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Aero-Thermodynamic Loads on Lightweight Advanced Structures II

Final Report Summary - ATLLAS II (Aero-Thermodynamic Loads on Lightweight Advanced Structures II)

Executive Summary:
The design of a high-speed aircraft is quite a challenge as one cannot evolve from a pre-existing design and cannot intrinsically rely on the design practices of classical aircraft. A new design methodology needed to be worked out which covered not only the various disciplines but had to cope also with the very different flight conditions, i.e. high altitude, high stagnation temperatures and pressures. In particular the choice of airframe materials and engine operation need to be carefully chosen. With the help of MDO-tools at different design levels, i.e. from engineering and analytical tools up to high-fidelity tools, a 200PAX Mach 5 aircraft based on kerosene fuel was worked out with a range of about 9000km.
In parallel, various high-temperature materials such TMC, CMC, UHTC and compositions such Ni-based hollow sphere and tube stacking were developed supporting the need for both the external (airframe, fuselage, control panels) as the internal flowpath (intake, combustor, nozzle). Their materials’ properties were characterized at room and various high temperatures. This enabled to complement the high-temperature materials’ handbook of ATLLAS-I with additional materials.
These materials were then also exploited to demonstrate their applicability to functional geometries such as flight control panels, combustor chambers, sandwich panels for nozzles, injector struts… Their functionality was then also extensively tested in representative environments, either for the external aerodynamics as for the hot combustion gases. The various tests allowed to further extend their exposure time to fluid-structure interactions, thermo-mechanical fatigue, combustion, hot external flow… Where ATLLAS-I proved their functionality for minutes, ATLLAS-II allowed them to extend them to hours or more.
In parallel, basic research and technology development was carried out in terms of porous transpiration cooling aspects and pin-fin cooling channels for combustors. Aerodynamic research focused on high-speed boundary layer transition on heated models along with newly developed high-speed transition models.
Environmental results indicated that the sonic boom level was lower than Concorde despite the higher Mach number but having a larger carpet width. Effects such as wind, turbulence, caustics were addressed as well. With respect to the exhaust, the emissions influence the ozone depletion but need further dedicated investigations to assess their long-life time impact.

Project Context and Objectives:
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Project Results:
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Potential Impact:
The activity allowed designing a technically viable high-speed aircraft resulting into a 200PAX vehicle travelling at Mach 5. To achieve this goal, the tools deployed and developed along the project time-line forced the researchers to make them both multi-disciplinary all along the different fidelity levels as well as closely integrated to allow for embedded design of propulsion and airframe.
The generated models and codes, along with the gained insight and expertise of the researchers will allow deploying them in various other design projects independently of the envisaged application.
The sonic boom codes and their extension towards real environmental conditions, i.e. turbulence, wind… provided the related teams the necessary background for future ICAO regulations and certifications.
The high-temperature materials’ handbook, accumulated over two projects, will provide the various partners access to unique temperature dependent characterization of various properties for a wide range of metallic and non-metallic materials. This will be exploited in design for any kind of applications i.e. combustor, furnaces, nozzles, turbine components…
The experimental databases related to aerodynamics and cooling helped in setting up new and improving existing simulation models. These data will also in the future continue to be used as benchmark testing.
Finally, the worked-out vehicle concept represents a particular point in the design space of high-speed vehicles, i.e. PAX-size, speed, fuel… This will now complement the database of various HST (High-Speed Transport) designs enabling to cover a wide range of size, fuel and speed. This will serve as a good starting basis for section the most appropriate design range for HST which is commercial and environmentally viable and attractive. Hopefully this will allow then identification of those critical technologies to assure a breakthrough innovation for commercial high-speed transportation.

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