Turbulence measurements in a developing mixing layer with mild destabilising curvature

Single-point hot-wire measurements have been made in the developing regions of a plane and an unstably curved single-stream mixing layer. In each case the high-velocity potential flow was constrained by a solid surface to form a thick wall jet. The mean flow in the plane layer had reached approximate self-similarity before the turbulent region reached the surface at a point corresponding to the maximum length Reynolds number of 10⁶ but turbulence quantities, particularly the individual normal stresses, were still changing appreciably with downstream distance. The curved mixing layer created by a convex surface had a spreading rate 9% greater than that of the plane flow with increases of 14% in the maximum level of shear stress.