The effect of length scale of free stream turbulence on boundary layer transition

Abstract

The present experiment focused on revealing effect of scale and directional component of free stream turbulence on boundary layer transition, especially growth rate of disturbance energy in the boundary layer. The free stream turbulence generated by a turbulence grid mounted upstream of the contraction has typical character of axisymmetric turbulence with strong anisotropy. The experimental results with anisotropic free stream turbulence show the non-modal growth disturbance even at 0.7 % turbulence intensity. The correlation between the filtered free stream fluctuation and growth rates of the disturbance in the boundary layer suggests that the wall-normal velocity fluctuation in the free stream dominates the disturbance growth. © 2006 Springer.