Research Papers: Gas Turbines: Structures and Dynamics

A Test Rig for Noncontact Traveling Wave Excitation of a Bladed Disk With Underplatform Dampers

[+] Author and Article Information
Teresa Berruti

Department of Mechanical Engineering, Politecnico di Torino, Corso Duca degli Abruzzi, 24 10129 Turin, Italyteresa.berruti@polito.it

Christian M. Firrone

Department of Mechanical Engineering, Politecnico di Torino, Corso Duca degli Abruzzi, 24 10129 Turin, Italychristian.firrone@polito.it

Muzio M. Gola

Department of Mechanical Engineering, Politecnico di Torino, Corso Duca degli Abruzzi, 24 10129 Turin, Italymuzio.gola@polito.it

J. Eng. Gas Turbines Power 133(3), 032502 (Nov 11, 2010) (8 pages) doi:10.1115/1.4002100 History: Received May 11, 2010; Revised June 03, 2010; Published November 11, 2010; Online November 11, 2010

This paper presents a static test rig called “Octopus” designed for the validation of numerical models aimed at calculating the nonlinear dynamic response of a bladed disk with underplatform dampers (UPDs). The test rig supports a bladed disk on a fixture and each UPD is pressed against the blade platforms by wires pulled by dead weights. Both excitation system and response measurement system are noncontacting. This paper features the design and the setup of the noncontacting excitation generated by electromagnets placed under each blade. A traveling wave excitation is generated according to a desired engine order by shifting the phase of the harmonic force of one electromagnet with respect to the contiguous exciters. Since the friction phenomenon generated by UPDs introduces nonlinearities on the forced response, the amplitude of the exciting force must be kept constant at a known value on every blade during step-sine test to calculate frequency response functions. The issue of the force control is therefore addressed since the performance of the electromagnet changes with frequency. The system calibration procedure and the estimated errors on the generated force are also presented. Examples of experimental tests that can be performed on a dummy integral bladed disk (blisk) mounted on the rig are described in the end.

Copyright © 2011 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.



Grahic Jump Location
Figure 13

Hammer test, FRF blade 1

Grahic Jump Location
Figure 14

FRF in “fully stick” configuration

Grahic Jump Location
Figure 15

Nonlinear FRF for nodal diameter 2

Grahic Jump Location
Figure 1

The test rig “Octopus”

Grahic Jump Location
Figure 2

The arm structure

Grahic Jump Location
Figure 3

Detail of the electromagnet unit

Grahic Jump Location
Figure 4

(a) Sketch of the electromagnet facing the steel blade. (b) Equivalent magnetic circuit. (c) Simplified equivalent magnetic circuit.

Grahic Jump Location
Figure 5

(a) Measured output current amplitude versus input voltage amplitude for different input voltage frequency. (b) Comparison of admittance values derived from experiments and from RL model.

Grahic Jump Location
Figure 6

Electromagnet calibration bench

Grahic Jump Location
Figure 7

Amplitude voltage versus electrical frequency calibration curves for the 24 electromagnets when Fa=5 N

Grahic Jump Location
Figure 8

Amplitude voltage V versus electrical frequency for EM1 at 5 N, 10 N, and 15 N: experimental curves (solid lines) and estimated (dashed lines)

Grahic Jump Location
Figure 9

FE model of the blisk and detail of the cylindrical underplatform damper

Grahic Jump Location
Figure 10

First two bending families, without UPDs (free condition) and with UPDs constrained between the platforms (stick condition)

Grahic Jump Location
Figure 11

(a) Disk and UPDs loading system. (b) Detail of platforms and UPD.

Grahic Jump Location
Figure 12

24 disk circular ODS, each of them measured with one EM switched on (a) before tuning and (b) after tuning



Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In