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

2010 ◽  
Vol 133 (3) ◽  
Author(s):  
Teresa Berruti ◽  
Christian M. Firrone ◽  
Muzio M. Gola
Keyword(s):  
Traveling Wave ◽  
Numerical Models ◽  
Experimental Tests ◽  
Calibration Procedure ◽  
Forced Response ◽  
Wave Excitation ◽  
Test Rig ◽  
Response Measurement ◽  
Static Test ◽  
Bladed Disk

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.

A Test Rig for Non-Contact Travelling Wave Excitation of a Bladed Disk With Underplatform Dampers

2010 ◽  
Author(s):  
Teresa Berruti ◽  
Christian M. Firrone ◽  
Muzio M. Gola
Keyword(s):  
Numerical Models ◽  
Experimental Tests ◽  
Calibration Procedure ◽  
Travelling Wave ◽  
Forced Response ◽  
Wave Excitation ◽  
Test Rig ◽  
Response Measurement ◽  
Static Test ◽  
Bladed Disk

The 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. The paper features the design and the set-up of the noncontacting excitation generated by electromagnets placed under each blade. A travelling 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.

scholarly journals Experimental Investigation on a Bladed Disk with Traveling Wave Excitation

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 3966
Author(s):  
Luigi Carassale ◽  
Elena Rizzetto
Keyword(s):  
Data Processing ◽  
Traveling Wave ◽  
Frequency Response Function ◽  
Wave Excitation ◽  
Test Rig ◽  
Real Situation ◽  
Bladed Disk ◽  
Experimental Identification ◽  
Alternative Techniques ◽  
Processing Techniques

Bladed disks are key components of turbomachines and their dynamic behavior is strongly conditioned by their small accidental lack of symmetry referred to as blade mistuning. The experimental identification of mistuned disks is complicated due to several reasons related both to measurement and data processing issues. This paper describes the realization of a test rig designed to investigate the behavior of mistuned disks and develop or validate data processing techniques for system identification. To simplify experiments, using the opposite than in the real situation, the disk is fixed, while the excitation is rotating. The response measured during an experiment carried out in the resonance-crossing condition is used to compare three alternative techniques to estimate the frequency-response function of the disk.

Traveling Wave Excitation: A Method to Produce Consistent Experimental Results

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Geofrey S. Cox ◽  
Anthony N. Palazotto ◽  
Jeffrey M. Brown ◽  
Tommy J. George
Keyword(s):  
Traveling Wave ◽  
Forced Response ◽  
Test Stand ◽  
Experimental Results ◽  
Wave Excitation ◽  
Alignment Position ◽  
Excitation System ◽  
Response Measurement ◽  
Signal Input

This paper describes the experimental framework to establish consistent, repeatable results associated with a traveling wave excitation system. The experiment is employed to ascertain the forced response and mistuning patterns for rotors. Several items attributing to existing experimental inconsistencies were identified and their effects were realized during this research. These experimental items were signal input locations, response measurement locations, and rotor alignment position. Accounting for these experimental variables, this paper develops a process which enables consistent rotor forced response results, independent of its orientation on the test stand.

Experimental Demonstration of Maximum Mistuned Bladed Disk Forced Response

2003 ◽  
Vol 125 (4) ◽  
pp. 673-681 ◽  
Author(s):  
J. A. Kenyon ◽  
J. H. Griffin
Keyword(s):  
Traveling Wave ◽  
Close Agreement ◽  
Maximum Amplitude ◽  
Forced Response ◽  
Maximum Response ◽  
Experimental Demonstration ◽  
Wave Excitation ◽  
Bladed Disk ◽  
Engine Order ◽  
Structural Mode

A theory was previously developed for predicting robust maximum forced response in mistuned bladed disks from distortion of a structural mode. This paper describes an experiment to demonstrate the theory. A bladed disk is designed to be sufficiently sensitive to mistuning to obtain maximum response. The maximum amplitude magnification from mistuning is predicted using the theory, 1.918. The bladed disk is intentionally mistuned to obtain the maximum response, and the response to an engine order traveling wave excitation is measured. The measured amplitude magnification is in close agreement with the theory. The robustness of the maximum response is demonstrated.

