Advances in Computational Methods and Technologies in Aeronautics and Industry

ECCOMAS, the European Community on Computational Methods in Applied Sciences brought together the scientific associations on numerical and computational methods in Europe. With its large conferences ECCOMAS created a world-wide recognized forum for scientific exchange of new methods and their applications. Within ECCOMAS, the Industry Interest Group (IIG), created in 2015, takes care for the link of science and industry. The Special Technology Session (STS) were organized at these big events since 1996. Their aim was and still is creating presentation possibilities for topics and applications of industrial relevance, in particular in aeronautics with its peculiar relation to computational methods, but also for other industrial sectors. This paper provides and overview over the development of STS and gives examples of the changes and improvements of numerical methods in their application to aeronautics. The experience, the focus on challenges and the effort for keep the momentum of industry /academy cooperation through the STS at the ECCOMAS events are addressed.

This article presents a synthesis of main results from the H2020 European Research project N 723,402 “Smart Morphing and Sensing for Aeronautical Configurations”, www.​smartwing.​org/​SMS/​EU concerning the design of disruptive wing configurations able to considerably increase the aerodynamic performances compared to conventional designs. This is achieved thanks to novel smart actuators electrically actuated and embedded under the “skin” of the lifting structure and new generation of sensors based on Bragg grating. Therefore, optimal deformations and vibrations are produced in multiple time and length scales, able to manipulate the surrounding turbulence structure in order to increase lift and simultaneously decrease drag and aerodynamic noise in all flight phases, take-off, landing and cruise. Results from High-Fidelity numerical simulations accompanied by experiments with morphing A320 non-swept wing configurations as well as a modified two-element high-lift configuration near scale 1 are discussed regarding the increase of the aerodynamic performances.

The feasibility of laminar flow control technology for future wing is bound to the development of a leading edge high-lift system that complies with the requirements on smooth surfaces to enable maintaining the laminar boundary layer flow, such as a Krueger flap. Although in principle the aerodynamic performance of a Krueger flap is known, the unsteady behaviour of the flow during deployment and retraction is completely unknown. This is as even more important as during deployment the Krueger flap is exposed to highly unfavourable positions perpendicular to the flow. To mitigate the risk of unfavourable aircraft behaviour, it is therefore expected that a Krueger flap has to be deflected significantly fast and may trigger unsteady aerodynamic effects. Within the European H2020 project UHURA (Unsteady High-Lift Aerodynamics—Unsteady RANS Validation), currently a wind tunnel test is conducted incorporating the vented foldable bull nose Krueger flap. A wind tunnel model based on the DLR-F15 airfoil has been designed and manufactured that features a part span and a full span Krueger device, which can be actuated at high deflection rates up to 360°/s. First wind tunnel tests have been conducted at the ONERA L1 wind tunnel in Lille in October 2020. The tests included the measurements of internal forces, steady and unsteady pressures, as well as phase-locked Particle Image Velocimetry (PIV) to achieve high quality validation data for comparison with numerical methods.

A spanwise traveling wave of blowing and suction method is applied to reduce the drag in a turbulent channel flow with \(Re_{\tau }=180\). The direction of the traveling wave reverses periodically to generate a similar oscillatory spanwise motion as the wall oscillation. Results from direct numerical simulations show that the blowing and suction control can achieve a slightly smaller drag reduction, compared with the wall oscillation with a same optimal period and strength. The pressure-strain correlation is found related to the drag reduction closely.

