Twodimensional mass transfer from blade surfaces

The spanwise averaged (i.e. in the z direction around the middle blade) mass transfer Sherwood number from the mid-span blade surfaces are plotted in 4.1 for different mainstream Reynolds numbers and turbulence intensities.

On the pressure surface (fig. 4.1(a)), the mass transfer rates decrease drastically from the leading edge up to the separation at about Sp/C = 0.05 for all cases. After the reattachment and perhaps transition for the high mainstream turbulence intensity case (Tu=12.0%) at about Sp/C = 0.15, the average Sh number distribution becomes less smooth, especially at high mainstream Reynolds number, due to the existence of unsteady Taylor-Gortler vortices. Downstream of the reattachment, higher mass transfer rates are obtained at higher mainstream Reynolds number. The effect of high mainstream turbulence intensity is also obvious: earlier separation and much higher mass transfer rates after separation. The effects of mainstream Reynolds number and turbulence intensity on the turbulent transition near the trailing edge are, however, not clearly shown on the pressure side.

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