash Khajehhasani Jul 11, 2018 10:45 AM

By boundary condition, I did not mean computational domain. I am referring to fan flow rate/velocity etc if possible to alter.

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4 Replies

Jon Dahlgren Jun 25, 2018 3:11 AM
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I've had simular problems with the fan tool. In the end I found a working point close enough to the fan curve and satisfied there, even though the warning was still there.

Following your thread to see if any solution appears.
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Siavash Khajehhasani Jul 5, 2018 7:26 PM
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If you fan operating in stall region, it affects the stability of fan and accordingly the outcome. You could stay away from that region by modifying your boundary condition. On the other hand, you could also add some extra points to fan cure in a way following the curve trend (a reasonable estimation) to see if the issue is this.
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- Tg R2 @ Siavash Khajehhasani on Jul 11, 2018 12:33 AM
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  Hi Siavash
  
  Could you be more specific about "You could stay away from that region by modifying your boundary condition" - you meant extending the comp domain or something else. Because after extending beyond the enclosure the analysis becomes external, and the domain has to be quite big not to encounter the other issue - the vortexes.
  I encountered the above problem a couple of times and could tell you that adding points to the fan curve never helped
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Siavash Khajehhasani Jul 11, 2018 10:45 AM
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By boundary condition, I did not mean computational domain. I am referring to fan flow rate/velocity etc if possible to alter.
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"Mass flow is out of fan curve's range" warning message

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