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Investigation of the Ignition Process of Pilot Injections Using CFD
Technical Paper
2019-24-0129
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
State of the art high-pressure fuel injectors offer the ability to inject multiple times per cycle, and can reach very low fuel amounts per injection event. This behaviour allows the application of pilot injections in diesel engine applications or dual fuel engines. In both diesel and dual fuel engines, the amount of pilot fuel affects the engine efficiency. The understanding of the underlying ignition mechanism of the pilot fuel is required to optimize injection parameters and the engines’ fuel consumption.
The present work focuses on the differences of ignition mechanisms between long and short injections. The investigation has been performed numerically, using CFD with a well-proven combustion model. The setup used employs a well characterized single orifice injector, injecting into a high temperature, pressurized environment with a composition of 15% oxygen. The duration of injection (DOI) has been gradually decreased form 1.5 ms to 0.3 ms, while a square mass flow rate profile has been employed.
The analysis distinguishes between long, medium and short DOIs: the reference ignition delay is defined by the long DOIs, for which constant ignition delays are found. Shortening the injection duration leads to a decrease in ignition delay for medium DOIs (accelerated case), while for short DOIs an ignition delay trend reversal is observed (prolonged case). The ignition location is close to the spray tip for the long and the short cases, while it moves towards the spray tail for the medium DOIs. The ignition delays of the medium DOIs are shorter due to enhanced mixing after end of injection. The relatively larger areas of leaner mixture increase the temperature and in particular the contribution of the low temperature reactions, which promotes ignition. In the short DOIs, the ignition delay is longer due to overmixing, which reduces the mixture reactivity and prolongs the ignition delay. The ignition moves towards the most fuel rich location in the spray, which lies close to the spray tip at a certain time after the end of injection.
Authors
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Citation
Barro, C., Seddik, O., Wright, Y., Pandurangi, S. et al., "Investigation of the Ignition Process of Pilot Injections Using CFD," SAE Technical Paper 2019-24-0129, 2019, https://doi.org/10.4271/2019-24-0129.Also In
References
- Aggarwal , S.K. Single Droplet Ignition: Theoretical Analyses and Experimental Findings Progress in Energy and Combustion Science 45 79 107 2014 10.1016/j.pecs.2014.05.002
- Borghesi , G. and Mastorakos , E. Spontaneous Ignition of Isolated N-Heptane Droplets at Low, Intermediate, and High Ambient Temperatures from a Mixture-Fraction Perspective Combustion and Flame 162 6 2544 2560 2015 10.1016/j.combustflame.2015.03.003
- Farouk , T.I. and Dryer , F.L. Isolated N-Heptane Droplet Combustion in Microgravity: “Cool Flames” - Two-Stage Combustion Combustion and Flame 161 2 565 581 2014 10.1016/j.combustflame.2013.09.011
- Krisman , A. , Hawkes , E.R. , Talei , M. , Bhagatwala , A. et al. Characterisation of Two-Stage Ignition in Diesel Engine-Relevant Thermochemical Conditions Using Direct Numerical Simulation Combustion and Flame 172 326 341 2016 10.1016/j.combustflame.2016.06.010
- Pei , Y. , Hawkes , E.R. , Bolla , M. , Kook , S. et al. An Analysis of the Structure of an N-Dodecane Spray Flame Using TPDF Modelling Combustion and Flame 168 420 435 2016 10.1016/j.combustflame.2015.11.034
- Musculus , M.P.B. and Pickett , L.M. 17 - In-Cylinder Spray, Mixing, Combustion, and Pollutant-Formation Processes in Conventional and Low-Temperature- Combustion Diesel Engines A2 Zhao , H. Advanced Direct Injection Combustion Engine Technologies and Development Woodhead Publishing 2010 644 675
