ERI: Computational Investigation of High-Pressure Turbulent Premixed Flames - Physical Insights and Two-Scale Predictive Modeling

Premixed combustion is observed in aeronautical and automotive engines, which are typically operated at high pressure and under turbulent flow conditions to yield higher fuel efficiency, compact design, and lower emissions. The interplay of various combustion processes such as species transport, chemical reactions, and heat release makes the computational investigation of flame-turbulence interactions in these applications a challenging task, particularly when a detailed chemical description is essential. Past fundamental studies have primarily focused on the analysis of such flames at atmospheric pressure. In this work, aspects of high-pressure turbulent premixed flames will be addressed by providing fundamental insights into the effects of pressure and establishing an efficient physics-based computational model. This investigation will also integrate research and education by enriching courses in fluid mechanics and thermal sciences; empower undergraduate and graduate students from diverse backgrounds with advanced knowledge and computational skills; and mentor university-supported undergraduate scholars to develop goals and skills. High-pressure turbulent premixed flames observed in energy conversion and propulsion devices are multi-scale in nature, which makes their fundamental investigation extremely challenging. While direct numerical simulation can provide detailed insights into flame-turbulence interactions, it tends to be computationally prohibitive for the study of practical applications. To this end, large-eddy simulation is a promising modeling strategy; however, some challenges need to be addressed for it to be predictive. Additionally, most of the past fundamental studies have focused on examining the characteristics of such flames at atmospheric pressure, thus requiring further studies, particularly, focusing on the analysis of the multi-scale interactions within the flame region. This proposal will address these challenges by (i) providing fundamental insights into the effects of pressure on premixed flame-turbulence interactions in canonical configurations, (ii) assessing the capabilities of a novel two-scale physics-based predictive modeling strategy, and (iii) examining the behavior of different types of fuels under high-pressure conditions. The outcomes of the project will have a broader impact on the field of turbulent combustion as it will lead to an improved understanding of features of high-pressure turbulent premixed flames, and demonstrate the capabilities of a multi-scale model, which can be used to study practical configurations. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.