Research on Rapid Start-Up Transient Cavitation Characteristics of Axial Flow Propulsion Pump
The transient cavitation calculation model of the axial flow propulsion pump is established based on the Reynolds averaged N-S equation,the SST k-ω turbulence model,and the Zwart cavitation model.Based on the transient experimental validation,numerical simulation methods are used to investigate the transient cavitation characteristics of an axial flow propulsion pump.The analysis includes an examination of the cavitation evolution process and the associated flow mechanisms during the rapid start-up period.The results indicate that the cavitation evolution of the axial flow propulsion pump during rapid start-up can be divided into three stages:the initial-peak stage,the cavitation-reorganization stage and cavitation-stabilization stage.The division of the different stages is determined by the start-up time of the pump and is independent of the flow rate.During rapid start-up,the development of the internal cavitation bubble structure is initially controlled by the impeller acceleration,and later influenced by the resistance properties of system pipe.After the pump speed reaches the rated value,the resistance properties determine the rate of flow rate change and the final flow rate at the end of the start-up,thereby causing the cavitation structure inside the pump to undergo secondary development and structural reorganization.Compared with the cavitation number,the net positive suction head(NPSH)of the axial flow propulsion pump can still intuitively reflect the transient cavitation evolution process under the rapid start-up conditions,and can serve as a reference value for transient cavitation.These conclusions have important guiding significance for the analysis of cavitation situations during the transient process of turbo pumps.
axial flow propulsion pumprapid start-uptransient cavitationflow field evolution
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