LES of Hydrogen-Fuelled Combustion in the First Stage of the Ansaldo Energia GT36 Constant Pressure Sequential Combustion System

Abstract Sequential combustion systems have demonstrated outstanding fuel flexibility, thus constituting an effective solution for burning hydrogen-based fuels at low emissions. The EU- and Swiss-funded FLEX4H2 project is leveraging sequential combustion advantages to enable operation with either pure methane, pure hydrogen or methane-hydrogen blends. The development focuses on the Ansaldo GT36 engine utilising a Constant Pressure Sequential Combustion (CPSC) system. In such a system the first stage generates the required inlet temperature to stabilise the second stage flame by self-ignition, providing an additional degree of freedom to accommodate changes in fuel reactivity while limiting emissions. The static and dynamic stability of the system is a key element of the development aiming at stable combustion across various operating conditions and ranges of fuels. Typically, varying the fuel composition from 0% to 100% of hydrogen has an important impact on the first stage flame stability and acoustic response. To investigate such possibilities a priori, numerical simulations—specifically Large Eddy Simulations—of the multi-burner first stage are performed for different blend ratios. These simulations provide valuable insights into the flame’s statistically stationary behaviour, anchoring and morphology. In the following, recent advancements in the Thickened Flame (TF) model for hydrogen flames and multi-fuels injection are specifically applied to this industrial configuration, demonstrating its effectiveness in capturing hydrogen’s impact on the system.