Heat and Mass Transfer978-3-642-56443-7/1.pdffrom the conservation laws for mass, energy and...
15
Heat and Mass Transfer Series Editors: D. Mewes and F. Mayinger
Transcript of Heat and Mass Transfer978-3-642-56443-7/1.pdffrom the conservation laws for mass, energy and...
Heat and Mass Transfer
Series Editors: D. Mewes and F. Mayinger
Franz Mayinger . Oliver Feldmann (Eds)
Optical Measurements Techniques and Applications
Second corrected and revised Edition
With 238 Figures
~ Springer
Series Editors Prof. -Dr.-Ing. DieterMewes Universität Hannover Institut für Verfahrenstechnik Callinstr. 36 30167 Hannover, Germany
Editors Prof. em. Dr.-Ing. E.h. Franz Mayinger Dr.-Ing. Oliver Feldmann Technische Universität München Lehrstuhl für Thermodynamik Boltzmannstr.15 85748 Garching, Germany
Library of Congress Control Number: 2001020640
Prof. em. Dr.-Ing. E.h. Franz Mayinger Technische Universität München Lehrstuhl für Thermodynamik Boltzmannstr.15 85748 Garching, Germany
Additional material to this book can be downloaded from http://extras.springer.com.
ISBN 978-3-642-63079-8 ISBN 978-3-642-56443-7 (eBook) DOI 10.1007/978-3-642-56443-7
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© Springer-Verlag Berlin Heidelberg 2001 Originally published by Springer-Verlag Berlin Heidelberg New York in 2001 Softcover reprint ofthe bardeover 2nd edition 2001
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Preface
Increasing possibilities of computer-aided data processing have caused a new revival of optical techniques in many areas of mechanical and chemical engineering. Optical methods have a long tradition in heat and mass transfer and in fluid dynamics. Global experimental information is not sufficient for developing constitution equations to describe complicated phenomena in fluid dynamics or in transfer processes by a computer program. Furthermore, a detailed insight with high local and temporal resolution into the thermoand fluiddynamic situations is necessary.
Sets of equations for computer program in thermo dynamics and fluid dynamics usually consist of two types of formulations: a first one derived from the conservation laws for mass, energy and momentum, and a second one mathematically modelling transport processes like laminar or turbulent diffusion. For reliably predicting the heat transfer, for example, the velocity and temperature field in the boundary layer must be known, or a physically realistic and widely valid correlation describing the turbulence must be available. For a better understanding of combustion processes it is necessary to know the local concentration and temperature just ahead of the flame and in the ignition zone.
Here optical measuring techniques provide comprehensive and detailed information. Its results also supply valuable evidence on the formation of phase interfaces, on particle movement, or on the size distribution of droplet swarms. By using the results of optical measuring techniques, not only is it possible to improve computer programs to give a better description of physical processes and a better adapt ion to the physical reality but also these optical techniques are very sensitive touchstones for checking the grade of reliability and the extent of general validity of computer programs.
On the other side, evaluating optical data, for example from a hologram, from an interferogram, from Raman-spectroscopy, or from laser-inducedfluo-rescence signals, has become much faster. A few years ago it took hours to evaluate an interferogram. The same work is done today by a computer within seconds. But also the huge storage capacity of modern computers -even of the PC type - was an important requirement for preparing the way for the revival of optical methods.
VI Preface
The book is intended to demonstrate the possibilities of optical measuring techniques - especially image-forming techniques - and to introduce the processes of recording, reprocessing and electronically evaluating the data. It is intended to inform the reader to such an extent that he can design and construct simple experimental set-ups. For more difficult and highly sophisticated techniques he is referred to the specialist literature in the field.
Munich, April 1996 Franz Mayinger
Preface to the 2nd Edition
The first edition of the book "Optical Measurements - techniques and applications" found so much interest, that it was out of sale within a few years. The present second edition comprises the completely revised first edition and is supplemented by new contributions on the latest developements in "PhaseDoppler-Velocimetry" and "Paticle-Image-Velocimetry" .
