University of Huddersfield Repository Elamin, Fathi Fault Detection and Diagnosis in Heavy Duty Diesel Engines Using Acoustic Emission Original Citation Elamin, Fathi (2013) Fault Detection and Diagnosis in Heavy Duty Diesel Engines Using Acoustic Emission. Doctoral thesis, University of Huddersfield. This version is available at http://eprints.hud.ac.uk/id/eprint/19324/ The University Repository is a digital collection of the research output of the University, available on Open Access. Copyright and Moral Rights for the items on this site are retained by the individual author and/or other copyright owners. 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For more information, including our policy and submission procedure, please contact the Repository Team at: [email protected]. http://eprints.hud.ac.uk/ Fault Detection and Diagnosis in Heavy Duty Diesel Engines Using Acoustic Emission Fathi Hassen Elamin A thesis submitted to the University of Huddersfield in partial fulfilment of the requirements for the degree of Doctor of Philosophy The University of Huddersfield November 2013 ABSTRACT A condition monitoring program applied to diesel engines, improves safety, productivity, increases serviceability and reduces maintenance costs. Investigation of a novel condition monitoring systems for diesel engine is attracting considerable attention due to both the increasing demands placed upon engine components and the limitations of conventional techniques. This thesis documents research conducted to assess the monitoring capabilities used acoustic emission (AE) analysis. It focuses on the possibility of using AE signals to monitor the fuel injector and oil condition. A series of experiments were performed on a JCB, four-stroke diesel engine. Tests under healthy operating conditions developed a detailed understanding of typical acoustic emission generation in terms of both the source mechanisms and the characteristics of the resulting activity. This was supplemented by specific tests to investigate possible acoustic emission generation due to the piston slap and friction. The effect of faults on the injector waveform was investigated using the injection system and at one sensor location. To overcome the reflections and injection system configuration effects the method of acoustic emission impedance was used. This enabled the injector signal to be successfully extracted and clearly shows its capability for detecting even minor combustion deviations between engine cylinders. Comparison between signals and measurement of the oil condition showed both provided useful information about the lubrication processes. Simulation and experimental work have demonstrated the capability of this technique to detect lubrication related faults and irregular lubrication variability between the engine's cylinders. 2 A review of the AE sources in diesel engines and how to represent the AE signals generated is presented. Three analysis methods were used: time-domain analysis using parameters such as Root Mean Square (RMS), variance, mean and kurtosis; frequency-domain analysis which relied on the amplitudes of the frequency components of the measured signals; and time-frequency domain analysis extracting features so that the energy content of the signals and the frequency components were localized simultaneously. In this work, data has been obtained from tests on a diesel engine, where the engine load, speed, temperature and the oil lubrication type were changed. The monitored signal and its difference from that obtained for normal engine conditions was noted as a fault signature that could be used for fault detection and diagnosis. 3 DEDICATION To my wife, my daughters and my sons, for your patience and absolutely everything with love. To my brothers and sisters, for their continuous support and encouragement, while I have been away from home. 4 LIST OF CONTENTS TITLE PAGE....................................................................................................................................1 ABSTRACT.....................................................................................................................................2 DEDICATION..................................................................................................................................4 LIST OF CONTENTS......................................................................................................................5 LIST OF FIGURES........................................................................................................................12 LIST OF TABLES..........................................................................................................................17 LIST OF NOMENCLATURE…....................................................................................................18 LIST OF NOTATION.....................................................................................................................19 DECLARATION.............................................................................................................................23 COPYRIGHT..................................................................................................................................24 AKNOWLEDGEMENTS...............................................................................................................25 CHAPTER ONE INTODUCTION..............................................................................................................................26 1.1 Introduction to Condition Monitoring.................................................................................27 1.1.1 Why Monitor and Diagnose Faults in Engines…………………………….……………..28 1.2 Motivation...........................................................................................................................30 1.3 Research Topic....................................................................................................................31 1.4 Implementation of Condition Monitoring System..............................................................31 1.4.1 Sensor Selection............................................................................................................31 1.4.2 Feature Extraction.........................................................................................................33 1.4.3 Feature Comparison......................................................................................................34 1.4.4 Decision Process Determination...................................................................................34 1.5 Introduction to Research Work...........................................................................................35 1.5.1 Aims of This Research..................................................................................................35 1.5.2 Research Objectives......................................................................................................36 1.6 Thesis Structure and Organisation......................................................................................37 5 CHAPTER TWO DIESEL ENGINE CONDITION MONITORING.........................................................................39 2.1 Introduction.........................................................................................................................40 2.2 Engine Fundamentals..........................................................................................................42 2.3 Diesel Engine Sensing.........................................................................................................43 2.4 A Review of Diesel Engine Condition Monitoring.............................................................44 2.4.1 Overview of Principal Faults in a Diesel Engine..........................................................44 2.4.2 Overview of Condition Monitoring Techniques...........................................................46 2.4.2.1 Vibration Monitoring..............................................................................................46 2.4.2.2 Oil / Lubrication Analysis.......................................................................................49 2.4.2.3 Cylinder Pressure Monitoring.................................................................................50 2.4.2.4 Instantaneous Angular Speed Monitoring..............................................................52 2.4.2.5 Airborne Acoustic Monitoring..............................................................................53 2.4.2.6 Exhaust Monitoring...............................................................................................55 2.4.2.7 Acoustic Emission Monitoring..............................................................................56 2.5 Summary………………………………....………………………………………………58 CHAPTER THREE ACOUSTIC EMISSION MONITORING AND ITS APPLICATION TO DIESEL ENGINES....60 3.1 Introduction..........................................................................................................................61 3.2