Numerical investigation of splitter blades on the performance of a forward-curved impeller used in a pump as turbine

Abstract

As a type of economical energy recovery device, pump as turbine (PAT) is generally used in micro-hydropower plants and energy recovery. To study the influence of the splitter blade on a special impeller used in PAT, impellers without and with splitter blades are designed in this paper. The influences of splitter blade on the energy loss, external characteristics and internal flow field distribution of a PAT were simulated via a verified computational fluid dynamics (CFD) method. The consequences present that the shaft power, efficiency, and head corresponding to the BEP of the PAT with splitter blades are 16.4%, 1.3%, and 8.8% better than those of the PAT without splitter blades. The total entropy production of the PAT without splitter blade is higher than that of the PAT with splitter blades at the same flow rate. Adding splitter blade increased the number of effective blades, made the fluid flow more evenly along the impeller flow passage, and reduced the flow separation inside the impeller. This paper displays that adding splitter blades not only obviously increases hydraulic performance under large flow conditions but also significantly widens the high-efficiency range of PATs.