THÈSE

Averiyanov

Sujets

• Acoustica (Alarm Will Sound)
• Vitesse maximale d'un avion
• The Wave
• Système de notation musicale de Jean-Jacques Rousseau
• Amplitude
• Turbulence

Informations

• Publié par: Chiwyir
• Nombre de lectures: 115
• Langue: English
• Poids de l'ouvrage: 3 Mo

Extrait

№ d'ordre : 2008-18 ANNÉE 2008 THÈSE Présentée devant L’ÉCOLE CENTRALE DE LYON Pour obtenir Le titre de DOCTEUR SPECIALITÉ ACOUSTIQUE Par Mikhail AVERIYANOV Propagation des ondes acoustiques à travers un milieu turbulent : études théorique et expérimentale des effets de diffraction et des effets non linéaires Nonlinear-diffraction effects in propagation of sound waves through turbulent atmosphere: experimental and theoretical studies Soutenue le 9 octobre 2008 devant la Commission d’Examen JURY Président : M. Daniel JUVÉ Examinateurs : M . Philippe BLANC-BENON (Co-Directeur de Thèse) Mme. Vera KHOKHLOVA (Co-Directeur de Thèse) M. Robin CLEVELAND (Rapporteur) M. Vladimir PREOBRAZHENSKY (Rapporteur) M. Oleg SAPOZHNIKOV Laboratoire de Mécanique des Fluides et d’Acoustique, UMR CNRS 5509 Ecole Centrale de Lyon et Département d’Acoustique, Faculté de Physique, Université d’État de Moscou  TABLE OF CONTENTS Nomenclature of main used notations ................................................................................................5 Introduction ..............................................................................................................................11 Chapter 1 NONLINEAR SOUND WAVES IN INHOMOGENEOUS MOVING MEDIA (REVIEW) ........................................................................................................................... 19 § 1.1 Sonic boom in turbulent atmosphere .......................................................................................19 1.1.1 Ecological aspects of the problem .........................................................................................19 1.1.2 Outdoor and laboratory experiments .....................................................................................21 § 1.2 Mathematical models for nonlinear sound waves propagating in inhomogeneous moving media ............................................................................................................................24 1.2.1 Wave equations in acoustics of inhomogeneous moving media ...........................................24 1.2.2 Parabolic approximation for nonlinear sound waves in media with scalar inhomogeneities....................................................................................................................28 1.2.3 Equations of nonlinear geometrical acoustics .......................................................................33 § 1.3 Theoretical modelling of turbulent media................................................................................36 § 1.4 Conclusion.................................................................................................................................41 Chapter 2 PROPAGATION OF NONLINEAR N-WAVES IN A TURBULENT VELOCITY FIELD (laboratory-scaled experiment)........................................................... 43 § 2.1 Generation and measurement of fully developed turbulent field............................................45 2.1.1 Experimental setup ................................................................................................................45 2.1.2 Measurement of the turbulent field parameters .....................................................................46 § 2.2 Acoustic measurements.............................................................................................................53 2.2.1 ...53 2.2.2 Characteristics of N-waves measured without turbulence.....................................................55 § 2.3 Analysis of the effects of turbulence on N-waves ....................................................................58 2.3.1 Typical measured waveforms. Estimation of the focusing zone width .................................58 2.3.2 Effect of the turbulence intensity on the N-wave statistics, average and peak characteristics...............................................................................................................60 2.3.3 Effect of propagation distance through turbulent medium on the statistics, average and peak characteristics of the acoustic N-wave ..................................................................64 § 2.4 Characteristic scales: atmosphere and laboratory experiment................................................67 § 2.5 Conclusion.................................................................................................................................68 Chapter 3 MEASUREMENT AND MODELLING OF SPHERICALLY DIVERGING SHOCK PULSES IN RELAXING AIR. CALIBRATION OF THE MICROPHONE. ................... 71 § 3.1 Acoustic measurements. Mean and peak characteristics of the N-wave parameters .............73 § 3.2 Theoretical model......................................................................................................................74 3.2.1 Modified Burgers equation for divergent waves in relaxing medium ...................................74 3.2.2 Numerical algorithm..............................................................................................................76 3.2.3 Effects of nonlinearity, thermoviscous absorption and relaxation on the acoustic wave propagation..................................................................................................................78 § 3.3 Calibration of measuring system based on nonlinear effects..................................................81 § 3.4 Amplitude and phase frequency characteristics of measuring system....................................82 § 3.5 N-wave characteristic parameters. Comparison of experimental data with the results of numerical modelling.....85 § 3.6 Conclusion.................................................................................................................................86 Chapter 4 NONLINEAR EVOLUTION EQUATION OF KHOKHLOV- ZABOLOTSKAYA TYPE FOR THE DESCRIPTION OF ACOUSTIC WAVE PROPAGATION IN INHOMOGENEOUS MOVING MEDIA ........................................................................... 89 § 4.1 Theoretical model. Parabolic equation for nonlinear sound waves in inhomogeneous moving media. .......................................................................................................................... 90 § 4.2 Self similarity property of the KZK type equation................................................................... 95 § 4.3 Numerical algorithms .............................................................................................................. 96 4.3.1 Frequency domain approach to model periodic waves with shocks..................................... 96 4.3.2 Time domain approach to model propagation of single shock pulses .................................. 98 § 4.4 Benchmark solutions and validation of the model................................................................ 106 § 4.5 Conclusion.............................................................................................................................. 108 Chapter 5 NONLINEAR AND DIFFRACTION EFFECTS DURING THE PROPAGATION OF ACOUSTIC SIGNALS IN RANDOMLY INHOMOGENEOUS MOVING MEDIUM (Numerical modelling)....................................................................................................... 111 § 5.1 Periodic waves ........................................................................................................................ 111 5.1.1 Nonlinear versus linear effects of random focusing in an inhomogeneous moving medium 111 5.1.2 Effect of the transverse component of turbulent velocity field: vector versus scalar contributions of inhomogeneities ...................................................................................... 115 5.1.3 Diffraction effects: ray tracing and acoustic field patterns obtained with the KZK equation .................................................................................................................... 116 5.1.4 Effect of spatial correlation lengths and intensity of the turbulence on acoustic field characteristics .................................................................................................................... 117 § 5.2 Acoustic pulses. N-waves ....................................................................................................... 120 5.2.1 Parameters of simulations, 2D patterns of randomly inhomogeneous velocity field ......... 120 5.2.2 Diffraction effects: ray tracing and acoustic field patterns obtained with the KZK equation. 121 5.2.3 Nonlinear versus linear effects on random focusing in an inhomogeneous medium ......... 124 5.2.4 Influence of randomly inhomogeneous medium on statistics, average and peak characteristics of the acoustic N-wave............................................................................... 127 5.2.5 Effect of the transverse component of turbulent velocity: vector versus scalar contributions of inhomogeneities ...................................................................................... 132 5.2.6 Effect of spatial correlation lengths and turbulent kinetic energy distribution law on acoustic field characteristics ......................................................................................... 134 § 5.3 Comparison of numerical model results with experimental data......................................... 136 § 5.4 Conclusion.............................................................................................................................. 146 CONCLUSION ........................................................................................................................... 149 Appendix A : GEOMETRICAL ACOUSTICS APPROACH