Flamelet modelling of turbulent reactive flows with non-premixed reactants and multiple inlets

Abstract

The present work describes an extension of the standard (i.e., two-inlet) mixture-fraction-based flamelet model, that is aimed at accommodating an arbitrary number of inlets. The corresponding framework relies on the consideration of inlet tracers, which allow to retrieve the fresh mixture composition, used in conjunction with a single mixture fraction variable that discriminates oxidizer inlets from fuel inlets contributions. This mixture fraction variable is also retained as a mapping variable to parameterize a chemical manifold generated from diluted one-dimensional non-premixed flamelets, with corresponding levels of dilution set from the knowledge of inlet tracers values. The resulting turbulent combustion model is presented in detail and subsequently applied to the Reynolds-averaged Navier–Stokes (RANS) and large-eddy simulation of an experimental benchmark featuring three distinct inlets. The detailed comparisons between computational results and experimental data together with ternary plots in the inlet tracers space confirm the relevance of the proposed modelling framework.

Novelty and significance statements

A modelling framework is introduced to describe turbulent non-premixed flames in situations featuring an arbitrary number of feeding inlet streams. It makes use of inlet tracers together with a single mixture fraction variable — used as a marker — to discriminate oxidizer inlets from fuel inlets contributions. By embedding an inlet tracer description within the tabulated flamelet framework, this original strategy can accommodate an arbitrary number of inlets and, as such, provides a significant generalization — as well as a strong mathematical background — to previous research efforts devoted to three-inlet flamelet models.