Acoustic and Convective Mechanisms Contributing to Non-Synchronous-Vibrations in a Multistage Compressor - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Communication Dans Un Congrès Année : 2019

Acoustic and Convective Mechanisms Contributing to Non-Synchronous-Vibrations in a Multistage Compressor

Résumé

In the present paper we show an analysis of Non-Synchronous-Oscillations in the rear stage of an experimental high-speed 3.5 stage compressor. The machine CREATE is representative of the rear median-stages of a modern civil turbofan engine except for an increased tip clearance on middle and last stage. Using distributed unsteady pressure measurements a comprehensive dataset during transient throttling maneuvers is presented, including temporal and spatial mode decomposition and the derivation of wave propagation speeds. To support the aerodynamic characterization, the steady flow structure at near stall conditions has been investigated using Laser-Doppler-Anemometry and unsteady pressure probes. In repeated experiments the machine has encountered alternating circumferential modes, several hundred revolutions before rotating stall at design speed. It was found that acoustic resonance of an upstream cut-on mode between the compressor stages enforces the development of particular modes. These phenomena have not been observed on the same machine with regular tip clearance. In contrast to front-stage observations reported in literature, where leading edge separations cause strong excitations of the blade eigenmodes, initially weak modulations of the flow in the rotor tip region are observed to be amplified due to acoustic feedback. With rising amplitude lock-in to distinct circumferential mode orders develops. Apart from the final lock-in procedure, signatures of solely aerodynamic fluctuations, discussed in literature as ‘Rotating Instabilities’ or ‘Part Span Stall’, are observed intermittently at different speedlines.
Fichier non déposé

Dates et versions

hal-03845646 , version 1 (09-11-2022)

Identifiants

Citer

Christoph Brandstetter, Benoît Paoletti, Xavier Ottavy. Acoustic and Convective Mechanisms Contributing to Non-Synchronous-Vibrations in a Multistage Compressor. ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition, Jun 2019, Phoenix, United States. ⟨10.1115/GT2019-91514⟩. ⟨hal-03845646⟩
12 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More