Implications of Switching Jet Fuel From Kerosene to Hydrogen on Turbine Performance and Design

Kurzfassung

This paper examines the impact of replacing kerosene with hydrogen as fuel in a geared turbofan engine with a cooled two-stage high-pressure turbine and a four-stage low-pressure turbine, focusing on turbine characteristics and design for several operation points. Hydrogen combustion increases the specific heat capacity of the hot gas and reduces the turbine mass flow due to lower required fuel mass flow. When the fuel type is switched in a given turbine design, the hydrogen combusted hot gas increases the overall power output but decreases efficiency in the high-pressure turbine. When the turbine design is modified to maintain the same power requirements, either the turbine inlet temperature or the turbine's enthalpy influx, i. e. the energy content of the turbine inflow, can be preserved. The first case results in a shorter turbine section giving the potential to reduce the engine weight but also deteriorates the turbines' performances and increases the coolant amount. For the latter case the turbine inlet temperature can be reduced up to 44~K yielding relaxed coolant requirements of the high-pressure turbine which in turn fosters the turbine and engine performance. Consequently, the hot gas from hydrogen combustion can yield more efficient turbine designs than from kerosene combustion.