A parametric study of multiple shock wave boundary layer interactions is presented in this paper. All results were obtained using the computational fluid dynamics solver of Glasgow University. Such interactions often occur in high-speed intakes, depending on the state of the upstream boundary layer, and can adversely affect the performance of the intake. First, RANS simulations with a Reynolds-stress based turbulence model of multiple shock wave boundary layer interaction in a rectangular duct were performed and compared to the experiments followed by simulations at different Mach and Reynolds numbers and flow confinement levels. The results showed that Reynolds-stress based turbulence models can predict the interaction well. The employed explicit algebraic Reynolds stress model showed good agreement for the corner and centreline separations and resulted only in a small underprediction of the wall pressure. Flow distortion and total pressure recovery efficiency metrics were defined and evaluated for each interaction. Lower upstream Mach number and/or lower levels of flow confinement were required to achieve higher total pressure recoveries and lower flow distortion levels.

Two validation cases for high-speed turbulent flows are considered. The first case is the supersonic flow at \(M=3\) and \(\textrm{Re}_h=4.9\cdot 10^6\) over the \(45^{\circ }\)-inclined backward facing step. The second one is the axisymmetric high-Reynolds dual-stream jet: slightly underexpanded at the bypass duct and subsonic at the main duct. The flows are simulated using higher-accuracy scale-resolving numerical algorithm implementing the hybrid RANS-LES method. The evaluation of numerical results is done by comparing with the available experimental data obtained by ITAM SB RAS, Novosibirsk, Russia. In contrast to the Menter SST RANS model considered, the scale-resolving method turned out to be able to correctly reproduce the complicated unsteady turbulent flow with shocks in both cases. It is shown that the impact of unsteady vortex structures on the flow physics, that is captured by the scale-resolving approaches, is of crucial importance. The IDDES method requires rather moderate computational costs compared with the requirements both of the fully LES and DNS approaches for the considered turbulent flows.

This paper presents the high-fidelity numerical simulation and analysis of ducted/un-ducted propeller aerodynamics and acoustics. High-fidelity CFD simulations at several operating conditions were performed using the in-house HMB3 solver and were validated against experiments and lower-order methods. Superior performance of the ducted propeller at lower advance ratios or in hover conditions was verified. Near-field acoustics was then extracted directly from the CFD simulations. Far-field acoustics was also calculated based on the FW-H equations taking the CFD results as inputs. The noise reduction, directivity changes, and fly-by signals are quantitatively presented and analysed.

Load control is an important topic in aerodynamics, as it can potentially provide an alternative way for drag reduction through decreasing the aircraft structure weight. To pursue ‘Green Aviation’, both new greener aircraft configurations and technologies for load control are under studying throughout the worldwide industries and academies. This paper presents a computational investigation on the load control effects by means of circulation control (CC) via blowing over trailing-edge Coanda surface on a blended-wing-body (BWB) configuration. A BWB model is firstly modified to include Coanda devices on the outer-wing, inner-wing and center-body sections with the same spanwise length. The load control effects in terms of lift reduction aiming for gust load alleviation of CC placed on different spanwise locations are evaluated and compared under steady conditions for subsonic and transonic speeds. The results show that CC has a strong capability for load control, especially for subsonic incoming flow, indicating a promising way for gust load alleviation to replace the traditional flaps.

The feasibility of laminar flow control technology for future wing is bound to the development of a leading edge high-lift system that complies with the requirements on smooth surfaces to enable maintaining the laminar boundary layer flow. Classical leading edge high-lift devices like slats are not suitable as they introduce disturbances in the very sensitive upper surface leading edge area. Within the European AFLoNext (Active Flow, Loads & Noise Control on Next Generation Wing) project, a full scale HLFC leading edge demonstrator was designed and built that incorporated the vented foldable bull nose Krueger. In summer 2018 this demonstrator was wind tunnel tested in the CIRA Icing Wind Tunnel facility. Within this test the aerodynamic design was verified. Additionally, it was tested whether the Krueger device would need a distinct de-icing system. The contribution summarizes the design of the Kruger device together with the findings from the full-scale wind tunnel test of the Krueger flap configuration.

An efficient computational framework is presented and applied to the inverse aerodynamic shape design problem. The main building block is a novel neural network capable to accurately predict the pressure distribution on aerofoils and wings. The trained neural network is used to accelerate the evaluation of the objective function in an optimisation algorithm based on the gradient-free modified cuckoo search method. Two applications are presented in two and three dimensions for problems involving up to 50 geometric parameters.

