ADVANCEMENT OF SEMI-ANALYTICAL METHODS FOR …
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11th World Congress on Computational Mechanics (WCCM XI) 5th European Conference on Computational Mechanics (ECCM V) 6th European Conference on Computational Fluid Dynamics (ECFD VI) July 20–25, 2014, Barcelona, Spain ADVANCEMENT OF SEMI-ANALYTICAL METHODS FOR SIMULATION OF AIRCRAFT DITCHING W. Gropengießer 1 , A. Tassin 2 , A. Korobkin 2 , M.J. Cooker 2 , L. Martin 3 and T. Rung 1 1 Institute for Fluid Dynamics and Ship Theory, Hamburg University of Technology, Schwarzenbergstraße 95C, 21073 Hamburg, Germany, [email protected], www.tuhh.de/fds 2 Mathematics, University of East Anglia, Norwich NR4 7TJ, United Kingdom, [email protected], www.uea.ac.uk/mathematics 3 Dassault Aviation, 78 Quai Marcel Dassault, 92552 Saint-Cloud, France, [email protected], www.dassault-aviation.com Key words: Fluid-Structure-Interaction, Coupled Problems, Multiphysics Computations. Figure 1: Hudson River ditching of US Airways Flight 1549 in 2009. Photo: [4] Figure 2: Simulation results of a semi-analytical approach for different ditching scenarios involv- ing an elastic fuselage material. The Hudson River ditching (Fig. 1) in 2009 has brought aircraft ditching into public attention. Since a significant fraction of air travel is over open water, ditching analysis is requested for the certification of civil aircraft by the authorities. The ditching process can be divided into three phases: first approach, then impact and thirdly flotation. Related certification requirements are devoted to the survivability for crew and passengers by minimising the risks for immediate injuries during the impact phase and the provision of fair chances for a subsequent evacuation during the flotation phase. These aims essentially restrict the impact loads and accelerations and demand a fair level of structural integrity to allow flotation. Engineering effort is usually focussed on an optimisation of the approach and impact conditions and the required strengthening of the structure.
Transcript of ADVANCEMENT OF SEMI-ANALYTICAL METHODS FOR …
11th World Congress on Computational Mechanics (WCCM XI)5th European Conference on Computational Mechanics (ECCM V)
6th European Conference on Computational Fluid Dynamics (ECFD VI)
July 20–25, 2014, Barcelona, Spain
ADVANCEMENT OF SEMI-ANALYTICAL METHODS FORSIMULATION OF AIRCRAFT DITCHING
W. Gropengießer1, A. Tassin2, A. Korobkin2, M.J. Cooker2, L. Martin3 andT. Rung1
1 Institute for Fluid Dynamics and Ship Theory, Hamburg University of Technology,Schwarzenbergstraße 95C, 21073 Hamburg, Germany, [email protected], www.tuhh.de/fds
2 Mathematics, University of East Anglia, Norwich NR4 7TJ, United Kingdom,[email protected], www.uea.ac.uk/mathematics
3 Dassault Aviation, 78 Quai Marcel Dassault, 92552 Saint-Cloud, France,[email protected], www.dassault-aviation.com
Key words: Fluid-Structure-Interaction, Coupled Problems, Multiphysics Computations.
Figure 1: Hudson River ditching of US AirwaysFlight 1549 in 2009. Photo: [4]
Figure 2: Simulation results of a semi-analyticalapproach for different ditching scenarios involv-ing an elastic fuselage material.
The Hudson River ditching (Fig. 1) in 2009 has brought aircraft ditching into publicattention. Since a significant fraction of air travel is over open water, ditching analysis isrequested for the certification of civil aircraft by the authorities. The ditching process canbe divided into three phases: first approach, then impact and thirdly flotation. Relatedcertification requirements are devoted to the survivability for crew and passengers byminimising the risks for immediate injuries during the impact phase and the provision offair chances for a subsequent evacuation during the flotation phase. These aims essentiallyrestrict the impact loads and accelerations and demand a fair level of structural integrity toallow flotation. Engineering effort is usually focussed on an optimisation of the approachand impact conditions and the required strengthening of the structure.
W. Gropengießer, A. Tassin, A. Korobkin, M.J. Cooker, L. Martin and T. Rung
Ditching physics is governed by violent flow dynamics, which includes simultaneous cav-itation, ventilation and slamming, and involves significant fluid-structure-interaction –e.g. the motion of the aircraft and the loss of components – and is unfortunately prone toscale effects. Thus, simulation tools have to be developed to support a safety-compliantaircraft design during all design phases. Accordingly, aircraft manufacturers are seekinga reliable and computationally efficient approach to the prediction of ditching loads.
The paper aims to advocate the benefits of real-time ditching-simulation approaches thatcan be used for rapid sensitivity studies in an industrial context and might even be usedto train pilots. To enhance the computational efficiency, emphasis is given to flow-physicsmodelling rather than resolution aspects. Accordingly, baseline approaches using semi-analytical impact models by e.g. Wagner [1], von Karman [2] or the Modified LogvinovichModel (MLM) [3] will be discussed in conjunction with refined models for complex flowphenomena - such as flow separation, ventilation or cavitation. Furthermore, the impor-tance of modelling the loss and drag of appendages (engines, landing gear) and niches willbe outlined.
Validation studies will be reported for a number of generic and industrial cases, the latterreferring to complete aircraft configurations. Results obtained from the semi-analyticalmethods will be compared with predictions of sophisticated simulation techniques suchas mesh-based and mesh-less Navier-Stokes approaches as well as high velocity impactexperiments conducted by INSEAN within the European FP7 SMAES project.
Figure 3: NACA TN2929 J-body ditching experiment: Comparison of test result (green) and Ditchsimulation (red) for pitch attitude (top) and height of center of gravity above water (bottom).
REFERENCES
[1] H. Wagner, Uber Stoß und Gleitvorgange an der Oberflache von Flussigkeiten,Zeitschrift fur Angew. Mathematik und Mechanik 12(4), Berlin, pp. 193-215, 1932
[2] T. von Karman, The Impact on Seaplane Floats During Landing, Technical Note321, National Advisory Committee for Aeronautics (NACA), Washington, 1929
[3] A. Tassin, D.J. Piro, A.A. Korobkin, K.J. Maki, and M.J. Cooker, Two-dimensionalwater entry and exit of a body whose shape varies in time, Journal of Fluids andStructures, 2013
[4] Associated Press photo/Janis Krums, Purdue University News Service (2 Sept. 2010),<http://www.purdue.edu/newsroom/events/2010/100902CordovaSullenberger.html>,viewed 9 Dec. 2013
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