Boundary layer transition under high free-stream turbulence and strong acceleration conditions .2. Turbulent transport results

Measurements from heated boundary layers along a concave-curved test wail subject to high (initially 8 percent) free-stream turbulence intensity and strong (K = nu/U-infinity(2) dU(infinity)/dx, as high as 9 X 10(-6)) acceleration are presented and discussed Conditions for the experiments were chosen to simulate those present on the downstream half of the pressure side of a gas turbine airfoil. Turbulence statistics, including the turbulent shear stress, the turbulent heat flux, and the turbulent Prandtl number are presented. The transition zone is of extended length in spire of the high free-stream turbulence level. Turbulence quantities are strongly suppressed below values in unaccelerated turbulent boundary layers. Turbulent transport quantities rise with the intermittency, as the boundary layer proceeds through transition. Octant analysis shows a similar eddy structure in the present flow as was observed in transitional flows under low free-stream turbulence conditions. To the authors' knowledge, this is the first detailed documentation of a high free-stream-turbulence boundary layer flow in such a strong acceleration field.