59074 - Center Body Burner for Sequential Combustion: Superior Performance at Lower Emissions 

Modern gas turbines call for ultra-high firing temperature and fuel flexibility while keeping emissions at very low levels. Sequential combustion has demonstrated its advantages toward such ambitious targets.

In a sequential combustion environment, as deployed in the GT26 and GT36 engines, the key element of the system is the sequential combustor. This is the key component, to enable the required performance at the boundary conditions dictated by F and H class engines, including versatile and robust operation with hydrogen-based fuels.

This paper describes the key combustion and fluid dynamic considerations establishing the latest highest performance sequential burner. A novel multi-point injector geometry was deployed to maximize fuel / air mixing quality at minimum pressure loss. Water channel experiments complemented by CFD describe the evolution of the fuel / air mixture fraction through the mixing section and combustion chamber to enable operation with major NOx reduction and a dramatic smoothening of the local temperature distribution at turbine inlet. Furthermore, Particle Image Velocimetry and Laser Induced Fluorescence were used to best characterize the injector flow-field, the interaction between hot-air and fuel and the fuel air mixing quality in the most critical regions. The outcome of 1D, CFD and fluid dynamic experimental findings were then validated through full-scale full-pressure single-burner combustion tests, also described in detail. They demonstrate the possibility to operate this burner at very low emissions, both at partload and full load conditions as well as enabling combustion with hydrogen-based fuels.