CA2205451A1

CA2205451A1 - Form drag reduced apparel, accessories, equipment, and vehicles for human-powered transportation and/or racing

Info

Publication number: CA2205451A1
Application number: CA 2205451
Authority: CA
Inventors: Hyoun Park
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-05-09
Filing date: 1997-05-09
Publication date: 1998-11-09

Description

CA 0220~4~1 1997-0~-09 ¦ ~3 o "Form Dr~ Reduced Apparel~ Acccs~ories~ Equipment~ and Vehicles for Human-P~ d Transportation and/or R~irl~"

Invention Background Traditionally and typically, apparel, iaccessories, eqllirm~nt~ and vehicles for~ oll~lion and/or racing have deliberately smooth sllrf~res in an attempt to improve the aerodynamics. Specifically, these smooth surfaces reduce skin friction (the frictional force impeding motion caused by the "rubbing" of the fluid or air against the object).
However, the total drag on the system by the fluid and/or wind is due to both skin friction and form drag (the force on the object impeding motion caused by fluid mechanic factors related to the shape of the object). Any practical means of form drag reduction that have not been implemented in the design of apparel, accessories, equipment, and vehicles for transportation and/or racing would be of great use.

Invention Summary This invention seeks to f~cilit~te the movement of objects and/or persons by reducing the form drag of any apparel, accessories, eqllipment and vehicles. This is accomplished by way of rough and/or dimpled s~lrf~ces covering in whole or in part the apparel, accessories, equipment, and vehicles. These rough and/or dimpled surfaces are used to trigger the formation of a turbulent boundary layer that produces a smaller flowseparation region or wake behind the objects and/or person in motion. This smaller separated region reduces the form drag on the objects and/or person allowing for faster movement.

Detailed Descl;~tion Under conditions where a smooth surface would produce a laminar boundary layer, a sufficiently rough and/or dimpled surface will trigger the formation of a turbulent boundary layer. The turbulent boundary layer (i) produces a smaller wake behind the object and/or person than a laminar boundary layer (2). Within this wake (3), the fluid and/or air circulates and is at a lower pl'eS:iule than the fluid and/or air impinging against the r~ "i"g surface. Since the ples~ule in front of the object and/or person and/or bodily part (4) is higher than that at the back of the object and/or person there is a net force impeding motion (5). The direction of motion is indicated (6) and the direction of fluid and/or air flow relative to the object and/or person and/or bodily part is also indicated (7). Since a turbulent boundary layer produces a smaller sep~led region or wake, the region where this dirr~.ellce in ~ is applied is reduced. This results in a reduction of the form drag component of the total drag on the system. In effect, in this way, the object, person, and/or bodily part becomes more aerodynamically stre~mlin~l This form drag reduced benefit applies to objects, persons, and/or bodily parts that are CA 0220~4~1 1997-0~-09 cylindrical and/or has any curved surfaces that are tangent to the direction of motion or flow. It must be stated that usually a turbulent boundary layer is not necess~ ;Iy desirable under high flow or speed conditions because it produces higher skin friction than a laminar boundary layer and the benefit of any reduced form drag is, under these high velocities, relatively small. However, under the conditions and speeds of human-powered transportation andlor racing, the benefits are significant.
These rough and/or dimpled surfaces which trigger the turbulent boundary layer are arranged in regular andlor irregular p~ttern~ covering in whole or in part the object and/or person. It is essçnti~l that the rough andlor dimpled surface be placed on the sides (8) of the object and/or person and/or bodily part and prefe.~bly in front, behind, on top and below as well to promote turbulent boundary layer triggering. The height, width, and/or depth of the small projections and/or dimples must be smaller than 1/2 of the effective meter of the object and/or person and/or bodily part. These surfaces can be made of cloth, plastic, glass, stone, and/or metal used to fashion or m~mlf~ *lre the body of the apparel, accessories, eq~ irm~nt, and vehicles. For example, a highly coarse weave of clothing m~t~ l can be used to give a sufficiently rough quality to the surface of the apparel to gain this benefit of form drag reduction. As well, as an example, the tubes forming the frame of a bicycle and/or cycling helmets can be m~mlf~ctured to incol~orate a rough and/or dimpled surface as part of the molding and/or m~nnf~ctllring process, again to gain form drag reduction. Furthermore, sllrf~re~ similar to sand paper ~tt~çlle~l to or build into the said m~tçri~l is also another example of a surface sufficient to gain from this form drag reduction. These surfaces can also be formed by a patch of clothing, plastic, stone, glass, and/or metal m~tçri~l that can be ~tt~ ecl to the apparel, accessories, eql-irment and vehicles by adhesive, sewing, Velcro(TM), or other methods of "~ent Examples of areas where these ~ulr~ces can be used to reduce form drag included the apparel, accessories, eqllipmPnt and/or vehicles used in cycling, skiing, ice-el~ting, inline-~ ting, rurming, and other similar activities.