Modelling Jet Noise Installation Effects Associated with Close-Coupled, Wing-Mounted, Ultra High Bypass Ratio Engines
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UNIVERSITY OF SOUTHAMPTON Modelling Jet Noise Installation Effects Associated with Close-coupled, Wing-mounted, Ultra High Bypass Ratio Engines by Juan Vera A thesis submitted in partial fulfillment for the degree of Doctor of Philosophy in the Faculty of engineering and the environment Institute of Sound and Vibration Research May 2018 Declaration of Authorship I, Juan Vera, declare that the thesis entitled Modelling Jet Noise Installation Effects Associated with Close-coupled, Wing-mounted, Ultra High Bypass Ratio Engines and the work presented in the thesis are both my own, and have been generated by me as the result of my own original research. I confirm that: • this work was done wholly or mainly while in candidature for a research degree at this University; • where any part of this thesis has previously been submitted for a degree or any other qualification at this University or any other institution, this has been clearly stated; • where I have consulted the published work of others, this is always clearly at- tributed; • where I have quoted from the work of others, the source is always given. With the exception of such quotations, this thesis is entirely my own work; • I have acknowledged all main sources of help; • where the thesis is based on work done by myself jointly with others, I have made clear exactly what was done by others and what I have contributed myself; • none of this work has been published before submission Signed: ....................... Date: ...................................................................... • • • •. • • • • • • • • • • • • • • • • • • • • • • III "We live on a placid island of ignorance in the midst of black seas of infinity, and it was not meant that we should voyage far." H. P. Lovecraft UNIVERSITY OF SOUTHAMPTON ABSTRACT FACULTY OF ENGINEERING AND THE ENVIRONMENT INSTITUTE OF SOUND AND VIBRATION RESEARCH Doctor of Philosophy Modelling Jet Noise Installation Effects Associated with Close-coupled, Wing-mounted, Ultra High Bypass Ratio Engines by Juan Vera The research has studied the jet noise installation effects associated with close-coupled, wing-mounted, ultra high bypass ratio engines, which main source is produced by the scattering of the hydrodynamic field passing the wing trailing edge. The objectives of the thesis were to understand the noise generation associated with this mechanism and to produce an analytical methodology able to predict the Sound Pressure Level that is radiated to the far-field. The hydrodynamic pressure field of a jet is studied from the theoretical and experi- mental point of view. Whether Lighthill's acoustic analogy is extended into the near-field by removing the far-field assumptions, three different terms can be found. These terms (near-field term, mid-field term and far-field term) were named regarding the geometric region in which each of them is dominant. When compared against experimental data, the three terms are found and the scaling laws, obtained from the theory, are proof. Wiener-Hopf technique is then used to obtain an expression for the scattered pressure field and the result is compared with the classic solution from Amiet. The knowledge learnt is used to create a prediction methodology for a static single-stream jet interacting with a parallel flat plate. Acknowledgements This research was sponsored by the Rolls-Royce University Technology Centre in Gas Turbine Noise of the University of Southampton, where the research has been car- ried out. I am specially thankful to Dr. Michael Kingan, his support and supervision was essential in the development of this thesis. Thanks to my academic supervisor Prof. Rod Self, I am grateful for his guidance. Also, I would like to thank Dr. Aldo Rona and Prof. Phillip Joseph for the recommendations given during the examination of the thesis. My thanks also go to Adolfo Serrano who awakened my interest in aeroacoustic and to Dr. Paul Strange who introduced me to jet noise. Thank you both. Dr. Jack Lawrence is responsible for the Doak laboratory data used in this thesis. I would like to acknowledge him for the help analysing it. This data was part of the test campaign that was conducted during the SYMPHONY project, funded by the UK Technology Strategy Board and Rolls-Royce Plc. Large eddy simulations f rom University of Cambridge was used i n this Thesis. I am grateful to Prof. Paul G. Tucker, Dr. I ffi Z. Naqavi, and Dr. Zhong-Nan Wang f or sharing the data. I would like to thank my parents for raising me the way they did and to my brother for being a role model to me; to my friends at ISVR for living with me this experience; to the people of Leyenda.net for helping me keep my sanity intact and last, but no means least, to my partner, Susana, for believing in my more than I did, thank you with all my heart. VI Contents Declaration of AuthorshipIV Abstract V AcknowledgementsVI ContentsXI List of FiguresXV List of Tables XVII NomenclatureXX 1 Introduction3 1.1 Thesis outline..................................4 2 Background and literature review7 2.1 Chapter overview................................7 2.2 Noise pollution.................................8 2.2.1 Effects of noise pollution........................9 2.2.2 Aircraft noise pollution........................ 