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54. Effect of Levels of Fidelity on Steady Aerodynamic and Static Aeroelastic Computations

Author

Crovato, Adrien, Almeida, Hugo S., Vio, Gareth, Silva, Gustavo H., Prado, Alex P., Breviglieri, Carlos, Guner, Huseyin, Cabral, Pedro H., Boman, Romain, Terrapon, Vincent E., and Dimitriadis, Grigorios

Subjects
Physics::Fluid Dynamics, benchmark, lcsh:Motor vehicles. Aeronautics. Astronautics, computational fluid dynamics, lcsh:TL1-4050, aerodynamics, ComputingMethodologies_COMPUTERGRAPHICS, aircraft design, static aeroelasticity
Abstract

Static aeroelastic deformations are nowadays considered as early as in the preliminary aircraft design stage, where low-fidelity linear aerodynamic modeling is favored because of its low computational cost. However, transonic flows are essentially nonlinear. The present work aims at assessing the impact of the aerodynamic level of fidelity used in preliminary aircraft design. Several fluid models ranging from the linear potential to the Navier&ndash, Stokes formulations were used to solve transonic flows for steady rigid aerodynamic and static aeroelastic computations on two benchmark wings: the Onera M6 and a generic airliner wing. The lift and moment loading distributions, as well as the bending and twisting deformations predicted by the different models, were examined, along with the computational costs of the various solutions. The results illustrate that a nonlinear method is required to reliably perform steady aerodynamic computations on rigid wings. For such computations, the best tradeoff between accuracy and computational cost is achieved by the full potential formulation. On the other hand, static aeroelastic computations are usually performed on optimized wings for which transonic effects are weak. In such cases, linear potential methods were found to yield sufficiently reliable results. If the linear method of choice is the doublet lattice approach, it must be corrected using a nonlinear solution.

Published
2020

59. A Cross-Validation Approach to Approximate Basis Function Selection of the Stall Flutter Response of a Rectangular Wing in a Wind Tunnel

Author

Kukreja, Sunil L, Vio, Gareth A, Andrianne, Thomas, azak, Norizham Abudl, and Dimitriadis, Grigorios

Subjects
Aerodynamics
Abstract

The stall flutter response of a rectangular wing in a low speed wind tunnel is modelled using a nonlinear difference equation description. Static and dynamic tests are used to select a suitable model structure and basis function. Bifurcation criteria such as the Hopf condition and vibration amplitude variation with airspeed were used to ensure the model was representative of experimentally measured stall flutter phenomena. Dynamic test data were used to estimate model parameters and estimate an approximate basis function.

Published
2012

60. The effect of spin level and ball exit speed on forearm muscle activity in the tennis forehand stroke.

Author

Rigozzi, Chantelle, Cox, Jeremy, Vio, Gareth A, Martens, William L, and Poronnik, Philip

Subjects
TENNIS elbow, FOREARM, ELBOW injuries, TENNIS, KRUSKAL-Wallis Test
Abstract

Elbow tendinopathy injuries are very common in tennis players. One of the commonly accepted theories describing the development of elbow tendinopathy in tennis is based on stiffness of the forearm skeletal muscle units and their repetitive overuse in the forehand stroke. Our objective was to use a novel microcontroller based wearable device to compare the influence of different forehand spin levels (flat, topspin and lob) and ball exit speed on forearm muscle activity in the potential onset of elbow tendinopathy in experienced adult tennis players. Peak normalised extensor carpi radialis (ECR) and flexor carpi radialis (FCR) muscle activity corresponding to each forehand shot and ball exit speed were determined and analysed. For the ECR shots (flat = 121, topspin = 272 and lob = 273) by 8 players, Kruskal-Wallis test (p < 0.001) and Post-Hoc tests revealed a significant difference between the flat and topspin spin levels (p < 0.01) and flat and lob spin levels (p < 0.001). For the FCR shots (flat = 125, topspin = 301 and lob = 303) by 9 players, Kruskal-Wallis test showed no significant difference between the three spin levels. For the corresponding ball speed, the Kruskal-Wallis (p < 0.001) and subsequent Post-Hoc (p < 0.001) showed that flat hits had the significantly highest ball speed followed by topspin then lob accordingly for both muscles included shots. Our results suggest that coaches could consider recommending players to hit forehands with topspin in order to potentially reduce the risk of developing lateral elbow tendinopathy. [ABSTRACT FROM AUTHOR]

Published
2022
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66. Structural Topology Optimisation of the HEXAFLY-INT Vertical Fin

Author

Munk, David J, Vio, Gareth A, Verstraete, Dries, Villace, Victor F, and Steelant, Johan

