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Exploring the Geometric Effects of Turbulence on Cyclic Variability
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 12, 2010 by SAE International in United States
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Cyclic variability in spark ignition engine combustion, especially at high dilution through lean burn or high EGR rates, places limits on in-cylinder NOx reduction and thermal efficiency. Flame wrinkling, resulting from interactions with turbulence, is a potential source of cyclic variations in turbulence. Previous studies have shown that flame kernels are subject to significant distortions when they are smaller than the integral length scale of turbulence. With the assumption that flame development is not subject to noticeable variations, after it reaches the integral length scale, the authors have shown that turbulent-burning-caused combustion variability can be successfully modeled as a function of laminar flame speed and turbulence intensity. This paper explores the contributions of flame wrinkling to flame kernel growth variation. As the kernel growth problem is complex, this study only explores one of the many aspects of the problem. The complete description of the phenomenon requires consideration of additional effects, which are discussed here. However it is shown that geometric variations of the flame kernel can potentially constitute a significant portion of variability. These variations can be considered to be present at all operating conditions at almost constant magnitude. Although the problem is non-linear, studying individual phenomena can provide useful information in understanding variability.
CitationMehrani, P. and Watson, H., "Exploring the Geometric Effects of Turbulence on Cyclic Variability," SAE Technical Paper 2010-01-0540, 2010, https://doi.org/10.4271/2010-01-0540.
- Khan, M.A., Watson, H., Baker, P., Liew, G. et al., “SI Engine Lean-Limit Extension Through LPG Throttle-Body Injection for Low CO2 and NOx,” SAE Technical Paper 2006-01-0495, 2006.
- Ozdor, N., Dulger, M., and Sher, E., “Cyclic Variability in Spark Ignition Engines A Literature Review,” SAE Technical Paper 940987, 1994.
- Brehob, D.D. and Newman, C.E., “Monte Carlo Simulation of Cycle by Cycle Variability,” SAE Technical Paper 922165, 1992.
- Roberts, J.B., Peyton Jones, J.C., and Landsborough, K.J., “Cylinder Pressure Variations as a Stochastic Process,” SAE Technical Paper 970059, 1997.
- Ayala, F.A. and Heywood, J.B., “Lean SI Engines: the Roles of Combustion Variability in Defining Lean Limits,” SAE Technical Paper, 2007-24-0030, 2007.
- Mehrani, P. and Watson, H.C., “Modeling the Effect of Mixture Composition on Cyclic Variability,” SAE Technical Paper 2007-01-0672, 2007.
- Peters N., “Turbulent Combustion”, Cambridge University Press, 2000.
- Heywood J. B., “Internal Combustion Engine Fundamentals”, McGrawHill, 1988.
- Fung J. C. H., Vassilicos J. C., “Two particle dispersion in turbulentlike flows”, Physical Review E, Vol 57(2), 1677-1690, 1998.
- Tabaczynski R. J., Trinker F. H., and Shannon B. A. S.. “Further refinement and validation of a turbulent flame propagation model for sparkignition engines”. Combustion and Flame, 39:111-121, 1980.
- Pischinger, S. and Heywood, J.B., “How Heat Losses to the Spark Plug Electrodes Affect Flame Kernel Development in an SI-Engine,” SAE Technical Paper, 900021, 1990.
- Sethian J. A., “A Fast Marching Level Set Method For Monotonically Advancing Fronts”, Applied Mathematics, Vol. 93, 1591-1595, 1996.
- Watson Harry C. and Dingli R. J. and De Zylva M. N., “The prediction of cycle variability in cylinder pressure using a quasi-dimensional flame propagation model”, IMechE, C465/055, 1993.
- Mehrani, P. and Watson, H.C., “Optimized Design of a Cyclic Variability Constrained Lean Limit SI Engine at Optimum NOx and Efficiency Using a PSO Algorithm,” SAE Technical Paper 2007-01-3551, 2007.