The turbulent flows in a low speed wind tunnel of the flow around the reattaching region due to a backward-facing step with and without a bevelled edge have been investigated using LDA. Experimental results revealed that the logarithmic law of the wall does not hold in the near-wall region. The Reynolds normal stresses and streamwise turbulence intensities decreases rapidly near the reattachment point and continues to decay downstream from the reattachment point. The reattachment length is increased by raising the step height and decreased with the step bevelled to a smaller angle. Such difference in reattachment lengths may be attributed to the change of adverse pressure gradient. The flow and turbulence structure very near the wall zone showed that the shear stress throughout the layer is predominantly viscous, even though the fluctuation levels are very high. The results suggested that the flow is laminar-like for the region from the wall surface to the region of maximum local back-flow velocity.
|Number of pages||8|
|Journal||Journal of the Chinese Society of Mechanical Engineers, Transactions of the Chinese Institute of Engineers, Series C/Chung-Kuo Chi Hsueh Kung Ch'eng Hsuebo Pao|
|State||Published - Dec 1991|