Radial Fan Outlet measurements
 

Hi Forum,

I have done some initial tests to establish inlet conditions for a CFD analysis. The objective is to predict electronic and optics cooling. However when I perform velocity measurements at the outlet of the fan house, about 1/4 of fan outlet area have 'negative velocities' - which appears to be a constant recirculation. My question to the forum is (if anybody have worked with radial blowers for similar applications), does this kind of behaviour arise from a bad design or is this to be expected of any radial blower fan.

I am willing to disclose the measurements and give further details, if anyone wants to discuss this further.

Re: Radial Fan Outlet measurements
 

My guess would be that if you are at 'design' flow then there is room for improvement in the housing. Otherwise, I would expect it to be somewhat typical depending on the geometry, etc. Areas of interest definitely being the wheel, cutoff, and the housing...

Re: Radial Fan Outlet measurements
 

Hi Erich,

Thanks for your quick response. I am running the fan at the design point, so I will try to get some samples from other manufacturer to compare the measurements and pick the best solution.

Your comments are really appreciated.

Re: Radial Fan Outlet measurements
 

I think it is standard for radial fans that there exist a region with reversed flow. I once had to look at the flow distribution in a duct system where the flow was from a radial fan. In the data from the fan there was a sketch of the flow distribution out of the fan where a recirculation zone was clearly seen. I did try to get some measurement, but either they were not available or I could not get them. But I was told that they would expect 1/3 or the section to be reversed flow and in the region with maximum velocity, would the peak velocity be around 2*mean. Have you looked into the housing is there niót an obstruction in the region with reversed flow? I do not know if this helps, but your results sounds familiar