Identification of coupled natural frequencies in a rotor-stator test-rig for different gas properties
Barabas, B. and Brillert, D. and Dohmen, H.J. and Benra, F.-K.
12TH EUROPEAN CONFERENCE ON TURBOMACHINERY FLUID DYNAMICS AND THERMODYNAMICS, ETC 2017
In this paper a rotor-stator cavity test rig for experimental investigations of acoustic fluid-structure interactions in side cavities of radial compressors is introduced. The instrumentation of the test rig and the evaluation methodology are presented. The fluid is excited at frequencies, which are independent from the disk rotational speed, with loudspeakers. The acoustic pressure patterns are detected with a pressure sensor rotatable in circumferential direction. The gas properties are varied via different pressure levels in the test rig. First experimental results of natural frequencies are presented. The structure and acoustic dominant m = 4, n = 0, l = 1 modes have been excited and identified. The experimental results of the resonance frequencies of coupled modes on the dependence of the surrounding gas pressure are compared to a coupled numerical modal analysis and an analytical approach of other researchers. The main trend is in good accordance to them. Copyright © by the Authors.