Analysis of LES-based combustion models applied to an acetone turbulent spray flame

Investigations of Evaporative Cooling and Turbulence Flame Interaction Modeling in Ethanol Turbulent Spray Combustion Using Tabulated Chemistry

“…Although both interactions are strongly coupled, they are not always comprehensively addressed in numerical simulations. The cooling down of the gas mixture caused by the evaporation process, namely the evaporative cooling (EC), is often neglected [4][5][6][7][8] or simplified [9,10] in the context of tabulated chemistry. Herein, the consideration of heat losses is not trivial and typically involves high computational efforts [11][12][13].…”

“…Nevertheless, as analyzed in [16] for one-dimensional flames propagating in droplet mists, the inclusion of the evaporative cooling is quite relevant in the spray combustion modeling. Yet the importance of the proper modeling of the turbulence-flame interaction is a well known topic in the spray combustion community [1,4,[6][7][8][9][10]13,[17][18][19][20][21]. In view of the application of the artificially thickened flame (ATF) approach, many works have been using a similar value for the exponent of the power-law function used to model the flame surface wrinkling (FSW), namely 0.5.…”

“…An initial approach to account for evaporative cooling effects is to consider heat losses in the mixture without including modifications in the chemistry table [9,10]. According to this formalism, influences of heat losses concentrate on the computation of droplet evaporation rates which indirectly interfere with the combustion process.…”

“…The ATF model stands out among methods based on deterministic approaches to characterize the turbulence-flame interaction in turbulent spray flames [9,10,17,20,21]. This model showed a great capability to predict the behavior of turbulent spray flames in the Eulerian-Eulerian two-phase flow approach (e.g., [9,17]) as well as in the Euler-Lagrangian framework (e.g., [10,20,21]). Initially proposed to model laminar premixed flames [26], the ATF was gradually expanded to address turbulent premixed [27,28] and stratified flames [29].…”

“…In view of turbulent spray combustion, a further extension to include effects of the dispersed phase in the Euler-Lagrangian context are recently presented in [21]. A common characteristic to all of these preceding works involving turbulent flames (i.e., [9,10,20,21]) refers to the usage of a global and presumed definition of the exponent of the power-law function (β) proposed by Charlette et al [28] to model the FSW. According to the analysis conducted for premixed flames in [30], no universal value exists for this parameter, which may be determined by adjusting with experimental data or by some modeling approach (e.g., the dynamic method proposed by Charlette et al [30]).…”