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Turbulent boundary layer over a flat plate with strong stepwise heating

Conference ·
OSTI ID:7031321

The turbulent boundary layer over a flat plate with stepwise wall temperature rise from room temperature to 1250/sup 0/K and free stream velocity of 10.5 m/s was studied. Thermal structures in the heated boundary layer were observed using high-speed schlieren cine. Mean and root-mean-square (rms) density distributions were obtained from Rayleigh scattering intensity measurements. Velocity statistics were provided by a single-component laser Doppler velocimetry (LDV) system. Mean and rms velocity profiles, the Reynolds stress, the streamwise and the cross-stream turbulent kinetic energy diffusion were determined. Data were collected by a computer-based data acquisition and control system. The overall shape of the thermal structures observed in the schlieren pictures of the heated boundary layer is similar to that of the large-scale turbulent structures in an isothermal turbulent boundary layer. Strong wall heating causes expansion of the boundary layer, but the effects of heating on the mean and rms velocities are small. The Reynolds stress near the surface is reduced due to the density decrease. The most important effect of the strong stepwise temperature rise is to change the turbulent kinetic energy diffusion pattern. Significant streamwise diffusion of kinetic energy is induced near the leading edge of the heating section, suggesting that in modeling this flow a modification of the boundary layer assumption would be required in this region.

Research Organization:
Lawrence Berkeley Lab., CA (USA)
DOE Contract Number:
AC03-76SF00098
OSTI ID:
7031321
Report Number(s):
LBL-14942; CONF-820706-3; ON: DE83001554
Country of Publication:
United States
Language:
English