CAREER: Turbulent Boundary Layer Flashback of Lean Hydrogen Flames

About This Grant

Industrial turbines that burn natural gas currently generate about 40 percent of all electricity and nearly 15 percent of all CO2 in the US. A transition from natural gas to clean hydrogen could significantly reduce CO2 production. While gas turbine manufacturers anticipate 100 percent hydrogen utilization in the future, current industrial turbines operate closer to 50 percent hydrogen by volume. One of the main obstacles slowing the transition to hydrogen is flame flashback, a phenomenon wherein the flame proceeds upstream of the combustor with catastrophic consequences. When flashback happens near the wall of a combustor, it is called boundary layer flashback. The addition of hydrogen as a fuel significantly increases the likelihood of such boundary layer flashback phenomena. The goals of this project are to better understand the physical and chemical mechanisms responsible for flashback and to develop general, accurate and affordable models capable of predicting its occurrence. The project also aims to provide rural communities affected by hydrogen projects with a source of information on the impact of the fuel on their lives and to encourage students to participate in STEM starting from high school and continuing through their undergraduate careers. The goal of this project is to enable a new modeling paradigm for boundary layer flashback of turbulent lean hydrogen flames that allows for general, accurate, and affordable prediction of its occurrence. The primary hypothesis guiding this work is that there is a fundamental relationship between the onset of boundary layer flashback in turbulent premixed lean hydrogen flames and strained premixed flames at the extinction limit, and that this relationship can be leveraged to develop and extend a new class of boundary layer flashback models. As part of this project, direct numerical simulations of boundary layer flashback will be performed to understand the fundamental physical relationship between flashback and extinction limit flames. Insights from these simulations will be used to build engineering models capable of predicting the onset of flashback in a wide range of practical combustors. Finally, wall models will be developed to capture boundary layer flashback in computational fluid dynamics simulations even without fully resolving the flow at the wall. The models developed as part of this project will ultimately aid in the design of next generation low-to-no carbon combustors capable of enabling carbon-free power. 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.