Riblet structure and object
AssigneeJapan Aerospace Exploration Agency
InventorsKie Okabayashi, Yasuhiro Koshioka, Akira Nishizawa, Mitsuru Kurita, Hidetoshi Iijima
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Abstract
The present invention provides a riblet structure that further reduces drag, which is a sum of turbulent friction drag and pressure drag, and an object including such a riblet structure. An object such as an aircraft, plant, and pipeline includes a wavelike riblet pattern on a surface. The wavelike riblet pattern includes a large number of wavelike riblets. Each of the large number of wave riblets includes a wavelike ridge line, and a height thereof changes cyclically with respect to a fluid flow direction. With such a configuration, drag, which is a sum of turbulent friction drag and pressure drag, can be further reduced.
Claims4
A riblet structure, comprising
- a plurality of wavelike riblets,
- a height of each of the plurality of wavelike riblets being set in a first direction to become smaller as an angle formed between a ridge line and a surface of the riblet structure becomes larger,
- wherein a fluid flow direction is parallel to the surface of the riblet structure,
- wherein the first direction is perpendicular to the fluid flow direction,
- wherein the ridge line of each of the plurality of wavelike riblets has a sinusoidal shape of a first wavelength, and
- the height of each of the plurality of wavelike riblets increases/decreases in a sinusoidal shape of a second wavelength as a half wavelength of the first wavelength in the fluid flow direction.
An object, comprising
- a wavelike riblet pattern including wavelike ridge lines, a height of the wavelike riblet pattern in a first direction changing cyclically with respect to a surface of the object,
- wherein a fluid flow direction is parallel to the surface of the object,
- wherein the first direction is perpendicular to the fluid flow direction,
- wherein the wavelike ridge lines have a sinusoidal shape of a first wavelength, and
- the height of the wavelike riblet pattern increases/decreases in a sinusoidal shape of a second wavelength as a half wavelength of the first wavelength in the fluid flow direction.
Dependencies are inferred from the claim text.