For centuries, combustion has played an important role in human development, yet as Giusti and Mastorakos notes [29], ”with some 100,000 years of development, combustion might be expected to be a mature technology. In fact, it is the least developed technology of modern engineering systems”. As the world transitions away from carbon-based fuels, hydrogen has emerged as a promising alternative due to its carbon free combustion. However, replacing conventional fuels with hydrogen introduces significant technical challenges. Pure hydrogen–air flames exhibit high laminar flame speeds and low ignition energies, making combustor hardware more susceptible to flame flashback. Flashback not only disrupts stable operation but can also result in damage and system failures. A thorough understanding of flame stabilization and flashback mechanisms is therefore essential.

In this context, the present work investigates a combustor geometry designed to generate a trapped vortex, a recirculation zone that enhances flame stabilization. Accurate numerical predictions of such phenomena require realistic thermal boundary conditions, yet these are often unavailable in experimental configurations and are commonly oversimplified in simulations. This study evaluates how different thermal wall boundary conditions modify flame stability and flow behavior in a premixed pure hydrogen–air trapped vortex combustor at lean conditions. A 2D and 3D simplified version of the FlameSheet™ burner, originally developed by Power Systems Manufacturing (PSM), is modeled in this study, using
PeleLMeX [24].

The study begins with a 2D cold flow simulation performed using DNS. This computation is analyzed in light of a previously performed 3D study of the same geometry, with the same numerical solver and following the same numerical approach [25]. Differences are acknowledged and explained. After examining the baseline flow behavior, six reactive cases are then simulated, varying the main flow Reynolds number (12,000 and 8,000) and the thermal boundary conditions applied to the liner walls (adiabatic, isothermal at 300 K, and a fitted temperature profile based on experimental data). Results show that wall thermal conditions significantly affect flame stability and structure. Time averaged fields reveal that
thermal boundary conditions also influence recirculation zone size and peak flame temperatures. The 2D simulations, while limited in capturing full 3D turbulence, offer valuable insights into flame wall interactions and highlight the importance of accurate thermal boundary conditions in predicting flashback propensity and flame stabilization in hydrogen combustors.