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Summary of Flow Modulation and Fluid-Structure Interaction Findings Results of the Collaborative Research Center SFB 401 at the RWTH Aachen University, Aachen, Germany, 1997-2008

:	Wolfgang Schröder
:	Wolfgang Schröder
:	Summary of Flow Modulation and Fluid-Structure Interaction Findings Results of the Collaborative Research Center SFB 401 at the RWTH Aachen University, Aachen, Germany, 1997-2008
:	Springer-Verlag
:	9783642040887
:	1
:	CHF 189.50
:

:	Luft- und Raumfahrttechnik
:	English

:	420
:	Wasserzeichen/DRM
:	PC/MAC/eReader/Tablet
:	PDF

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"Development of a Modular Method for Computational Aero-structural Analysis of Aircraft(S. 205-206)

Lars Reimer, Carsten Braun, GeorgWellmer, Marek Behr, and Josef Ballmann

Abstract.This paper outlines the development of the aero-structural dynamics method SOFIA over the duration of the Collaborative Research Center SFB 401. The algorithms SOFIA applies for the spatial and the temporal aero-structural dynamics coupling are presented. It is described in particular how SOFIA’s load and deformation transfer algorithms suitable for non-matching grids at the coupling interface were enhanced towards the application to complete aircraft configurations. The application of SOFIA to various subsonic and transonic aeroelastic test cases is discussed.

1 Introduction

The design of high-performance wings for large commercial aircraft requires the inclusion of their aeroelastic properties into the aerodynamic and structural design process. During preliminary design, the geometry of the wing is defined as a compromise between good flight performance during take-off, landing and cruise flight on the one hand and load capacity and weight of the structure on the other hand. In an iterative fashion, the aerodynamic shape, the loads, the construction of the wing assembly and the deformation are studied sequentially and more or less independently. Aerodynamic wind tunnel testing with rigid or nearly-rigid reduced-scale models plays a key role.

But in those tests, similarity with the full scale body can only be achieved in a very limited manner, primarily with respect to the aerodynamic parameter Mach number and to a certain extent also with respect to the Reynolds number. Aeroelastic similarity is usually not achieved. Based on the aerodynamic analysis, wing loads, deformations and particularly the aerodynamic twist are determined. Then the wing geometry and construction of the wing assembly are modi- fied a posteriori so that after taking into account the static aeroelastic deformation in cruise flight sufficient lift and minimum drag are ensured.

The described design and construction procedure requires several iterations because in every step the aeroelastic coupling and the nonlinearity of the problem cannot be captured completely. Besides that, nonlinear flutter possibly occuring in the transonic flow regime cannot be predicted with such a procedure. Therefore it is necessary to develop numerical methods, which reliably predict the interaction between aerodynamic, structural and inertial forces. Such a numerical method has been progressively developed in the past four funding periods of the Collaborative Research Center SFB 401 Flow Modulation and Fluid-Structure Interaction at Airplane Wings at RWTH Aachen University. This paper gives an overview about this numerical method named SOFIA and its past and present development stages. The organization of the subsequent sections of this paper is as follows."

	Title Page	2
	Preface	6
	Contents	8
	List of Contributors	10
	Introduction	14
	Vortex Sheets of Aircraft in Takeoff and Landing	18
	Introduction	19
	Experimental Facilities	20
	Wind Tunnel	20
	Water Tunnel	20
	Towing Tank	21
	Measurement Instrumentation	22
	Hot-Wire Anemometry	22
	Particle Image Velocimetry	22
	Model	23
	Results	24
	Near Field	24
	Extended Near Field	28
	Far Field	32
	Force Fluctuations	37
	Conclusion	38
	References	39
	An Adaptive Implicit Finite Volume Scheme for Compressible Turbulent Flows about Elastic Configurations	41
	Introduction	41
	Physical Model	43
	Governing Equations	43
	Turbulence Models	44
	Transition Modeling	46
	Boundary Conditions	48
	Numerical Methods	48
	Finite Volume Scheme	48
	Matrix-Free Newton-Krylov Method	52
	Fluid Structure Interaction	53
	Results	53
	Fishtail	54
	Laminar Flat Plate	55
	Transitional Flow over a Flat Plate	56
	High-Lift Configuration	57
	BAC 3-11 Airfoil - Shock Buffet	60
	FSI - HIRENASD	60
	Performance of the Matrix-Free Newton-Krylov Method	63
	Conclusion	65
	References	65
	Timestep Control for Weakly Instationary Flows	68
	Introduction	68
	Governing Equations and Finite Volume Scheme	70
	Adjoint Error Control - Adaptation in Time	72
	Variational Formulation	72
	Adjoint Error Representation for Target Functionals	73
	Space-Time Splitting	74
	The Conservative Dual Problem	75
	Adaptive Concept	76