Etude de la combustion de gaz de synthèse issus d'un processus de ...

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Chapter 3 Light from a point source A is transformed into a parallel beam and let through the zone to be investigated, E. All the rays which are not deflected converge at the focus of lens D and are cut off by diaphragm F. refracted rays bypass the diaphragm and are collected by lens G, which projects them onto screen H. Lens G is placed in such a way as to produce a sharply defined image of plane E on the screen. Simple geometrical considerations are not sufficient to determine precisely the changes in screen illumination due to a given disturbance, since they are greatly influenced by the diffraction of light on the diaphragm and by the source dimensions. Approximately, however, the relative illumination at the image plane, ∆I/I, is proportional to the beam deflection angle θ and the focal length f of lens D, as follows: ∆I ≈ θf (3.11) I tel-00623090, version 1 - 13 Sep 2011 The schlieren image is greatly influenced by the form and size of the light source and diaphragm. Placing a diaphragm at the lens focus amounts to removing a specific group of harmonics from the diffraction pattern, this, of course, introduces significant changes in the schlieren image. Hence all schlieren photography apparatus should consist of a large choice of diaphragms from which selection can be made experimentally to obtain the most contrasting picture of a given effect. By using a slit source of white light and a slit diaphragm color schlieren images can also be achieved. The dependence of changes in illumination at the screen on the refraction angle implies that the schlieren image visualizes density gradients of the flame: ∆I ∂Q ≈ (3.12) I ∂ n Where n represents a normal to the surface of constant density. Superimposed on this relationship is a spatial function dependent on the structure of the system and its arrangement relative to the disturbance. The situation is therefore largely qualitative, although an appropriate setting of the apparatus (on removing the diaphragm, a sharm image of the flame should appear on the screen) should ensure fairly faithful representation of the disturbance pattern. To obtain quantitative estimates of the density gradients at a given setting of the apparatus, optical calibrations are used with known refraction angles. Figure 3.18 shows a scheme of the used schlieren apparatus. The laser source (Laser Árgon Spectra Physics Series 2000) with a maximum power of 6 W generates a 83
Experimental set ups and diagnostics continuous beam of light, composed for two respectively equal main rays with wave length of 488 and 514.5 nm. This laser beam is cut, by the acoustic-optical deflector (Errol) in a succession of luminous impulses of adjustable duration and frequency. At the exit of the acoustic-optical deflector, the rays cross a convergent lens making them to converge into a focal point in the image where is placed a diaphragm of 50µ diameter. The diaphragm is placed in the center of the object of a spherical mirror with focal length of 1m, in order to reflecting the luminous rays into a parallel beam that crosses the combustion chamber (Taillefet, 1999). tel-00623090, version 1 - 13 Sep 2011 Figure 3.18– Schlieren scheme (Malheiro, 2002) When a phenomenon in the chamber cause a change of the refractive index, the light is deviated and passes with the same dimensions to the screen that can be record by a camera. To this end, a fast camera APX RS PHOTRON (CMOS, 10 bits, run at 6000 fps, 1024×512 pixels) is used to record the schlieren flame images during combustion. Exposure time is imposed by the acoustic-optical deflector and is fixed to 5 ms. 84
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THÈSE Pour l’obtention du Grade
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Acknowledgements Acknowledgements T
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Résumé __________________________
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Nomenclature Nomenclature Roman tel
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Nomenclature Subscripts tel-0062309
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Contents tel-00623090, version 1 -
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Contents 6.4. SYNGAS FUELLED-ENGINE
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Introduction CHAPTER 1 INTRODUCTION
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Introduction proves to have higher
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Introduction Chapter 3 - Experiment
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Bibliographic revision CHAPTER 2 BI
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Bibliographic revision point today
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Bibliographic revision - Boudouard
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Bibliographic revision Table 2.1 -
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Bibliographic revision Biomass Dryi
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Bibliographic revision Circulating
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Bibliographic revision or eliminate
Page 35 and 36: Bibliographic revision established
Page 37 and 38: Bibliographic revision Hydrogen Hyd
Page 39 and 40: Bibliographic revision of low moist
Page 41 and 42: Bibliographic revision scrubbing an
Page 43 and 44: Bibliographic revision suggests tha
Page 45 and 46: Bibliographic revision 1 d( δ A) 1
Page 47 and 48: Bibliographic revision Since n is
