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

Abstract

Evaporative cooling effects and turbulence flame interaction are analyzed in the large eddy simulation (LES) context for an ethanol turbulent spray flame. Investigations are conducted with the artificially thickened flame (ATF) approach coupled with an extension of the mixture adaptive thickening procedure to account for variations of enthalpy. Droplets are tracked in a Euler–Lagrangian framework, in which an evaporation model accounting for the inter-phase non-equilibrium is applied. The chemistry is tabulated following the flamelet generated manifold (FGM) method. Enthalpy variations are incorporated in the resulting FGM database in a universal fashion, which is not limited to the heat losses caused by evaporative cooling effects. The relevance of the evaporative cooling is evaluated with a typically applied setting for a flame surface wrinkling model. Using one of the resulting cases from the evaporative cooling analysis as a reference, the importance of the flame wrinkling modeling is studied. Besides its novelty, the completeness of the proposed modeling strategy allows a significant contribution to the understanding of the most relevant phenomena for the turbulent spray combustion modeling.

Influence of the simplifications applied to the surrounding gas composition of evaporating droplets in air-blown and oxy-fuel combustion atmospheres

“…This is a typical problem in tabulated chemistry simulations, where only a few species are available in order to save memory [2,6,14]. Within this context, vapor species is one of the few that must be available for the computation of droplet evaporation, where the remaining gas mixture is often represented by air [11,12]. Both approaches presented in [14] overcomes such a simplification by including a few more species to represent the surrounding gas properties.…”

Numerical Simulation of the Effects of Oil Gun Location and Oil Feed Rate on Coal Ignition and Burner Wall Temperature in a Tiny Oil Ignition Burner

“…The result showed that the high temperature region where the oil combustion was intense and generated a high temperature was located from 0 to 0.4 m. Figure 16 depicts the profiles of the gas temperature obtained along the burner axis. Actually, the turbulence-flame interaction in turbulent flames accounting for the presence of a dispersed phase may affect the axial position where the maximum temperature is [37][38][39]. However, this interaction may not affect the overall temperature tendency.…”

Numerical Prediction of Turbulent Spray Flame Characteristics Using the Filtered Eulerian Stochastic Field Approach Coupled to Tabulated Chemistry

“…Many different groups have investigated the burner as it provides an extensive database for model validation as well as a reduced modeling effort due to the dilute nature of the spray. Herein, most of the investigations based on LES either opted for a flame thickening strategy [7,9,42,43], a presumed PDF approach [8,42], or a combination of these methods [44]. In the context of transported PDF methods applied to this burner, only a few contributions can be found in the literature.…”