- Singh , S. , Musculus , M.P.B. , and Reitz , R.D. Mixing and Flame Structures Inferred from OH-PLIF for Conventional and Low-Temperature Diesel Engine Combustion Combustion and Flame 156 10 1898 1908 2009 10.1016/j.combustflame.2009.07.019
- Assanis , D.N. , Filipi , Z.S. , Fiveland , S.B. , and Syrimis , M. A Predictive Ignition Delay Correlation under Steady-State and Transient Operation of a Direct Injection Diesel Engine Journal of Engineering for Gas Turbines and Power 125 2 450 457 2003 10.1115/1.1563238
- Kadota , T. , Hiroyasu , H. , and Oya , H. Spontaneous Ignition Delay of a Fuel Droplet in High Pressure High Temperature Gaseous Environments Bull. JSME 19 130 437 445 1976
- Wolfer , H.H. Ignition Lag in Diesel Engines. VDI-Forschungsheft 392 1938
- Lakshminarayanan , P.A. and Aghav , Y.V. Ignition Delay in a Diesel Engine Modelling Diesel Combustion Dordrecht Springer Netherlands 2010 59 78
- Alfazazi , A. , Kuti , O.A. , Naser , N. , Chung , S.H. et al. Two-Stage Lagrangian Modeling of Ignition Processes in Ignition Quality Tester and Constant Volume Combustion Chambers Fuel 185 589 598 2016 10.1016/j.fuel.2016.08.017
- Barro , C. , Lucjan , A. , Li , Z. , Kyrtatos , P. et al. Development and Experimental Validation of a Fast Spray Ignition Model for Diesel Engines Using Insights from CFD Spray Calculations SAE International Journal of Fuels and Lubricants 10 2 304 317 2017 10.4271/2017-01-0812
- Malbec , L.-M. , Eagle , W.E. , Musculus , M.P.B. , and Schihl , P. 2015 10.4271/2015-01-1830
- Miles , P.C. , Sahoo , D. , Busch , S. , Trost , J. , et al. 2013 10.4271/2013-01-2531
- Musculus , M.P.B. , Lachaux , T. , Pickett , L.M. , and Idicheria , C.A. End-of-Injection Over-Mixing and Unburned Hydrocarbon Emissions in Low-Temperature-Combustion Diesel Engines SAE Technical Paper 2007-01-0907 2007 10.4271/2007-01-0907
- Barro , C. , Nani , C. , Hutter , R. , and Boulouchos , K. Spray Model Based Phenomenological Combustion Description and Experimental Validation for a Dual Fuel Engine SAE Technical Paper 2017-24-0098 2017 10.4271/2017-24-0098
- Srna , A. , Barro , C. , Hutter , R. , Möri , F. et al. POMDME as an Alternative Pilot Fuel for Dual-Fuel Engines: Optical Study in a RCEM and Application in an Automotive Size Dual-Fuel Diesel Engine SAE Technical Paper 2018-01-1734 2018 10.4271/2018-01-1734
- Klimenko , A.Y. and Bilger , R.W. Conditional Moment Closure for Turbulent Combustion Progress in Energy and Combustion Science 25 6 595 687 1999
- Wright , Y.M. , De Paola , G. , Boulouchos , K. , and Mastorakos , E. Simulations of Spray Autoignition and Flame Establishment with Two-Dimensional CMC Combust. Flame 143 4 2005
- Wright , Y.M. , Margari , O.N. , Boulouchos , K. , De Paola , G. et al. Experiments and Simulations of N-Heptane Spray Auto-Ignition in a Closed Combustion Chamber at Diesel Engine Conditions Flow Turbul. Combust. 84 1 49 78 2010 10.1007/s10494-009-9224-0
- Bolla , M. , Wright , Y.M. , Boulouchos , K. , Borghesi , G. et al. Soot Formation Modeling of N-Heptane Sprays under Diesel Engine Conditions Using the Conditional Moment Closure Approach Combustion Science and Technology 185 5 766 793 2013 10.1080/00102202.2012.752362
- Bolla , M. , Gudmundsson , T. , Wright , Y.M. , and Boulouchos , K. Simulations of Diesel Sprays Using the Conditional Moment Closure Model SAE International Journal of Engines 6 2 1249 1261 2013 10.4271/2013-01-1618
- Bolla , M. , Farrace , D. , Wright , Y.M. , Boulouchos , K. et al. Influence of Turbulence-Chemistry Interaction for N-Heptane Spray Combustion under Diesel Engine Conditions with Emphasis on Soot Formation and Oxidation Combustion Theory and Modelling 18 2 330 360 2014 10.1080/13647830.2014.898795