10 2.3 Civil aviation legislation............................ 11 2.4 Aircraft noise sources.............................. 17 2.4.1 Airframe noise............................. 17 2.4.2 Engine noise.............................. 19 2.4.3 Jet-Wing installation effects...................... 20 2.4.4 Computation of jet flow field using CFD............... 23 2.5 Jet mixing noise theory............................ 24 2.5.1 Jet flow field.............................. 24 2.5.2 Jet acoustics.............................. 25 2.6 Trailing edge noise............................... 28 2.6.1 Curle's theory for solid bodies..................... 28 2.6.2 Extension for moving sources..................... 30 2.6.3 Noise produced by turbulent flow past a trailing edge....... 31 2.6.4 Amiet's model for noise due to turbulent flow past a trailing edge. 34 3 Study of the jet near-field 39 3.1 Chapter overview................................ 39 VII VIII CONTENTS 3.2 Near-field extension of Lighthill's acoustic analogy............. 41 3.2.1 Cross-power spectral density..................... 43 3.2.2 Scaling of the jet near-field...................... 46 3.3 Near-field experimental data.......................... 48 3.3.1 Near-field experimental setup..................... 48 3.3.2 Radial Scaling............................. 53 3.3.3 Velocity Scaling............................. 60 3.4 Jet near-field prediction............................ 63 3.4.1 A model for the fourth order correlation tensor........... 63 3.4.2 A prediction model based on the extended Lighthill's theory... 63 3.4.3 Comparison with experimental data................. 66 4 Theoretical model for the scattered pressure field 71 4.1 Chapter overview................................ 71 4.2 Problem description.............................. 72 4.3 Scattering process................................ 72 4.3.1 Incident pressure field......................... 72 4.3.2 Scattered pressure field........................ 74 4.3.2.1 Solution for P s using the Wiener-Hopf technique..... 75 4.3.2.2 Solution for P s on the flat plate.............. 80 4.3.2.3 Solution for P s far away from the flat plate........ 83 4.4 Far-field radiation................................ 86 4.4.1 Method 1:................................ 87 4.4.2 Method 2:................................ 88 4.5 Far-field directivity............................... 91 4.6 Acoustic spectrum............................... 92 4.7 Comparison with Amiet's trailing edge model................ 93 5 A prediction methodology for the jet-surface interaction 95 5.1 Chapter overview................................ 95 5.2 Problem specification and assumptions.................... 97 5.3 Hydrodynamic field model........................... 98 5.3.1 Numerical LES data.......................... 99 5.3.2 Jet source model............................ 99 5.4 Near-field propagation............................. 103 5.4.1 Benchmark of the propagation of a monopole source........ 107 5.4.2 Near-field propagation of LES data.................. 108 5.5 Trailing edge pressure field.......................... 109 5.5.1 Small-scale experimental data..................... 110 5.5.2 Trailing edge pressure Vs. Doak Laboratory data.......... 111 5.6 Jet-surface interaction prediction....................... 112 5.6.1 Small-scale experimental setup.................... 113 5.6.2 Far-field prediction........................... 114 .................................. 116 5.7 Jet-surface interaction methodology and its use in more realistic cases.. 116 6 Summary and further work 121 CONTENTS IX 6.1 Conclusions................................... 121 6.2 Further work.................................. 123 A Schwarzchild's method 125 B Remarks on the eigenvalues of the associated Legendre function with application to conical problems 127 B.1 Numerical results................................ 127 B.2 Summary.................................... 132 C Jet-surface interaction prediction against Doak laboratory data. 133 D Jet-surface interaction methodology and its use in more realistic cases145 D.1 Effect of the bypass ratio to the JSI..................... 145 D.2 Effect of the flight stream in the JSI..................... 147 List of Figures 1.1 A350-XWB in an approach trajectory at the Airbus site in Toulouse, 2013.3 2.1 Number of people exposed to noise