Condition Monitoring of Turbines

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  • Topic: Turbine, Turbofan, Jet engine
  • Pages : 170 (22184 words )
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  • Published : March 10, 2013
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Condition Monitoring
of
Gas-Turbine Engines

David Clifton
St. Cross College
Supervised by
Professor Lionel Tarassenko
Submitted: January, 2006

This Transfer Report is submitted to the
Department of Engineering Science, University of Oxford.

Condition Monitoring
of Gas-Turbine Engines
David Clifton
St. Cross College, December, 2005

Summary
Condition monitoring assesses the operational health of gas-turbine engines, in order to provide early warning of potential failure such that preventative maintenance action may be taken. Gas-turbine engine manufacturers are increasingly offering a “service-based” approach to marketing their products, in which their customers are guaranteed certain availability of the engine after purchase. To achieve this, manufacturers take on the responsibilities of engine condition monitoring, by embedding health monitoring systems within each engine unit and prompting maintenance actions when necessary.

This report describes preliminary research into condition monitoring approaches for modern gas-turbine aircraft engines, and outlines plans for novel research to contribute to machine learning techniques in the condition monitoring of such systems, leading to the D.Phil. degree. A framework for condition monitoring of aircraft engines is introduced, using signatures of engine vibration across a range of engine speeds to assess engine health. Inter- and intra-engine monitoring approaches are presented, in which a model of engine normality is constructed using vibration data from other engines of its class, or from the test engine itself, respectively.

Results of inter-engine analysis of final engine vibration tests prior to their release into service are presented, showing that the approach described within this report provides a more reliable estimate of engine condition than manufacturers’ conventional engine vibration tests, leading to better discrimination between “good” and “bad” engines.

Intra-engine analysis of an engine undergoing cyclic endurance testing, in which a set operational manoeuvre is performed repeatedly, shows that the method described in this report provides early warning of engine failure that eventually resulted in a hazardous engine fire, undetected by engine developers until it had to be shut down manually.

Future research is planned in application of this condition monitoring framework to an engine currently under development, improving upon existing methods and investigating new approaches, ultimately leading to the formulation of a general “black box” monitoring approach that can learn a model of system normality without prior knowledge of that system.

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Contents
1 The
1.1
1.2
1.3
1.4

Need for Condition Monitoring
Introduction . . . . . . . . . . . . . . . . . . .
Aerospace Gas-turbine Engines . . . . . . . .
Existing Techniques for Condition Monitoring
Overview of this Report . . . . . . . . . . . .

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of Aerospace Gas-turbine Engines
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1
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2 Novelty Detection for Gas-turbine Engines
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2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.2 Modelling Normality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.3 Novelty Detection using TORCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3 TORCH for Inter-engine Analysis

3.1 Introduction . . . . . . . . . . . .
3.2 Data Set of Vibration Signatures
3.3 Vectorisation . . . . . . . . . . .
3.4 Normalisation . . . . . . . . . . .
3.5 Visualisation . . . . . . . . . . .
3.6 Clustering . . . . . . . . . . . . .
3.7 Choosing a Model of Normality .
3.8 Calculation of Novelty . . . . . .
3.9 Conclusion . . . . . . . . . . . .

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