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Session: Aeroelastic testing 5
Session starts: Thursday 20 June, 13:30
Presentation starts: 14:00
Room: Room 1.6

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Jos Aalbers (NLR)
Peter Blom (NLR)
Huub Timmermans (NLR)

Abstract:
In today’s search for lighter and more efficient aircraft significant research is spent on optimizing the structural and aerodynamic aircraft properties. One of the ways to reduce aerodynamic drag due to lift is by increasing the aspect ratio of the wing. However, this raises the structural flexibility resulting in significant challenges on aero-elastic stability. Disturbances such as gusts in the flow potentially could disturb the flow leading to instable behaviour resulting in loss of structural integrity. Control surfaces can be used to alleviate the structural loads and stabilize the wing due to a gust. One of the research goals of the Clean Aviation UP WING project is to test a wind tunnel model in transonic conditions and disturb the incoming flow using a ‘gust-rig’. In this paper an aero-elastic analysis of the UP WING wind tunnel model will be presented. Specifically, as a result of the high flexibility of the wing, the flight shape during nominal test conditions may be significantly different from the jig shape. This results in a ‘pre-stressed’ structure, which may have different dynamic structural properties such as mode shapes and eigen frequencies. Due to the high deformations, this may be beyond the validity of linear structural methods. In the first part of the paper a method will be presented how to obtain the flight shape using a coupling between the aerodynamics and the structure solvers. Regarding computation of the aerodynamic forces, a low-fidelity method based on potential theory (ZAERO) will be presented and a high-fidelity method will be presented based on NLR’s in-house tool (ENSOLV). On the structural side a MSC NASTRAN non-linear solution will be used allowing for large deflections. In the second part of the paper a one-minus-cosine gust will be applied to the newly obtained flight shape to see the effect of the pre-stressed structure.