Evaluation AC3-12
Particle-laden swirling flow
Application Challenge AC3-12 © copyright ERCOFTAC 2013
Comparison of Test Data and CFD
A rather good agreement between the experiments and predictions was obtained for gas and particle phase in both swirling cases considered. The comparison of the calculated streamlines of the gas flow with those obtained from the integration of the measured axial velocity shows that the flow field is predicted reasonably well for both conditions (Figure 10). The most obvious difference is that the axial extension of the central recirculation bubble is predicted to be larger at the top and downstream ends for both cases. The predicted width of the central recirculation bubble and the extension of the recirculation at the edge of the pipe expansion are in good agreement with the measured results.
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| Figure 10: Measured and calculated gas-phase streamlines (the upper parts of each figure corresponds to the calculations and the lower parts show the measurements); (a) Case 1; (b) Case 2. |
The measured cross-sectional profiles of the three velocity components are compared with the calculations in Figure 11 for Case 2. The agreement is very good, except for the tangential velocity which is under-predicted in the region downstream of the location where the recirculation bubble has its largest radial extension. Although, the turbulent kinetic energy of the gas phase is considerably under- predicted in the initial mixing region between the primary and annular jets and within the recirculation at the edge of the pipe expansion (z = 52 mm), the agreement is reasonably good for the cross-sections further downstream. Similar results have been obtained for swirl Case 1 which was summarized in a previous publication (Sommerfeld et al. 1992).
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| Figure 11: Comparison between measurements and numerical calculations for the gas-phase in Case 2: (a) axial mean velocity; (b) radial mean velocity; (c) tangential mean velocity; (d) turbulent kinetic energy. |
Contributed by: Martin Sommerfeld — Martin-Luther-Universitat Halle-Wittenberg
© copyright ERCOFTAC 2013