초록 ▼

Turbulence is controlled in boundary layer or wall-bounded 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 turb

Turbulence is controlled in boundary layer or wall-bounded 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.

대표청구항 ▼

A method for controlling turbulence in boundary layer or other wall-bounded fluid flow field having a turbulent wall region characterized by a system of roll pairs or steaks whose diameter is functionally related to the strength of the flow, and which extend in the direction of flow, and by propagat

A method for controlling turbulence in boundary layer or other wall-bounded fluid flow field having a turbulent wall region characterized by a system of roll pairs or steaks whose diameter is functionally related to the strength of the flow, and which extend in the direction of flow, and by propagating structures of coherent patterns that propagate obliquely to the direction of flow at a substantially constant group speed, said method including introducing into the turbulent wall region two separate disturbances that are effective in said region to produce 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 for locally increasing or decreasing the turbulence in the flow field.