The proposed research programme aims at identifying noise-generating mechanisms in subsonic turbulent jets, and at the development of closed-loop control laws for the reduction of jet noise through flow actuation. An interdisciplinary approach combines experiment, numerical simulation and theoretical modelling in a coordinated effort, between three partner institutions with complementary expertise. While optimal control laws can, in principle and at enormous computational cost, be devised on the empirical basis of numerical simulations, taking into account the entire turbulent spectrum, the present proposal focuses on the dominant noise component associated with large-scale coherent flow structures, that drive the low-angle sound field. Fundamental progress in the understanding of the dynamics of these coherent structures, as well as their sound generation, will provide guidance for novel strategies to actively control and reduce jet noise. The programme addresses the following questions: Which mechanisms govern the formation of orderly structures in jet turbulence? Can these structures be accurately described as instability wavepackets forming on top of a steady mean flow, as has often been conjectured? To what extent do nonlinear phenomena determine the wavepacket structure and the resulting acoustic field? And how can knowledge of these mechanisms be leveraged for jet noise reduction? Control strategies will be devised, and these will be tested in a real experiment during the final stage of the project. The proposal builds on ongoing research activities at the three partner institutions, which so far have been developed independently without formal collaboration. The synergy potential of these complementary activities is considerable, and the proposal precisely aims to provide a framework for a coordinated interaction with a common set of objectives. Operational tools and preliminary results exist for all the main stages of the proposed programme. These include ongoing experiments on jet dynamics and their acoustic signature at PPRIME; a validated LES code; numerical tools for jet instability analysis at LadHyX, that are currently used on model configurations and await application on real-life jet data; model-free control concepts, developed at LadHyX, ONERA and LIMSI, that have been successfully deployed to reduce sound emission from flow over cavities; and reduced-order modeling for flow control (ANR Chair of Excellence at Pprime). International collaborations on jet noise research, with Tim Colonius at the California Institute of Technology and with André Cavalieri at Instituto Tecnológico de Aeronáutica (Sao José dos Campos, Brazil), are already in place and will be further intensified during the course of the proposed programme. The proposal seeks funding for (i) one PhD student (3 years) and four postdoc years; (ii) experimental equipment for particle image velocimetry in high-speed jets; (iii) travel expenses for conference participation and for the collaboration between partners, including the external collaborators at Caltech and at ITA.

IRMA seeks to develop efficient and non-invasive strategies for manipulating the morphology and the opto-electronic properties of vapor-deposited Ag nanostructures grown by magnetron sputtering at room temperature (i.e., 3D islands and ultrathin continuous layers). This will be achieved via selective deployment of additives (i.e., gaseous species and solute metals), either at the growth front (acting like surfactants) or using a seed layer, to improve wetting of Ag layers with the ultimate goal to produce conductive layers at sufficiently low thickness to ensure optical transparency. In order to capture the structural, morphological, and chemical evolutions at the nano- and atomic-scales while the materials are ‘alive’, IRMA proposes a novel and challenging experimental approach combining: - A detailed, real-time lab-based study providing simultaneous information on the optical, electrical, and stress evolution during growth and establishing a knowledge base for the impact of different surfactant approaches on the growth of ultrathin Ag films (work package 1). - An in situ ultra-high vacuum surface-characterization study providing complementary information about chemical state and local morphology of the as-grown films (work package 2). - A synchrotron-based study giving real-time information about the growth dynamics, structure evolution, and stress development, through X-ray diffraction, X-ray reflectivity and grazing incidence small-angle X-ray scattering combined with wafer curvature measurements (work package 3). - The determination of optical and electrical properties in situ and ex situ, including ageing effects on the structural and functional properties (work package 4). More specifically, different sputter-deposited Ag layers will be critically examined and benchmarked against reference Ag films grown in pure argon on silicon oxide surfaces: 1) the use of gas additives by performing Ag growth in argon/nitrogen plasma discharge, and 2) the growth of Ag on amorphous Ge seed layers, as these two approaches are the most efficient in promoting metal wetting, according to the literature. Additionally, we will explore the intelligent deployment of these surfactants, such as the use of Ag(1-x)-Ge(x) seed layers grown by co-deposition or the addition of nitrogen at specific nanostructure-formation key stages. Three main research objectives are foreseen: - To gain fundamental understanding on the impact of additives on the early-growth stages of Ag ultrathin films, in terms of interface chemistry, growth morphology, crystal structure, stress development, and surface roughness. - To study relaxation processes after short-time growth interruptions as well as long-term and thermal stability of the investigated systems. - To propose guidelines for efficient design strategies with the aim of achieving ultrathin metal layers with optimal optical transmittance, electrical conductivity, and improved durability for use as transparent conductive electrodes. The IRMA project leverages on the complementary expertise and existing collaboration of three academic partners, Pprime Institute and SOLEIL in France, and Karlsruhe Institute of Technology in Germany, which offer unique research facilities to reach these objectives. On a grander scale, the fundamental knowledge generated by the IRMA project paves the way toward intelligent in-line control of industrial nanostructure synthesis processes.

