Effects of Inlet Temperature on Hydrogen-Enriched Jet A-1 Fuel and Air Combustion
D. Miranda Magalhães Serra (TU Delft - Aerospace Engineering)
I. Langella – Mentor (TU Delft - Flight Performance and Propulsion)
P. Rouco Pousada – Mentor (TU Delft - Flight Performance and Propulsion)
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Abstract
A growing concern over the irreversible effects of global warming has led to the creation of international carbon neutrality goals by 2050. The mounting demand placed on the aviation sector creates growing pressure on new and innovative solutions to offset the growth in predicted aircraft emissions. Among many, hydrogen combustion offers a uniquely auspicious yet challenging approach to carbon neutrality in aviation. This project aims to study the effect of low temperature hydrogen and air injection on fuel mixing quality, the emission of secondary combustion pollutants, and the reaction zone interactions with the flow field. Large Eddy Simulations using detailed combustion models and a skeletal chemical kinetic mechanism are implemented to simulate the combustion of a hydrogen enriched jet A-1 spray flame. Using a scale model of the Auxiliary Propulsion and Power Unit (APPU) combustor, two similar simulations are set up, the first with an air/hydrogen inlet static temperature of 250\,K and the second with an air/hydrogen inlet static temperature of 400\,K. The final results are post processed and analysed. The results show a clear increase in mixing quality between hydrogen and jet A-1 when the temperature is decreased for this combustor geometry, strongly corroborating the initial hypothesis. Additional results show that the combined effect of lower injection velocity and lower temperature injection of air/hydrogen leads to an increase in the stretch rate applied to the reaction zones closest to the injector and a decrease in flame structure length. Analysis of species distributions reveals significant spatial variations across the combustor. Still, only a significant and conclusive reduction in CO emissions with a decrease in inlet temperature could be established. The limited computational resources associated with this research consequently limit the quantification of the observed phenomena, however, the analysed trends provide sufficient evidence to support the use of lower temperature hydrogen as a potential solution to the issues associated with the mixing of both fuels and towards lower emissions combustion.