Conversaziones were held on 19 May and 28 June 1955. At the first there were thirty-six exhibits, covering a wide range of research activities. An acoustical demonstration of the instability of the laminar boundary layer on a rotating disk was given by Mr N. Gregory, Mr J. T. Stuart and Mr W. S. Walker, of the Aerodynamics Division, National Physical Laboratory. The rotating disk illustrates a phenomenon which also occurs in the flow over the swept wings of modern aircraft, the instability in the latter case being due to the growth of self-amplifying vortices in the three-dimensional boundary layer over the nose of the wing. By using a stethoscope the vibrations produced by the vortices and by the random turbulent fluctuations at the edge of the disk can clearly be heard.
Transonic buffet instability: From two-dimensional airfoils to three-dimensional swept wings