The thermodynamic cycle used in a gas turbine (GT) has undergone little change since its early development. Over the last decades effort has been put into increasing efficiency through reducing losses and raising overall pressure ratio and peak temperature. To break out of current limits a different cycle is required. One of the most promising is the case where a pressure rise across the combustion process is allowed. Cycle models show that such a change would reduce the fuel consumption of a large turbofan engine by ~15% and of a small engine by ~25%. An efficiency increase of up to 20% is also expected for land based GT. The pan-European team assembled offers the possibility of studying the most promising Pressure Gain Combustion, PGC solutions on an innovative integrated level. Current PGC solutions are of two types, the subsonic type, which is limited by low heat release rate but is practical and the detonative type, with very high heat release rate but currently impractical. PGC solutions are expected to be key technologies for the efficient use of carbon neutral fuels such as hydrogen. INSPIRE is aimed at studying both technologies, the Constant Volume Combustion, CVC and the Rotating Detonation Combustor, RDC. Around the two WP focusing on CVC and RDC, where institutions such as TUB, ENSMA, CERFACS, and SAFRAN will supervise the experimental and modelling activities of the involved ESR, two additional WP will aim at studying the main phenomena and technologies required to enable PGC solutions on actual engines. Topics as heat transfer, unsteady components interaction, noise generation and overall system performance will be faced by ESR supervised by UNIFI, UNIGE, KTH and TUB. The training of new researchers familiar with the concepts of PGC will ease the adoption of the technology in European industry. Since the developmental life cycle of GT is long, familiarizing a generation of new researchers with PGC will allow them to grow along with the technology.

Electrification of vehicles and improved efficiency of internal combustion engines (ICE) are the main levers to reduce greenhouse gas emissions. Recent studies indicate that in 2040 thermal cars sales will still remain an important part of the market and the spark-ignition engine (SIE) is seen as the most interesting ICE technology. However, technological challenges must be tackled before meeting real driving emissions expectation due to the diversification and complexity of hybrid applications. For flow aerodynamics, mixing and combustion down to the individual engine cycle, challenges are for example associated to robustness of concepts on a cycle basis, rapid variations of engine loads observed in hybrid technologies during transients, the occurrence of extreme cycles for a wider range of operating conditions. Numerical, experimental and analyzing tools have made significant progress in recent years for the analysis of spatial and temporal scales of the unsteady in-cylinder flows. Large-Eddy Simulation (LES) is an essential tool for the design of robust concepts. While LES has been validated against well-defined experiments, the prediction of internal turbulent dynamics and combustion during a cycle is affected by epistemic uncertainties. Therefore, progress is still needed to obtain optimal and robust design. The main objective of ALEKCIA is to develop game-changing tools for augmented prediction and analysis of turbulent reactive flows with a focus on real SIE operations to better capture time-resolved events and increase understanding and control of the origins of undesired behaviors. The key hypothesis is that future progress and success is tied to the synergistic, strong combination of experimental and numerical tools at every stage of the project, which will provide advancement in the analysis of physical scales and boundary conditions (BCs). The major scientific challenges addressed by ALEKCIA are to 1/ quantify and reduce uncertainties (UQ) due to model parameters and BCs, 2/ develop new Data Assimilation (DA) approaches for coupling LES with experimental measurements, 3/ develop new decomposition methods to analyse big data generated by LES and high-speed PIV, 4/ combine them with UQ and DA methods for detailed analysis of individual SIE cycles during steady operations and fast transients. We stress that this methodology could also be used more widely for industry and energy applications. To achieve