# 3D Fan:Calculation of induced flow rate by fan rotation at free delivery

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 June 11, 2013, 06:29 3D Fan:Calculation of induced flow rate by fan rotation at free delivery #1 Member   Join Date: May 2010 Posts: 57 Rep Power: 9 Sponsored Links Hi guys, I would like to ask if there is any way to model this (or if there's smth wrong in my thinking) I have a 3D model of the periodic (1/6th) section of a fan + ducting and would like to get the the flow rate caused by the fan rotation at free delivery (0 pressure rise and max. flow rate from the performance curve). So far I have reproduced the fan performance curve by varying the flow rates at the inlet and getting the corresponding pressure rise. Now I am trying to set 0 pressure rise across and get the flow rate as a result of the fan rotation only. I tried pressure inlet and outlet at 0 gauge pressure and got 0 flow rate The reason I want to do this simulation is so I can see the effect of different fan designs on the flow rate at fixed RPM later on. I should be able to figure this out by theory I guess but I'm not there yet. Thanks for the help in advance. Thanos

 September 13, 2013, 02:42 #2 Member   Join Date: Aug 2013 Posts: 50 Rep Power: 6 i have a question , what are the boundaries of inlet and outlet to be used when i want to vary the rpm and want to get the flowrate so that i can have the perfomance curve (Speed rpm and flow rate)?? __________________________________________________ __________________________________________________ __________________________________________________ _________________________ btw. for the fixed rpm, i use totalpressure for both inlet and outlet. I set the p0 at outlet to the value that i want while keep the p0 as 0 at the inlet. Basically you can plot the performance curve (flowrate and static pressure) easily without need to do extra calculation.

September 13, 2013, 05:30
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Quote:
 Originally Posted by Catthan Hi guys, I would like to ask if there is any way to model this (or if there's smth wrong in my thinking) I have a 3D model of the periodic (1/6th) section of a fan + ducting and would like to get the the flow rate caused by the fan rotation at free delivery (0 pressure rise and max. flow rate from the performance curve). So far I have reproduced the fan performance curve by varying the flow rates at the inlet and getting the corresponding pressure rise. Now I am trying to set 0 pressure rise across and get the flow rate as a result of the fan rotation only. I tried pressure inlet and outlet at 0 gauge pressure and got 0 flow rate The reason I want to do this simulation is so I can see the effect of different fan designs on the flow rate at fixed RPM later on. I should be able to figure this out by theory I guess but I'm not there yet. Thanks for the help in advance. Thanos
Do you want to use the zero gauge pressure (0+101325 = 101325 pa absolute pressure) at inlet and outlet?

But I am not convinced with the idea of having zero pressure rise and still have some + mass flow rate.

 November 6, 2013, 06:19 #4 Member   Abdul Afoo Parkar Join Date: Oct 2012 Posts: 42 Rep Power: 6 Very quickly: If my fan runs at fixed rpm, is it sufficient to give it a Domian Interface conservative massflow rate BC? Which would be preferred: Interface massflow rate or pressure change?

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