Fluid–structure instabilities in the axial balancing system of a turbo-pump

Abstract

This article is devoted to the experimental and theoretical modelling of a fluid structure instability that affects the axial balancing system cavities of spatial turbo-pumps. After having explained the design of the laboratory experiment that mimics the real industrial set-up, we describe the observation of the instability that emerges due to the coupling of acoustic modes of a fluid cavity with the deformations of a metallic disc that closes the cavity when a flow passes through the system. The system bifurcates towards a vibrational state via a Hopf bifurcation that can be super critical or sub critical, depending on the flow rate and inlet aperture. The experimental arrangement is fully described and tested in order to build a theoretical model that predicts the observed threshold of the instability. Therefore, we expect our model to be predictive for real industrial cases.