scholarly journals Determination of Simultaneous Steady-State Movements Using Blade Tip Timing Data

2019 ◽  
Author(s):  
Mohamed Mohamed ◽  
Philip Bonello ◽  
Peter Russhard
Keyword(s):  
Previous Method ◽  
Vibration Measurement ◽  
Single Type ◽  
Bladed Disk ◽  
Shaft System ◽  
Axial Movement ◽  
Timing Data ◽  
Blade Tip ◽  
Uncertainty Level

Abstract Blade tip timing (BTT) includes a number of uncertainties that discourage its use. One of the main ones is the shift in the equilibrium position of the blade tip due to steady (non-oscillatory) bending and/or twisting of the blade, and axial movement of the bladed disk (blisk)-shaft system. This results in a shift in the effective measurement position of the probe relative to the blade chord, resulting in errors in the tip vibration measurement which can translate to a huge error in the corresponding stress estimate, which relies on calibration against finite element (FE) models. Previous experimentally validated research by the authors introduced a method for quantifying steady movement of a single type (axial, lean, or untwist), using BTT data from not more than two probes. In this paper, a development of the previous method is presented that provides a solution for the case of simultaneous types of blade steady movements. Additional probes are used for determining the direction, but these can be placed at any angular positions. The developed method is validated using a BTT simulator of a blisk, and accurate results obtained. The simultaneous axial and lean movements can be accurately determined when the untwist is negligible, and an uncertainty level can be specified when the untwist is not negligible. The untwist itself can be calculated accurately in all cases of simultaneous movements. Guidelines for the use of the method in different scenarios are provided.

scholarly journals Determination of Simultaneous Steady-State Movements Using Blade Tip Timing Data

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Mohamed Elsayed Mohamed ◽  
Philip Bonello ◽  
Peter Russhard
Keyword(s):  
Previous Method ◽  
Vibration Measurement ◽  
Single Type ◽  
Bladed Disk ◽  
Shaft System ◽  
Axial Movement ◽  
Timing Data ◽  
Blade Tip ◽  
Uncertainty Level

Abstract Blade tip timing (BTT) includes a number of uncertainties that discourage its use. One of the main ones is the shift in the equilibrium position of the blade tip due to steady (non-oscillatory) bending and/or twisting of the blade, and axial movement of the bladed disk (blisk)-shaft system. This results in a shift in the effective measurement position of the probe relative to the blade chord, resulting in errors in the tip vibration measurement which can translate to a huge error in the corresponding stress estimate, which relies on calibration against finite element (FE) models. Previous experimentally validated research by the authors introduced a method for quantifying steady movement of a single type (axial, lean, or untwist), using BTT data from not more than two probes. In this paper, a development of the previous method is presented that provides a solution for the case of simultaneous types of blade steady movements. Additional probes are used for determining the direction, but these can be placed at any angular positions. The developed method is validated using a BTT simulator of a blisk, and accurate results obtained. The simultaneous axial and lean movements can be accurately determined when the untwist is negligible, and an uncertainty level can be specified when the untwist is not negligible. The untwist itself can be calculated accurately in all cases of simultaneous movements. Guidelines for the use of the method in different scenarios are provided.

Simulation of Tip-Timing Measurements of a Cracked Bladed Disk Forced Response

2010 ◽  
Author(s):  
Vsevolod Kharyton ◽  
Jean-Pierre Laine ◽  
Fabrice Thouverez ◽  
Olexiy Kucher
Keyword(s):  
Dynamic Model ◽  
Harmonic Balance Method ◽  
Time History ◽  
Forced Response ◽  
Bladed Disk ◽  
Crack Behavior ◽  
Timing Data ◽  
History Of ◽  
Blade Tip ◽  
Blade Frequency

The study intends to simulate the process of the blade tip amplitude calculation by the tip-timing method. An attention is focused on tip-timing measurements for detection of a cracked blade from the bladed disk forced response. The cracked blade is considered within frameworks of the bladed disk dynamic model that takes into account mistuning presence. Nonlinear formulation of a crack behavior is done with the harmonic balance method in its combination with the contact analysis that allows simulation of crack breathing. In order to make the cracked blade detection process evident, the crack length and location are set in such a way as to produce the cracked blade frequency localization. Reconstruction of the blade tip amplitudes is attained with the arriving time of measured probes of the blade tips. The results are compared with the blade forced response obtained by the bladed disk dynamic model. A possibility is also considered how to reconstruct time-history of the bladed disk forced response with tip-timing data.

A Subspace Method for Modal Identification of Bladed Assemblies Using Blade Tip-Timing Data

2007 ◽  
Author(s):  
Bendali Salhi ◽  
Marc Berthillier ◽  
Joseph Lardies ◽  
Philippe Voinis ◽  
Charles Bodel
Keyword(s):  
Natural Frequencies ◽  
Standard Procedure ◽  
Modal Identification ◽  
Subspace Method ◽  
Subspace Analysis ◽  
Bladed Disk ◽  
Fast Fourier Transform Analysis ◽  
Timing Data ◽  
Vibration Responses ◽  
Blade Tip

Unknown excitation forces are applied to bladed disk assemblies, such as turbines blades, leading to forced vibration responses. Non contact measurement of such vibrations using blade tip-timing data has become an industrial standard procedure and current research focuses on analysis methods for interpretation of measured vibrations. Our purpose is to develop a method for identification of the blade’s natural frequencies and damping ratios using blade tip-timing data. The method is based on a subspace analysis. Its performance is compared to the traditional Fast Fourier Transform analysis. A detailed description of these methods and results are presented.

