FFIT: Role of Fuel Flow Fluctuations In Thermoacoustic Combustion Instabilities

• Applicant: Professor Dr.-Ing. Christian Oliver Paschereit
• Subject Area: Fluid Mechanics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 568773014

Modern combustors capable of firing clean fuels, e.g. hydrogen, ammonia, gasified biomass and offering fuel-flexibility entail non-stiff fuel injection. Thus, the fuel inflow is coupled to combustion instabilities. Development of these combustors therefore requires an understanding of the influence of fuel flow fluctuations on fuel-air mixing, burner acoustics, and flame response. The proposal focuses on investigating thermoacoustic combustion instabilities, with a particular emphasis on the role of fuel flow fluctuations in driving these instabilities. Thermoacoustic instabilities occur due to complex interactions between heat release fluctuations and acoustic waves in combustion systems. These instabilities can severely impact the performance, emissions and safety of gas turbines, rocket engines, and industrial combustion systems. The research aims to understand the mechanisms by which fuel flow fluctuations contribute to thermoacoustic instabilities and to develop predictive models for instability onset based on fuel flow variations. The central idea of this project is to artificially oscillate the air flow and quantify the flow fluctuations induced in the fuel supply for varying acoustic impedance of the fuel injector. This will allow for understanding and modelling the influence of fuel flow fluctuations on the dynamic fuel-air mixing process and acoustic characteristics of the burner. The intended project aims to experimentally characterise, understand, and model the effects of fuel-flow perturbations on the dynamic fuel-air mixing, 3-port burner acoustics, and flame response facilitating a reliable assessment of thermoacoustic instabilities. A combination of experiments and analytical modelling will be employed. The study will integrate high-speed imaging, laser diagnostics, acoustic measurements and advanced data analysis techniques. The expected outcomes are improved understanding of the coupling between fuel flow dynamics and acoustic modes, predictive tools for designing more stable combustion systems and practical strategies for suppressing instabilities in industrial applications. The findings will benefit the aerospace and energy industries by enhancing the efficiency and reliability of combustion-based systems.

• DFG Programme: Research Grants