Matrice de transfert et sources hydroacoustiques d'une pompe centrifuge à faibles charges

Transmission matrix and hydroacoustic sources of a centrifugal pump at very low load

EDF/DER, Département Machines

Abstract

Transmission matrix and hydroacoustic sources of a centrifugal pump, at very low load, are determined by an experimental method ; with an external excitation (f1ow fluctuations generated by a small rotating valve connected on a by-pass around the machine), more important than the hydroacoustic sources of the pump (even at very low load), the transmission matrix is accurately determined. Then pump sources are obtained by a simple difference. The main results are :

- in terms of load, no variation of the transmission matrix,

- about hydroacoustic sources, under a particular load (beginning of recirculation phenomena), spectra are distorted and the peak amplitude at the blade passing frequency (and multiples) increases appreciably,

- at low load, wide band noise becomes important (x20), and this has a very bad influence on arounding pipes, because their hydroacoustic modes are necessarily excited.