Suggestions for ducted fan analysis using flotran? 1

[gyronewbie]

I want to design a ducted fan. I need to evaluate air flow through the inlet, into the fan and out the exhaust. The duct is not the big problem. The big problem is modeling a rotating airfoil as the load inducer. A pressure gradient will be induced by the fan. ANSYS appears to evaluate the gradient and flow based on an input deltaP between the inlet and exhaust. So how to create a deltaP in the middle when the deltaP is a function of the combined performance of the fan and duct? Inlet Po is ambient air at V=0. P reduces due to fan suction. P increases through the fan/propeller and then decays slightly to something above ambient. I'm looking for flowstreams, velocities, and surface forces through the system.

 

[vivekjohn]

Hello Gyronewbie,
Well, my project is similar to yours. Flotran has a built in Fan model, in a sense that it automatically incorporates a momentum source (fan) , without requiring us to model the fan explicitly( geometrical modelling).
All it requires is information from the fan curve, which shld be provided using real constants.
For more info, pls check the Element Manual for Fluid 141/142 under FAN MODEL sub heading and also from chapter titled "Flotran Special Features" in the Flotran CFD Manual under distributed resistance/source.
In my case, the fan model is working but I am getting very high magnitudes for velocities, which is not reasonable, but the pressure rise is correct. I am working on it right now and to hope I fix it.
Reply me if u need more info,
Regards
vivek

 

[lzcfan]

Hi, vivekjohn

I am now working on the flow field analysis of a fan with Flotran,but as a layman,I am not getting well along with it,
I even get confused at the modeling of a fan.so I would like to get help from you who I think may help me like a God in time of trouble.
could you please send me your Ansys command flow file about fan flow field analysis by e-mail, together with some tips of the analysis.
You will be of great help and meaning to me,I am looking forward to your reply.
best wishes with appreciation and regards.
Lzc105@sohu.com