Some Investigations into the Spanwise Non-Uniformity of Nominally Two-Dimensional Incompressible Boundary Layers Downstream of Gauze Screens

摘要

The investigations are aimed at assessing the importance of the type of screen for use in wind tunnels for various purposes. Spanwise boundary layer non-uniformity was investigated at low subsonic speeds for a wide range of conditions. All the experiments were done in one tunnel (a two-dimensional blower tunnel designed for boundary layer research) but by the use of vertical and horizontal central flat plates and a central flat splitter extending upstream to the gauzes the following variations were investigated, in addition to changing the open-area ratio and number of screens and the type of honeycomb: (a) Flow contraction in the plane of the test surface, by comparing vertical and horizontal flat plates. (b) Surface curvature of the contraction wall, by comparing rear wall with splitter. (c) Continuity of surface from screen, by comparing flat plate in test section with splitter. (d) Distance of measurement plane from screens along direction of flow. (Author)