It was a special matter of concern of both the editors and the authors not only to describe and to explain the fundamentals of optical measuring techniques, but also to give guidelines for their application and to demonstrate the capability of the various methods. In combination with that effort, a CD-ROM is added as a supplement to this book, which demonstrates the applicability of visualisation methods, such as Fluorescence, Schlierenphotography, Holography and Holografic Interferometry combined with High Speed Cinematography. The high-speed-movies on the CD-ROM give vigorous impressions of fluiddynamic transport phenomena in technical processes.
The book provides comprehensive and detailed information on most of the modern optical measuring techniques being of interest for engineers and physicists in practice. It is also of interest to Master- and Ph.D.- students who want to become familiar with optical measuring techniques.
The editors would like to thank each author for his outstanding contribution to this book. We also wish to acknowledge "Springer Verlag" for its contribution towards the publication of the book.
Munich, August 2000
Franz Mayinger Oliver Feldmann
List of Contributors
Prof. P. Andresen Fakultat fur Physik D3 Universitat Bielefeld D - 33501 Bielefeld [email protected]bielefeld.de
Dr. M.Buchmann Institut fur Verfahrenstechnik Universitat Hannover D - 30167 Hannover [email protected]
Dr. A. Chavez l
Lehrstuhl A fur Thermodynamik Technische Universitat Munchen D - 85747 Garching [email protected]
B.Durst l
Lehrstuhl A fur Thermodynamik Technische Universitat Munchen D - 85747 Garching [email protected]
Dr. V.Ebert Physikalisch-Chemisches Institut Universitat Heidelberg D - 69120 Heidelberg [email protected]heidelberg. de
A.Eder Lehrstuhl A fur Thermodynamik Technische Universitat Miinchen D - 85747 Garching [email protected]
O.Feldmann Lehrstuhl A fur Thermodynamik Technische Universitat Munchen D - 85747 Garching [email protected]
Dr. P. Gebhard l
Lehrstuhl A fur Thermodynamik Technische Universitat Miinchen D - 85747 Garching [email protected]
C. Gerlach Lehrstuhl A fur Thermodynamik Technische Universitat Munchen D - 85747 Garching [email protected]
U. GHickert Lehrstuhl A fur Thermodynamik Technische Universitat Munchen D - 85747 Garching [email protected]
X List of Contributors
Dr. M. Jordanl Lehrstuhl A fur Thermodynamik Technische Universitat Munchen D - 85747 Garching [email protected]
Dr. B. Kruppal Lehrstuhl A fUr Thermodynamik Technische Universitat Munchen D - 85747 Garching [email protected]
Prof. F. Mayinger Lehrstuhl A fur Thermodynamik Technische Universitat Munchen D - 85747 Garching [email protected]
Prof. W. Merzkirch Lehrstuhl fur Stromungslehre Universitat GH Essen D - 45117 Essen wolfgang.merzkirch@uniessen.de
Prof. D. Mewes Institut fur Verfahrenstechnik U niversitat Hannover D - 30167 Hannover [email protected]
B.Ofner Lehrstuhl A fur Thermodynamik Technische Universitat Munchen D - 85747 Garching [email protected]
M. Pitschmann Lehrstuhl A fur Thermodynamik Technische Universitat Munchen D - 85747 Garching [email protected]
R.Schmidt Lehrstuhl A fur Thermodynamik Technische Universitat Munchen D - 85747 Garching [email protected]
Prof. J. Straub Lehrstuhl A fur Thermodynamik Technische Universitat Munchen D - 85747 Garching [email protected]
Dr. G. Strubel Lehrstuhl A fur Thermodynamik Technische Universitat Munchen D - 85747 Garching [email protected]
R.Tauscher Lehrstuhl A fur Thermodynamik Technische Universitat Munchen D - 85747 Garching [email protected]
Prof. J. Wolfrum Physikalisch-Chemisches Institut Universitat Heidelberg D - 69120 Heidelberg [email protected]
1 Authors marked with 1 formerly worked at the "Lehrstuhl A fur Thermodynamik". Please refer to the given e-mail address in case of any questions.
