Rotor–stator interaction and its induced noise suppression in a centrifugal pump with the staggered impeller

The staggered impeller (SI) is an effective strategy for enhancing flow stability, improving energy efficiency, and suppressing pressure pulsations in double-suction pumps. In the present paper, SI in an end-suction centrifugal pump is proposed. Its effect on the acoustic signature is investigated using an acoustic analogy method combined with the broadband noise source model. The correlation between flow structures and acoustic responses is clarified by integrating the λ2 criterion and the Lamb vector analysis, thereby revealing the noise reduction mechanism associated with the SI design. These results demonstrate that, compared to the normal impeller, the SI leads to a significant reduction in acoustic power on the blade surfaces, particularly on the pressure side, while the contribution from quadrupole sources remains negligible. The staggered configuration exhibits a pronounced effect in suppressing low-frequency noise. The reductions in sound pressure level at the blade-passing frequency reach 21% at the pump inlet and 20.9% at the outlet. Across the entire frequency range, the average reduction in overall sound pressure level is 13.9%, with the most significant decrease observed in the intensity of the volute dipole. The internal flow analysis confirms that the periodic shedding of wake flow and its interaction with the tongue are the dominant excitation source of pump noise. The interaction between the wake shed from staggered blades not only improves the circumferential uniformity of velocity distribution at impeller outlet and weakens the shedding intensity of the wake flow, but also alters the pattern of rotor–stator interaction, ultimately achieving the effective suppression of flow-induced noise.