A modular generic optimization scheme is applied to CFD-based shape optimization of helicopter rotors in hovering flight. An efficient domain element shape parameterization method is linked to a radial basis function global interpolation to provide direct transfer of domain element movements into deformations of the design surface and the CFD volume mesh, which is deformed in a high-quality fashion, and the parameterization method requires very few design variables to allow free-form design. The method of shape and CFD mesh parameterization is independent of mesh type (structured or undstructured) and optimization independence from the flow solver (inviscid, viscous, aeroelastic) is achieved by obtaining sensitivity information for an advanced parallel gradient-based algorithm by finite-difference. This has resulted in a flexible and versatile method of "wrap around" optimization. Previous fixed-wing results have shown that a large proportion of the design space is accessible with the parameterization method and heavily constrained drag optimization has shown that significant improvements over existing designs can be achieved. In the present work, the method is extended to a rotor blade, and this is optimized for minimum torque in hovering flight with rigid constraints in thrust, internal volume and pitching moments. Initial results presented here using only twist parameters, at two levels, global and local, as a method of both validating the approach and investigating the effects of different parameterization levels. Torque reductions of 9% are shown for a fully subsonic case, and 15% for a transonic case, using only three and 15 twist parameters.
|Translated title of the contribution||CFD-based aerodynamic shape optimization of hovering rotors|
|Title of host publication||27th AIAA Applied Aerodynamics Conference, San Antonio, Texas, USA|
|Number of pages||13|
|Publication status||Published - Jun 2009|
Bibliographical noteConference Organiser: AIAA
Other identifier: AIAA 2009-3522