The objective of SIMUMOPS is to develop high-fidelity LES (Large Eddy Simulation) tools, in the field of propulsion (helicopter, aircraft, missile) for reacting two phase flows, in moving geometries, taking into account liquid film formation on walls. It is an HPC project because the resources needed for such simulations will require the largest parallel computers. Developments will be based on the AVBP LES software of CERFACS and IFPEN, which is the leading LES tool for reacting flows worldwide. Additional developments are needed in AVBP to handle moving meshes and liquid films on walls as well as the impact of droplets on films and walls. Two target applications have been identified for the second part of the project: (1) Constant Volume Combustion (CVC) chambers and (2) Oil-separation devices for helicopter engines. Application 1 corresponds probably to the last drastic efficiency improvement, which can be expected for all civil or military engines: burning at constant volume can improve the cycle efficiency from 10 to 20 %. Simulation is required to understand how a combustor can operate at constant volume in practice: here valves will be used at the inlet and outlet of the chamber, thereby requiring LES capabilities in moving systems. LES first tests performed in 2015 at CERFACS in collaboration with Pprime in Poitiers where an experiment has been installed, also show that liquid fuel injection will be a major issue, especially because significant amounts of kerosene will flow along the walls. Interestingly, the numerical machinery required for CVC systems is exactly the one needed for oil-separation devices in helicopters which are used to centrifuge oil and send it back to the engine: this is done in a rotating system and oil flow along the walls is a controlling phenomenon. Therefore the same numerical tool will be used for both cases (CVC and oil-separators). An additional issue which will be tackled in SIMUMOPS is 'integrated' LES. Up to now, most engines are computed in a 'modular' way: compressor, chamber and turbine are simulated separately, exchanging very limited information (flow rates, mean temperatures). In a CVC chamber, however, the whole flow is pulsated and the turbine is fed with an unsteady inlet: turbine and chamber must be computed together to provide reliable results. CERFACS has developed an overset-grid method that allows splitting the domain in multiple elements that run on the same machine using multiple instances. This efficient method allows 'integrated' LES. It will be applied here for the first time to the simulation of a CVC chamber coupled to a turbine. It is also used for all moving geometry cases as for the oil-separator. Optimizing it on HPC systems will be another task of SIMUMOPS. SAFRAN TECH and CERFACS bring complementary expertise for SIMUMOPS: SAFRAN TECH is leading a research project on CVC chambers and will provide industry guidelines for design and objectives, as well as experimental results. CERFACS will work on the physical modeling and the numerical HPC aspects of the project.

The electrification of transport implies a strong increase in power and voltage in on-board networks (particularly in aeronautics). The risk of damages due to arcing faults is thus increased. The arc fault is unavoidable, so it must be detected. The arc detection involves a minimum delay during which the damages generated by the arc must be minimized. The objective of the DESMARC project is to propose a passive protection of embedded systems, based on polymer materials, which would mitigate the consequences of the arc on its environment. This protection consists in a layer of materials deposited on the usual cables whose degradation products by the arc would modify the characteristics of the arc and reduce the consequences. For that, the project focuses on the defects at the level of cables. Several challenges are identified. It is necessary to identify the key parameters between the nature of the polymers that are stable at cable operating temperatures, the nature of their degradation products and the behavior of the arc in their presence. To reach these objectives we propose to model the arc-material interaction and to develop an approach (test/selection criteria) to ensure the beneficial effects of the proposed material. It will be necessary to define a validation process and success/failure criteria based on existing materials and standards and the expertise of the partners. In this project, two laboratories (GeePs and UMET) and two industrial companies (Protavic and Safran) have complementary roles in interaction. UMET and Protavic are developing and characterizing functionalized polymeric materials resistant to extreme conditions. GeePS and UMET characterize the materials during and after the arc in terms of arc resistance. Safran, GeePS and UMET are modeling the arc/material interaction and degradation modes (validation will be done by experiment) to propose material design options.

