Unsteady Flow and Pressure Pulsation Characteristics in an Ultra-High-Speed Centrifugal Pump Considering the Weak Compressibility Effect

Ultra-high-speed centrifugal pumps are frequently utilized in chemical and aerospace industries, yet the impact of fluid weak compressibility on pressure pulsation remains unclear. This study employs the delayed detached eddy simulation (DDES) numerical method to investigate the effects of the medium's weak compressibility on the internal flow field structure of an ultrahigh-speed centrifugal pump, with a particular focus on pressure pulsations. The DDES numerical results were validated through experimental tests, showing good agreement with the experimental pump performance and measured pressure pulsation data, particularly at the blade passing frequency and under various flow conditions. Results indicate that under weak compressibility conditions, the density and velocity distribution of the fluid inside the pump are influenced. Moreover, the weak compressibility of the medium impacts the pressure pulsation signals under the design condition, especially for the monitoring points around the volute tongue where the amplitude is approximately 60∼85% of that in the incompressible state, besides, a significant impact under low flowrate is generated. By comparing the blade passing frequency–amplitude and the root-mean-square (RMS) energy within the 0-100 kHz frequency band, it is evident that considering weak compressibility effects results in overall lower pressure pulsation energy within the pump compared to the incompressible state. This finding suggests that the weak compressibility effect of the fluid has a suppressive influence on pressure pulsation in the ultrahigh-speed centrifugal pump.