# fan model's drawback

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January 31, 2012, 10:25
fan model's drawback
#1
Member

Yolk
Join Date: Nov 2011
Posts: 38
Rep Power: 12
hi everybody,
When I use the fan model in fluent to simulate the propeller, I find that the pressure distribution along the central line parrallel to the hub is not the one I want. I show it in the attached picture to descripe the idea more clearly.
the left picture is the pressure distribution in fan model and, the right one is the case I want. Is there any method to achieve my objective by fluent?
I have tried the momentum source, but it still is as same as the left distribution.
thank you very much!
Yannian
Attached Images
 different pressure jump.jpg (44.9 KB, 25 views)

 January 31, 2012, 23:33 #2 Member   DB Join Date: Apr 2011 Posts: 87 Rep Power: 12 Could you explain the graphs and your model in more detail. Hwat are P1 and P2 and when you say centre line I hope you are saying about a circle at half the blade height. Also are you simulating a single blade or the entire propeller ? What is the flat line at the end ? Everyone will be able to help you better if you provide these details. __________________ -D.B

 February 1, 2012, 06:07 #3 Member   Yolk Join Date: Nov 2011 Posts: 38 Rep Power: 12 Hi D.B, Thank you for your reply. I will interpret the question more detailed. I use the actuator disk model to simulate the propeller so there is no belde or propeller in the geometry. I use the fan boundary in fluent, I have to prescribe pressure jump 'P' in the panel. The pressure jump is added to the nodes by fluent core code. The method fluent uses is to prescribe '-P/2' before the disk and 'P/2' after the disk, so the sum of pressure jump is 'P'. However,the condition I want is '-P' before the disk and '0' after the disk. The sum of pressure jump is also 'P'. The falt line at the end tells that the pressure after the disk is constant. The central line is the line go through the actuator disk. I hope I describe more clearly to you. If you are still uncertain please ask me, I want to discuss it with you further. Yannian