Tip-Timing Data Analysis for Mistuned Bladed Discs Assemblies

2008 ◽  
Author(s):  
Cyrille Ste´phan ◽  
Marc Berthillier ◽  
Joseph Lardie`s ◽  
Arnaud Talon
Keyword(s):  
Spectral Analysis ◽  
Optical Sensors ◽  
Fundamental Problem ◽  
Spectral Estimation ◽  
Minimum Variance ◽  
Vibration Measurement ◽  
Blade Vibration ◽  
Autocorrelation Matrix ◽  
Timing Data ◽  
Blade Tip

In turbomachine industry, bladed assembly vibration measurements are very important for blades behaviour estimation. These measurements are generally obtained from strain gauges. However, one of the most promising methods for the analysis of blade vibrations in rotating bladed assemblies is the Blade Tip Timing or Optical Blade Vibration Measurement method. A set of optical sensors is mounted on an engine casing, in front of a disc, and measures the times of arrival of each blade. These timings are then used to compute the vibrations of the blades. However the fundamental problem for spectral analysis of blade tip timing data is that the signals are undersampled and aliased. We propose here a new method for spectral estimation of blades responses from tip timing data that overcome these difficulties. The method proposed in this communication is based on the use of a minimum variance filter associated with an iterative updating of the autocorrelation matrix. That allows to process correctly a signal even if the number of known signal samples is less than equivalent Nyquist criterion. This approach is suitable for spectral analysis of undersampled and aliased signals. Perfomances of the spectral estimator have been evaluated for one simulated and one experimental test cases. The method seems very promising for the monitoring of mistuned bladed discs.

Sparse Reconstruction Method of Non-Uniform Sampling and its Application in Blade Tip Timing System

2020 ◽  
Author(s):  
Jie Tian ◽  
Xiaopu Zhang ◽  
Yong Chen ◽  
Peter Russhard ◽  
Hua Ouyang
Keyword(s):  
Compressive Sensing ◽  
Sparse Reconstruction ◽  
Reconstruction Method ◽  
Blade Vibration ◽  
Uniform Sampling ◽  
Blade Vibrations ◽  
Timing Data ◽  
Blade Tip ◽  
Simultaneous Identification ◽  
Multi Mode

Abstract Based on the blade vibration theory of turbomachinery and the basic principle of blade timing systems, a sparse reconstruction model is derived for the tip timing signal under an arbitrary sensor circumferential placement distribution. The proposed approach uses the sparsity of the tip timing signal in the frequency domain. The application of compressive sensing in reconstructing the blade tip timing signal and monitoring multi-mode blade vibrations is explored. To improve the reconstruction effect, a number of numerical experiments are conducted to examine the effects of various factors on synchronous and non-synchronous signals. This enables the specific steps involved in the compressive sensing reconstruction of tip timing signals to be determined. The proposed method is then applied to the tip timing data of a 27-blade rotor. The results show that the method accurately identifies the multi-mode blade vibrations at different rotation speeds. The proposed method has the advantages of low dependence on prior information, insensitivity to environmental noise, and simultaneous identification of synchronous and non-synchronous signals. The experimental results validate the effectiveness of the proposed approach in engineering applications.

scholarly journals A Class of Methods for the Analysis of Blade Tip Timing Data from Bladed Assemblies Undergoing Simultaneous Resonances—Part II: Experimental Validation

2007 ◽  
Vol 2007 ◽  
pp. 1-10 ◽  
Author(s):  
J. Gallego-Garrido ◽  
G. Dimitriadis ◽  
I. B. Carrington ◽  
J. R. Wright
Keyword(s):  
Experimental Test ◽  
Experimental Validation ◽  
Test Rig ◽  
New Techniques ◽  
Analysis Techniques ◽  
Simultaneous Resonances ◽  
Timing Data ◽  
Blade Tip ◽  
Using Data ◽  
Double Resonances

Blade tip timing is a technique for the measurement of vibrations in rotating bladed assemblies. In Part I of this work a class of methods for the analysis of blade tip timing data from bladed assemblies undergoing two simultaneous synchronous resonances was developed. The approaches were demonstrated using data from a mathematical simulation of tip timing data. In Part II the methods are validated on an experimental test rig. First, the construction and characteristics of the rig will be discussed. Then, the performance of the analysis techniques when applied to data from the rig will be compared and analysed. It is shown that accurate frequency estimates are obtained by all the methods for both single and double resonances. Furthermore, the recovered frequencies are used to calculate the amplitudes of the blade tip responses. The presence of mistuning in the bladed assembly does not affect the performance of the new techniques.

The Influence of Diagnostic Signal Measurement Period on Blades Technical Condition Images Determined from Phase Shift Difference

2013 ◽  
Vol 199 ◽  
pp. 67-72 ◽  
Author(s):  
Rafał Grądzki
Keyword(s):  
Phase Shift ◽  
Damage Detection ◽  
Technical Condition ◽  
New Method ◽  
Diagnostic Model ◽  
Inductive Sensor ◽  
Blade Tip ◽  
Space Range ◽  
Measurement Period

In the article, new method of monitoring of rotor machine blades technical condition is presented. This method is based on diagnostic model φT12T01 [ which uses phase shift difference of signal fragments resulting from blade operation y (t) during blade recession from sensor and during approach of blade tip towards the sensor as well as signal of its environment x (t) described using proper distribution. The assumed diagnostic model also indirectly includes actual blade environment x (t) without necessity of its measurement [3,. Contactless inductive sensor constantly measures the signal of operating blade transition below the sensor. However, several difficulties with determination of last sample of blade receding from the sensor with first sample of blade approaching the sensor exist. Additionally the problem occurs with measurement of space between blades. So far, the case was solved by use 90% of this space range (in order to eliminate the overlapping of adjacent blades signals). Hence the problem of assessment of measurement period breadth on obtained models (images) of blades. The possibility of blade damage detection by analysis of less than 90% signal course was tested.

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