simulation settings for wind tunnel testing

[Anonymous]

Hi everybody,

Autodesk CFD is quite new for me, so I may not know everything. I'm currently building a model wind tunnel and I want to do the simulation to see how the air moves insde the model wind tunnel (because I'm going to build one in real life). In front of my wind tunnel, there is a fan with fixed RPMs and the air moves from the fan, pass through a section which will "convert" turbulent air flow to laminar air flow, and will eventually pass through the test section (it's an open wind tunnel). Assuming that there is no wind outside the wind tunnel in the beginning, which settings should I apply to the simulation so that the simulated air flow inside the wind tunnel would be nearly as same as the one in real life?

What I did was creating an inner air volume by using "Void fill", then velocity = 0m/s and pressure = 101325 Pa in front of the wind tunnel (using "Boundary conditions") and pressure = 0 Pa at the end. So I don't know if what I did, was correct (enough).

Thanks in avance!

[frederic.gaillard.7 · Accepted solution]

Hello Ly, 

I try your last model, there is a lot of improvement since the first iteration, good job. 

Pressure distribution and velocity field are looking good near your impeller 

Pressure scalar field

However some issue remain. The biggest that your dealing with is a recirculation problem.  This problem arise when you have an inward flow and an outward flow leaving the model through the same surface. This must be avoided otherwise your mass conservation principle will be violated. 

The simpliest way to correct that is to extend the length of your air volume. Try for a least 5 times the actual length. 10 times if you want to play safe. 

Hope it helps 

Fred