E-fuels obtained from renewable energy stocks are foreseen to play an important 
role in helping decarbonize the electricity producing and industrial sectors. 
Among them, ammonia is of high interest as an efficient energy carrier in 
relation with its capacity as a liquid fuel for a safe and efficient energy 
storage. It can subsequently be burned in flexible gas turbine powerplants as a 
single fuel or mixed with hydrogen. In this context, micro gas turbines (MGT) 
burning ammonia-hydrogen mixtures are a key technology for decentralized energy 
systems, since they are operationally flexible, and can represent an interesting 
solution for applications requiring heat at elevated temperatures.

In this context, IFPEN is an active partner of the ADONIS project aiming at 
producing a technically-sound and accurate assessment of the impact of ammonia 
and ammonia-hydrogen mixtures on MGT cycle performance for distributed power 
generation. The collaborative research aims at addressing open questions in 
terms of fuel injection, combustion dynamics and flame-wall interactions when 
burning those highly specific fuels, and to deepen the understanding of their 
impact on the stability, efficiency, pollutant emissions and overall cycle 
performance of such devices. This is achieved by combining advanced experimental 
and modelling & simulation approaches performed by two Japanese partners (AIST 
and Univ. of Tokyo) and five European partners (IFPEN, Silesian Univ. of 
Technology, SINTEF, Univ. of Orléans and Zürich Univ. of Applied Science), all 
integrated into the ADONIS consortium funded in the frame of the CONCERT Japan 
program.

Whilst ammonia is usually stored as a liquid, most existing MGT combustors use 
gaseous ammonia, requiring vaporizers, accumulators and additional heat 
consumption leading to extra costs and long start up times. Consequently, 
considering MGT directly fueled with liquid ammonia could allow cost reduction 
and efficiency improvements. The development of such combustors needs however 
addressing different challenges. Published studies on gaseous ammonia MGT report 
a strong influence of mixing in the primary zone of the combustor on flame 
stabilization and emissions (NOx and unburned NH3). Those difficulties could 
probably become even more important when burning liquid ammonia. Indeed, its 
large latent heat of vaporization, as well as the low flame speed of NH3-air 
mixtures may complexify flame stabilization and promote high unburned fuel 
emissions. Moreover, the vaporization process needs to be further studied and 
understood. Thermodynamic conditions encountered in the burner may e.g. lead to 
flash boiling of the liquid ammonia at the injector exit. Recent experimental 
studies indicate a very specific behavior of the ammonia
spray as a function of the thermodynamic conditions. The high saturation 
pressure combined with the high latent heat of vaporization induce that a liquid 
spray can still be observed despite operating under flash boiling conditions, 
showing that the vaporization process is not instantaneous.

The objective of the 12 months post-doctoral position opening at IFPEN is to set 
up and perform 3D CFD simulations aimed at contributing to a better 
understanding of observations reported for different detailed experimental 
databases on liquid ammonia injection and combustion acquired by the ADONIS 
partners. The CFD work will be based on the CONVERGE software that includes the 
required injection and turbulent combustion models, both in terms of RANS and 
LES approaches, and which will have to be validated and where necessary adapted 
to ammonia combustion in the course of the post-doc.
The envisaged research work will comprise three main phases:
• The objective of a first phase will be to set up and validate 3D CFD 
simulations of combustion in the chamber of a MGT fueled with gaseous ammonia, 
studied experimentally and numerically by other ADONIS partners. By avoiding the 
difficulties related to liquid injection, the aim will be to concentrate on 
exploring and modelling aspects related to the turbulent combustion of both pure 
ammonia and ammonia/hydrogen mixtures. A LES approach using the Thickened Flame 
Model coupled with an AMR technique developed at IFPEN within CONVERGE will be 
used to allow a detailed and accurate exploration of the underlying phenomena 
and of their interactions, and to ease comparisons with experimental findings.
• In parallel, a second phase will be dedicated to set up and validate a 3D CFD 
model for the liquid injection of ammonia under conditions representative of MGT 
applications. This will be based on simulations of an experimental database 
acquired by Univ. of Orléans on liquid ammonia injection into a non-reactive 
constant volume chamber allowing a detailed characterization of key spray 
parameters as a function of different injection parameters and operating 
conditions. By comparing the CFD predictions against experimental findings, the 
objective will be to yield a better understanding of the underlying physics, and 
to calibrate the standard spray model to be valid under such very specific 
conditions.
• After having acquired confidence in the spray and combustion modelling, the 
last phase will aim at simulating a MGT configuration using liquid ammonia 
injection for which experimental results are available to the ADONIS partners. A 
coupled simulation of injection and combustion will allow assessing the impact 
of liquid break-up and vaporization on the mixing and combustion processes for 
different MGT operating conditions. After having validated the predictions of 
the developed CFD approach against experimental findings, an extensive and 
detailed post-processing of the CFD results will aim at contributing to a better 
mastering of such combustion devices, and to extract first design rules for 
their future optimization and industrialization. This work will be performed in, 
close collaboration with the ADONIS project partners.

The successful candidate will be integrated in the applied 3D CFD Team of 
IFPEN’s Mobility & Systems Research Division and will work in close 
collaboration with IFPEN’s CFD model development Department. Moreover, he will 
exchange and collaborate with the different partners of the ADONIS consortium in 
charge of experiments and complementary simulation work.
Requested profile and skills:
• PhD in combustion science / multiphase flow modeling
• Experience in 3D CFD modelling and simulations
• Experience with a coding language, ideally Python or C++
• Very good proficiency in written and spoken English; Notions of French not 
mandatory, yet appreciated