Project A01 will design and realize a high-fidelity, medium scale wind tunnel experiment, including an exchangeable rear fuselage with force measurement and Electric Propulsor Simulators (EPS) for SynTrac’s 1a configuration. In close cooperation with projects A02, C03 and B04 the data generated with the model in the Propulsion Test Facility (PTF) tunnel will be used to validate the Power Balance method and thus help to close gap in thrust-drag bookkeeping for highly integrated propulsion systems. This will allow for full consideration and assessment of new airframe-to-propulsion interface technologies such as BLI, thrust vectoring and heat management.

Project A02 contributes a comprehensive assessment method and corresponding practical tools for accounting aircraft flow losses and possible power savings through propulsion integration to SynTrac. Project A02 will provide a methodological extension for the assessment of all types of flow losses by analysing the system by methods based on an extended Power Balance and by methods based on the Second Law of Thermodynamics. This also enables a detailed analysis of the composition of the entropy production and of the losses. The extended Power Balance will be validated by data from experiments in project A01.

Project A3 will investigate the synergetic use of propulsion concepts to provide thrust and simultaneously support the flight control functionalities by detailed aerodynamic studies on a full configuration level based on tailored high fidelity simulation methods. Building up on the conceptual design input information, CAD representations of all three configurations 1a, 1b, and 2a are generated and provided. The aerodynamic investigations will deliver aerodynamic performance figures, but also reveal deceive interference phenomena for the wing-mounted distributed propulsion concepts as well as for the rear-mounted BLI and strut based installation of the jet engine. Moreover, project A03 provides the input for flight mechanical assessments of all three propulsion integration concepts. Technology advancements from other projects on a component level will be integrated and assessed.

Project A04 contributes advanced control allocation methodologies, by which new degrees of freedom offered by distributed propulsion and thrust vectoring can be fully exploited. The mapping from actuation to force and torque will become multivariable, and uncertain. It is exactly that mapping that has to be inverted for any flight control system. Considering certification, any inversion algorithm must be real-time applicable, it must not be conservative, and most important, computational bounds must be guaranteed. Furthermore, it must be possible to consider actuator failures. All of these certification-driven constraints make the overall inversion problem difficult. The objective of this project is to exploit the controllability potential of new distributed and/or integrated propulsion configurations of SynTrac. The solution will be approached in two ways, model-based and data-driven.

For integrating all findings from aerodynamic investigations, advances in propulsion, and new flight control (and allocation) algorithms, project A05 will contribute open-source flight dynamics models which are beyond the current state of the art and an analysis and exploration of the handling qualities. New methods for flight dynamic modelling will be investigated and a module that evaluates the handling qualities as automatically as possible for both distributed propulsion and thrust vector control will be provided. It shall be further explored to which extent handling qualities can be even improved through exploitation of the distributed propulsion or thrust vectoring concepts together with new control allocation algorithms.

Project A06’s aim is integrating a multitude of individual effects on aircraft level of the SynTrac’s guiding configurations. It is achieved on the basis of conceptual aircraft design which draws on the results of many projects and hence is highly interlinked within SynTrac: This requires novel design methodologies expanding the conceptual aircraft design workflow on three levels, paving the path towards a future System-of-Systems (SoS) inspired tool and methods design environment.

A07 addresses an essential goal of SynTrac, namely the efficient combination of all disciplines involved to enable holistic optimisation of the aircraft concepts by exploiting maximum synergy effects of the highly integrated onboard systems. To realise such a holistic Systems Engineering (SE) approach, great atention has to be paid to the parameterisation and information processing. The integration of high-fidelity methods, tools and data formats also requires new approaches, such as the integration of AI or dynamically reconfigurable workflows, to efficiently enable the desired multidisciplinary optimisation.

