Project B4.1 addresses, in close collaboration with B4.2, the technological challenge of dissipating the waste heat from a fuel cell system via the aerodynamic surfaces, which is one of the key aspects to develop future sustainable aircraft. This will be made representative for unconventional aircraft configurations such as the Blended Wing Body (BWB) to identify potential solutions and to study the feasibility of such systems.
In particular B4.1 is a collaborative project were the TU Braunschweig, the German Aerospace Center (DLR) and the TU Delft take part and bring in their expertise in structural design and lightweight structures, aircraft aerodynamics, heat transfer and propulsion systems, respectively. Since the thermal fluid-structure-interaction (TFSI) is a multi-disciplinary coupled problem, it is studied with different specific solvers that need to be coupled to each other.
For the targeted application, the unknown sensitivities resulting from the coupling of the waste heat transport from the fuel cell to the aerodynamic surface via a cooling fluid and heat conduction through the surface structure, the heat transfer to the aerodynamic flow around the vehicle surface as well as its thermal-mechanical behaviour including structural integrity and adaptivity are considered. In addition to the precise modelling of the individual disciplines involved and their consistent three-field-coupling, an integral consideration of the overall system is carried out using advanced multi-fidelity approaches. This enables the efficient design and optimization focusing on the interaction of the surface with the outer flow field and the weight saving design of the internal structure with integrated cooling channels.
With the collaborative, multi-disciplinary analysis capability involving the individual disciplines, the design space is characterised by means of optimization algorithms, while the link between the solvers exploits the interactions between the disciplines to find a trade-off.
In a first attempt the complex multi-disciplinary problem is approached with a simplified 3D-Model depicting the individual regions of the external flow, internal channel flow and the domain connecting structure in between, considering the applying physics. Preparatory for the high-fidelity coupled simulation the simplified model is used to develop coupling mechanisms and study occurring phenomena. For that, various individual solvers as DLR’s TAU, Abaqus and OpenFOAM are coupled using the design framework developed by B4.2. Later on, the developed model will be used to execute high-fidelity simulations on the detailed BWB-Aircraft geometry.
Using the results of the high-fidelity model, surrogate models can be derived for individual disciplines to reduce computing time in following studies. With parameter and sensitivity studies varying initial conditions such as cooling fluid and structural material properties, flight maneuvers and hence varying required propulsion power, a parameter app will be developed. This will contribute to the knowledge representation graphs that can be used to develop semantic models and concepts for the overall thermal management system (TMS). Furthermore, the obtained knowledge is used to optimize certain parameters to account for e.g., the flow separation on the aircraft’s skin or the cooling flow resistance inside the channels.
Further studies using the design framework obtained by B4.2 aim for optimization of the thermal management system such as channel geometries, the channel layout in the aircraft’s skin and structural integrity regarding the aerodynamic and thermal loads in unusual and critic ambient conditions. The channel layout can be further optimized regarding strategic heating in particular aircraft skin regions such as fully-turbulent flow regions to decrease the overall aircraft drag.
Finally, the results of the new design methods and the integration framework are summarized and evaluated.
Dr.-Ing. Matthias Haupt
Institut für Flugzeugbau und Leichtbau, TU Braunschweig
m.haupt(at)tu-braunschweig.de
Prof. Dr.-Ing. Stefan Görtz
Institut für Aerodynamik und Strömungstechnik
stefan.goertz(at)dlr.de
Dr.ir. Chiara Falsetti
Department of Flight Performance and Propulsion, TU Delft
c.falsetti(at)tudelft.nl
Dr.ir. Carlo de Servi
Department of Flight Performance and Propulsion, TU Delft
c.m.deservi(at)tudelft.nl