CHARACTERISTICS OF TURBULENT BOUNDARY LAYERS AT HIGH FREE-STREAM TURBULENCE.

Experimental data on the effect of the free-stream turbulence Tu on the structure of a flat turbulent boundary layer at Re equals 4 multiplied by (times) 10**5 are presented. It is shown that a variation in Tu from 0. 76 to 6. 85% significantly increases the thickness of the turbulent boundary layer with a simultaneous rise in the shear stress at the wall, reduction in shape factor and of the rate of generation of disturbances in the boundary layer. The redistribution of components of fluctuations at Tu greater than 1. 7% results in corresponding changes in the kinetic energy of turbulence, and the correlation coefficients become universal at Tu less than equivalent to 3. 52%. The results point to a high sensitivity of the flow microstructure to external turbulence.