Experimental Demonstration of Maximum Mistuned Bladed Disk Forced Response

2003 ◽  
Author(s):  
J. A. Kenyon ◽  
J. H. Griffin
Keyword(s):  
Traveling Wave ◽  
Close Agreement ◽  
Maximum Amplitude ◽  
Forced Response ◽  
Maximum Response ◽  
Experimental Demonstration ◽  
Wave Excitation ◽  
Bladed Disk ◽  
Engine Order ◽  
Structural Mode

A theory was previously developed for predicting robust maximum forced response in mistuned bladed disks from distortion of a structural mode. This paper describes an experiment to demonstrate the theory. A bladed disk is designed to be sufficiently sensitive to mistuning to obtain maximum response. The maximum amplitude magnification from mistuning is predicted using the theory, 1.918. The bladed disk is intentionally mistuned to obtain the maximum response, and the response to an engine order traveling wave excitation is measured. The measured amplitude magnification is in close agreement with the theory. The robustness of the maximum response is demonstrated.

Experimental and Numerical Assessment of Mistuning Effects on Vibratory Response of a Bladed Disk with Underplatform Dampers

2021 ◽  
Author(s):  
S. Mehrdad Pourkiaee ◽  
Teresa Berruti ◽  
Stefano Zucca ◽  
Geoffrey Neuville
Keyword(s):  
Model Identification ◽  
Forced Response ◽  
Response Level ◽  
Static Test ◽  
Bladed Disk ◽  
Experimental Campaign ◽  
Proposed Model ◽  
Numerical Assessment ◽  
Linearized Model ◽  
Forced Responses

Abstract This paper presents experimental and numerical investigation of mistuned forced responses of an integrally bladed disk with full set of underplatform dampers (UPDs). This research aims at providing: 1. An experimental benchmark for nonlinear dynamics of a mistuned bladed disks with UPDs. 2. A numerical model that can account for features of a mistuned forced response level. Accordingly, a detailed experimental campaign is conducted on a static test rig called Octopus. This rig is specifically designed to investigate the dynamics of a full-scale integrally bladed disk (blisk) with UPDs in a noncontact manner so that the dynamic response of the system is not modified. The effect of mistuning on experimental forced response levels is assessed and a linearized model is proposed to predict the modulation of frequency response functions (FRFs) due to the frequency splitting. In the development of the model, the mistuning pattern identified from the linear blisk without UPDs is used and it is assumed that adding the dampers does not change the structural mistuning of the blisk. In this study, the fundamental mistuning model identification (FMM ID) was employed to identify the mistuning pattern of the blisk. It is shown that the proposed model successfully predicts the modulation of linear mistuned FRFs. The linearized model is also able to predict the modulation of nonlinear mistuned FRFs in stick condition (when nonlinear friction damping is negligible) with a good accuracy validating this assumption that adding the dampers does not change the mistuning pattern.

Experimental Investigation of Mode Localization and Forced Response Amplitude Magnification for a Mistuned Bladed Disk

2000 ◽  
Author(s):  
John Judge ◽  
Christophe Pierre ◽  
Oral Mehmed
Keyword(s):  
Experimental Investigation ◽  
Traveling Wave ◽  
Forced Response ◽  
Response Amplitude ◽  
Mode Shapes ◽  
Bladed Disks ◽  
Element Analysis ◽  
Mode Localization ◽  
Bladed Disk ◽  
Out Of Plane

The results of an experimental investigation on the effects of random blade mistuning on the forced dynamic response of bladed disks are reported. The primary aim of the experiment is to gain understanding of the phenomena of mode localization and forced response blade amplitude magnification in bladed disks. A stationary, nominally periodic, twelve-bladed disk with simple geometry is subjected to a traveling-wave, out-of-plane, “engine order” excitation delivered via phase-shifted control signals sent to piezo-electric actuators mounted on the blades. The bladed disk is then mistuned by the addition of small, unequal weights to the blade tips, and it is again subjected to a traveling wave excitation. The experimental data is used to verify analytical predictions about the occurrence of localized mode shapes, increases in forced response amplitude, and changes in resonant frequency due to the presence of mistuning. Very good agreement between experimental measurements and finite element analysis is obtained. The out-of-plane response is compared and contrasted with the previously reported in-plane mode localization behavior of the same test specimen. This work also represents an important extension of previous experimental study by investigating a frequency regime in which modal density is lower but disk-blade interaction is significantly greater.

