A method of micro-texturing a surface is disclosed. The method includes printing an etchant onto a substrate surface and forming a micro-texture on the substrate surface by removing material from the substrate surface.

A vortex generator for use in a flowtube of a meter is provided. The vortex generator includes a plurality of raised elements on an inner surface of a flowtube. The plurality of raised elements are positioned on the inner surface of the flowtube upstream of a widening of the flowtube. The presence of the plurality of raised elements improves boundary layer adherence. Related systems and meters are provided.

A coating apparatus for the reduction of aerodynamic noise and vibrations. The coating apparatus is configured to include a group of fibrillar structures, wherein each fibrillar structure is configured with a diverging tip so that the coating reduces the size of and shifts downstream, a separation bubble, and modulates large-scale recirculating motion. Each fibrillar structure can be configured as a cylindrical micropillar. The group of fibrillar structures can be configured as a group of uniformly distributed cylindrical micropillars (e.g., one or more micropillar arrays). The surface coating is effective in reducing the separation bubble and displacing the separation bubble downstream. The coating facilitates a reduction in noise (e.g., aerodynamic noise) and vibrations due to the reduction in the size of the separation bubble.

A phononic material includes an interface surface and a subsurface feature mechanically connected to the interface surface. When a hypersonic flow having at least one instability flows past the interface surface, the interface surface vibrates in response to one or more frequency components of the pressure. The interface surface couples each frequency component into the subsurface feature, which at least partially reflects and phase-shifts each frequency component to generate a corresponding phase-shifted frequency component. The interface surface vibrates in response to the phase-shifted frequency component, thereby coupling the phase-shifted frequency component back into the hypersonic flow. The phase-shifted frequency component interferes with said each frequency component within the hypersonic flow. The subsurface feature may perform phase-shifting such that the phase-shifted frequency component destructively interferes with said each frequency component, thereby reducing the at least one instability.

An airflow profile structure having a leading and/or trailing edge profiled with a serrated profile having a succession of teeth and depressions. Along the leading and/or trailing edge, from a first location to a second location, the teeth of the serrated profile are individually inclined towards the second location.

A compressor blade having a leading edge and a trailing edge, and a surface pattern between the leading and trailing edges, the surface pattern comprising at least one set of herringbone riblets formed of a plurality of v-shaped riblets, wherein the v-shaped riblets are spaced apart by a distance of between 200-400 m, and have a height of between 50-120 m.

A structural component for a vehicle has a surface with a riblet structure. The riblet structure includes a plurality of grooves, including a first groove having a first longitudinal section forming a first angle with a main longitudinal direction of the structural component. The first angle is larger than 0 and the main longitudinal direction corresponds to a flow direction of a fluid along the surface of the structural component.

Wavy riblets are disposed at one or more auditorily important acoustical boundary layers of a sound producing device. Wavy riblets can be deployed directly onto the surface of the device, and/or onto a film or other carrier that is then positioned in or on the device. Wavy riblets can be advantageously deployed in sets, in a herringbone pattern, and sets of smaller riblets can be disposed between sets of larger riblets. Wavy riblets can also be superimposed onto other wavy or non-wavy riblets. Contemplated sound producing devices include speakers, musical instruments, fan blades and ducts.

An aerodynamic element is provided with at least one set of protruding elements, each of the protruding elements is produced in the form of an elongate and profiled rib projecting from a surface of the aerodynamic element. The protruding elements are arranged at the surface of the aerodynamic element, one beside the other, being oriented substantially parallel to one another so that each of them generates a vortex, the set of vortices thus generated making it possible to reduce crossflow instability.

A method of applying a riblet structure coating on the internal surface of a pipe includes coating the internal surface of a pipe with a resin layer and applying a cavity mold having a reverse riblet pattern structure to the coated internal surface of the pipe. A flexible air bag is inserted into the interior of the pipe and charged with air to hold the mold against the coated internal surface of the pipe. The air bag may be charged with air for a sufficient amount of time to allow the coating to cure in the riblet shape of the mold. Afterwards, the air bag and the mold are removed from the pipe to yield a pipe coated with an internal riblet structure.