Amongst the objectives of the EU's Green Rotorcraft programme is the development of a functional and airworthy Active Gurney Flap (AGF) for a full-scale helicopter rotor blade. Interest in the development of this 'smart adaptive rotor blade' technology lies in its potential to provide a number of aerodynamic benefits, which would in turn translate into a reduction in fuel consumption and noise levels. With a technical specification informed by helicopter manufacturer Agusta Westland as a starting point, the AGF concept developed emerged from the application of a design methodology consisting of an initial concept generation phase and a subsequent selection process based on a series of problem-specific qualitative and quantitative performance criteria. This methodology resulted in a novel AGF concept design where the use of flexural pivots was favoured over bearing-type joints. As a first step towards full validation of both the concept design and the theoretical aerodynamic benefits of the AGF, a baseline design of the mechanism was successfully tested both in a fatigue rig and in a 2D wind tunnel environment at flight-representative deployment schedules. This baseline design was then reengineered with a view to making it fit for flight test. However, analysis of the flight test baseline design under full in-flight loading and blade deformations revealed that the stresses arising in the flexures exceeded the allowable limits. In order to overcome this problem, two complementary alternatives were investigated. Initially, a generic 2D and 3D shape optimisation of leaf-type crossed flexure pivot springs was carried out considering the pivots as individual isolated elements. This route produced important novel results in the field of crossed flexure pivots and proved that there is great scope for stress reduction through shape optimisation. Furthermore, a parametric optimisation of the AGF mechanism as a whole was performed, where the effect of a range of topological parameters was investigated. This second approach resulted in very significant stress reductions" sufficient so as to conclude that the proposed AGF concept has potential to become an airworthy design, although further work is needed to achieve a sufficiently mature technology readiness level.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:690378 |
| Date | January 2015 |
| Creators | Gómez, Jon Freire |
| Publisher | University of Bristol |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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