An Experimental Study of the Intermittent Region of a Corner Turbulent Boundary Layer : Fluids Engineering

Abstract

An experimental investigation is reported of the zero pressure gradient boundary layer along a 90 degree streamwise corner. Turbulent and non-turbulent conditional sampling measurements in the outer intermittent region of the boundary layer as well as a comprehensive set of conventional measurements were made in a cross section 1.7m downstream from the leading edge. The results of a turbulent zone-averaged secondary velocity field indicate a pair of closed streamwise vortex patterns near the corner, as in conventional measurements. A large difference was found in the outer part of the boundary layer, where the turbulent zone-averaged secondary flow moves from the wall to the free stream direction. On the contrary, the non-turbulent zone-averaged counterpart moves from the free stream to the wall and it includes almost no streamwise vorticity, indicating that the secondary flow of the second kind is generated only when the flow is turbulent.