Visualisation des figures de cavitation à l'entrée d'un inducteur fretté

Cavitation forms visualisation upstream of a shrouded inducer

Equipe Hydraulique INSA de Lyon, Laboratoire de Mécanique des Fluides et d'Acoustique, E.C.L., U.C.B., Lyon 1, U.M.R. CNRS 5509

Abstract

At part load and with low available NPSH, cavitation induces instabilities in inducers. The visualization of the flow upstream of an inducer through a 500 mm long clear suction pipe allows us to map the inception and the evolution of the different forms of cavitation appearing upstream of this inducer. The plane NPSHa/Q is explored using two methods. First, the flowrate is reduced at constant NPSHa, it is possible to observe successively blade cavitation then backflow cavitation. The second method consists in lowering the NPSHa at constant flowrate, this brings to the fore the inception of cavitation surge. A great part of load instabilities take place with a head drop minus than 3%.