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Description:
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This work presents a numerical method for the analysis of fully nonlinear aeroelastic
problems . The aeroelastic model consisted of a Navier -Stokes flow solver , a nonlinear
structural model , and a solution methodology that assured synchronous interaction
between the nonlinear structure and the fluid flow .
The flow around the deforming wing was modeled as unsteady , compressible and
viscous using the Reynolds -averaged Navier -Stokes (RANS ) equations . To reduce the
computational time , a three -level multigrid algorithm was implemented and the flow
solver was parallelized . The message -passing interface (MPI ) standard libraries were
used for the parallel interprocessor communication .
The computational domain was divided into topologically identical layers that
spanned from the root to past the tip of the wing . A novel mesh deformation algorithm
was developed to deform the mesh as the structure of the wing was being displaced .
The mesh deformation algorithm was able to handle wing tip deformations of up to
60 % of the wing semi -span . Besides being robust , the mesh deforming algorithm was
computationally more efficient than regriding , since deforming an existing mesh was
computationally less expensive than generating a new mesh for each wing position .
Results are presented for the validation and verification of both the flow solver
and the aeroelastic solver . The flow solver was validated using : (1 ) the flow over
a flat plate , to validate the turbulent model implementation , and (2 ) the flow over
the NACA 0012 airfoil and over the F -5 wing , to validate the implementation of the convective and viscous fluxes , the time integration algorithm , and the boundary
conditions . The aeroelastic solver was validated using : (1 ) the unsteady F -5 wing
undergoing forced pitch motion , and (2 ) the Nonlinear Aeroelastic Test Apparatus
(NATA ) wing . In addition , aeroelastic results were generated for the Goland wing .
The aeroelastic solver developed herein allows the analysis of aeroelastic phenomena
using a fully nonlinear approach . Limit cycle oscillations , which are highly
nonlinear phenomena , were captured by the nonlinearities of the flow solver and the
structural solver . The impact of the nonlinearities was assessed for the Goland wing ,
where nonlinear terms changed dramatically the aeroelastic behavior of the wing . |