Against the background of the big environmental and societal challenges as formulated for example in Flightpath 2050, current developments in aircraft design are aiming at further emission reduction through integrated, unconventional propulsion, systems and airframe innovations. This requires the further integration of methods for multidisciplinary modelling, analysis and optimization for aircraft design, but also for propulsion and system level designs. Moreover, experimental validation of the methods and physical testing of critical unconventional propulsion and system designs are prerequisites for industrially relevant development processes. This paper presents some key technologies for computationally efficient collaborative MDO (multidisciplinary design and optimization) frameworks for multidisciplinary design and validation of advanced aeronautic products like aircraft and propulsion systems.

In the face of growing public awareness of environmental issues such as climate change, the pressure to provide efficient and ecological new air transport solutions is higher than ever on the aviation community. To this aim, unconventional aircraft configurations, which are radically different from the established tube-and-wing architecture, may hold a lot of potential. However, original equipment manufacturers today usually shy away from such configurations due to the significantly increased uncertainty and risk connected to such drastic design changes. In order to reduce the risk and increase knowledge about a new configuration, the application of physics-based analyses on a virtual aircraft can add significant value, when applied in the early stages of the design process by bringing new technologies to higher technology readiness levels quickly. Due to the highly multidisciplinary nature of the aircraft design task, the success of this approach largely depends not only on the well-organized handling of the available product data at any point in the design process but also the smart sequencing of the disciplinary contributions based on their mutual dependencies. In this paper, a methodology for an integrated and collaborative approach to preliminary aircraft design is presented. Furthermore, the requirements for a disciplinary analysis and design tool to contribute to an integrated multidisciplinary design process are highlighted. Three examples are given, assuming the perspective of a structural designer to demonstrate the initial investment necessary in order to integrate a disciplinary tool into a multidisciplinary environment as well as the potential benefits of being able to perform the analysis within a larger context.

This research deals with the comparison of dynamic metamodels based on Radial Basis Functions and Artificial Neural Networks. The relevant framework is the robust optimal design in aeronautics under aeroacoustic objectives and constraints. This class of applications is constrained by the computational burden required by high–fidelity solvers to guarantee accurate solutions and the high number of function evaluations needed by the optimiser to converge. Consequently, the identification of efficient metamodelling techniques represents a crucial aspect for the designers. The use of metamodels can significantly reduce the number of high-fidelity evaluations, alleviating the overall computing costs. Accordingly, the engineering community has gradually switched from the design approach based only on direct simulations to the extensive use of metamodelling techniques. Recently, to make the metamodelling process even more efficient, function-adaptive strategies have been developed to improve the fitting capabilities. The dynamic properties of such approaches are mainly related to the self–tuning of the algorithmic parameters and the adaptive sampling of the domain. Here, dynamic metamodels based on Radial Basis Functions and Artificial Neural Networks are formalised and used to model the noise shielding properties of Blended Wing Body aircraft configurations. Special attention is paid to the definition of the metamodel uncertainty, which estimates the surrogate model goodness outside the known points. Both the formulations are demonstrated to correctly reproduce the phenomenon dynamics, although with substantial differences in the convergence properties.

De-icing of general aviation aircraft is usually realized by chemical or thermal processes. These lead to an increase in fuel consumption or usage of electrical energy. Mechanical de-icing is a way to significantly reduce this consumption. In mechanical de-icing, a surface is deformed so that the required failure mechanisms are induced in the ice, causing it to detach. In this paper, the release behavior of ice on a carbon fiber reinforced plastic (CFRP) layer is investigated. The CFRP layer consists of two plies, each \(0.3\,\textrm{mm}\) thick. A numerical calculation is performed to determine natural frequency and required amplitudes of the vibration. In addition, the relationship between the various failure mechanisms of ice and the ice layer thickness, as well as the control values are determined. Tests are also being conducted to demonstrate the feasibility of mechanical de-icing. For this purpose, the surface of a CFRP layer is iced with water in a climate chamber at \(-20\,\mathrm {^\circ C}\). A modal shaker is connected to the CFRP and generates the required displacements at desired frequencies to observe detachment of the ice.

