Cross influence of rotational speed and flow rate on pressure pulsation and hydraulic noise of an axial-flow pump

Axial-flow pumps may experience significant pressure pulsation and high hydraulic noise when deviating from design conditions, and this article investigates the cross influence of rotational speed and flow rate on inlet pressure pulsation and hydraulic noise of an axial-flow pump based on coherence theory through physical model experiments. The energy amplitude of pressure pulsation is directly proportional to rotational speed and inversely proportional to flow rate, as rotational speed increases, the energy distribution of the blade passage frequency (fBPF) within different frequency bands of pressure pulsation improves. Pressure pulsation and the overall natural frequency of the pump device work together to define the primary and secondary frequencies of the sound pressure level, as rotational speed increases, these frequencies eventually move toward 2fBPF, and the coherence coefficient at frequencies of fBPF and 2fBPF is above 0.9. To reduce hydraulic noise, both pressure pulsation and natural frequency should be given sufficient attention.