Conversion of Gas Turbine Combustors to Operate with a Hydrogen-Air Mixture: Modifications and Pollutant Emission Analysis

Abstract

In this work, an overview of the use of hydrogen in aviation, the modifications needed to adapt an existent gas turbine to use hydrogen, and a CFD simulation of an existent gas turbine burning hydrogen are performed. The CFD simulation was done in a CFM56-3 combustor burning hydrogen and Jet A. It was intended to evaluate the viability of conversion of existent gas turbines to hydrogen, in a combustion point of view, by analyzing the emissions while burning it through ICAO’s LTO cycle. The pollutant emissions (only NOx, since hydrogen combustion produce only water vapor and NOx) were evaluated through a detailed mechanism and the Ansys Fluent NOx model to get a better agreement with the ICAO’s values. For this assessment, several sensibility studies were made for hydrogen burn, for example, the analysis of the air flow with/without swirl in the primary zone and different inlet temperature and pressure for fuel. In the end, it was concluded that theoretically the CFM56-3 combustor can be converted to operate with hydrogen fuel with minor changes (related to injection system). The quantity of NOx produced for each power setting when burning hydrogen is expected to be almost twice the values for Jet A.