Title: CFD-Based Aeroservoelastic Predictions on a Benchmark Configuration Using the Transpiration Method
Author(s): C.H. Stephens
Date: July 1998
Pages: 204
Formats: pdf (2296 KB)
Abstract:
Scope and Method of Study:Surface transpiration has been applied to the BACT wind-tunnel model for the prediction of steady and unsteady flow calculations. The transpiration boundary condition was also used to simulate static control surface deflections, unsteady aeroelastic response, and controlled aeroservoelastic response of the BACT wing.
Transpiration has proven to be a very quick alternative to current grid deformation techniques. As opposed to deforming grid algorithms, or the re-meshing option, the transpiration method accounts for steady and unsteady surface deformations on an existing CFD grid through boundary condition modification. Using a superposition of the natural structural mode shapes, arbitrary structural deformations and velocities are accounted for through an additional transpiration velocity that essentially forces a change in the flow tangency boundary condition.
Application of the transpiration boundary condition allows the analysis of both continuous and discontinuous surface deformations. In the case of the BACT wing, a finite length trailing edge control surface is modeled without encountering difficulties with newly exposed surfaces or mesh shearing along the wing/control surface interface. In a culmination of efforts from steady control surface deflections, and the aeroelastic problem, the trailing edge control surface is used as a means of flutter suppression.
Findings and Conclusions:Results indicate the very good agreement between simulated and actual structural deformations, both modeled and experimental. Predicted flutter points agreed well with experimental data for a range of Mach numbers from 0.51 to 0.82. Finally, flutter suppression at Mach 0.51, 0.77, and 0.82 show the usefulness of the transpiration method in the full aeroservoelastic simulation.
Revised: October 25, 2000 [CHS]