The research on a centrifugal pump of low specific speed with splitter blades was carried out in recent years by our group, is systematically introduced in this paper. The design method is summarized also. At the beginning, based on the former L9(34) orthogonal test, Particle Imagine Velocity (PIV) tests and Computational Fluid Dynamics (CFD) simulations were carried out for several designs with different splitter blade length. Results show that for an impeller with splitter blades the “jet-wake” flow at the impeller outlet is improved, and the velocity distribution inside the impeller is more uniform. This explains that the impeller with splitter blades shows higher performance (especially in head and efficiency). Meanwhile, the numerical simulation results were compared with the test results, which confirm that, CFD technology can be used to observe inner flow distribution and forecast pump performance tendency. Later, a further L9(34) orthogonal test, which adopt the blade number as a new variable, was designed to explore the relationship between geometry parameters of splitter blade and pump performance, and corresponding CFD simulations for the flow field with volute were also done. From the test results the influence of the main design parameters on the hydraulic performance of a centrifugal pump and its reasonable value range are determined. The simulations forecasted pump performance show good consistency with that from tests at the rated point, and the simulated error at other flow rates were analyzed. Thirdly, in order to save research cost, numerical simulations were done for the full flow field including the cavity inside the volute and impeller. By analyzing the distribution law of blade torque and turbulent kinetic energy in the impeller, the value fetching principle for the splitter blade inlet diameter is presented as “the splitter blades torque should be positive”, and by analyzing the distribution of blades loading, the flow distribution rules and pump performance influenced by different splitter blades off-setting angles and inlet diameters were discovered. The disk friction loss, which consuming much energy in centrifugal pumps, was also forecasted at various operating conditions. The results were compared with that from empirical formulas, which show great accordance at the rated point, and the forecasted results at off-design points were analyzed also. Finally, the research results and the design method for the centrifugal pump with splitter blades, such as how to select splitter blade number, the off-setting angle, the inlet diameter and the deflection angle, were summarized.
Effects of blade number on hydrodynamic force perturbation on impeller of voutte type centrifugal pump.
