Session: 04-21 Combustion Emissions I

Submission Number: 176374

Fuel Jet Dynamics and Mixing in a Constant Section Recursive Sequential Combustor 

Recursive Sequential Combustion (RSC) has emerged as a promising pure-lean, low-emission concept for aeroengine applications, combining exhaust gas recirculation and sequential, diluted combustion principles to achieve significant reductions in NOx and soot while maintaining flame stability in lean operation. Its practical implementation requires novel combustor architectures such as the Constant Section Recursive Sequential Combustor (CSRSC), which generates a toroidal swirl pattern that strongly influences fuel-air interactions. A central challenge in CSRSC is fuel placement and mixing: injected jets must penetrate the swirl structure to ensure effective mixing with air and trapped recirculated exhaust gases at the right place, while remaining locally non-combustible near the injector to prevent flame anchoring. These challenges are amplified for hydrogen, a possible fuel of the future, whose low density results in low-momentum injection highly susceptible to swirl-induce deflection.

In this study, the focus is put on fuel placement and mixedness. Helium is employed as a surrogate for hydrogen to investigate cold-flow jet dynamics in a CSRSC model designed for gaseous fuels (methane, hydrogen). Jet flapping frequencies are quantified using laser vibrometer measurements, while jet penetration and mixing performance are assessed through background-oriented Schlieren imaging. Complementary non-reactive, unsteady RANS simulations are performed and validated against the experiments, providing further insights into jet-swirl interaction and mixing. Finally, early reactive tests establish the connection between injector design, jet dynamics, and combustion stability. The findings advance the understanding of fuel injection and mixing under CSRSC conditions and support development of injector strategies for hydrogen-fuelled RSC systems in future low-emission aeroengines.

 

Presenting Author: Nina Paulitsch Graz University of Technology - Institute of thermal Turbomachinery and Machine Dynamics

Presenting Author Biography: - born 1995
- graduate of the University of Leoben in the field of energy technologies
- 8 years of professional experience as a research assistant at Combustion Bay One e.U.
- responsible for burner design, CFD simulations, experimental setups, measurement techniques

Authors:

Nina Paulitsch Graz University of Technology - Institute of thermal Turbomachinery and Machine Dynamics
Sami Tasmany Graz University of Technology - Institute of thermal Turbomachinery and Machine Dynamics
Jakob Woisetschläger Graz University of Technology - Institute of thermal Turbomachinery and Machine Dynamics
Robert Krewinkel Graz University of Technology - Institute of thermal Turbomachinery and Machine Dynamics
Andrea Hofer Combustion Bay One e.U.
Fabrice Giuliani Combustion Bay One e.U.