The Influence Of Free Stream Turbulence On The Zero Pressure Gradient Fully Turbulent Boundary Layer

Experimental research has been conducted to determine the influence of free-stream turbulence on zero pressure gradient fully turbulent boundary layer flow. During this period convective heat transfer coefficients, boundary layer mean velocity and temperature profile data, and wall static pressure distribution data were obtained for five flow conditions of constant free-stream velocity and free-stream turbulence intensities ranging from approximately 1/4% to 7%. Free-stream multi-component turbulence intensity, longitudinal integral scale, and spectral distributions were obtained for the various turbulence levels. The test results with 1/4% free-stream turbulence indicate that these data are in excellent agreement with classic two-dimensional low free-stream turbulence, turbulent boundary layer correlations, thus establishing the absolute accuracy of the experiment. The data obtained for the test cases with higher free-stream turbulence indicate that the turbulence has a significant effect on turbulent boundary layer skin friction and heat transfer. It has been shown that these effects are a function of the free-stream turbulence intensity, the turbulence length scale, and the boundary layer momentum thickness Reynolds number. Suggested correlations for the influence of free-stream turbulence on skin friction, heat transfer, and Reynolds analogy factor are given. Also during this period, a boundary layer prediction method has been assessed as to its ability to predict free-stream turbulence effects on flat plate heating and skin friction. Comparisons with the experimental data obtained here showed that adequate predictions can be made for this case with an existing turbulence model. (Author).