Development of wake in presence of both curvature and pressure gradient

Measurements of mean velocity and turbulent stresses are carried out in the wake of an airfoil developing in a straight duct, in a curved duct of constant area and in a curved diffuser. Curvature and pressure gradient affect the mean flow and turbulent properties significantly. It is seen that curvature makes the wake asymmetric; the wake half width increasing on the inner side and decreasing on the outer side. With the additional presence of adverse pressure gradient the asymmetry increases. The velocity defect is found to be almost same in the straight duct and in the curved duct with mild curvature (b'avg/R = 1.4%) but the presence of the pressure gradient causes a slower decay of velocity defect. The effect of curvature is to make the Reynolds stresses and turbulent kinetic energy profiles more and more asymmetric with distance. When a pressure gradient is also present, the extent of asymmetry increases.