Numerical Modeling of Swirl Stabilized Lean-Premixed H2-CH4 Flames With the Artificially Thickened Flame Model

The lean premixed technology is a very convenient combustion strategy to progressively move from natural gas to high hydrogen content fuels in gas turbines limiting the pollutants emissions at the same time. The enabling process that will allow the combustor to manage a full H-2 operation requires relevant design modifications, and in this framework, the numerical modeling will be a pivotal tool that will support this transition. In this work, high-fidelity simulations of perfectly premixed swirl stabilized flames have been performed varying the H-2 content in the fuel from 0 to 100% to investigate the effect of the hydrogen addition on the methane flame. The artificially thickened flame model (ATFM) has been used to treat the turbulent chemistry interaction. The numerical results have been compared with the detailed experimental data performed at Cardiff University's Gas Turbine Research Center. After the numerical model validation against experimental OH* chemiluminescence maps has been presented, a deep numerical investigation of the effect of the H-2 addition on the flame has been performed. In this way, the work aims to highlight the good prediction capability of the ATFM, and, at the same time, highlight the change in the different contributions that govern the flame reactivity moving from 100% CH4 to 100% H-2 in very lean conditions.