Analyse de l'écoulement instationnaire dans l'entrefer roue-diffuseur d'une pompe centrifuge

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During the design of a turbomachine, the flow is considered to be steady and uniform at the entry of each element. For a centrifugal pump with a vanned diffuser, satisfying this assumption requires a large interface between the rotor and the diffuser so that the mixing process of the flow leaving the impeller can take place. Otherwise, an unsteady flow at the leading edge of the diffuser vanes represents a source of low efficiency and instability. Furthermore, the internal flow of the impeller can be affected by asymmetric downstream conditions which results in extra flow unsteadiness and instabilities. The aim of the actual study is a better understanding of the mechanisms leading to such a complex flow and more realistic numerical models. LDA measurements were performed ta investigate the flow in the rotor and the vanned diffuser of a centrifugal pump of industrial type.