- Wright , Y.M. , Boulouchos , K. , De Paola , G. , and Mastorakos , E. Multi-Dimensional Conditional Moment Closure Modelling Applied to a Heavy-Duty Common-Rail Diesel Engine SAE International Journal of Engines 2 1 714 726 2009 10.4271/2009-01-0717
- De Paola , G. , Mastorakos , E. , Wright , Y.M. , and Boulouchos , K. Diesel Engine Simulations with Multi-Dimensional Conditional Moment Closure Combustion Science and Tech. 180 5 883 899 2008 10.1080/00102200801894273
- O'Brien , E.E. and Jiang , T.L. The Conditional Dissipation Rate of an Initially Binary Scalar in Homogeneous Turbulence Physics of Fluids A - Fluid Dynamics 3 12 3121 3123 1991
- Luo , Z. , Som , S. , Sarathy , S.M. , Plomer , M. et al. Development and Validation of an N-Dodecane Skeletal Mechanism for Spray Combustion Applications Combustion Theory and Modelling 18 2 187 203 2014 10.1080/13647830.2013.872807
- Pandurangi , S.S. , Bolla , M. , Wright , Y.M. , Boulouchos , K. et al. Onset and Progression of Soot in High-Pressure N-Dodecane Sprays under Diesel Engine Conditions International Journal of Engine Research 18 5-6 436 452 2016 10.1177/1468087416661041
- Wehrfritz , A. , Kaario , O. , Vuorinen , V. , and Somers , B. Large Eddy Simulation of N-Dodecane Spray Flames Using Flamelet Generated Manifolds Combustion and Flame 167 113 131 2016 10.1016/j.combustflame.2016.02.019
- Pei , Y. , Hawkes , E.R. , Kook , S. , Goldin , G.M. et al. Modelling N-Dodecane Spray and Combustion with the Transported Probability Density Function Method Combustion and Flame 162 5 2006 2019 2015 10.1016/j.combustflame.2014.12.019
- Kahila , H. , Wehrfritz , A. , Kaario , O. , Ghaderi Masouleh , M. et al. Large-Eddy Simulation on the Influence of Injection Pressure in Reacting Spray A Combustion and Flame 191 142 159 2018 10.1016/j.combustflame.2018.01.004
- Gong , C. , Jangi , M. , Lucchini , T. , D’Errico , G. et al. Large Eddy Simulation of Air Entrainment and Mixing in Reacting and Non-Reacting Diesel Sprays Flow, Turbulence and Combustion 93 3 385 404 2014 10.1007/s10494-014-9566-0
- Pei , Y. , Som , S. , Pomraning , E. , Senecal , P.K. et al. Large Eddy Simulation of a Reacting Spray Flame with Multiple Realizations under Compression Ignition Engine Conditions Combustion and Flame 162 12 4442 4455 2015 10.1016/j.combustflame.2015.08.010
- Blomberg , C.K. , Zeugin , L. , Pandurangi , S.S. , Bolla , M. et al. Modeling Split Injections of ECN “Spray A” Using a Conditional Moment Closure Combustion Model with RANS and LES SAE International Journal of Engines 9 4 2107 2119 2016
- Pei , Y. , Davis , M.J. , Pickett , L.M. , and Som , S. Engine Combustion Network (ECN): Global Sensitivity Analysis of Spray a for Different Combustion Vessels Combustion and Flame 162 6 2337 2347 2015 10.1016/j.combustflame.2015.01.024
- Musculus , M.P.B. and Kattke , K. 2009 10.4271/2009-01-1355
- Naber , J.D. and Siebers , D.L. Effects of Gas Density and Vaporization on Penetration and Dispersion of Diesel Sprays SAE Technical Paper 960034 1996 10.4271/960034
- Srna , A. , Bolla , M. , Wright , Y.M. , Herrmann , K. et al. Effect of Methane on Pilot-Fuel Auto-Ignition in Dual-Fuel Engines Proceedings of the Combustion Institute 37 4 4741 4749 2019 10.1016/j.proci.2018.06.177
- Livengood , J.C. and Wu , P.C. Correlation of Autoignition Phenomena in Internal Combustion Engines and Rapid Compression Machines Symposium (International) on Combustion 5 1 347 356 1955 10.1016/S0082-0784(55)80047-1
- Weisser , G. , Tanner , F.X. , and Boulouchos , K. Modeling of Ignition and Early Flame Development with Respect to Large Diesel Engine Simulation SAE Technical Paper 981451 1998 10.4271/981451
- Vandersickel , A. , Hartmann , M. , Vogel , K. , Wright , Y.M. et al. The Autoignition of Practical Fuels at HCCI Conditions: High-Pressure Shock Tube Experiments and Phenomenological Modeling Fuel 93 1 492 501 2012 10.1016/j.fuel.2011.10.062
- Blomberg , C.K. , Mitakos , D. , Bardi , M. , Boulouchos , K. et al. 2016 10.4271/2016-01-0755