Page 49 and 50: Bibliographic revision 2 ( rsr ) 2
Page 51 and 52: Bibliographic revision This evoluti
Page 53 and 54: Bibliographic revision The burning
Page 55 and 56: Bibliographic revision δVG = − a
Page 57 and 58: Bibliographic revision 2 1 − −
Page 59 and 60: Bibliographic revision where the su
Page 61 and 62: Bibliographic revision the stretche
Page 63 and 64: Bibliographic revision burning velo
Page 65 and 66: Experimental set ups and diagnostic
Page 85: Experimental set ups and diagnostic
Page 89 and 90: Chapter 4 CHAPTER 4 EXPERIMENTAL AN
Page 91 and 92: Chapter 4 4.1 Laminar burning veloc
Page 93 and 94: Chapter 4 4.1.1.1 Flame morphology
Page 95 and 96: Chapter 4 P i = 1.0 bar, Ti = 293 K
Page 97 and 98: Chapter 4 Figure 4.5 shows schliere
Page 99 and 100: Chapter 4 P i = 2.0 bar, T i = 293
Page 101 and 102: Chapter 4 Sn (m/s) 3.0 2.5 2.0 1.5
Page 103 and 104: Chapter 4 5 ms 10 ms 15 ms 20 ms 25
Page 105 and 106: Chapter 4 behaviour of the curves r
Page 107 and 108: Chapter 4 1.50 Sn (m/s) 1.25 1.00 0
Page 109 and 110: Chapter 4 0.5 0.4 φ =1.0 Su (m/s)
Page 111 and 112: Chapter 4 variation of the normaliz
Page 113 and 114: Chapter 4 4.1.1.6 Comparison with o
Page 115 and 116: Chapter 4 The values of laminar bur
Page 117 and 118: Chapter 4 Pressure (bar) 7 6 5 4 3
Page 119 and 120: Chapter 4 0.5 0.4 φ=1.2 Su (m/s) 0
Page 121 and 122: Chapter 4 0.3 φ=0.8 Su (m/s) 0.2 0
Page 123 and 124: Chapter 4 a minimum pressure to exp
Page 125 and 126: Chapter 4 Notice the similar behavi
Page 127 and 128: Chapter 4 A very good agreement bet
Page 129 and 130: Chapter 4 ( ) Q = h T − T (4.21)
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Page 133 and 134: Chapter 4 are tested and discussed.
Page 135 and 136: Chapter 4 7 500 Pressure (bar) 6 5
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Chapter 4 Pressure (bar) 7 6 5 4 3
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Chapter 4 4.2.3.4 Quenching distanc
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Chapter 4 10000 Quenching distance
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Chapter 5 CHAPTER 5 EXPERIMENTAL ST
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Chapter 5 30 10 25 8 Pressure (bar)
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Chapter 5 30 Piston position (mm) 2
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Chapter 5 5.1.1.4 In-cylinder press
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Chapter 5 estimation of various par
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Chapter 5 TDC 1.25 ms 2.5 ms 3.75 m
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Chapter 5 Piston position (mm) 500
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Chapter 5 tel-00623090, version 1 -
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Chapter 5 From figure 5.15 is possi
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Chapter 5 From figure 5.16 is obser
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Chapter 5 80 Pressure (bar) 70 60 5
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Chapter 5 80 10 Pmax (bar) 70 60 50
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Chapter 5 -5.0 ms -3.75 ms -2.5 ms
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Chapter 5 observation emphasis the
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Chapter 6 CHAPTER 6 NUMERICAL SIMUL
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Chapter 6 centered at the spark plu
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Chapter 6 H 2 O, (3) N 2 , (4) O 2
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Chapter 6 For all the above express
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Chapter 6 motions within the cylind
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Chapter 6 tel-00623090, version 1 -
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Chapter 6 Heat transfer Wei et al.,
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Chapter 6 The calibration coefficie
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Chapter 6 6.3.2.2 In-cylinder volum
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Chapter 6 40 Experimental 30 Numeri
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Chapter 6 80 70 60 Numerical Experi
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Chapter 6 downdraft syngas than for
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Chapter 6 80 23º BTDC 60 29.5º BT
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Chapter 6 with experimental results
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Conclusions CHAPTER 7 CONCLUSIONS 7
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Conclusions radius and time for syn
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Conclusions conditions, therefore s
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Conclusions tel-00623090, version 1
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References References tel-00623090,
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References tel-00623090, version 1
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Appendix A - Overdetermined linear
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Appendix A - Overdetermined linear
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Appendix B- Syngas-air mixtures pro
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Appendix C -Rivère model Heat flux
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Appendix C -Rivère model The work
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tel-00623090, version 1 - 13 Sep 20
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