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Certification is the most demanding potential application for simulation. For a decision
about the safety of an aircraft to be based on calculations, a high degree
of certainty in the results would be required. How this certainty might be established
is the research topic of ECERTA. The goal is to establish methodology which can
contribute to establishing confidence in simulation results. Aeroelastic certification
is used as the particular example since this topic fits well with the team's past
experience. It is expected that the conclusions of the research will be applicable
more widely.
The first task of the project was to define more precisely what "establishing confidence"
involves, and to translate this into expanded methodology for simulation. At a high level we might
identify the following as the requirements for "confidence": we should be able to
- simulate the complete aircraft problem, with the minimum of simplifications
required. For aeroelastic certification, this means having the option to include
CFD based aerodynamic predictions, nonlinear structural effects, trimming and the flight
control system, full geometry and structural damping
- predict undesired behaviour in small regions of the flight envelope without
any prior knowledge of its existence
- identify the important weaknesses in the simulation, including the influence of uncertainties in
input parameters
- design physical tests that would provide data to remove the main uncertainties in
the predictions.
At a lower level of detail, research was targetted at the following areas:
- Complete aircraft modelling:
- how can the representation of structural damping be improved?
- Flight envelope search:
- how can CFD based flutter tools be made to run order of magnitude more efficiently
than time domain tools to allow flight envelope search?
- how can a hierarchy of aerodynamic tools be coordinated to search the flight envelope?
- Accomodate uncertainties
- develop methodologies that allow structural parameter uncertainty to be propagated to
the uncertainty in flutter speed through CFD based simulations
- how can an aerodynamic model be parameterised to allow uncertainty in the aerodynamic
predictions to be propagated to the flutter speed
Contact
Ken Badcock
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