Polytechnic University of Valencia Congress, ILASS2017 - 28th European Conference on Liquid Atomization and Spray Systems

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Influence of the chemical mechanism in the frame of diesel-like CFD reacting spray simulations using a presumed PDF flamelet-based combustion model
Francisco Payri, José María García-Oliver, Ricardo Novella, Eduardo Javier Pérez-Sánchez

Last modified: 18-07-2017

Abstract


The ability of a computational fluid dynamics (CFD) simulation to reproduce the diesel-like reacting spray ignitionprocess and its corresponding flame structure strongly depends on both the fidelity of the chemical mechanismfor reproducing the oxidation of the fuel and also on how the turbulence-chemistry interaction (TCI) is modeled.Therefore, investigating the performance of different chemical mechanisms not only in perfect stirred reactors butdirectly in the diesel-like spray itself is of great interest in order to evaluate their suitability for being further appliedto CFD engine simulations.This research work focuses on applying a presumed probability density function (PDF) unsteady flamelet combustionmodel to the well-known spray A from the Engine Combustion Network (ECN), using three chemical mechanismswidely accepted by the scientific community as a way to figure out the influence of chemistry in the keycharacteristics of the combustion process in the frame of diesel-like spray simulations. Results confirm that in spiteof providing all of them correct trends for ignition delays (ID) and lift-off lengths (LOL), when comparing with experimentalresults, the structure of the flame presents noticeable differences, especially in the low and intermediatetemperatures and high equivalence ratio regions. Consequently, the selection of the chemical mechanism has animpact on the zones of influence of key species as observed in both spatial coordinates and also in the equivalenceratio-temperature maps. These differences are expected to be relevant considering the implications when couplingpollutant emissions models. The analysis of temperature and oxygen concentration parametric studies evidenceshow the observed differences are consistent and moderately dependent on the ambient conditions.

DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4746


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