Natural frequencies of rotating disk-like structures submerged viewed from the stationary frame

28th IAHR symposium on Hydraulic Machinery and Systems

Presas, Alexandre^1 ; Valentin, David^1 ; Egusquiza, Eduard^1 ; Valero, Carme^1 ; Seidel, Ulrich^2 ; Weber, Wilhelm^2

Centre de Diagnòstic Industrial i Fluidodinàmica, Universitat Politècnica de Catalunya, Av. Diagonal, 647. ETSEIB. Pab. D+l., Barcelona

08028, Spain^1

Voith Hydro Holding GmbH and Co. KG, Alexanderstraße ll, Heidenheim

89522, Germany^2

关键词: Experimental test;    Laser Doppler vibrometers;    Natural frequencies and modes;    Pump turbine runners;    Rotating frame;    Rotating structures;    Stationary frame;    Stationary reference frames;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/49/8/082023/pdf
DOI  :  10.1088/1755-1315/49/8/082023

来源: IOP

【 摘 要 】

To understand the effect of rotation in the dynamic response of pump-turbine runners, simplified models such as disk-like structures can be used. In previous researches the natural frequencies and mode shapes of rotating disk-like structures submerged and confined have been analysed from the rotating frame. Nevertheless to measure these parameters experimentally from the rotating point of view can be a difficult task, since sensors have to withstand with large forces and dynamic loads. In this paper the dynamic response of rotating disk-like structures is analysed from the stationary frame. For this purpose an experimental test rig has been used. It consists on a disk confined that rotates inside a tank. The disk is excited with a PZT attached on it and the response is measured from both rotating frame (with miniature accelerometers) and from the stationary frame (with a Laser Doppler Vibrometer). In this way the natural frequencies and mode shapes of the rotating structure can be determined from the stationary reference frame. The transmission from the rotating to the stationary frame is compared for the case that the rotating structure rotates in a low density medium (air) and in a high density medium (water).