Contents lists available at ScienceDirect Fuel journal homepage: www.elsevier.com/locate/fuel Full Length Article Description of kerosene / air combustion with Hybrid Transported- Tabulated Chemistry Bastien Duboc, Guillaume Ribert ⁎ , Pascale Domingo CORIA – CNRS, Normandie Univ., INSA de Rouen Normandie, 76000 Rouen, France ARTICLE INFO Keywords: Hybrid chemistry Kerosene ABSTRACT A strategy to introduce the detailed chemistry of kerosene-air combustion into simulations of flames is reported. Despite the rise in computer power achieved during the last decade, simulations of combustion chambers using detailed chemistry mechanisms are still not possible because of the large number of species to be transported. The Hybrid Transported-Tabulated Chemistry method (HTTC) has been designed to overcome these obstacles and radically reduce the computational cost, by transporting only a reduced set of major species and tabulating the intermediate species while making use of their self-similarity property to downsize the table. HTTC has already been validated for light hydrocarbons such as methane. In this work, HTTC is extended to kerosene-air combustion showing that the number of species to be transported is unchanged compared to methane/air and that the self-similarity can still be applied. The chemistry of nitrogen oxides is also addressed with HTTC. The method allows for a reduction of the computational cost by around four orders of magnitude when computing laminar premixed flames. HTTC appears as a flexible tool since its prediction capabilities are maintained even if the table for intermediate species is generated in different conditions than those encountered in the simulation. 1. Introduction Direct Numerical Simulation (DNS) of a reactive flow with detailed chemistry requires to solve the transport equations for energy, mo- mentum and mass fractions of all chemical species. For the latter, the computation of many source terms, thermodynamical quantities and transport coefficients using the full set of species contained in the ki- netic mechanism is needed. Solving for the mass fraction of the species leads to two main difficulties: the number of computing operations increases dramatically with the number of species, and the stiffness of the chemical system imposes fine mesh and time resolutions [1,2]. Implicit numerical schemes can be used to overcome this stiffness, and increase the stability limit of the time step [3–8]. However, those nu- merical schemes do not solve the issue raised by the first point: the computational cost does not scale linearly with the number of species and it may become very high for large chemical mechanisms [9]. In contrast, reduced kinetics feature smaller numbers of species and may be a solution to the two difficulties presented above [10], but at the cost of a lack of precision or a limited range of application for highly sim- plified mechanisms [9]. An alternative method able to take all the species of a full kinetic mechanism into account during a simulation, with a computational cost compatible with today’s computer capabilities, has been proposed by Ribert et al. 11. It is called “Hybrid Transported-Tabulated Chemistry” (HTTC). With HTTC, the full set of species is split into two parts: the main species, carrying most of the mass, and the remaining minor species. The mass fractions of the main species are computed by solving a transport equation, using a detailed chemistry solver. Instead of being transported, the minor species are read in a look-up table which is built from self-similar flame profiles [12–14]. The standard momentum and energy transport equations are still solved. The basis of HTTC is to keep unaltered the detailed kinetic mechanisms without the suppression of species or reactions. Radical and minor intermediate species are involved in chemical reactions that mostly take place in the flame front and which are re- sponsible for the stiffness of the chemical system. Consequently, re- moving them from the set of transported species by reading their values in a table, makes the chemistry of combustion easier to solve. In the frame of explicit solvers, the chemical time step is then expected to be largely increased without any stability issue, thanks to the tabulation of the minor species. In the case of kinetic mechanisms for heavy fuels, the chemical time step is usually far below the convective time step [15], which leads to prohibitive computation costs. For such fuels, it could be increased by several orders of magnitude, to become larger than the convective time step when using HTTC. Simulations of reactive flows with very large detailed mechanisms using fully explicit numerical https://doi.org/10.1016/j.fuel.2018.06.014 Received 11 February 2018; Received in revised form 4 June 2018; Accepted 6 June 2018 ⁎ Corresponding author. E-mail address: guillaume.ribert@coria.fr (G. Ribert). Fuel 233 (2018) 146–158 0016-2361/ © 2018 Elsevier Ltd. All rights reserved. T