Flows generated by the interaction of an inlet and a cross-flow

The structure of the flow generated by the interaction of suction into a circular inlet and a cross-flow was studied using flow visualization and measurements with hot-wire and yaw probes. Surface flow visualization tests allowed the identification of a distinct and repeatable flow pattern in the horizontal plane close to the surface, characterized by critical points, i.e. a nodal separation point behind the inlet with adjacent saddle points lying symmetrically on either side of the node. The flow pattern can be divided into four separate regions. In the aft flow region, the measurements show that the velocity changes very rapidly with distance from the surface in terms of flow yaw angle as well as magnitude. This trend is also found, but to a lesser extent, in the external flow region. The ratio of the inlet velocity to the cross-flow velocity influences the relative location and extent of the flow domains. The yaw and velocity measurements exhibit a highly complex and segmented shear layer structure in the boundary layer. The shear layer is shown to be highly skewed and generally dissimilar to the nominal profile of two-dimensional turbulent boundary layer theory. The boundary layer structure is very different from that modelled by standard wall laws due to considerable pressure gradients at the surface and the complex shear layer.