Entropy Production Analysis of a Vertical Mixed-Flow Pump Device with Different Guide Vane Meridians

With the aim of investigating the influence of guide vane meridians on the external characteristics and internal flow field of the mixed-flow pump device, this research constructed seven guide vane meridians and applied computational fluid dynamic (CFD) and entropy production theory to investigate the spread of hydraulic loss in a mixed-flow pump. As observed, when the guide vane outlet diameter D(gvo) decreased from 350 mm to 275 mm, the head and efficiency increased by 2.78% and 3.05% at 0.7 Q(des), respectively. At 1.3 Q(des), when D(gvo) increased from 350 mm to 425 mm, the head and efficiency increased by 4.49% and 3.71%, respectively. At 0.7 Q(des) and 1.0 Q(des), the entropy production of the guide vane increased with the increase of D(gvo) due to flow separation. When D(gvo) < 350 mm, at 1.0 Q(des) and 1.3 Q(des), entropy production of the outlet channel increased as D(gvo) decreased owing to the excessive flow rate, but at 0.7 Q(des), entropy production did not change much. When D(gvo) > 350 mm, at 0.7 Q(des) and 1.0 Q(des), due to the expansion of the channel section, the flow separation intensified, which resulted in an increase of the entropy production, but the entropy production decreased slightly at 1.3 Q(des). These results provide guidance for improving the efficiency of pumping stations.