Manipulation of the structure of a turbulent boundary layer

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6998399

Lynn, T B

Manipulation of a turbulent boundary layer for the purpose of net drag reduction is an attractive topic for research, because even modest success will result in large energy savings. The focus of this work is passive manipulation, one of the simplest manipulation techniques. The most-promising manipulator to date is the so-called BLADE device, consisting of two thin ribbons or foils suspended in the outer portion of the boundary layer. BLADE devices were devised and researched first at the Illinois Institute of Technology (IIT), and NASA Langley. When this research began, there was significant controversy over the magnitude of net drag reduction possible (20% reported by the IIT group) and the maximum skin friction reduction obtainable (50% reported by the IIT group). Accurate local skin-friction measurements were made using sublayer fences in a perturbed boundary layer. By comparing his direct measurements with those obtained by indirect methods, the author determined that the degree of drag reduction obtained depends on the method used to calculate the combined device drag and skin friction drag. Using auto and two-point correlation measurements as well as space-time correlations, effects of BLADE devices on the turbulent structures in the boundary layer, were studied, comparing them with wire devices, which are not known to produce a net reduction in drag.

• Research Organization: Yale Univ., New Haven, CT (USA)
• OSTI ID: 6998399
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420400* -- Engineering-- Heat Transfer & Fluid Flow
BOUNDARY LAYERS
DRAG
ENERGY CONSERVATION
FLUID FLOW
FRICTION
LAYERS
TURBULENT FLOW