• A weakly compressible computational model is established, which significantly improves the accuracy of transient pressure pulsation prediction for high-speed centrifugal pumps. The prediction error of 1.0 fBPF amplitude is reduced from 123.5% to 55.1%, and the head prediction error under low flow conditions is also narrowed from 9.7% to 5.43%. • Weak compressibility has little effect on the internal flow field distribution of the pump, but it expands the cavitation region under critical cavitation and 10% head drop conditions, enhancing cavitation-induced flow effects. • After considering weak compressibility, the amplitudes of key frequencies such as 0.5 fBPF and 1.0 fBPF as well as pressure pulsation energy (RMS*) in the pump are increased, with a more pronounced increase in the region downstream of the volute tongue. The formation and collapse of cavitation in high-speed centrifugal pumps can induce unsteady excitation forces, leading to abnormal vibration and noise, and may also cause blocking effects in the impeller passages, thereby affecting the normal operation of the pump. Furthermore, the extreme pressure rise inside the pump can result in weak compressibility of the working medium, which significantly influences the pump flow and the induced pressure pulsations. This study investigates the impact of weak compressibility on cavitation structures and pressure pulsation characteristics in a high-speed pump through numerical simulation and experimental analysis, with the aim of mitigating unstable excitation forces and associated pressure pulsation effects. The results demonstrate that, under the 0.2Q d flow condition, the head prediction error from the weakly compressible simulation is approximately 5.43%, markedly lower than the 9.7% error obtained from the incompressible simulation. In terms of pressure pulsation, the average error at the blade-passing frequency (f BPF ) monitoring point is 55.1% for the weakly compressible model, significantly lower than the 123.5% error of the incompressible model. For the pump under cavitation conditions, the pressure spectra clearly capture the blade-passing frequency and its higher harmonics. Comparison reveals that when weak compressibility is considered, both the pressure amplitude at the blade-passing frequency and the pressure pulsation energy within typical frequency bands increase. These findings indicate that accounting for the weak compressibility of the fluid not only improves computational accuracy but also influences the prediction of cavitation performance and pressure pulsation in high-speed centrifugal pumps, and therefore should be incorporated in numerical simulations of the high-speed pump.
Ji et al. (Sat,) studied this question.