Abstract:

The application of high pressure radial compressors is expected to have an above-average growth rate in future. When vibrations are matter of investigations, impellers surrounded by dense gases cannot be treated separately but as a coupled system comprising the impeller structure and the fluid.In this paper experimental results gathered in a rotor-stator test rig at different gas pressures are presented. The modal properties of a weakly coupled acoustic mode and a strongly coupled acoustic mode are determined. The results show no influence of the gas pressure on the natural frequency of the weakly coupled acoustic mode. The damping of it is approaching a minimum with increasing gas density. The natural frequencies of the strongly coupled modes diverge from each other when the gas pressure is increased.