WO1997008966A1 - Reducing drag on bodies moving through fluid mediums - Google Patents
Reducing drag on bodies moving through fluid mediums Download PDFInfo
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- WO1997008966A1 WO1997008966A1 PCT/US1996/014362 US9614362W WO9708966A1 WO 1997008966 A1 WO1997008966 A1 WO 1997008966A1 US 9614362 W US9614362 W US 9614362W WO 9708966 A1 WO9708966 A1 WO 9708966A1
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- WIPO (PCT)
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- line
- human body
- protuberance
- stagnation
- εaid
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- A—HUMAN NECESSITIES
- A41—WEARING APPAREL
- A41D—OUTERWEAR; PROTECTIVE GARMENTS; ACCESSORIES
- A41D31/00—Materials specially adapted for outerwear
- A41D31/04—Materials specially adapted for outerwear characterised by special function or use
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- A—HUMAN NECESSITIES
- A41—WEARING APPAREL
- A41D—OUTERWEAR; PROTECTIVE GARMENTS; ACCESSORIES
- A41D13/00—Professional, industrial or sporting protective garments, e.g. surgeons' gowns or garments protecting against blows or punches
- A41D13/02—Overalls, e.g. bodysuits or bib overalls
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- A—HUMAN NECESSITIES
- A41—WEARING APPAREL
- A41D—OUTERWEAR; PROTECTIVE GARMENTS; ACCESSORIES
- A41D2400/00—Functions or special features of garments
- A41D2400/24—Reducing drag or turbulence in air or water
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- A—HUMAN NECESSITIES
- A41—WEARING APPAREL
- A41D—OUTERWEAR; PROTECTIVE GARMENTS; ACCESSORIES
- A41D7/00—Bathing gowns; Swim-suits, drawers, or trunks; Beach suits
Definitions
- the present invention relates generally to improving the aerodynamic conditions on objects moving through fluid mediums and more particularly to a method and system for (1) reducing aerodynamic drag on athletes, (2) increasing aerodynamic lift and stability on athletes and/or (3) increasing the athlete's ability to transfer heat away from the body.
- the effect is attained by providing trip mechanisms at preselected locations along the athlete's body to prematurely trip the boundary layer of fluid medium around the body from laminar to turbulent flow thereby establishing a boundary that has more momentum and when properly applied achieves the aforementioned results.
- Fluid flow can be categorized as viscous or inviscous, laminar or turbulent, and compressible or incompressible.
- the fluid flow about an athlete is considered viscous and incompressible and depending on the speed of the sport and the geometry of the body part, the flow is laminar or turbulent.
- a boundary layer exists near the body. Only in the boundary layer are the effects of the fluid viscosity important.
- this boundary layer there is a velocity profile (relative to the body) of the fluid ranging from zero at the surface of the body to a free stream velocity at a finite distance from the body.
- the finite distance from the .body to the point where the fluid velocity equals the free stream velocity is termed the boundary layer thickness and is a function of velocity and geometry.
- the velocity gradient in this boundary layer results in a shear stress acting between differential layers of fluid. This is the origin of the skin friction drag component.
- the boundary layer in turbulent flow is thicker than that for a laminar flow and as a result the turbulent boundary flow possesses more momentum than a laminar boundary flow. Reducing the skin friction on a body tends to reduce the thickness of the boundary layer, i.e. minimizes the viscous forces acting on the body.
- the pressure drag component is possibly best illustrated by reference to the fact that a circular cross-section will experience a much higher drag force than a well-streamlined body that has the same projected area into the flow stream. This is because the circular body leaves behind a large wake whereas the streamlined body has only a small wake if any.
- the fluid pressure in the wake of the body is lower than the fluid pressure acting on the front of the body thus a force resulting from the pressure differential resists the motion of the body.
- This force is termed pressure drag.
- the dominating drag component on a bluff body is, in the velocity ranges in which most athletes compete, the pressure drag component.
- the athlete's performance can be enhanced where speed is important to performance.
- increased speed in addition to the lift and stability experienced by an athlete has a direct bearing on how far the athlete can fly before gravity returns the athlete to ground level. It is also well known that increasing an athlete's heat dissipation capability during performance, within bounds, enhances the athlete's performance.
- the present invention has been made to achieve advantageous effects on an athlete caused by the afore ⁇ noted normally occurring aerodynamic characteristics as the athlete moves through a fluid medium.
- the present invention relates primarily to a method and a system for reducing aerodynamic drag on an athlete's body as the athlete moves through a fluid medium.
- the reduced drag increases the athlete's speed through the fluid medium.
- the principles of the invention are also applicable to increasing aerodynamic lift on the athlete's body.
- the manner in which the aerodynamic drag is reduced creates an improved heat transfer medium which permits an increase in heat dissipation capabilities, thereby enhancing athletic performance.
- the method and system for reducing aerodynamic drag is embodied in prematurely tripping the laminar boundary layer of fluid passing around the athlete's body from laminar flow to turbulent flow by providing trip mechanisms on the athlete's body at predetermined locations. It has been found that by prematurely tripping the boundary layer of fluid flow around the athlete's body from laminar to turbulent, the pressure differential across the athlete's body can be reduced, thereby reducing the resistance to the movement of the athlete's body through the fluid medium.
- the trip mechanism can be releasably bonded or otherwise connected directly to the athlete's body or provided in or on a garment that the athlete would wear.
- Such a trip mechanism can increase the pressure on the downstream side of a body, thereby minimizing the pressure differential across the athlete's body. Not only can the athlete's body be enabled to move through the fluid medium with less resistance but by properly placing the trip mechanism, aerodynamic lift and stability can also be obtained. Accordingly, selective placement of trip mechanisms on the athlete's body are determined by the desired movement of the athlete's body through the fluid medium.
