Detailed investigation of soot formation from jet fuel in a diffusion flame with comprehensive and hybrid chemical mechanisms

Soot Emission Simulations of a Single Sector Model Combustor Using Incompletely Stirred Reactor Network Modeling

“…A similar approach was followed in Ref. [9], where the HyChem model was combined with the KAUST PAH mechanism 2 [34] to study soot evolution in a jet fuel laminar co-flow flame. Overall, the combined HyChem and PAH chemistry consists of 886 reactions and 136 species, whereas the original HyChem approach has 843 reactions and 119 species.…”

“…To ensure that soot related quantities remain realistic, reaction rate constants affecting soot surface growth via hydrogen-abstractioncarbon-addition (HACA) routes, have been adjusted and reduced by a factor of 20. This modification is similar to what is commonly done in laminar sooting flames, where the HACA growth parameter, often referred to as "parameter alpha", is adjusted to match the maximum soot volume fraction obtained by simulations with values originated from experiments (e.g., [9,12] The NAPS soot model relies on a gas-phase mechanism containing PAH species up to pyrene [10,11]. For this purpose, the HyChem approach was here extended with an additional subset of PAH growth reactions, as discussed in Section 3.…”

“…Nevertheless, recently developed comprehensive soot models [7][8][9][10][11] cannot easily be used in conjunction with high-fidelity CFD simulations to perform parametric studies during the design phase of combustors,…”

“…given their high dimensionality and computational cost. This becomes even more evident in jet fuel combustion, where detailed chemical schemes with additional Polycyclic Aromatic Hydrocarbons (PAH) routes (e.g., [9,12]) also demand high computational requirements since a wide range of intermediate products and soot precursors should be considered. As a result, there is motivation to develop computationally inexpensive methods that simplify calculations with very complex chemistry and soot models, but also ensure the prediction of soot emissions within a reasonable degree of accuracy in both magnitude and trend.…”

“…The chemical composition and reactivity of soot particles generally vary between fuels; therefore soot models developed for simple fuels, such as the NAPS model here for ethylene, are generally not expected to perform similarly for real fuels. Typically, an empirical soot surface growth parameter is used (see e.g.,[9,12]) to tune surface reactions, therefore a similar modification has been applied here by reducing the equivalent reactivity of particles subject to surface growth. It Single Sector Model Combustor Using Incompletely Stirred Reactor Network Modeling number density (N s,tot ) and the number density of larger soot particles (N s,d>7nm ) for the HyChem-NAPS model in…”