[Anandltvs]

Hi,

From CFD simulation of 294 frame axial flow fan, i got fan performance as 22.95% at P=100.3 Pa,Q=582 m3/hr,2863 RPM.But the same fan during the air flow test provides fan efficiency as 42.20% at P=100.72 Pa,Q=1157 m3/hr,2879 RPM.Both operating points are same, but cfd predict around 50% less flow rate than test. What would have gone wrong in the simulation? kindly seek your help to address this issue. For your reference
CFD Setup info:
1. Physics: In compressibility flow
2. Analysis type: transient
3. Approach: Frozen rotor
4. Convergence ratio: 0.0001
5. Turbulence Model: K- epsilon
6. Fan and chamber considered(Shroud ignored)
7. Boundary layer: Single layer used
Test info:
1.Air flow test chamber-According to ANSI/AMCA 210-07
2.Fan-Shroud and Chamber used in test
( Shroud ignored in CFD we have got good correlation between test and CFD other frames of fan(350 mm,370 mm) but in this frame 294 mm i am getting unreasonable correlation of 50% in CFD.)


Thus, I could see my CFD simulation has failed to capture large flow generated by fan in the test. How to capture resonable flow prediction in CFD simulation.

Regards
Anand madeshwaran

[jackchilvers]

Hi Anand,

It is perhaps a trivial comment, but have you ensured your mesh is of sufficient quality and resolution to capture all flow phenomenon within the solution? You could also check the quality of the boundary layer resolution; a single layer may not be enough. Another possibility is to switch to the SST k-omega model and fully resolve the boundary layer.

To solve mesh issues in general you could try adaptation to increase resolution in areas of high gradients.

I hope this is of some help!

Regards,
Jack