Distributed Turbulent Premixed Combustion: Regimes, Mechanisms, and Modeling
Abstract
Distributed turbulent premixed combustion occurs due to the suppression of radical concentrations and chemical reactivity by intense turbulent mixing between reactants and products and/or dilution and preheating of reactants. Because of the suppression of reactivity, combustion occurs over larger length scales but can be stabilized over a broader range of thermochemical conditions compared to laminar premixed flame propagation. However, the fundamental nature of distributed turbulent premixed combustion remains unclear. In this research program, a series of Direct Numerical Simulations (DNS) will be conducted in order to answer the fundamental question: what is distributed combustion? Two configurations will be considered: an enclosed chamber featuring intense mixing of reactants and recirculating products and a series of turbulent planar premixed jet flames with systematically increasing turbulence intensity. These databases will be analyzed from both a physical and a modeling perspective. From a physical perspective, the central hypothesis of the research program is that distributed combustion is preceded by reaction zone-reaction zone interactions resulting from fine-scale wrinkling of reaction zones by intense, small-scale turbulence. Furthermore, as reactants are diluted by products, whether or not a thin reaction zone can persist remains an open question. From a modeling perspective, distributed combustion in any regime leads to apparent modeling paradoxes, specifically for manifold-based combustion models, which balance local mixing with chemistry. The progress variable dissipation rate is conventionally thought to be a mixing rate between products and reactants, which is very large in distributed combustion, or as a measure of the inverse length scale of combustion, which is very small in distributed combustion. Likewise, chemistry can be thought to be fast relative to mixing, that is, a prevalence of autoignition, or slow relative to the intense mixing.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 21, 2022
- Source ID
- FA95502110060XX0
Entities
People
- Michael Mueller
Organizations
- Air Force Office of Scientific Research
- Trustees of Princeton University
- United States Air Force