B01 is dedicated to the investigation of fundamental effects and sensitivities coupled to the functional integration of heat transferring structures for improved waste heat transfer in highly integrated propulsion systems. The high amount of heat that has to be transferred into the propulsor annulus within the given spatial boundaries lead to heat transfer intensification with micro structured surfaces. The additional pressure drop of these micro structures and their time dependent behaviour in terms of fouling due to particle laden flows shall be investigated in this project. This will be accomplished by simplified experiments and scale resolving numerical calculations. The result is a surrogate model that will be exchanged within Syntrac.

Project B02 focuses on the exploration of local, unsteady aerodynamic interactions between propellers and laminar wings. In order to increase the overall efficiency of an aircraft, it will be investigated whether a certain laminar run can be retained despite the propeller influence on the wing boundary layer transition. The project is based on high-fidelity CFD simulations using the DLR flow solver TAU as well as time resolved experiments in a laminar wind tunnel. By developing a surrogate model based integrated design methodology, combining multi fidelity CFD methods, the principal parameter dependencies of the propeller-wing-interactions will be identified in the first project phase. In the following phases, the propeller and the shape of a low-drag laminar wing will finally be optimized to enhance the overall efficiency.

Shape-morphing technologies with significantly stronger functional integration could provide a clear technological boost. However, for a morphing engine outlet, the morphing structure must be double-curved to form a closed cross section. Project B03 pursues a biomimetic approach of shape morphing based on pressure-actuated cellular structures (PACS). The PACS approach will be applied to double-curved morphing structures with closed cross sections to enable thrust vectoring and a variable nozzle area.

Project B04 will analyse new aero-thermodynamic effects of engines with low specific thrust and pressure ratio having their exhaust systems operated on the steep side of the flow and thrust characteristics. This covers non-uniform flow conditions within the intake system and the exhaust system. Special attention is paid to the impact on fan aerodynamics and performance. Transient performance modelling will be extended to embrace waste heat recovery and water recovering exhaust gas treatment as well as mild thrust vectoring. The model will also provide an interface to the power balance method as thus couple detailed aero-thermodynamic results with reduced order models within SynTrac.

Bringing acoustics into the preliminary design process to ensure a comprehensive assessment, is one of the major objective of the project. The effect of highly integrated transport aircraft on cabin noise is investigated. In the examinations, a clear focus is put on SynTrac’s mission of a cross-disciplinary, cross-system integration. The sound fields are made accessible in early design phases through appropriate mid-fidelity models of the entire aircraft. For this purpose, a configuration-specific selection of required modelling aspects as well as a design-loop-appropriate numerical solution are investigated. The novel concept require specific reductions of wave-resolving, high-fidelity FE computations.

Project B06 investigates the structural integration of the aft-mounted engines, as planned in configuration 1a (with BLI) and 1b (podded engine) to develop design solutions for the cross-system integration of the aircraft tail structure which are fed back into the overall design. With a focus on the entire rear structure and the engine mounts, new technological bricks such as morphing and auxetic structures are considered. To reach the targets novel solution approaches for multidisciplinary design optimisation (MDO) and new fundamental methods for machine-learned (ML) surrogate models and polymorphic uncertainty quantification (PUQ) will be developed in order to exploit the synergies and potentials of multidimensional functional integration.

The higher weight of novel energy storage solutions in aircraft call for a higher lightweight potential as well as load-path oriented orthotropic design options. Furthermore, new functionalities such as optimised heat distribution zones are also required. Hence, the project C01 will examine the potential of structure-integrated thermal management by using hybrid laminates with continuous (fibre reinforced polymers doped with graphene materials) and discrete (fibre metal laminates, hybridisation) functionalisation. The investigations will include experimental and numerical methods that are suitable to design and validate dedicated intra- and interlaminar heat flux paths of these composite materials with realistic boundary conditions e.g. for the known thermal convection in a dedicated test chamber.

Project C02 considers porous media as a promising technology for various applications such as exhaust gas treatment and waste heat recovery for integration into different aircraft configurations. A key physical cross-scale aspect here is condensation from the vapor phase and the removal of the condensate. Understanding the connection between the microscopic processes and their macroscopic effect is essential to the successful exploitation of porous media. To achieve this goal, we combine complementary experimental and numerical methods in this project.

