Influence of the upper-rotor device on the axial flow pump head characteristics

The paper considers results of the experimental study of an axial flow pump with the upper-rotor device in the form of axial and inclined grooves. It shows the influence of their number and length on the pressure characteristics. Relevance of the work is based on the fact that pressure characteristics of pumps with the axial wheels in vast majority of cases have the non-monotonic curves complicating their design and regulation processes. This topic is of theoretical and practical interest, since ensuring monotonically decreasing pressure characteristic of an axial pump is one of the most important goals in design and optimization of the unit. The pressure characteristics shape could be changed (from non-monotonic to monotonically decreasing) by installing various upper-rotor devices. An attempt was made to correct the non-monotonic pressure characteristic using the upper-rotor devices. Pressure characteristics of the studied axial pump with the upper-rotor device were experimentally obtained. The obtained results were analyzed. Optimal geometric parameters of the upper-rotor device were identified. It was established that optimal geometric parameters of the upper-rotor device were having no negative impact on its efficiency, improving the pressure characteristic by eliminating the pressure block and changing the pressure characteristic shape to the monotonically decreasing.
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