A finite element computation of a solder filling problem with contact angle condition and volume constraint is shown as an application to solve industrial problem where amount of solder needs to be optimized during manufacturing process. The solder that fills the gap between two plates is found through incremental process of the filling volume by solving a nonlinear elliptic problem as an extremal of a total free energy with a double well potential, which enforces separation of solder and air regions. The nonlinear elliptic partial differential equation is discretized by P2 finite element and whose solution is obtained by combination of a gradient flow solver and a stationary Newton iteration solver. Several open source software for numerical computation are used, for example, finite element computation is carried out by ‘FreeFEM’, mesh generation by ‘Gmsh’, mesh adaptation by ‘mmg3d’, and parallel computation on distributed memory environment by ‘HPDDM’.

This paper presents an algorithm to solve mechanical contact problems between two bodies or more, for linear elastic and finite deformation problems. The contact problem is considered as a minimization problem of an energy. The interior point method is used to solve the minimization problem. This algorithm is symmetric and the user no longer needs to specify a slave body and a master one. The algorithm was developed using FreeFEM and IPOPT software.

In this paper, we utilized a simulation approach based on the dynamic explicit FEM (Finite Element Method) to evaluate the stress distribution and the bulk density of catalyst pellets filled in a pipe reactor. We clarified that the shape of catalyst pellets affects their bulk density and stress distribution and found an optimal catalyst pellet shape that can increase the bulk density and reduce the average stress in the pipe reactor. The optimally shaped catalyst pellets are expected to improve their filled state in the pipe reactor, extend the durability of the catalyst pellets and increase the efficiency of vapor-phase synthesis process. At the same time, the proposed simulation method can contribute to speeding up the development of production equipment and improving its completeness.

In the concept design stage for composites parts, there can be an overwhelming amount of options available to the development team in terms of materials, material design, processing/manufacturing and part design. In order to decide on any of the combinations of options to pursue, a Business Decision Support System (BDSS) supporting this decision process is key in order to select and evaluate options and obtaining an overall assessment of the design in the concept stage. The Key Performance Indicators (KPIs) for a composite part can be a combination of technical, financial and environmental indicators, each requiring data from different actors within an organization, and are tracked in a dashboard throughout the part development. Within the COMPOSELECTOR platform, the business decision process for the composite part is structured and defined using the industry standard BPMN. This business decision layer links to databases and simulation and modeling applications, which are activated to generate data needed for the evaluation of the KPIs and which will populate the dashboard. The development and use of the business layer will be showcased for a composite part design which has technical KPIs requiring simulations to be run, as well as financial KPIs like part costs which are obtained through running cost modeling apps. The business decision support system and its business decision layer can be structured and run to reflect the existing decision process with all its actors within an organization or across the value chain, also including analysis based on optimization and uncertainty quantification.

In this article, the translation movement of a thermoelastic web performing transverse vibrations caused by initial disturbance, is considered. It is supposed that the web moving with a constant translation velocity is described by the model of a thermoelastic panel with simply supported edges of the examined span. The problem of the optimal suppression of transverse vibrations of a multispan panel supported at discrete points is formulated with consideration of forces applied to the web. In order to solve the optimization problem, we use modern methods developed in the control theory of distributed parameter systems. We will present a framework of correct mathematical formulation of optimization problem for the case of 1-D structural element related to application of active control to dynamics problems of moving materials. In frame of given statement we include different inertia and active forces and also take into account the actuators action and mechanical and thermal interaction.