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Job Record #16653
TitlePhD in CFD modeling of trans-critical multicomponent flows
CategoryPhD Studentship
EmployerUniversity of Perugia, Department of Engineering
LocationItaly, Perugia
InternationalYes, international applications are welcome
Closure DateFriday, July 31, 2020
Computational Fluid Dynamics (CFD) modeling of trans- and super-critical
multicomponent flows

Trans- and supercritical conditions are often found in recent designs of 
direct injection engines, rocket engines and gas turbines for jet propulsion 
at take-off.
More efficient and cleaner combustion technologies can be achieved increasing 
the operating pressure of the combustion chamber, leading to trans-critical 
trajectories of the injected liquid fuel. Detailed understanding of real-
fluid flows under these operating conditions is crucial. With the increase of 
liquid bio- and synthetic fuels for aviation and transportation, further 
challenges are encountered in the engineering design of reliable and low-
emission combustors. Recent computational studies have clearly shown the link 
between the injector flow and the mixing and auto-ignition occurring under 
these conditions, but numerical challenges  and real-device complexities 
still pose challenges to full model predictivity.

Despite its engineering importance, multi-component real-fluid spray in hot 
turbulent flows has not been explored thoroughly, yet and the scientific 
community lacks detailed understanding of the non-linear physics. The reason 
lies in the complex transitioning thermodynamics and in the multi-scale and 
multi-physic nature of the problem.

At the realistic physical scale of combustion chambers, accurate description 
of the early phase of the dense spray break-up and atomization for multi-
component fuels is especially important, but first-principle prediction of 
such complex phenomena is a challenging task. Two main classes of Eulerian 
methods exist.
On one hand, sharp interface methods, like level-set (LS) and volume-of-fluid 
(VOF) methods, can be used in the subcritical regime for directly resolving 
the interface mechanics [12-14], but these methods are computationally 
demanding as the interface features may be extremely small. On the other 
hand, diffuse-interface models, based on two-fluid or single-fluid 
formulations [1-7,15,16], are less computational demanding and can be applied 
to large scale spray or combustion chamber design, but research is needed for 
accurate closure models of sub-grid effects. 

Our recent work has already investigated the possibility of introducing real-
fluid properties in to single-fluid Eulerian models. 

In this PhD project, in order to enhance the prediction capabilities in high-
pressure high-temperature multi-component two-phase regions, we plan to 
explore and compare multiple paths, by developing new solvers in OpenFOAM 
-	Single-fluid model description, 
-	Two-fluid model, where two phases are directly transported,
with the addition of a transport equation for the interfacial area density, 
which will allow to calculate the local level of atomization, like 
droplet/ligament size, and which will vanish at supercritical condition.  
Each approach will combine real-fluid thermodynamics properties. These models 
can be naturally and seamlessly coupled to already exiting combustion models, 
then enabling the unified simulation of two-phase and reactive flow cases.
These approaches represent the first attempt in the literature to couple the 
surface area density with the flow variables, in the context of real-fluid 
thermophysical models.
Ultimately, these solvers will be applied to the study of novel fuel 
injection conditions, novel high-efficiency engines, and renewable e-fuel 
injection and combustion.

Short description and objectives of the research activity:	

The research aims to develop a new two-phase flow solvers for fuel sprays 
with specific focus on high pressure and high temperature conditions, and 
multicomponent thermodynamics. The code will be developed in OpenFOAM and 
will be able to describe in Eulerian form the processes of primary 
atomization and mixing in subcritical and supercritical conditions.

Desired skills:

The project is within the area of CFD Modeling of Fuel Sprays and Combustion. 
The candidate is expected to have good knowledge of 
-	CFD modeling and numerics, 
-	C/C++ programming, 
-	python/matlab scripting is a plus.
The successful candidate will perform large-eddy simulations (LES) of two-
phase flows using high-performance computing (HPC) resources; he will also 
incorporate state-of-the-art experimental measurements to improve the 
accuracy of the models. Eventually, the candidate will write peer-reviewed 
journal articles, and present the results of the work at international 
conferences and events.

Contact Information:
Please mention the CFD Jobs Database, record #16653 when responding to this ad.
NameMichele Battistoni
Email ApplicationYes
Record Data:
Last Modified10:30:37, Thursday, July 02, 2020

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