Carol Ann May

US Patent:

RE41398, Jun 29, 2010

Filed:

Feb 10, 2005

Appl. No.:

11/054719

Inventors:

Carol L. May - Falls Church VA, US
Gennadiy A. Voropayev - Kiev, UA

Assignee:

Cortana Corporation - Falls Church VA

International Classification:

G01N 19/02
G01N 3/56

US Classification:

73 10

Abstract:

A method is provided to select appropriate material properties for turbulent friction drag reduction, given a specific body configuration and freestream velocity. The method is based on a mathematical description of the balance of energy at the interface between the viscoelastic surface and the moving fluid, and permits determination of the interaction of turbulent boundary layer fluctuations with a viscoelastic layer by solving two subtasks—i. e. , a hydrodynamic problem and an elasticity problem, which are coupled by absorption and compliancy coefficients. Displacement, velocity, and energy transfer boundary conditions on a viscoelastic surface are determined, and a Reynolds stress type turbulence model is modified to account for redistribution of turbulent energy in the near-wall region of the boundary layer. The invention permits drag reduction by a coating with specified density, thickness, and complex shear modulus to be predicted for a given body geometry and freestream velocity. For practical applications, viscoelastic coatings may be combined with additional structure, including underlying wedges to minimize edge effects for coatings of finite length, and surface riblets, for stabilization of longitudinal vortices.

US Patent:

6516652, Feb 11, 2003

Filed:

Apr 10, 2000

Appl. No.:

09/546380

Inventors:

Carol L. May - Falls Church VA
Gennadiy A. Voropayev - Kiev, UA

Assignee:

Cortana Corporation - Falls Church VA

International Classification:

G01N 356

US Classification:

73 10

Abstract:

A method is provided to select appropriate material properties for turbulent friction drag reduction, given a specific body configuration and freestream velocity. The method is based on a mathematical description of the balance of energy at the interface between the viscoelastic surface and the moving fluid, and permits determination of the interaction of turbulent boundary layer fluctuations with a viscoelastic layer by solving two subtasksâi. e. , a hydrodynamic problem and an elasticity problem, which are coupled by absorption and compliancy coefficients. Displacement, velocity, and energy transfer boundary conditions on a viscoelastic surface are determined, and a Reynolds stress type turbulence model is modified to account for redistribution of turbulent energy in the near-wall of the boundary layer. The invention permits drag reduction by a coating with specified density, thickness, and complex shear modulus to be predicted for a given body geometry and freestream velocity. For practical applications, viscoelastic coatings may be combined with additional structure, including underlying wedges to minimize edge effects for coatings of finite length, and surface riblets, for stabilization of longitudinal vortices.