Realtime Computation of Wall Shapes in a Two-Dimensional Adaptive Test Section.

Abstract

By adapting solely top and bottom flexible walls of a solid-walled test section of rectangular cross section it can be achieved that the wall interferences (Mach number correction, angle of attack correction) are zero along the test section centreline, when testing three-dimensional models. The shapes of the flexible top and bottom walls are determined by the well- known Wedemeyer/Lamarche method of two-dimensional wall adaptation for three-dimensional models. The method performs the wall shape determination in a single computational step, at least when starting from the wall shapes of a preceding Mach number or angle of attack. It uses - in the original computer code of Lamarche - a numerical representation of the necessary mathematical operators. The computing time of 17 seconds on a personal computer could be reduced to 0.3 seconds by using an analytical representation of the operators - following a proposal of E. Wedemeyer. This facilitates the development of a high productivity strategy for wall adaptation in the modernized transonic facility of DLR Goettingen which is equipped with a two-dimensional adaptive test section of 1.0 m x 1.0 m.