Evaluation of Gaseous Emissions From Hydrogen Combustion Aircraft Engines

From an engineering point of view, hydrogen is an interesting aircraft fuel. Compared to hydrocarbon fuels, the number of emission species that may occur is reduced, if pure hydrogen is considered as fuel. All emissions containing carbon atoms might be neglected. Thus, the well known relationships for emission indices, combustion efficiency as well as the dry air–fuel–ratio, especially the presented analytic equations, are no longer applicable. Hence, a new set of equations for hydrogen air combustion is derived in this paper, which has not yet been done according to the author’s knowledge. This derivation is based on the basic definitions and assumptions from ARP1533B. Thus, the analysis strategy is very similar. As modern computational power is large enough to invert a small matrix in real time, the matrix method already described was chosen. This also has the advantage of incorporating interference effects easily. The emission analysis algorithm is validated by means of a generic test case. Furthermore, a statistically non–linear sensitivity analysis of the input parameters was carried out in order to quantify their measurement uncertainty as a propagated error on the output parameters. Additionally, some small mistakes and improvements, which attracted attention in ARP1533B, will also be mentioned within this paper