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Sloshing Wing Dynamics

Periodic Reporting for period 1 - SLOWD (Sloshing Wing Dynamics)

Reporting period: 2019-09-01 to 2021-02-28

Project Description:
SLOshing Wing Dynamics (SLOWD) aims to investigate the effect of sloshing on the dynamics of flexible, wing-like structures carrying a liquid (fuel), through the development of experimental, numerical and analytical methods. Primarily it looks to positively use the effect of sloshing to reduce the undesirable loads occurring from gusts and turbulence. Its main goal is to provide a holistic approach (both experimental and numerical) in order to quantify the energy dissipation effects associated with the liquid movement inside the fuel tanks, as the wing undergoes dynamic excitations. An increase of the order of 50% in the damping characteristics of the structure is expected.
The primary focus of the project is the application of modelling capabilities to the wing design of large civil passenger aircraft (subject to EASA CS-25 type certification), which are designed to withstand the loads occurring from atmospheric gusts and turbulence and landing impacts. SLOWD is the first project to propose full scale wing tests which include slosh dynamics. The proposed work is therefore aiming to advance the state-of-the-art capabilities in the field of sloshing/structure/control interaction to increase significantly the international competitiveness of the European aerospace industry. Also, it aims at making recommendations to EASA so as to make aerospace design practices safer and more competitive.

Main Objectives:
1) Setup of an Experimental Campaign to investigate the response to dynamic loading of the wings of a modern passenger airliner (200 passengers or more) carrying fuel.
2) Further Develop Numerical Methods for the concurrent modelling of the experimental setup and generation of a high-fidelity in-silico representation.
3) Evaluate Reduced-Order and Analytical Models, as surrogates of the numerical models for subsequent inclusion into an industrial design framework.
4) Integration of the Models into a Multidisciplinary Design Framework using an industrialized version of the developed software to understand the influence of design parameters and define an optimal architecture of the wing fuel tanks, which maximizes the dissipation effects due to fuel sloshing.
The project is organized into eight interdependent Work Packages (WP).

WP1 is led by the coordinating entity Airbus Operations, with support of EASN-TIS, and deals with scientific coordination and financial/administrative management of the project.

WP2 is coordinated by University of Bristol, with contributions from Universidad Politécnica de Madrid, University of Rome La Sapienza and Airbus Ops. All aspects of experimental testing are covered, including the development of scaling laws and real and small test-rigs under both idealized and operational loading environment. The results of the work-package have been used to gain a physical understanding of the energy dissipation mechanism due to sloshing, and to provide benchmark data for numerical validation.

WP3 is coordinated by the University of Cape Town, with contributions from Universidad Politécnica de Madrid and Consiglio Nazionale delle Ricerche. It deals with the fluid-dynamic modelling of sloshing with state-of-the-art techniques including both mesh and particle-based methods. This work-package has also developed metrics for the assessment of high-fidelity numerical simulations in terms of accuracy and computational efficiency, which have been benchmarked against the experimental data provided by WP2.

WP4 is strongly linked with WP2. Under the coordination of University of Bristol, structural dynamic models are developed with the support of Airbus Ops and University of Rome La Sapienza. A key achievement is the development of numerical and analytical models capable of representing the dynamics of flexible wings in both dry and wet configurations. These models inform the test design of WP2, and together with WP3 provide the basis for the Fluid-Structure Interaction modelling of WP5.

WP5 is led by UKRI-STFC, supported by University of Cape Town, Consigilo Nazionale delle Ricerche, Airbus Ops and University of Bristol. The work-package has developed a significant software framework to underpin capability to simulate the complex interaction of sloshing fluids (WP3) and flexible structure (WP4), using both commercial and open-source software. Another important achievement was the definition of a set of benchmark experimental datasets for validation, including those of WP2.

WP6 is under the coordination of University of Rome La Sapienza, with contributions from University of Cape Town and University of Bristol. The activities within this work-package led to the development of surrogates based on the high-fidelity simulations of WP3, 4 and 5 as well as physics-informed equivalent mechanical models from the experimental data of WP2.

WP7 is coordinated by Ariane Group, and provided all partners with the definition and initial prototype software for the industrial use of the methods and tools of WP5 and 6.

WP8 manages the exploitation and dissemination of the SLOWD results. Led by EASN-TIS with support of Airbus and Airbus Defence & Space, the activities in this work-package have resulted in a strong social media and web presence for the project, including the setup of the Zenodo page for open access to its scientific publications.
The expected impacts of the project are:

Advancement in multidisciplinary capabilities for whole Aircraft:
- Integration of methods into the industrial design process will have an enormous potential for already certified aircraft.
- Expensive and unnecessary structural reinforcements / weight increase will be mitigated.
- Estimated 3% saving on total wing weight with direct impact on fuel consumption.
- Exploiting conservatism in existing designs will increase the variety of active and passive load control strategies for optimal aircraft design.

Reduction in the aircraft design cycle and higher complexity decision trade-offs:
- Optimal design in a shorter time frame.
- Innovative design solutions, novel wing tank layouts.
- Target weight savings of 6% (twice that achievable for an existing design).

Development of synergies on visualization methods & big-data analytics:
- Integration of full order and reduced order / analytical models.
- Interpretability of simulation results and comparison of the accuracies of the different types of models.
- Identification of the key simulation parameters and development of visualization/analysis techniques.

Increase the European innovation potential in Aeronautics and Air Transport:
- Exchange of personnel between large aerospace groups SMEs and Academia.
- Involvement of partners active in space-industry and other transport sectors, for cross fertilization of ideas.
An overview of the experimental, numerical and analytical studies performed within SLOWD