Spatial-temporal evolution mechanism of mass transfer under synergetic gaseous and vapour cavitating effects in a micropump

As the vital power and the energy management systems for satellite life extension, the on-orbit refuelling system pressurizes the gas-containing propellants via the micropump, where the mixed transportation involves gas-liquid transitions and hydrodynamic oscillation. To achieve accurate predictions for the complex gas-liquid dynamic processes, the coupling methods of vapour and gaseous cavitations were proposed for the first time. The multifactor instabilities induced by the mass-transfer behaviors and rigid disturbance of the impeller were investigated, and the synergetic cavitating mechanism on its frequency spectrum, amplitude distribution and propagation law was revealed. The results indicated that the large absorbed concentration suppressed the fluctuating frequency, but enhanced the fluctuating amplitude. The absorbed-evolved characteristic frequency occupied the largest proportion of the mixing frequency about 5.5 % in the suction chamber. For the impeller, rigid disturbances by the impeller were the principal cause of hydraulic instability, and the amplitude of the absorbed–evolved condition accounted for 11–23 % of the amplitude of rotational frequency, demonstrating the non–negligible role of gaseous cavitation. In the volute, the degree of the gas consumption attenuation decreased as the total gas content increased, and the surges of turbulence kinetic energy and mass–transfer rate demonstrated the coupling mechanism between the flow and mass transfer.