Internal Fluid Flow Analysis

[Anonymous]

Good Morning All,

I have been trying to run a Unsteady Fluid Flow on a Telecommunication system enclosure (about the size of a dorm fridge)

it has 9 internal fans (fantray) with intake openings on the bottom of the chassis with outlets located on top. I cannot seem to get the analysis to run through all of the parameters, stops after getting through the first time step. I was hoping that someone was running a setup similar to mine.

thanks all,

Tony

[Joey.X]

This might be related to many possible factors. Could you state the model setup more specific?  or attached the model if it is small, or attach log file with error message in.

Without detail info, the first checks should be the model setup of the internal fans.

(1) Make sure in internal fan were defined on the part external surfaces, i.e., the model has to be having multiple parts, And a fan BC has to be defined on one of the surface of the part contact pair.

(2) What kind of sub-types for the specified fan BCs, We have velocity fan BC, pressure fan BC, flow rate fan BC and fan curve BC. 

(3) If using fan curve BC, note that the fan curve BC has to be physical meaningful and it prone to have solution convergence issue depending on the model setup.

[Anonymous]

Thanks Joey X for getting back to me.  i am using a Inventor .iam file, i was able to get it to run on the new computer that showed up yesterday, but the results were not what i had thought would happen. is it better to use a derived part instead of an assembly file. i have attached a compressed file of the derived part.

[Joey.X]

As I have mentioned before,  the internal fan has to be applied to one of the contact pair surface of two parts or multiple parts, i.e., CAD assembly has to be imported.  The singe part Inventor file can't have internal fan modeled.  

Here are the reasons needing contact pair is the CFD fan modeling. Fan model is a simplified model to simulate the physical fan which has usually complicated fan blade and hub geometry which will tremendously make large CFD model (in DOF),  This is an approach to address on relative big view of system design instead of design for fan itself.  In fan modeling, a planar circle (or other shape) is used to represent the fan's fundamental properties (flow rate, pressure jump, swirling etc.), note that the pressure jump is very important in fan modeling, it implies that the same position need a jumped pressure. in other words, in numerical approach, it need two nodes from different parts to present the pressure difference), most of CFD packages do the similar approaches like this.

Attached are a simple 2D model with two internal fans in an enclosure and two images for velocity and pressure pattern, you can see the pressure jump on the fan surface from the pressure pattern.

[Anonymous]

Hey Joey,

thanks for the pics they were helpful in fixing my mode (I think) cause right now I keep getting a error message "Warning: Quit for zero Loading please check model parameters and try again, is this caused by me setting up my fans incorrectly.

thanks again,

Tony