Identification of Flame Regimes in Partially Premixed Combustion from a Quasi-DNS Dataset

Abstract

Identifying combustion regimes in terms of premixed and non-premixed characteristics is an important task for understanding combustion phenomena and the structure of flames. A quasi-DNS database of the compositionally inhomogeneous partially premixed Sydney/Sandia flame in configuration FJ-5GP-Lr75-57 is used to directly compare different types of flame regime markers from literature. In the simulation of the flame, detailed chemistry and diffusion models are utilized and no turbulence and combustion models are used as the flame front and flow are fully resolved near the nozzle. This allows evaluating the regime markers as a post-processing step without modeling assumptions and directly comparing regime markers based on gradient alignment, drift term analysis and gradient free regime identification. The goal is not to find the correct regime marker, which might be impossible due to the different set of assumptions of every marker and the generally vague definition of the partially premixed regime itself, but to compare their behavior when applied to a resolved turbulent flame with partially premixed characteristics.

Heat Release Rate Markers for Highly Stretched Premixed CH4/Air and CH4/H2/Air Flames

“…Cantera is incorporated for the calculation of reaction rates and transport coefficients. This code was used in recent studies on premixed flames. − More details on numerical schemes and code validation can be found in refs and .…”

Combustion Regime Identification in Turbulent Non-Premixed Flames with Principal Component Analysis, Clustering and Back-Propagation Neural Network

“…Therefore, a global characterization parameter could not reflect all location conditions. Accurate and detailed combustion regime identification (CRI) in non-premixed flames is helpful to understand combustion phenomena, the structure of the flame and the flame characterizations, such as ignition delay time, flame lift-off height, flame thickness, flashback, etc., and further help to study the energy transfer, the transport and change of species, the interactions between flow and reaction, and combustion modeling [2][3][4][5]. In the present work, we propose a method to characterize the local regimes within turbulent non-premixed flame, and validate it in two well-known flames.…”

Implementation and Validation of a Computationally Efficient DNS Solver for Reacting Flows in OpenFOAM

“…The details are given below and further information can be found in [4,5,6,7,8,9]. The solver has thus far been validated and used in a number of works [10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27].…”

“…Spatial gradients are discretized with OpenFOAM's fourth order interpolation scheme cubic and for the temporal discretization, a second order implicit Euler method is used. For more details about the setup, see [5,14,10].…”