Abstract

ispartof: Proceedings of HiSST ispartof: HiSST: International Conference on High-Speed Vehicle Science Technology location:Moscow, Russia date:26 Nov - 29 Nov 2018 status: published

Published
2018

84. Design Optimization and Analysis of Long-Range Hydrogen-Fuelled Hypersonic Cruise Vehicles

Author

Hendrick, Patrick, Verstraete, Dries, Vio, Gareth, Degrez, Gérard, Bottin, Benoit, Thornber, Ben, Dimitriadis, Gregorios, Sharifzadeh, Shayan, Hendrick, Patrick, Verstraete, Dries, Vio, Gareth, Degrez, Gérard, Bottin, Benoit, Thornber, Ben, Dimitriadis, Gregorios, and Sharifzadeh, Shayan

Abstract

Aviation industry is continuously growing especially for very long distance flights due to the globalisation of local economies around the world and the explosive economic growth in Asia. Reducing the time of intercontinental flights from 16-20 hours to 4 hours or less would therefore make the, already booming, ultra-long distance aviation sector even more attractive. To accomplish this drastic travel time reduction for civil transport, hypersonic cruise aircraft are considered as a potential cost-effective solution. Such vehicles should also be fuelled by liquid hydrogen, which is identified as the only viable propellant to achieve antipodal hypersonic flight with low environmental impact. Despite considerable research on hypersonic aircraft and hydrogen fuel, several major challenges should still be addressed before such airliner becomes reality. The current thesis is therefore motivated by the potential benefit of hydrogen-fuelled hypersonic cruise vehicles associated with their limited state-of-the-art.Hypersonic cruise aircraft require innovative structural configurations and thermal management solutions due to the extremely harsh flight environment, while the uncommon physical properties of liquid hydrogen, combined with high and long-term heat fluxes, introduce complex design and technological storage issues. Achieving hypersonic cruise vehicles is also complicated by the multidisciplinary nature of their design. In the scope of the present research, appropriate methodologies are developed to assess, design and optimize the thermo-structural model and the cryogenic fuel tanks of long-range hydrogen-fuelled hypersonic civil aircraft. Two notional vehicles, cruising at Mach 5 and Mach 8, are then investigated with the implemented methodologies. The design analysis of light yet highly insulated liquid hydrogen tanks for hypersonic cruise vehicles indicates an optimal gravimetric efficiency of 70-75% depending on insulation system, tank wall material, tank diamet, Doctorat en Sciences de l'ingénieur et technologie, This thesis was conducted in co-tutelle between University of Sydney and Université Libre de Bruxelles.Professor Dries Verstraete was my supervisor at the University of Sydney (so as a member of SydneyUni), but is automatically registered here as a member of ULB because he worked at ULB almost ten years ago.Ben Thornber is also a member of the University of Sydney but the application does not save it for an unknown reason., info:eu-repo/semantics/nonPublished

Published
2017

90. Multiobjective and multi-physics topology optimization using an updated smart normal constraint bi-directional evolutionary structural optimization method.

Author

Munk, David J., Kipouros, Timoleon, Vio, Gareth A., Parks, Geoffrey T., and Steven, Grant P.

Subjects
TOPOLOGICAL derivatives, STRUCTURAL optimization, PARETO distribution, PARETO analysis, MATHEMATICAL models, COMPUTER software
Abstract

To date the design of structures using topology optimization methods has mainly focused on single-objective problems. Since real-world design problems typically involve several different objectives, most of which counteract each other, it is desirable to present the designer with a set of Pareto optimal solutions that capture the trade-off between these objectives, known as a smart Pareto set. Thus far only the weighted sums and global criterion methods have been incorporated into topology optimization problems. Such methods are unable to produce evenly distributed smart Pareto sets. However, recently the smart normal constraint method has been shown to be capable of directly generating smart Pareto sets. Therefore, in the present work, an updated smart Normal Constraint Method is combined with a Bi-directional Evolutionary Structural Optimization (SNC-BESO) algorithm to produce smart Pareto sets for multiobjective topology optimization problems. Two examples are presented, showing that the Pareto solutions found by the SNC-BESO method make up a smart Pareto set. The first example, taken from the literature, shows the benefits of the SNC-BESO method. The second example is an industrial design problem for a micro fluidic mixer. Thus, the problem is multi-physics as well as multiobjective, highlighting the applicability of such methods to real-world problems. The results indicate that the method is capable of producing smart Pareto sets to industrial problems in an effective and efficient manner. [ABSTRACT FROM AUTHOR]

Published
2018
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