METHOD OF AND APPARATUS FOR CONTROLLING TURBULENCE IN BOUNDARY LAYER AND OTHER WALL-BOUNDED FLUID FLOW FIELDS

摘要

Turbulence is controlled in boundary layer or wallbounded fluid flow fields having a turbulent wall region characterized by a system of roll pairs extending in the direction of flow, and obliquely propagating structures interacting with the system of roll pairs, by locally introducing into the turbulent wall region two separate disturbances that are effective to produce, in a local region, a composite disturbance field that is strongly coupled to and modifies the obliquely propagating structures in a manner that increases or decreases the interaction of the propagating structures with the system of roll pairs thereby locally increasing or decreasing the turbulence in the flow field. One of the disturbances may result from the interaction of the fluid with a linear strip, or an array of strips, of delta-shaped protrusions positioned spanwise on the wall (i.e., transverse to the flow direction); and the second disturbance may result from injecting sonic energy into the local region. Furthermore, a linear strip or an array of airfoil shaped protrusions can be used for producing a pair of counter rotating rolls for controlling turbulence in the boundary layer.