Numerical Investigation of Swirl-Enhanced Jet Burner for Fuel-Flexible Hydrogen-Methane Combustion

The combustion of hydrogen has become crucial for the next generation of gas turbines aimed at decarbonizing electrical energy production. In recent years, the adoption of lean-premixed combustion systems in gas turbines for power generation has led to consistent reductions in emissions. However, swirl burners remain susceptible to flashback and exhibit a noticeable rise in emission levels when operated with high hydrogen blends. While the long-term goal is the operation of gas turbines with pure hydrogen, this transition will occur gradually, with an intermediate phase dominated by mixtures of hydrogen and natural gas of increasing hydrogen content. It is therefore essential to develop burner concepts capable of maintaining stable and clean combustion across a broad range of fuel compositions. In this context, jet burners have attracted growing interest in both research and industry as a promising solution for combustors operating across a wide fuel flexibility, thanks to their suitability for stabilizing flames characterized by high flame speeds, such as pure hydrogen combustion. Although jet burners can stabilize hydrogen flames effectively, the significantly lower burning velocity of natural gas leads to long, detached flames when operated with pure natural gas. To address this limitation, we introduce a swirler upstream of the fuel injection, generating a slight swirl that redefines the recirculation zone of the jet-stabilized flame. The resulting configuration is then investigated by means of a set of reactive 3D-CFD simulations. The numerical model is first validated against experimentally acquired mean-flame OH* chemiluminescence images from the TU Berlin POShyDON jet burner. The redesigned configuration is numerically tested, demonstrating that the introduction of a moderate swirling motion can stabilize both methane and hydrogen flames, enabling a fully fuel-flexible jet burner design.