Ozge Suelozgen, Matthias Wustenhagen

DOI Number: N/A

Conference number: IFASD-2019-081

The framework of this research paper concerns a phenomenon called ”flutter” which is a well-known dynamic aeroelastic instability caused by an interaction between structural vibrations and unsteady aerodynamic forces, whereby the level of vibration may trigger large amplitudes, eventually leading to catastrophic failure of the aircraft within a couple of seconds. Flutter prediction and flutter clearance are major issues in the design, development and certification process of an aircraft. Hence, it is mandatory for certification to guarantee that the aircraft is free from flutter throughout the entire flight envelope. Within the framework of the FLEXOP (Flutter Free FLight Envelope eXpansion for ecOnomic Performance improvement) project, an output-only operational modal parameter estimation algorithm in frequency domain has been implemented for monitoring the evolution of the aeroelastic modes for the nearly real-time surveillance of flutter. Therefore an integrated aeroelastic simulation model for the FLEXOP aircraft has been generated. This paper primarily addresses the application of the frequency-domain output-only Operational Modal Analysis (OMA) method during the simulated flight flutter test of the FLEXOP aircraft. An automatically running modal parameter estimation method called PolyMax will be introduced, which needs the measured responses of the aircraft preprocessed into output spectra. The output-only OMA requires non-deterministic natural and/or operational excitations which are provided by atmospheric turbulence excitation and/or pilot control inputs. In addition, a straightforward robust flutter analysis method in frequency-domain called µ-V method is presented. Robust flutter analysis deals with aeroelastic (or aeroservoelastic) stability analysis taking structural dynamics, aerodynamics and/or unmodeled system dynamics uncertainties into account [1]. The primary motivation of the robust flutter analysis is that this method allows the computation of the worst-case flutter velocity which can support the flight test program by a valuable robust flutter boundary.

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In Categories: Flight Testing, IFASD 2019
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