Abstract In order to investigate the influence of blade outlet angle on the performance of a chemical centrifugal pump, a chemical centrifugal pump with the specific speed of 180 was taken as a model, three different blade outlet angles, such as 27°, 37°, and 47°, were designed except the original impeller with 22°blade outlet angle. Then, the software ANSYS 14.5 was applied to carry out numerical calculations. The results show that blade outlet angle can affect the performance significantly, an appropriately increased blade outlet angle can improve the head and efficiency of the pump, but it shouldn′t exceed 47°. With increasing blade outlet angle, the low energy fluid area gradually expands from the blade leading edge to the trailing edge, and the pressure distribution tends to be disordered, but also an adverse pressure gradient exists near the blade pressure side, and the unsteady fluid with low energy gathers there. Under design condition, when the blade outlet angle is less than 37°, the amplitude of pressure fluctuation is lower, and the amplitude of high frequency fluctuation is very small. The secondary frequency tends to shift to a lower frequency with increasing blade outlet angle. The impeller radial thrust in each design is the smallest under the design condition, and the difference is the largest under part-load condition. The impeller radial thrust force is the minimum at 27° blade outlet angle compared with the other impellers under the same flow rate. It is suggested that there is an optimal blade outlet angle for unsteady flows. Meanwhile, a performance experiment was conducted on the pump with 22° blade outlet angle, and it was found that the results of numerical simulation were reliable. Generally, this study has certain referential significance to development of chemical centrifugal pumps.
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