A Hydraulic Analysis of the Long Crossover Passage in a Multi-Stage Pump

In response to market demands, Flowserve Corporation is investigating methods for reducing hydraulic losses in certain pumps. After being manufactured and tested, a recent crossover design was seen to be a great improvement over the typical design. This crossover passage was modeled and analyzed using CFD in order to identify further areas for improvement. The Reynold's Averaged Navier-Stokes (RANS) equations are solved using the k-epsilon turbulence model. The velocity and pressure fields were simulated in the passage as well as the shear stress along the walls. The velocity and pressure fields are plotted at several cross-sections. It is shown here that total pressure drop of only 1.2% is predicted from the inlet to the outlet of the new crossover design. This is considered to be a significant performance improvement to these pumps. It is also noted that the low shear flow region is on the inner part of the bends. Secondary flows were identified in the areas of the passage with the highest curvature, but their effect on losses is minimal since the velocity pressure is shown to be only accounts about 10% of the total pressure. The new design was seen to be very well designed with minimal areas for improvement, specifically straightening the flow exiting the crossover passage. It is also shown that the significant level of swirl is passed into the suction volute of the succeeding impeller. That could impede the hydraulic efficiency of the next impeller. Future studies are planned to write a crossover generating program for future pumps of this type at varying specific speeds.