Contents
1 Introduction.............................................. 1 Franz Mayinger and Oliver Feldmann
2 The Schlieren Technique .................................. 5 Andreas Eder, Martin Jordan 2.1 Introduction............................................... 5 2.2 Basic Principle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3 Optical and Thermodynamic Interrelations. . . . . . . . . . . . . . . . . . . . 6
2.3.1 Refraction Index and Temperature Field. . . . . . . . . . . . . . . 7 2.3.2 The Deflection of Light in an Inhomogeneous Medium. . . 7
2.4 Application of the Schlieren Technique. . . . . . . . . . . . . . . . . . . . . . . . 9 2.4.1 Application to Transient Combustion Research. . . . . . . .. 13
The Schlieren Cinematography . . . . . . . . . . . . . . . . . . . . . .. 13 The Color Schlieren Technique. . . . . . . . . . . . . . . . . . . . . .. 15
2.4.2 Application to Fuel-Injection Systems. . . . . . . . . . . . . . . .. 15
3 Fundamentals of Holography and Interferometry . . . . . . . . .. 17 Franz Mayinger 3.1 Abstract.................................................. 17 3.2 Introduction............................................... 17 3.3 Principle of Holography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 18 3.4 Simple Holographic Arrangement. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 20 3.5 Holographic Interferometry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 24
3.5.1 Double Exposure Technique. . . . . . . . . . . . . . . . . . . . . . . . .. 24 3.5.2 Real-Time Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 28 3.5.3 Evaluation of the Interferograms. . . . . . . . . . . . . . . . . . . . .. 31 3.5.4 Finite Fringe Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 33
3.6 An Interference Method for Simultaneous Heat and Mass Transfer 36 3.7 Comparison with Classical Methods .......................... 40
4 Holographic Interferometry ... . . . . . . . . . . . . . . . . . . . . . . . . . . .. 43 Robert Tauscher 4.1 Introduction............................................... 44 4.2 Components of a Holographic Interferometer. . . . . . . . . . . . . . . . . .. 44
4.2.1 Light Source. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 44 4.2.2 Optical Table .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 44
XII Contents
4.2.3
4.2.4 4.2.5 4.2.6 4.2.7 4.2.8 4.2.9 4.2.10
Shutter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . .. 45
Beam Splitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 45 Attenuation Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 45 Beam Expander . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 45 Mirrors, Lenses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 46 Recording Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 46 Piezo Mirror . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 47 Test Facility ....... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 48
4.3 Evaluation of Interferograms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 48 4.3.1 Theoretical Principles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 48 4.3.2 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 53
4.3.3 Calculation of Temperature and Concentration Distribu-tions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 53
4.3.4 Determination of the Local Heat Transfer Coefficient. . .. 54 4.4 Examples................................................. 54
4.4.1 Determination of the Temperature Distribution in a Com-pact Plate Heat Exchanger with Plain Fins ..... . . . . . .. 54 Description of the Test Section . . . . . . . . . . . . . . . . . . . . . .. 54 Description of the Interferograms . . . . . . . . . . . . . . . . . . . .. 56
5 Short Time Holography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 59 Oliver Feldmann, Peter Gebhard, Anselmo Chavez 5.1 Introduction............................................... 59
5.1.1 Historical development of holography . . . . . . . . . . . . . . . . .. 59 5.1.2 The holographic image. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 60 5.1.3 Holography as an optical measurement method. . . . . . . .. 61
5.2 Elements of holography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 62 5.2.1 Recording materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 62 5.2.2 The pulsed laser. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 65 5.2.3 Optical set-up ..................................... 66 5.2.4 Adjusting the holographic camera .................... 67 5.2.5 Recording, development and reconstruction of holograms 69
Amplitude hologram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 69 Phase hologram .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 69
5.3 Application example: Dispersion characteristics in stirred bubble columns. . . . . . . . . . . .. 70 5.3.1 Statement of the problem. . . . . . . . . . . . . . . . . . . . . . . . . . .. 70 5.3.2 Recording the holograms. . . . . . . . . . . . . . . . . . . . . . . . . . .. 72 5.3.3 Reconstruction and evaluation of the holograms. . . . . . .. 73 5.3.4 Stereo matching of the two holograms. . . . . . . . . . . . . . . .. 74 5.3.5 Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 75
Contents XIII
6 Evaluation of holograms by digital image processing. . . . . .. 79 Oliver Feldmann, Robert Tauscher 6.1 Introduction............................................... 79
