Session: 30-02 Damping evaluation and effect I

Paper Number: 79980

79980 - An Experimental Investigation on the Dynamic Response Variability of a Turbine Blade With Mid-Span Dampers 

This paper addresses two main subjects. Firstly, a novel test set-up is described to experimentally study the nonlinear dynamic behavior of a turbine blade coupled with two mid-span dampers. To this end, a representative turbine blade and mid-span friction dampers are originally designed, and they are assembled to a special test rig which has been previously developed at Politecnico di Torino. Secondly, the variability of the dynamic response of the blade under the same nominal conditions is investigated in detail. To understand the blade-damper interaction, contact forces between the frictional surfaces are recorded by means of the architecture of the experimental campaign, during which the system is forced with a harmonic excitation. The rotational motion of the damper and the relative displacement between the bodies are also measured with a differential laser to be able to extract the inherent kinematics of the system in operation. A purposely defined loading strategy is applied in the experiments and a large number of cases with several excitation levels and pre-loads are thoroughly examined. It is shown that multiple responses obtained in successive tests by keeping all user-controlled inputs identical are due to non-unique contact forces that provide different static force equilibria on the damper.

Presenting Author: Erhan Ferhatoglu Politecnico di Torino

Presenting Author Biography: The presenter is currently a PhD student at Politecnico di Torino, Italy. He investigates one of the main mechanisms of the ​dynamic response variability in turbine bladed disks with frictional interfaces. He specifically studies the effects of non-unique contact forces on the vibration behavior and how they provide a non-repeatability under the same nominal conditions.

Authors:

Erhan Ferhatoglu Politecnico di Torino
Daniele Botto Politecnico di Torino
Stefano Zucca Politecnico di Torino