Modelling of unsteady aerodynamics for aircraft design

Abstract: This thesis present a simple mathematical prediction model for high angles of attack aerodynamics, including dynamic effects over delta wings, and an extension to full configuration. The model presented is intended for application in conceptual design and is extended to parameters identifications in preliminary design with validation against experimental data.The aerodynamic model is based on leading edge suction analogy. In order to extend it to high angles of attack and dynamic motions, internal state variables are used to describe the different flow conditions, or state, over the wing/aircraft.In conceptual design the parameters used are determined from geometrical considerations and analogies with delta wings. For slender delta wings, the parameters are determined from flow visualisation, determining the three transition states used here; potential, vortex and fully separated. Results from conceptual design have shown good agreement with published data and demonstrates the usefulness of integration of dynamic effects in aerodynamic predictions. To extend the mathematical model to later design phases and augment the accuracy, the parameters were determined from wind tunnel data. The results obtained then showed high accuracy in both static and dynamic cases.The results obtained both in conceptual design and from parameters identifications are suitable for flight simulation and stability analyses, and will allow the aircraft designer to increase his knowledge of the behaviour at high angles of attack and large pitch motions. The present model allows to keep the same mathematical structure through the entire design, the parameters being refined when new data is available from wind tunnel tests or CDF or flight tests.The present model will be included in a distributed aircraft analyse to simulate the whole aircraft including systems and sub-systems.