its ambitious objectives, work in ALEKCIA is structured into one management task (T0) and three technical tasks (T1 to T3). We will address non-cyclic phenomena under transient and fired operations and develop novel analysis from the acquired experimental and LES databases of a SIE performed respectively at PRISME (T1) and IFPEN (T3) laboratories. The partners of the project will also collaborate on the development of crank-angle resolved spatio-temporal EMD decomposition (T1 and T3) for engine flows to obtain an unprecedented detailed understanding of the mechanisms involved in the generation of in-cylinder flow, turbulent dynamics and their impact on combustion. The development of UQ tools to quantify and reduce uncertainties in complex LES of SIE flows is also targeted (T3). Finally, the capabilities of DA methods to calibrate realistic BCs on-the-fly is investigated by PPRIME (T2 and T3). This task is particularly relevant when assimilating experimental data (in the form of BC and in-cylinder large-scale flow patterns from EMD) obtained in extreme cycles. EMD obtained from a selected number of measured cycles presenting very slow or fast combustion rates will be coupled with UQ and DA tools for their inclusion in LES (T3). In this scenario, LES will be able to properly follow the assimilated aerodynamic behaviour of these cycles while turbulent dynamic will be modelled. Finally, the application of the developed tools will allow to identify the main key parameters controlling internal aerodynamics.

Mn+1AXn phase is the generic formula for a family of layered ternary carbides and nitrides where M is an early transition element, A is an element of group III-A or IV-A and X is either C or N. The structure of these phases consists in layers of A element between Mn+1Xn layers. Mn+1AXn phases combine a unique set of properties: some of them are characteristic of the Mn+1Xn ceramic block (stiffness, resistance to oxidation…) while the others are typical of metallic materials and unique for ceramic ones (thermal and electrical conductivities, machinability, damage tolerance…). Such a combination of properties gives rise to many possible applications. The unusual macroscopic properties of MAX phases are closely related to the electronic and structural properties of the constituent atomic layers on the nanoscale. However, the investigation of their intrinsic properties and their anisotropy have so far been remained partially hindered by the lack of the availability of single crystals. The main goal of the present project is to remove the technological barrier limiting the development of large single crystals of MAX phases and to investigate their physical and mechanical properties. The feasability of MAX phases synthesis using metallic melts as solvents has been clearly demonstrated by several authors. In the present project we aim to develop and adapt crystal growth techniques in order to promote and control the growth of large single crystals of MAX phases. To do so, the mechanisms responsible of growth have to be elucidated and controlled. The layered structure of MAX phases and particularly the weakly bonded A layers induces an original reactivity with a possibility of reversible exchange of A atoms. Therefore, the reverse case of the decomposition of MAX phases and particularly the exfoliation of the A atoms layer leading to two-dimensional graphene-like structures will also be carefully investigated. The large size single crystals obtained during the first stage of the project will be characterized with the aim of acquiring intrinsic electronic and mechanical properties of MAX phases. With large size crystals, it will be possible to investigate the properties along different crystallographic orientation and to correlate the expected anisotropy of the properties to the anisotropy of the structure. It is worth noticing that, ab-initio calculations will be used in order to correlate the measured physical properties with the electronic structure of MAX phases. Of course, the physical properties of two-dimensional structures obtained by exfoliation of MAX phases will also be investigated by the same techniques as soon as they will be available. We expect from this project a significant boost and progress in our academic knowledge of MAX phases and in their synthesis, and as a consequence to fill a substantial part of the gap still separating these materials from the application.