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

Contents
tel-00623090, version 1 - 13 Sep 2011
4.1 LAMINAR BURNING VELOCITY .......................................................................................................... 87
4.1.1 Constant pressure method ........................................................................................................ 87
4.1.1.1 Flame morphology ........................................................................................................................ 89
4.1.1.2 Flame Radius .............................................................................................................................. 100
4.1.1.3 Flame speed ............................................................................................................................... 102
4.1.1.4 Laminar burning velocity ........................................................................................................... 104
4.1.1.5 Karlovitz and Markstein numbers ............................................................................................. 106
4.1.1.6 Comparison with other fuels ..................................................................................................... 109
4.1.2 Constant volume method ........................................................................................................ 111
4.1.2.1 Pressure evolution ...................................................................................................................... 112
4.1.2.2 Burning velocity .......................................................................................................................... 114
4.1.2.3 Laminar burning velocity correlations ...................................................................................... 119
4.2. MULTI-ZONE SPHERICAL COMBUSTION .......................................................................................... 123
4.2.1 Mathematical model ............................................................................................................... 123
4.2.1.1 Flame propagation ..................................................................................................................... 123
4.2.1.2 Chemical equilibrium .................................................................................................................. 124
4.2.1.3 Heat transfer ............................................................................................................................... 124
4.2.2 Calculation procedure ........................................................................................................... 126
4.2.3 Results discussion and code validation .................................................................................. 128
4.2.3.1 Influence of the heat transfer model ........................................................................................ 129
4.2.3.2 Influence of equivalence ratio ................................................................................................... 129
4.2.3.3 Influence of the pressure ........................................................................................................... 133
4.2.3.4 Quenching distance and heat flux estimations ....................................................................... 135
4.3 CONCLUSION .................................................................................................................................. 137
CHAPTER 5 EXPERIMENTAL STUDY OF ENGINE-LIKE TURBULENT COMBUSTION ... 139
5.1 RCM SINGLE COMPRESSION ........................................................................................................... 139
5.1.1 Sensibility analysis ................................................................................................................. 140
5.1.1.1 TDC position ............................................................................................................................... 140
5.1.1.2 Initial piston position ................................................................................................................... 141
5.1.1.3 Spark time ................................................................................................................................... 143
5.1.1.4 In-cylinder pressure reproducibility .......................................................................................... 145
5.1.1.5 Conclusion ................................................................................................................................... 146
5.1.2 In-cylinder pressure ............................................................................................................... 147
5.1.3 In-cylinder flame propagation ............................................................................................... 148
5.2 RCM COMPRESSION-EXPANSION .................................................................................................... 150
5.2.1 Sensibility analysis ................................................................................................................. 150
5.2.1.1 Piston position ............................................................................................................................. 150
5.2.1.2 Equivalent rotation speed .......................................................................................................... 153
5.2.1.3 In-cylinder pressure repeatability ............................................................................................. 155
5.2.1.4 Conclusion ................................................................................................................................... 157
5.2.2 In-cylinder pressure ............................................................................................................... 157
5.2.3 Ignition timing ........................................................................................................................ 160
5.2.4 In-cylinder flame propagation ............................................................................................... 161
5.3 CONCLUSION .................................................................................................................................. 165
CHAPTER 6 NUMERICAL SIMULATION OF A SYNGAS- FUELLED ENGINE ..................... 167
6.1 THERMODYNAMIC MODEL .............................................................................................................. 168
6.1.1 Conservation and state equations .......................................................................................... 169
6.1.2 Chemical composition and thermodynamic properties .......................................................... 170
6.1.3 Heat Transfer ......................................................................................................................... 173
6.1.4 Mass burning rate .................................................................................................................. 174
6.2. NUMERICAL SOLUTION PROCEDURE .............................................................................................. 175
6.3 CODE VALIDATION.......................................................................................................................... 178
6.3.1 CFR engine ............................................................................................................................ 178
6.3.1.1 Sub-models ................................................................................................................................. 178
6.3.1.2 Results and discussion .............................................................................................................. 181
6.3.2 RCM ....................................................................................................................................... 182
6.3.2.1 Flame propagation ..................................................................................................................... 182
6.3.2.2 In-cylinder volume ...................................................................................................................... 183
6.2.2.3 Heat transfer ............................................................................................................................... 184
6.3.2.4 Turbulent burning velocity ......................................................................................................... 185
6.3.2.5 Results and discussion .............................................................................................................. 185
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