Project C03 will study the relevance of the intake shape for highly integrated aft-mounted engines on the overall efficiency of the aircraft. Different intake shapes will be developed and optimized for, both, a full-size aircraft and for the wind tunnel model (Project A01). Also, the potential of active flow control methods to tailor the inhomogeneous flow in the inlet will be explored and assessed in terms of benefit for the overall energy balance of the aircraft. The design will be based on detailed numerical simulations of the intake region. To validate the design method C03 will also participate in a wind tunnel experiment (Project A01) and will design and fabricate a suitable model of the intake.

In the project C04, the development of an efficient, accurate and predictive simulation method, which allows the detailed investigation of the effect of structural nonlinearity sources on cabin noise in future highly integrated aircraft is pursued. The structural transfer paths of vibration and noise in aircraft consist of many components, which are mechanically connected via e.g. rivets and bolts. Such mechanical joints are known to introduce significant vibration-amplitude-dependence of effective stiffness and damping at component interfaces, especially under increased vibratory response ranges of future aircraft designs. The Harmonic Balance method is capable of providing predictions for such cases but is computationally costly when used for acoustic purposes. To account for these challenges, a computational method combining the Harmonic Balance Method with ideas from Multi-Fidelity modelling is developed that is particularly suitable for predicting acoustic quantities.

Project C05 predicts the acoustic fuselage surface pressure fluctuations, generated by a complex, thrust vectoring propulsor. Configurations with podded and tightly integrated engines will be considered. Furthermore, the acoustic relevance of morphing techniques regarding nozzle and rear fuselage deformation is investigated. These pressure data are coupled via an interface to a structural code to analyse the cabin excitation. To capture all source mechanisms the highly efficient Tam & Auriault source model concept is generalized, to enable accelerations by installation and thrust vectoring, and interaction of the convecting pressure near field with surfaces. This extended approach will be validated by zonal LES simulation.

To benefit from the efficiency gains of an integrated system design – in this case utilizing distributed propulsion – community acceptance of the technology is paramount. Acoustics and noise are an important driver for this. The goal of C06 is thus to allow an accurate prediction of the main parameter dependencies of sound generation and propagation and further on to integrate acoustics into the design optimization loop for the full aircraft.

SynTrac establishes a large, cross-location and interdisciplinary research network dissolving traditionally rigid hierarchies and priorities of current aircraft development to unleash synergies of highly integrated transport aircraft. This is especially challenging for young researchers. Therefore, a structured graduate program that supports the CRC’s doctoral researchers is indispensable to achieve the following strategic goals: Scientific excellence of doctoral research, in-depth cross-location and interdisciplinary research, optimum individual qualification, early scientific independence, international scientific exchange and networking, joint work culture uniting competencies from all relevant fields.

The INF project is dedicated to ensure that the a) research data, b) research software and c) models originating from SynTrac follow the FAIR guiding principles requiring them to be Findable, Accessible, Interoperable and Reusable. In this way, the INF project supports good research practice by acknowledging that the management and long-term archiving of research data is closely linked to the sustainability of research software.

The supporting structure CA serves as the operational backbone of our research group, ensuring effective coordination and management across various activities. Led by our speaker and the managing director, the structure focuses on financial oversight, strategic planning, and facilitating scientific events, while providing essential support to both the management committee and the general assembly. This central body is dedicated to fostering collaboration and driving progress within SynTrac.

The fundamental research of SynTrac has a high social impact with regard to the pursuit of an environmentally compatible air transport industry and the necessary transformation of the air transport system. In the associated public discourse, it is important to communicate to a broad public the challenges involved and how the basic research contributes to minimizing the environmental impact of society’s need for mobility. At the same time, it is important to enter into a veritable dialogue with the broader public for an improved comprehension of societal expectations. The PR-project is positioned at this interface between SynTrac’s basic research and society.