6.1.1 Digitization of a picture ............................ 80 6.1.2 Gray value pictures ................................ 80 6.1.3 Operations with gray value images. . . . . . . . . . . . . . . . . . .. 82
6.2 A digital image processing system for the evaluation of holo-graphic reconstructions ..................................... 85 6.2.1 Evaluation of holographic images .................... 85
Scanning of in-line holograms ....................... 85 Scanning of off-axis holograms . . . . . . . . . . . . . . . . . . . . . .. 86
6.2.2 set-up of a digital image processing system ... . . . . . . . .. 87 6.3 Image processing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 87
6.3.1 Evaluation of single pulsed holograms. . . . . . . . . . . . . . . .. 88 6.3.2 Evaluation of double pulsed holograms . . . . . . . . . . . . . . .. 89 6.3.3 Stereo matching algorithm. . . . . . . . . . . . . . . . . . . . . . . . . .. 93 6.3.4 Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 93
6.4 Evaluation of interferograms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 94
7 Light Scattering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 99 Boris Kruppa, Gernoth Strube, Christo! Gerlach 7.1 Introduction............................................... 99 7.2 Scattering Processes ........................................ 101
7.2.1 Interaction of Light and Matter ...................... 101 7.2.2 Elastic Scattering ................................... 102 7.2.3 Inelastic Scattering ................................. 103
7.3 Light Scattering Techniques in Heat Transfer .................. 104 7.3.1 Mie-Scattering ..................................... 104 7.3.2 Rayleigh-Scattering ................................. 107 7.3.3 Raman-Scattering .................................. 108 7.3.4 Laser Induced Fluorescence (LIF) ..................... 111 7.3.5 Absorption ........................................ 112
7.4 Concluding Remarks ........................................ 115
8 Laser-Doppler Velocimetry ............................... 117 Andreas Eder, Bodo Durst, Martin Jordan 8.1 Introduction ............................................... 117 8.2 Principles of LDV .......................................... 118 8.3 Optics .................................................... 119 8.4 Signal Processing ........................................... 121 8.5 Seeding Particles ........................................... 123 8.6 Determination of Characteristic Turbulence-Quantities .......... 124
8.6.1 Fundamentals of Turbulent Flows ..................... 124 8.6.2 Measurement of Turbulence-Quantities ................ 134
XIV Contents
9 Phase Doppler Anemometry (PDA) ....................... 139 Bernd Oiner 9.1 Introduction ............................................... 139 9.2 General considerations for the application of PDA .............. 139 9.3 Principles of PDA .......................................... 140
9.3.1 Light-scattering by particles ......................... 140 9.3.2 Optical parameters of a Phase Doppler Measurement Sys-
tern ............................................... 142 9.3.3 Phase-diameter relationship ......................... 142
9.4 Measurement accuracy ...................................... 146 9.5 Applications of PDA ........................................ 147
10 Dynamic Light Scattering . ............................... 153 Boris Kruppa, Martin Pitschmann, Johannes Straub 10.1 Introduction ............................................... 153 10.2 Overview .................................................. 153 10.3 Light Scattering Theory ..................................... 156
10.3.1 Scattering Geometry and Assumptions ................ 156 10.3.2 Temporal and Spatial Behavior of Scattered Light ...... 158 10.3.3 Correlation Functions ............................... 159 10.3.4 Hydrodynamic Fluctuation Theory ................... 164
10.4 Experimental Methods ...................................... 166 10.4.1 Homodyne Method ................................. 166 10.4.2 Heterodyne Method ................................. 169
10.5 Measurement of Thermal Diffusivity .......................... 170
11 Raman Scattering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 Gernoth Strube 11.1 Introduction ............................................... 173 11.2 Theoretical Basics of Raman Spectroscopy. . . . . . . . . . . . . . . . . . . . . 174
11.2.1 Concentration Measurements ......................... 177 11.2.2 Temperature Measurement ........................... 180
General Considerations .............................. 180 Thermometry by Rotational Raman Spectroscopy ...... 182 Thermometry by Vibrational Raman Spectroscopy ...... 185
11.3 Experimental set-up ........................................ 188 11.3.1 Laser ............................................. 190 11.3.2 Focussing and Collection Lenses ...................... 191 11.3.3 Spectral Frequency Selection ......................... 192 11.3.4 Photon Converters .................................. 192 11.3.5 Data Acquisition and Control ........................ 193
11.4 Selected Applications ....................................... 194 11.5 Concluding Remarks ........................................ 198
Contents XV
12 Laser induced Fluorescence .............................. 199 Peter Andresen 12.1 Introduction ............................................... 199 12.2 Basic Principles of Laser Induced Fluorescence ................. 201
