Effects of fuel cetane number on the structure of diesel spray combustion: An accelerated Eulerian stochastic fields method

An Eulerian stochastic fields (ESF) method accelerated with the chemistry coordinate mapping (CCM) approach for modelling spray combustion is formulated, and applied to model diesel combustion in a constant volume vessel. In ESF-CCM, the thermodynamic states of the discretised stochastic fields are mapped into a low-dimensional phase space. Integration of the chemical stiff ODEs is performed in the phase space and the results are mapped back to the physical domain. After validating the ESF-CCM, the method is used to investigate the effects of fuel cetane number on the structure of diesel spray combustion. It is shown that, depending of the fuel cetane number, liftoff length is varied, which can lead to a change in combustion mode from classical diesel spray combustion to fuel-lean premixed burned combustion. Spray combustion with a shorter liftoff length exhibits the characteristics of the classical conceptual diesel combustion model proposed by Dec in 1997 (http://dx.doi.org/10.4271/970873), whereas in a case with a lower cetane number the liftoff length is much larger and the spray combustion probably occurs in a fuel-lean-premixed mode of combustion. Nevertheless, the transport budget at the liftoff location shows that stabilisation at all cetane numbers is governed primarily by the auto-ignition process.

[1]  Nasser Darabiha,et al.  Approximating the chemical structure of partially premixed and diffusion counterflow flames using FPI flamelet tabulation , 2005 .

[2]  S. Voglsam,et al.  A global combustion model for simulation of n-heptane and iso-octane self ignition , 2012 .

[3]  Epaminondas Mastorakos,et al.  Turbulent combustion modeling : advances, new trends and perspectives , 2011 .

[4]  Mehdi Jangi,et al.  A multi-zone chemistry mapping approach for direct numerical simulation of auto-ignition and flame propagation in a constant volume enclosure , 2012 .

[5]  W. Leuckel,et al.  Experimental investigation on the stabilization mechanism of jet diffusion flames , 1985 .

[6]  J. Dec.  A Conceptual Model of DI Diesel Combustion Based on Laser-Sheet Imaging* , 1997 .

[7]  Yasuhiro Mizobuchi,et al.  A numerical study on the formation of diffusion flame islands in a turbulent hydrogen jet lifted flame , 2005 .

[8]  Zhuyin Ren,et al.  Reduced description of reactive flows with tabulation of chemistry , 2011 .

[9]  D. Haworth.  Progress in probability density function methods for turbulent reacting flows , 2010 .

[10]  S. Pope.  PDF methods for turbulent reactive flows , 1985 .

[11]  Robert L. Gordon,et al.  Transport budgets in turbulent lifted flames of methane autoigniting in a vitiated co-flow , 2007 .

[12]  A. Liñán,et al.  Effects of heat release on triple flames , 1995 .

[13]  L. Valiño,et al.  A Field Monte Carlo Formulation for Calculating the Probability Density Function of a Single Scalar in a Turbulent Flow , 1998 .

[14]  Norbert Peters,et al.  Liftoff characteristics of turbulent jet diffusion flames , 1982 .

[15]  J. Buckmaster,et al.  Edge-flame-holding , 1996 .

[16]  Stephen B. Pope,et al.  An improved algorithm for in situ adaptive tabulation , 2009, J. Comput. Phys..

[17]  X. Bai,et al.  Large Eddy Simulation of Air Entrainment and Mixing in Reacting and Non-Reacting Diesel Sprays , 2014, Flow, Turbulence and Combustion.

[18]  R. Reitz,et al.  Structure of High-Pressure Fuel Sprays , 1987 .

[19]  Mehdi Jangi,et al.  Multidimensional chemistry coordinate mapping approach for combustion modelling with finite-rate chemistry , 2012 .

[20]  Ramanan Sankaran,et al.  Three-dimensional direct numerical simulation of a turbulent lifted hydrogen jet flame in heated coflow: flame stabilization and structure , 2009, Journal of Fluid Mechanics.

[21]  Zhuyin Ren,et al.  A cell agglomeration algorithm for accelerating detailed chemistry in CFD , 2009 .

[22]  Long Liang,et al.  A Dynamic Multi-Zone Partitioning Scheme for Solving Detailed Chemical Kinetics in Reactive Flow Computations , 2009 .

[23]  X. Bai,et al.  Effects of EGR on the structure and emissions of diesel combustion , 2013 .

[24]  Robert J. Kee,et al.  On reduced mechanisms for methaneair combustion in nonpremixed flames , 1990 .

[25]  L. Vanquickenborne,et al.  The stabilization mechanism of lifted diffusion flames , 1966 .

[26]  X. Bai,et al.  On large eddy simulation of diesel spray for internal combustion engines , 2015 .

[27]  Daniel C. Haworth,et al.  Stabilization and liftoff length of a non-premixed methane/air jet flame discharging into a high-temperature environment: An accelerated transported PDF method , 2015 .

[28]  Luc Vervisch,et al.  Effects of heat release in laminar diffusion flames lifted on round jets , 2003 .

[29]  Robert J. Kee,et al.  A FORTRAN COMPUTER CODE PACKAGE FOR THE EVALUATION OF GAS-PHASE, MULTICOMPONENT TRANSPORT PROPERTIES , 1986 .

[30]  Denis Veynante,et al.  Turbulent combustion modeling , 2002, VKI Lecture Series.

[31]  Konstantinos Gkagkas,et al.  Transported PDF modelling with detailed chemistry of pre- and auto-ignition in CH4/air mixtures , 2007 .

[32]  Robert W. Dibble,et al.  Lifted methane–air jet flames in a vitiated coflow , 2005 .

[33]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[34]  X. Bai,et al.  Investigation of Chemical Kinetics on Soot Formation Event of n-Heptane Spray Combustion , 2014 .

[35]  Janet Elizabeth Hope.  Open Source , 2017, Encyclopedia of GIS.