Experimental Nonlinear Vibration Analysis of a Shrouded Bladed Disk Model on a Rotating Test Rig
The optimization of the mechanical design process of turbomachinery has already been subject of research for decades. In this context, many researchers developed efficient numerical methods to calculate the vibration response of bladed disks. In particular, shrouded bladed disks with frictional contacts present a major challenge in the design process. Beside efficient simulations, the validation process plays an important role in most recent studies. The quality of the comparison depends directly on the system’s boundary conditions in the simulation as well as in the experiment. For instance, the estimation of the excitation forces should be as precise as possible, because the vibration response, in particular in the nonlinear case, depends strongly on the excitation forces.
In this paper, a newly developed rotating test rig for bladed disks is introduced. The test rig consists of a rotating shaft mounted in a vacuum chamber, in order to avoid any aerodynamic loadings and damping, and an excitation with multiple permanent magnets. Here, a large number of permanent magnets is applied to approximate a continuous force distribution along the circumference. To estimate the overall force distribution, magnetic field simulations are performed and compared to the measurements with a very good agreement. Compared to other excitation methods such as a single ac-magnet or air jet excitation, the presented method manages a high energy input at a specific engine order or frequency with modest complexity. The nonlinear vibration response is measured by strain gauges for various numbers of magnets and excitation force amplitudes. The presented results are characterized by an excellent repeatability and precise measurements of resonance passages. Especially, the nonlinear behavior of the structure such as rotational speed and excitation force dependent resonance amplitudes and frequencies as well as jumping phenomena can be shown. The developed rotating test rig proves to be particularly suitable for the vibration analysis of rotating bladed disks considering nonlinearities.
KeywordsNonlinear dynamics Bladed disk Shroud contact Rotating test rig
The investigations were conducted as a part of the joint research program COOREFlex-turbo in the frame of AG Turbo. The work was supported by the Bundesministerium für Wirtschaft und Technologie (BMWi) as per resolution of the German Federal Parliament under grant number 03ET7020K. The authors gratefully acknowledge AG Turbo and MAN Energy Solutions SE for their support and permission to publish this paper. The responsibility for the content lies solely with its authors.
- 1.Petrov, E.P., Ewins, D.J.: Analytical formulation of friction interface elements for analysis on nonlinear multi-harmonic vibrations of bladed discs discs. In: Proceedings of ASME Turbo Expo 2002. American Society of Mechanical Engineers, New York (2002)Google Scholar
- 2.Siewert, C., Panning-von Scheidt, L., Wallaschek, J., Richter, C.: Multiharmonic forced response analysis of a turbine blading coupled by nonlinear contact forces. In: Proceedings of ASME Turbo Expo (2009)Google Scholar
- 6.Kielb, J.J., Abhari, R.S.: Experimental study of aerodynamic and structural damping in a full-scale rotating turbine. In: Proceedings of ASME Turbo Expo (2001)Google Scholar
- 7.Judge, J., Pierre, C., Mehmed, O.: Experimental investigation of mode localization and forced response amplitude magnification for a mistuned bladed disk. In: Proceedings of ASME Turbo Expo (2000)Google Scholar
- 9.Gibert, C., Kharyton, V., Thouverez, F., Jean, P.: On forced response of a rotating integrally bladed disk: predictions and experiments. In: Proceedings of ASME Turbo Expo (2010)Google Scholar
- 12.Szwedowicz, J., Sextro, W., Visser, R., Masserey, P.A.: On forced vibration of shrouded turbine blades. In: Proceedings of ASME Turbo Expo (2003)Google Scholar
- 13.Laxalde, D., Gibert, C., Thouverez, F.: Experimental and numerical investigations of friction rings damping of blisks. In: Proceedings of ASME Turbo Expo (2008)Google Scholar
- 14.Charleux, D., Gibert, C., Thouverez, F., Dupeux, J.: Numerical and experimental study of friction damping blade attachments of rotating bladed disks. Int. J. Rotating Mach. (2006). http://dx.doi.org/10.1155/IJRM/2006/71302Google Scholar
- 15.Kaptan, F., Panning-von Scheidt, L., Wallaschek, J.: Numerical and experimental study of shrouded blade dynamics considering variable operating points. In: ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, New York (2018)Google Scholar
- 17.Kenyon, J.A., Griffin, J.H., Kim, N.E.: Sensitivity of tuned bladed disk response to frequency veering. In: ASME Turbo Expo 2004: Power for Land, Sea, and Air. American Society of Mechanical Engineers, New York (2004)Google Scholar