Abstract: A method and system delay the laminar-to-turbulent transition of a supersonic or hypersonic boundary layer flow moving in a flow direction over a surface. For supersonic boundary layer flow, oblique first-mode instability waves present in the boundary layer and propagating at an oblique angle relative to the flow direction cause a laminar-to-turbulent transition in the boundary layer flow. These instability waves have a wavelength associated therewith in a direction perpendicular to the flow direction. Flow disruptors are used to generate modulations within the boundary layer flow wherein a wavelength of the modulations along the direction perpendicular to the flow direction is less than one-half of the wavelength of the instability waves.

Abstract: A method and system delay the laminar-to-turbulent transition of a supersonic or hypersonic boundary layer flow moving in a flow direction over a surface. For supersonic boundary layer flow, oblique first-mode instability waves present in the boundary layer and propagating at an oblique angle relative to the flow direction cause a laminar-to-turbulent transition in the boundary layer flow. These instability waves have a wavelength associated therewith in a direction perpendicular to the flow direction. Flow disruptors are used to generate modulations within the boundary layer flow wherein a wavelength of the modulations along the direction perpendicular to the flow direction is less than one-half of the wavelength of the instability waves.

Abstract: The invention relates to improved non-efflorescing cement-free and water-dispersible powder building material compositions comprising a homopolymer or copolymer as binder, useful for the preparation of wet formulations of plasters grouts, waterproofing coatings or mortars for the construction and the civil engineering industry. The binder is obtained by spray-drying or lyophilization of a dispersion containing a polymer and a protective colloid. These compositions also comprise a deprotection agent and a specific adsorbent filler. The invention also refers to the methods of preparation of these dry compositions and wet formulations, the application of these latter onto the surface of buildings or civil engineering works, the so obtained coatings as well as the so coated elements. The hardened products obtained therefrom are remarkably water-resistant, non efflorescent and easy to obtain.

Abstract: A dry powder composition for preparing a dry form of an acrylic finish is provided. The dry powder composition includes: calcium carbonate filler, coalescing aid, pH adjuster, and an acrylic-based re-dispersible polymer in powder form. In various embodiments, aggregate, silica sand, titanium dioxide, cellulose thickener, biocide, clay, cellulose fiber, mica filler, and/or defoamer are added. The dry powder composition can further comprise a hydrophobic agent. The dry powder can be mixed with a volume of water to produce a wet coating for application to a substrate.

Abstract: The invention relates to improved non-efflorescing cement-free and water-dispersible powder building material compositions comprising a homopolymer or copolymer as binder, useful for the preparation of wet formulations of plasters grouts, waterproofing coatings or mortars for the construction and the civil engineering industry. Redispersible dry composition of polymer finish comprising: a powdery organic binder included a polymer obtained by spray-drying or lyophilisation of a dispersion containing said polymer and a protective colloid; a deprotection agent; a specific adsorbent filler; and/or a load; and/or a water retentive agent; and/or a mineral rheological agent; and/or a defoamer; and/or a biocide; and/or a pigment. The invention also refers to the methods of preparation of these dry compositions and wet formulations, the application of these latter onto the surface of buildings or civil engineering works, the so obtained coatings as well as the so coated elements.

Abstract: A dry powder composition for preparing a dry form of an acrylic finish is provided. The dry powder composition includes: calcium carbonate filler, coalescing aid, pH adjuster, and an acrylic-based re-dispersible polymer in powder form. In various embodiments, aggregate, silica sand, titanium dioxide, cellulose thickener, biocide, clay, cellulose fiber, mica filler, and/or defoamer are added. The dry powder composition can further comprise a hydrophobic agent. The dry powder can be mixed with a volume of water to produce a wet coating for application to a substrate.