Rotation flow calculation.

Hans

I am having trouble with a calculation. The fluid is air. The velocity is max 10m/s and much lower in the plenum. It is a design with a tangential inlet into a plenum chamber. The air is then guided from the plenum to the outlet tube via 3 x 90° turns. It is not at cyclone, but the flow does rotate in the plenum.

A physical model has been made and measurements have been done. And the calculations are not the least comparable to the measurements (axial outlet velocity in segments). The measurements show that the segment axial velocity deviation is approx 3% and the calculation say approx 50%. This is a huge difference.

I use RSM, velocity inlet and pressure outlet.

Can anyone comment on possible errors in setup? I know that it impossible for you to debug my calculation, but if you could come with some general suggestions/thoughts related to rotating flows.

If you need more information regarding the design please let me know, and I will provide them.

Thank you in advance.