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.

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.

Experimental Investigation on Natural Characteristics and Forced Response of Bladed Disks

2011 ◽  
Vol 105-107 ◽  
pp. 34-37
Author(s):  
Zhi Bin Zhao ◽  
Er Ming He ◽  
Hong Jian Wang
Keyword(s):  
Travelling Wave ◽  
Primary Objective ◽  
Forced Response ◽  
Dynamic Responses ◽  
Experimental Investigations ◽  
Wave Excitation ◽  
Bladed Disks ◽  
Bladed Disk ◽  
The Impact ◽  
Natural Characteristics

The results of an experimental investigations on the natural characteristics of tuned bladed disk and forced dynamic responses of mistuned bladed disks are reported. Three experimental bladed disks are discussed: a tuned specimen of periodic symmetry with 12-blades which are nominally identical, and two mistuned specimens, which feature small blade-to-blade variations by adding slight blocks to blade tips. All the specimens are subject to travelling wave excitation produced by piezo-electric actuators sticking on the root of blades. The primary objective of this experiment is to observe the natural characteristics of tuned bladed disk, and to research the impact of mistuning on the forced response blade amplitude magnification. Analytical predictions about the blade amplitude magnification factor are verified by the experimental results.

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.

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 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.

scholarly journals On Forced Response of a Rotating Integrally Bladed Disk: Predictions and Experiments

2010 ◽  
Author(s):  
Claude Gibert ◽  
Vsevolod Kharyton ◽  
Fabrice Thouverez ◽  
Pierrick Jean
Keyword(s):  
Dynamic Response ◽  
Piezoelectric Actuators ◽  
Travelling Wave ◽  
Forced Response ◽  
Phase Shifting ◽  
Electronic Circuits ◽  
Bladed Disk ◽  
High Pressure Compressor ◽  
Pressure Compressor ◽  
Finite Elements Model

An experimental setup is described which permits to rotate a bladed disk in vacuum and to measure its dynamic response to excitations provided by some embedded piezoelectric actuators. A particular spatial placement of actuators associated with phase-shifting electronic circuits is set for simulating travelling wave excitations with respect to the rotating frame. The system is demonstrated on an actual high-pressure compressor (HCP) integrally bladed disk. The dynamic response of the blisk is analyzed experimentally and results are correlated with those obtained from a simplified finite elements model taking into account Coriolis effect. The paper focuses on the influence of the latter which is most of the time neglected and its implication on the forced response levels is studied into two situations without or with mistuning.

Acoustic Measurements of Perforated Liners in Hot and Pressurized Flow

2013 ◽  
Author(s):  
Claus Lahiri ◽  
Karsten Knobloch ◽  
Friedrich Bake ◽  
Lars Enghardt
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Numerical Models ◽  
Experimental Tests ◽  
Acoustic Measurements ◽  
Test Rig ◽  
Acoustic Data ◽  
Bias Flow ◽  
Acoustic Instabilities ◽  
Acoustic Losses

Thermo-acoustic instabilities in gas turbine combustors can prevent the implementation of modern combustion concepts, which are essential for higher efficiency and lower emissions. Perforated combustor liners, especially in combination with a bias flow through the liner, are able to suppress the instabilities by increasing the acoustic losses of the system. Some insight into the parameter dependencies of the acoustic absorption has been gained by means of atmospheric testing at ambient temperature. The next step towards realistic testing conditions is taking into account high temperature and high pressure, which increases the effort of the experimental tests and the complexity of their analysis significantly. Tests in a real combustor can serve as a quality check of a given liner design, but are not appropriate for parameter studies. So far, numerical models accurate enough to enable the design of hot stream liners are simply not available, so that the experimental investigation of the liner’s dependency on temperature and pressure is essential for the transfer of laboratory scale results to a real engine application. A new test rig has been designed to overcome these problems. The Hot Acoustic Test rig (HAT) enables the study of the influence of pressure and temperature on the damping performance in an acoustically well defined environment, although the high temperature and high pressure conditions are challenging in terms of accurate acoustic measurements. This paper introduces the Hot Acoustic Test rig with its features and limitations and shows first examples of test results. The focus lies on the hardware, instrumentation, and analysis techniques that are necessary to obtain high quality acoustic data in hot and pressurized flow environments.

Fatigue Damage Prevention on Turbine Blades: Study of Underplatform Damper Shape

2007 ◽  
Vol 347 ◽  
pp. 159-164 ◽  
Author(s):  
Teresa Berruti ◽  
Christian M. Firrone ◽  
M. Pizzolante ◽  
Muzio M. Gola
Keyword(s):  
Turbine Blades ◽  
Forced Vibrations ◽  
Forced Response ◽  
Numerical Code ◽  
Vibration Energy ◽  
Test Rig ◽  
Blade Vibration ◽  
Static Test ◽  
Underplatform Damper ◽  
Contact Parameters

Forced vibrations can lead to an irreparable damage of a blade array. Devices called “underplatform damper” that dissipate the vibration energy are employed in order to reduce blade vibration amplitude. The present paper deals with the design of the underplatform damper. A numerical code to calculate the forced response of a blade array with dampers has been previously purposely developed. A method is here proposed for the estimation of the unknown contact parameters demanded by the code. The computation results are here validated by means of comparison with experimental results on a static test rig. Three dampers with different shape are tested.

Finite-Element Modelling of an Experimental Mistuned Bladed Disk and Experimental Validation

2013 ◽  
Author(s):  
Jean de Cazenove ◽  
Scott Cogan ◽  
Moustapha Mbaye
Keyword(s):  
Finite Element ◽  
Model Building ◽  
Numerical Models ◽  
Dynamic Properties ◽  
Forced Response ◽  
Operating Conditions ◽  
Machining Process ◽  
Fe Model ◽  
Bladed Disk ◽  
Full Disk

Integrally bladed rotors dynamic properties are known to be particularly sensitive to small geometric discrepancies due to the machining process or in-service wear. In this context, it is straightforward that setting up accurate numerical models which take into account real mistuning patterns is a key issue in the prediction of forced response amplitudes under operating conditions. The present study focuses on an experimental bladed disk. Due to strong inter-blade coupling, the geometric mistuning is supposed to result in severe mode localization for the studied bladed disk, thus emphasizing the need of a realistic, predictive finite-element model. This paper describes the procedure which leads to the development and validation of a high-fidelity FE model for a realistic bladed disk, based on coordinate measurements by means of fringe projection. After giving an overview of the coordinate measurement and model building for the studied bladed disk, the comparison of cantilevered-blade and full disk calculated eigenfrequencies to individual blade and full disk in quasi-vacuum measurements are presented.

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

2020 ◽  
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.

Sign in / Sign up

Export Citation Format

Share Document