Session: 04-20 Atomization and Spray Combustion I

Paper Number: 152443

Development and Assessment of Dual-Fuel Capabilities in Next-Generation Aero-Engine Injectors for Hydrogen and Liquid Fuels 

The aviation industry is under increasing pressure to reduce carbon emissions in response to the European
Green Deal’s goal of achieving carbon neutrality by 2050. Introducing hydrogen as a novel fuel for aero en-
gines is gaining significant attention and has emerged as a major focus of research aimed at achieving carbon-
neutral aviation. However, in addition to the technical challenges of ensuring safe hydrogen combustion in
aero-engines, the need for large-scale hydrogen infrastructure at airports worldwide presents a significant ob-
stacle to its adoption. Therefore, liquid fuels will still play a role in the transition period. Retrofittable dual-fuel
systems, capable of operating on both hydrogen and Sustainable Aviation Fuel (SAF)or kerosene, are necessary
to ensure a smooth transition. A key aspect of this effort is the development of a fuel injector that can operate
with both fuels while ensuring optimal performance in terms of emissions and combustion stability, regardless
of the fuel used.
This study focuses on modifying the current kerosene injector of a Rich-Quench-Lean (RQL) combustor in
the Rolls-Royce Pearl family to enable dual-fuel operation. Key constraints of this retrofit task arise from the
distinct combustion characteristics of the two fuels, the available space for dual-fuel injector integration, and
the need to maintain comparable effective areas between the current injector and the new dual-fuel injector. In
this study, an injector geometry featuring coaxial integration of kerosene and hydrogen channels is considered.
The shapes of the inner air channel, inner swirler, and inner kerosene passage are kept nearly identical to those
of the standard injector. An additional air channel is integrated to ensure that hydrogen is injected between
two sheets of air, preventing the hydrogen flame from stabilizing on the injector.
To explore the impact of injector geometry on the mixture field and emissions, an automated workflow was
developed. This workflow enables rapid geometry modifications and subsequent performance evaluations in
terms of emitted nitrogen oxide (NOx) and soot using computational fluid dynamics (CFD) simulations. The
process involves reactive CFD simulations of a parametrized 3D injector model inside a single-sector aero-
engine combustion chamber, operated under realistic operating conditions of the Pearl engine. A large-scale
parametric variation was conducted to identify the favourable geometric configuration. The optimal parameters
were identified by developing a surrogate model based on the obtained CFD data, linking geometric features
to expected emission levels.
To systematically study a wide range of geometry variations, Reynolds-Averaged Navier-Stokes (RANS)
approach was employed for CFD simulations. Large Eddy Simulations (LES) were conducted for selected ge-
ometries to confirm the observed emission trends. The Flamelet Generated Manifold (FGM) method was used
to introduce detailed chemistry into the simulations while maintaining low computational costs. The com-
putational methodology was initially validated against available measurements for a range of concept injector
geometries and operating conditions and demonstrated the capability to accurately predict emission trends.
This numerical study confirms that dual-fuel injectors can be used in future aero engines. Through the
described CFD-based workflow, optimal geometrical features for the proposed injector configuration have been
identified. In the future, this injector will undergo further evaluation through experimental testing to confirm
the predicted performance and set the next milestone towards dual duel capable combustion systems.

 

 

Presenting Author: Sofya Buro Technical University of Darmstadt

Presenting Author Biography: Sofya Buro obtained her M.S. at the Technical University of Darmstadt in Engineering Science. Since 2022 she is a research associate at the Institute for Simulation of reactive Thermo-Fluid Systems at the Technical University of Darmstadt. She works in the field of hydrogen combustion modelling in gas turbine engines using numerical methods.

Authors:

Sofya Buro Technical University of Darmstadt
Ruud Eggels Rolls-Royce Deutschland Ltd & Co KG
Hendrik Nicolai Technical University of Darmstadt
Christian Hasse Technical University of Darmstadt