Grant: Discovery Grants Program - Individual

Despite over 100 years of research on flame acceleration (FA), unintended explosions pose a significant risk and cause billions of dollars of damage to industries around the world every few years. While a slow moving flame (deflagration) can develop into a detonation during an incident, its prediction remains challenging. Current predictions of the distance to flame choking in tubes or pipelines are only leading-order accurate, and prediction of the distance for deflagration to detonation transition (DDT) to occur has yet to be realized. The long-term goal of this program is to gain a fundamental understanding of the relationship between turbulence-chemistry interactions and compressibility in the context of FA and DDT, and to use this knowledge to advance amenable numerical simulations of explosions beyond the micro-scale to reach industrially-relevant scales. In the short-term, the research aims to develop the capability to accurately predict onsets of flame choking and DDT in ducts at laboratory-scales using a numerical strategy that has appropriate closure of turbulent scales. We will develop novel and efficient large eddy simulation (LES) strategies designed to resolve FA and DDT beyond the laboratory-scales (Objective 1); validate these models and determine the specific conditions for detonation to occur in pre-established and choked shock-flame complexes (Objective 2); and investigate laboratory-scale FA and DDT in a long smooth duct (Objective 3). The challenge is to model flows where turbulence and reaction time scales are constantly evolving through different combustion regimes and where chemical reactions are sensitive to compressed gases. My team will develop LES strategies, derived from the compressible linear eddy model, that do not require a priori knowledge of combustion regimes. These will be coupled to recently developed 4-step reaction mechanisms, which only require memory and overhead for a few supplemental transport equations. Such low-memory strategies will permit hi-fidelity solutions of scales beyond what is currently feasible by one or two orders of magnitude, reaching beyond laboratory scales. We will use these models to determine the qualitative and quantitative physics governing the transition to detonation process, and discover the exact conditions required for DDT to occur in a duct. This will pioneer a transformative prediction strategy for larger-scale compressible, turbulent, and reactive flows, and will lead to a unified understanding of the roles of turbulence and compressibility on flame choking and DDT. This will allow for better explosion prediction and mitigation at industrial scales, which will influence design and mitigation strategies to reduce losses associated with unintended explosions, e.g. in the oil & gas industries and also for emerging hydrogen infrastructure. The program will train students at uOttawa on using the latest numerical simulation approaches through high performance computing.