Numerical studies of the influence of casing shape on the hydraulic performance of a centrifugal boiler circulating pump

Semispherical casing was adopted in a boiler circulating pump considering the operating safety. In order to improve the hydraulic performance and reduce the manufacture cost of the pump casing, a modification attempt on pump casing has been made by adopting a volute shape. By using both steady and unsteady numerical simulations with SST k-ω turbulence model, the hydraulic performances of pumps with two different casings were compared in several aspects. It was found that after modification: 1) The hydraulic performance, including hydraulic efficiency and head, was improved; 2) The pressure fluctuation was analyzed by FFT. Its amplitude of dominant frequency kept almost unchanged in the entrance of diffuser but became larger in the trailing of diffuser passage; 3) The manufacture cost of the pump casing decreased by 4%.