12.2.1 General Considerations .............................. 201 12.2.2 Concentration Measurement ......................... 207 12.2.3 Temperature Measurement ........................... 208 12.2.4 'Itacer LIF ......................................... 210
12.3 Experimental Setup and Procedures .......................... 211 12.3.1 Experimental Setup ................................. 211 12.3.2 Experimental and Evaluation Procedures .............. 215
12.4 Selected Applications ....................................... 221 12.5 Concluding Remarks ........................................ 228
13 Absorption ............................................... 231 Volker Ebert, Jiirgen Wolfrum 13.1 Introduction ............................................... 231 13.2 Line spectra ............................................... 232
13.2.1 Position ........................................... 233 13.2.2 Shape and width ................................... 233
A. Natural line broadening ........................... 234 B. Doppler broadening .............................. 234 C. Collisional broadening ............................ 235 D. Voigt function-Mixed line shapes .................. 236
13.2.3 Line strength ...................................... 238 13.3 Experimental techniques .................................... 243
13.3.1 Overview .......................................... 243 Techniques used in absorption spectroscopy ............ 246
13.3.2 Experimental examples .............................. 248 A. In situ measurements of ammonia concentration in
industrial combustion systems .................. 248 B:sFast temperature measurements with tunable diode
lasers ........................................ 252 C; Harmonic detection techniques for the measurement
of small absorptions . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 D. Simultaneous in-situ detection of oxygen and water
in a full scale waste incinerator with near infrared diode lasers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260
E. In situ determination of free radicals in flames . . . . . . . 266
14 Pyrometry and Thermography ........................... 270 Udo L. Gliickert, Robert Schmidt 14.1 Introduction ............................................... 270 14.2 Temperature Radiation ..................................... 271 14.3 Method of 'Itansmission ..................................... 278
XVI Contents
14.4 Radiation Receiver (Detector) ............................... 280 14.5 Thermal Cameras - Thermography Image Systems ............. 283 14.6 Pyrometers ................................................ 286
14.6.1 Classification According to Construction Types ......... 289 14.6.2 Filament and Quotient Pyrometers ................... 289 14.6.3 IR Recording Heads ................................. 290
14.7 Error Potential. ............................................ 290 14.7.1 Error Sources During Recording ...................... 290 14.7.2 Equipment Error ................................... 291 14.7.3 Problems with Thermograph Readings ................ 293
14.8 Appendix ................................................. 294 14.8.1 Important Constants ................................ 294 14.8.2 Further Information and Tables ...................... 294
15 Tomography ............................................. 300 Mathias Buchmann, Dieter Mewes 15.1 Introduction ............................................... 300 15.2 Integral Measurement Methods .............................. 303
15.2.1 Absorption Methods ................................ 305 15.2.2 Interferometric Methods ............................. 305
15.3 Mathematical Reconstruction Methods ........................ 307 15.3.1 Algebraic Reconstruction Methods .................... 309
Matrix Methods .................................... 309 Iterative Series Expansion ........................... 312
15.3.2 Explicit Reconstruction Methods ..................... 318 Fourier Transform Method ........................... 319 Analytical Solution of Integral Equations .............. 322
15.3.3 Comparison of Reconstruction Methods ............... 324 15.4 Implementations ........................................... 329
15.4.1 Measurement of temperature fields in stirred vessels ..... 330 15.4.2 Measurement of micro- and macromixing with the tomo-
graphical dualwavelenght tomography ................. 333 15.4.3 Tomographic measurements of flames with the Schlieren
effect .............................................. 336 15.4.4 Chemical species tomography by near infra-red absorption 337
16 Particle Image Velocimetry .............................. 340 Wolfgang M erzkirch 16.1 Introduction ............................................... 340 16.2 Hardware for the experimental set-up ......................... 341 16.3 Evaluation software ......................................... 345 16.4 Three-dimensional flow ..................................... 353 16.5 Applications ............................................... 354
Contents XVII
Nomenclature . ............................................... 358
References . ................................................... 371
Index ......................................................... 397
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