Experimental and Numerical Investigation of Rotating Bladed Disk Forced Response Using Underplatform Friction Dampers

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Ibrahim A. Sever ◽  
Evgeny P. Petrov ◽  
David J. Ewins
Keyword(s):  
Measurement Techniques ◽  
Measured Data ◽  
Forced Response ◽  
Imperial College ◽  
Test Rig ◽  
Response Curves ◽  
Friction Dampers ◽  
Bladed Disk ◽  
Prediction Tools ◽  
Numerical Predictions

In this paper, we present a methodology and results from an experimental investigation of forced vibration response for a bladed disk with fitted underplatform “cottage-roof” friction dampers, together with the corresponding numerical predictions. A carefully designed and constructed rotating test rig is used to make precise measurements, which involve only the phenomena of interest. For this purpose, the measurement rig is operated under vacuum to eliminate aerodynamic effects on the rotating blisk and noncontact excitation and measurement techniques are employed so as not to modify the bladed disk dynamics. The experimental data measured are used for validation of multiharmonic balance-based prediction tools developed at the Imperial College. Predictions are carried out both with and without taking inherent mechanical mistuning into account, which is identified from measured data. Measured and predicted response curves are compared with each other and the degree of correlation is discussed.

Testing and Calibration Procedures for Mistuning Identification and Traveling Wave Excitation of Blisks

2009 ◽  
Author(s):  
Darren E. Holland ◽  
Sergio Filippi ◽  
Matthew P. Castanier ◽  
Steven L. Ceccio ◽  
Bogdan I. Epureanu
Keyword(s):  
Traveling Wave ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Calibration Procedure ◽  
Testing Procedure ◽  
Wave Excitation ◽  
Minimal Set ◽  
Testing Strategies ◽  
Calibration Algorithm ◽  
Alternative Testing

In this work, an integrated testing and calibration procedure is presented for performing mistuning identification (ID) and traveling wave excitation (TWE) of one-piece bladed disks (blisks). The procedure yields accurate results while also being highly efficient and is comprised of three basic phases. First, selected modes from a tuned blisk finite element model are used to determine a minimal set of measurement degrees of freedom (and locations) that will work well for mistuning ID. Second, a testing procedure is presented that allows the mistuning to be identified from relatively few vibration response measurements. A numerical validation is used to investigate the convergence of the mistuning ID results to a prescribed mistuning pattern using the proposed approach and alternative testing strategies. Third, a method is derived to iteratively calibrate the excitation applied to each blade so that differences among the blade excitation magnitudes can be minimized for single blade excitation, and also the excitation phases can be accurately set to achieve the desired traveling wave excitation. The calibration algorithm uses the principle of reciprocity and involves solving a least squares problem to reduce the effects of measurement noise and uncertainty. Because the TWE calibration procedure re-uses data collected during the mistuning ID, the overall procedure is integrated and efficient.

System Identification of Mistuned Bladed Disks From Traveling Wave Response Measurements

2003 ◽  
Author(s):  
D. M. Feiner ◽  
J. H. Griffin ◽  
K. W. Jones ◽  
J. A. Kenyon ◽  
O. Mehmed ◽  
...  
Keyword(s):  
System Identification ◽  
Modal Analysis ◽  
Traveling Wave ◽  
Natural Frequencies ◽  
Wave Excitation ◽  
New Approach ◽  
Operational Conditions ◽  
System Identification Method ◽  
Bladed Disk ◽  
Identification Method

A new approach to modal analysis is presented that allows the modes and natural frequencies of a mistuned bladed disk to be determined from its response to a traveling wave excitation. The resulting modes and natural frequencies are then used as input to a system identification method to determine the bladed disk’s mistuning while it is rotating. This capability is useful since it provides a basis for determining blade frequencies under engine operational conditions and could help monitor the health of the engine.

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