Experimental Validation of a Recursive Sequential Combustor and Study of the Model: ISABE-2024-157

The topics of fuel efficiency and emissions grow ever more important, especially in aviation. Novel combustor concepts can reduce NOx emissions by avoiding high flame temperature zones, also increasing combustor lifetime and maintenance intervals. One promising concept is the MOeBIUS technology as presented in [1] and [2]. It is intended to be highly heat conservative due to Recursive Sequential Combustion (RSC), which forces the burnt gases to interact with fresh reactants. In lean burn mode, this reburning effect significantly reduces NOx and soot emissions. The method used in this paper is called discrete sector RSC, where all steps (reactant injection, combustion, flue gas/new reactant mixing, exhaust) take place in a discrete area of one burner. These burners are arranged sequentially (one behind the other) along a torus enforcing a portion of flue gas to interact with the fresh reactants in the next burner, while the main portion of flue gas leaves the burner. This combination of recursive and sequential combustion allows for very robust, lean combustion in a more compact combustor with less pollutant emissions compared to conventional gas turbine (GT) combustors. This paper aims to validate RSC with conventional fuels. First, the geometry is optimised based on non-reactive and reactive CFD results. Then, a batch of discrete RSC burner has been additively manufactured using laser-powder bed fusion (L-PBF). Each burner has a maximum thermal power of 6 kW. Simulations and tests are carried out at 25/50/100% of maximum power operating point, in open-loop and in recursive configuration. This paper reports about the early established models, the main flow features, the basic experiments put into place to characterise a burner, and by extension the proposal for a full recursive sequential combustor geometry. Due to the speed of injection and rapid mixing strategies, this technology is promising regarding the combustion of hydrogen.