To obtain dynamic characteristics of cavitation and study the relationship between the cavitation and inlet pressure, large-eddy simulation(LES) is utilized to calculate unsteady flow field in the pilot stage. Lamb-Os...To obtain dynamic characteristics of cavitation and study the relationship between the cavitation and inlet pressure, large-eddy simulation(LES) is utilized to calculate unsteady flow field in the pilot stage. Lamb-Oseen vortex is observed. Simulation results show that vortex cavitation exists, and cloud cavitation begins to occur when inlet pressure reaches 7 MPa. Cavitation and cavitation-shedding are enhanced by the increment of inlet pressure. The main frequencies of the pressure oscillations of vortex cavitation and cloud cavitation increase with inlet pressure increasing. By comparing results of local cavitation and facet cavitation, it is known that cloud cavitation has a greater influence than vortex cavitation. Upon increasing the wedge length, the main frequency of vortex cavitation increases whereas that of cloud cavitation decreases, the volume fraction of the vapor phase and the energy efficiency decrease. Considering the above characteristics and the easiness of the process, the optimal wedge length is 0.03 mm.展开更多
基金Supported by the National Natural Science Foundation of China(No.51475338)the Natural Science Foundation of Hubei Province(No.ZRZ2014000117)。
文摘To obtain dynamic characteristics of cavitation and study the relationship between the cavitation and inlet pressure, large-eddy simulation(LES) is utilized to calculate unsteady flow field in the pilot stage. Lamb-Oseen vortex is observed. Simulation results show that vortex cavitation exists, and cloud cavitation begins to occur when inlet pressure reaches 7 MPa. Cavitation and cavitation-shedding are enhanced by the increment of inlet pressure. The main frequencies of the pressure oscillations of vortex cavitation and cloud cavitation increase with inlet pressure increasing. By comparing results of local cavitation and facet cavitation, it is known that cloud cavitation has a greater influence than vortex cavitation. Upon increasing the wedge length, the main frequency of vortex cavitation increases whereas that of cloud cavitation decreases, the volume fraction of the vapor phase and the energy efficiency decrease. Considering the above characteristics and the easiness of the process, the optimal wedge length is 0.03 mm.
