Model test and numerical simulation study on the hydraulic performance similarity theory and pressure pulsation characteristics of vertical axial flow pump device based on variable-speed and variable-angle adjustment

Pressure pulsation is a common hydraulic phenomenon in pump operation. This paper focuses on the pressure pulsation regularities in the impeller chamber under similar operating conditions. Under similar operating conditions of variable speed, the flow rate is converted by the pump's first similarity law. Whereas the flow rate and head for changing blade angle are derived by numerical approximation of the experimental data. The results show that: the ratio of head and the ratio of flow under similar operating conditions are both power exponentially related to the ratio of the tangent of the corresponding blade placement angle. The head-discharge characteristic curves obtained by conversion are highly consistent with the experimental results, with a head error of 2.02 %. Under variable-speed similar conditions, the magnitude and location of the main frequency values at each monitoring point remain essentially consistent; the pulsation peak-to-peak value ratio is proportional to the corresponding rotational speed squared. In case of varying blade angles, the pressure coefficient at the impeller inlet increases with the blade angle, while it decreases for the middle and outlet. These results are essential to ensuring stable regulation of pump operating conditions.