Experimental and Analytical Study of the Effects of Free-Stream Turbulence on Turbulent Boundary Layers with Heat Transfer.

摘要

Under the present investigation, detailed boundary layer turbulence structural data and turbulent heat transfer data were obtained for experimental test conditions and profile locations selected from the earlier text matrix. Numerous measurements assured that the present test conditions (boundary layer development and free-stream turbulence distributions) duplicated those of the earlier AFOSR contract. The purposes for making these present detailed boundary layer turbulence measurements were: (1) to provide data to which current finite-difference boundary layer turbulence models could be compared, and (2) to generate a data base for the development of new analytical models for boundary layer heat transfer prediction. The results from the present program have shown that the distributions of both the turbulence kinetic energy and the turbulence structural coefficients were affected by increased levels of free-stream turbulence. Local profile measurements indicated that the effect of increased free-stream turbulence was to decrease the near-wall turbulent Prandtl number relative to values expected for low free-stream turbulence. Turbulent Prandtl numbers in the outer region of the boundary layer were slightly increased for higher free-stream turbulence. A turbulence dependent correlation for the measured distribution of turbulent Prandtl number is given.