Air transport has grown by about 9% every year since 1950 and has made the world smaller on a human scale. However, commercial flights remain expensive and account for 2% of human emissions of CO2. As a result, airlines and the aviation industry envision tomorrow's transportation, which will require reduced costs, noise and greenhouse gas emissions. Aeronautics is a sector historically marked by a constant demand for innovation and technological progress. The search for reducing the environmental impact of air transport (emission of greenhouse gases and noise) is a natural part of this project. The evolution of thermal engine technologies, used for aeronautical propulsion (airplanes, helicopters, drones), arrives today at a limit which does not allow to glimpse of sufficient reduction of consumption and compatible pollutant emission of the fixed objectives with the new environmental standards (ACARE). To meet these expectations, electric power seems to be chosen for the development of future aircraft. Several manufacturers, governments and universities have started to work on hybrid or electric aircraft systems. At present, the electrically propelled architectures have been partially studied. Safeties, redundancy, the optimal use of hybrid architecture propulsion modules, or energy storage are just some of the steps that have yet to be taken. Each year, Airbus produces about 500 aircraft, ATR in pound about 50 and Eurocopter builds 300 helicopters. This represents a potential market of 1,500 high-power electric motors applied to hybrid or electric propulsion systems for aeronautics. For information, the average price of an Airbus A320 reactor (the CFM56-5B) is 7.6 million USD. "More electric" aircraft will reduce the overall cost of ownership, improve propulsive efficiency and reduce the impact on the environment. For example, developments for more electric aircraft are designed to replace the energy vectors that are hydraulic fluids and compressed air by the electric current in order to obtain a consequent significant reduction in fuel consumption. One of the most important parameters for aeronautical systems is the mass energy (Wh/kg) for storage systems and mass power (kW/kg) for electric actuators or power converters. The most electric aircraft currently is the Boeing 787. The total electric power installed is 1MW. This aircraft incorporates electric generators with a power density of 2.2 kW/kg. Projections for the next 20 years estimate that the power density could reach 9 kW/kg for conventional machines from 1 to 3 MW. To achieve higher objectives up to 20kW/ kg, disruptive technologies are studied. The use of materials such as superconductors could significantly increase the mass power of motors or generators. The main results obtained during the first RESUM project are: • Validation of electromagnetic design tools. • Realization of a superconducting machine at high speed, 5000 rpm, • Study of an original cryostat structure allowing a significant gain, about 30%, of mass torque. • Patent filings for ways to improve the proposed machine structure This new project that follows RESUM is devoted to the study and realization of a machine whose power is between 500 kW and 1 MW.

The market introduction of high temperature wide bandgap power semiconductor devices with junction temperature exceeding 200°C significantly accelerates the trend towards high power density and severe ambient temperature electronics applications. Such evolution may have a great impact in aeronautics applications, especially with the development of More Electric Aircraft (MEA), since it can allow to reduce the mass and volume of power electronics systems. As a consequence, the aircraft operating cost can decrease. However, for electronics used under such harsh conditions, the package reliability and the heat evacuation are very critical issues. The goal of this project is to design and fabricate high performance double sided cooled power electronics modules with optimized thermomechanical properties. The assembly is based on copper joints and a copper heat sink and integrates several technological breakthroughs. Three main technological bricks will be deeply addressed in order to reach the target: 1) Synthesis of nanoporous copper films, either freestanding or directly deposited on metallized substrates with controlled microstructure: In order to limit the risks, three independent strategies will be investigated during the project: the synthesis of nanoporous copper free standing films using melt-spinning and chemical dealloying techniques, the direct on-substrate electroforming of copper-alloy followed by anodic dealloying, and the direct growth of nanoporous structures without any additional treatment by tuning electrolyte formulation and plating parameters. 2) Thermocompression of the nanoporous copper films for die attach: Conventional heating will be achieved at low pressure and in inert/reductive atmosphere. An alternative method based on laser induced fast heating will also be evaluated to thermocompress the nanoporous copper in air. Both solutions allow to limit the oxidation copper issues. The underlying physical mechanisms taking place during the thermocompression of the various morphologies and microstructures of nanoporous copper films will be in-depth investigated. The joint stability under electro-thermo-mechanical aging conditions will be evaluated. 3) Deposition of thick copper layers for substrate/heatsink assembly using electroforming process: A thick dense metal layer will be deposited on a designed sacrificial polymer preform allowing to create a wide range of complex shapes directly on the metallized substrate with low residual stresses. This technology combined to virtual prototyping will allow us to fabricate high performance heat sink patterns (liquid forced convection without phase change) in terms of high local heat transfer coefficient and low pressure drop. The thermal-hydraulic performances of the heat sinks will be analyzed with an experimental setup. The robustness of the assembly (substrate/heat-sink) under repetitive temperature variations will be also evaluated. Silicon Carbide (SiC) devices based power modules (inverter phase leg) using the aforementioned technological bricks will be realized and evaluated in the project. Electrical, thermal and robustness tests are planned to estimate the module performances. The COPPERPACK project will contribute to validate and push our concept from Technology Readiness Level (TRL) 2 up to a TRL 3-4 with a functional technological demonstrator.

In this project, we study new machine-learning methodologies to improve statistical turbulence models for aeronautical applications. In aerodynamics, currently used turbulence models in industry are based on strong approximations and are tuned on very simple configurations. Such models exhibit strong weaknesses as soon as more complex industrial flows are considered. Machine-learning techniques may leverage the wealth of numerical high-fidelity and (incomplete) experimental data that is currently available to improve such models. ONERA / DLR / SAFRAN TECH / ROLLS-ROYCE intend to explore and improve the so-called field-inversion (FI)-machine learning (ML) methodology introduced recently by Duraisamy. The goal is to explore more sophisticated turbulence models, new AI-based techniques for the regularisation of the FI step in the case of incomplete reference data, new systematic tools for the selection of input flow features, and new learning strategies. These disruptive methodologies will be incorporated within numerical platforms that allow CFD codes to take advantage of data-driven techniques. The capabilities of such tools will finally be evaluated and assessed on industrially relevant configurations, such as an aircraft in high-lift configuration and a compressor cascade.