Date of Award
Doctor of Philosophy (PhD)
Mechanical & Aerospace Engineering
Duc T. Nguyen
Aeroelasticity is a classical discipline. However, even with recent advancement in computational technology, it still remains a challenging discipline. This is particularly true when aeroelasticity problems are solved in a loosely coupled manner. The advantage of a loosely coupled scheme is that the legacy codes of computational fluid dynamics (CFD) and computational structural mechanics (CSM) can be preserved and used as independent modules in solving the desired aeroelasticity problems. In such a scheme, maintaining proper data transfer (load transfer and deformation tracking between CFD and CSM codes) is crucial in ensuring successful coupled solutions. This can be a challenging task because the interface (the wetted area or the outer mold line) may be discretized differently as required by different levels of computational domains, which leads to mismatch and even gaps. Most published works overcome these drawbacks by transferring the aerodynamic loads and elastic deformation through projection and curve-fitting. The projection is used to find the “host” node, element or Gaussian point from a CSM mesh to the associated CFD mesh, or vice versa. It is then followed by local or global curve-fitting so that the nodal values on the projected surface can be extracted from interpolation. Most of these works can not guarantee a “consistent and conservative” load transfer. Further, they have not adequately demonstrated their availability to support coupled sensitivity analysis.
A new remeshing scheme that can guarantee consistent and conservative load transfer and smooth deformation tracking between CFD and CSM is proposed here not only for coupled analysis, but also for coupled sensitivity analysis. The method will introduce an artificial interface structure that is confined with the aerodynamic surface mesh and is supported at the structural surface nodes. This structure is used to redistribute the aerodynamic load as well as the structural deformation. With the help of this artificial structure, the same design parameter that guides the remeshing processes of the structural mesh can be used to guide the remesh processes of the artificial interface structural mesh as well as the aerodynamic interior mesh. This particular feature of the proposed remeshing scheme allows the aerodynamic sensitivity coefficients of a rigid wing to be predetermined and later used for coupled sensitivity analysis that includes only the structural sensitivity code in an iterative routine.
A flexible wing with a 3-dimensional Euler flow and a linear finite element model is considered in the present work to demonstrate the proposed scheme for coupled analysis and sensitivity analysis. Preliminary results obtained from the optimization process are presented to substantiate the efficiency of proposed schemes.
"Multidisciplinary Sensitivity Analysis and Design Optimization of Flexible Wings Using the Euler Equations on Unstructured Grids"
(1999). Doctor of Philosophy (PhD), Dissertation, Mechanical & Aerospace Engineering, Old Dominion University, DOI: 10.25777/tpaj-fs41