- a turbulent boundary layer is more capable of carrying heat away from an athlete's body than a laminar boundary layer. Since a turbulent flow is established prematurely by the trip mechanism the system provides a more efficient means for transferring heat from the athlete's body, thereby improving athletic performance.
- an athletic garment incorporating features of the present invention is designed so as to have a plurality of riblets, i.e., small parallel ridges extending in a preselected direction around the athlete's body.
- the riblets channel the turbulent flow in the boundary layer ⁇ uch that vortices of the fluid resulting from the turbulent flow do not interfere with adjacent vortices whereby the riblets reduce energy losses caused by disorganized turbulence. Research shows this assists in maintaining an attached fluid layer to the body (reducing the size of the wake) and obtaining a relatively high pressure behind the athlete's body as it moves through the fluid medium.
- FIG. 1 is a fragmentary diagrammatic front elevation of a human body for an athlete incorporating boundary layer trip mechanisms secured thereto in accordance with the present invention.
- Fig. IA is a fragmentary front elevation of a trip mechanism in accordance with the present invention, incorporated into a strip of adhesive for direct application to the skin or garment of an athlete as shown in Fig. 1.
- Fig. IB is a fragmentary side elevation of the trip mechanism and strip of adhesive illustrated in Fig. IA.
- Fig. 2 is a fragmentary diagrammatic front elevation of a garment showing the use of trip mechanisms and riblets at various locations on the garment in accordance with the present invention.
- Fig. 2A is a diagrammatic side elevation of a ski jumper wearing a garment incorporating a shoulder trip mechanism in accordance with the present invention.
- Fig. 2B is a fragmentary diagrammatic front elevation of a garment similar to that shown in Fig. 2 with the arms of the garment having netting as opposed to elongated trip mechanisms.
- Fig. 3 is a graph illustrating drag coefficient for smooth cylinders and a cylinder with a prematurely tripped boundary layer as a function of Reynolds numbers. It also illustrates the proportions of friction and pressure drag to the total drag as a function of the Reynolds number.
- Fig. 4 is a diagrammatic transverse cross-sectional representation of a cylindrical body in a fluid stream in laminar flow with separation at around 90° from the stagnation line.
- Fig. 4A is a graphical illustration of the local fluid pressure as a function of angular location across a cylindrical body that is not provided with a trip mechanism in accordance with the present invention.
- Fig. 5 is a diagrammatic view similar to Fig. 4 where a single trip mechanism is placed on the surface of the cylinder to illustrate the reduced size of the wake as a result of the trip wire.
- Fig. 6 is a view similar to Fig. 5 illustrating the use of two trip mechanisms and the added reduction in the size of the wake.
- Fig. 6A is a graph similar to Fig. 4A illustrating the local fluid pressure change across the body when a pair of trip mechanisms, in accordance with the present invention, are utilized.
- Fig. 7 is a graph plotting Reynolds numbers relative to fluid velocity for circular cylinders of varying diameters; the region of advantages is also depicted.
- Fig. 8 is a graphical representation of effective zones for large and small trip mechanisms on a cylinder.
- Fig. 9 is a geometrical representation of a circle showing angular relationships used to determine the slope of a tangent line at the location of a trip mechanism on a circle.
- Fig. 10 is a geometric view similar to Fig. 9, of an oval with its major axis oriented in the direction of fluid flow illustrating how the same slope line used in Fig. 11 can optimally position the trip mechanism on the oval.
- Fig. 11 is a geometric view similar to Fig. 10 showing how a slope line can optimally position a trip mechanism on an oval with its major axis located in the direction of fluid flow.
- Fig. 12 is a graph comparing boundary layer thickness to fluid velocity for given body radiuses.
- Fig. 13 is a diagrammatic front elevation of a human leg having a garment with double trip mechanisms, a front panel with riblets and mesh around the remainder of the leg.
- Fig. 14 is a fragmentary diagrammatic view of a mannequin leg having a ski boot with mesh covering the entire leg but not the boot.
- Fig. 15 is a fragmentary diagrammatic side elevation of a mannequin leg having a single trip mechanism extending along one side of a stagnation line substantially the entire length of the leg.
- Fig. 16 is a fragmentary diagrammatic front elevation of the mannequin leg shown in Fig. 15.
- Fig. 17 is a fragmentary diagrammatic front elevation similar to Fig. 16 wherein the leg includes two elongated trip mechanisms extending on opposite sides of the stagnation line.
- Fig. 18 is a graph illustrating the variations in drag force on a cylindrical tube having a single trip mechanism at various angular locations and with constant wind velocity.
- Fig. 19 is a graph illustrating the variations in drag force at various velocities comparing a Baseline mannequin leg with a mannequin leg modified with mesh on the leg down to the ski boot.
- Fig. 20 is a graph making still different comparisons of drag force at various velocities to mannequin legs having been modified in accordance with the present invention.
- Fig. 21 is a graph illustrating the drag force at varying velocities and making different comparisons than those in Fig. 19 of a Baseline mannequin leg with a mannequin leg modified in accordance with the present invention.
- Fig. 22 is a graph illustrating the percentage change in drag force from a Baseline mannequin leg to a mannequin leg having various modifications in accordance with the present invention.
- Fig. 23 is a graph illustrating the drag force at varying velocities on a mannequin leg comparing Baseline data with the use of double trip mechanisms.
- a bluff body is a body, whose cross-sectional geometry normal to the direction of fluid flow is nonstreamlined or not aerodynamic in shape, i.e., circular, elliptical, square, blunt-faced, blunt- ended, etc.
- the human body can be viewed as a conglomeration of several bluff bodies.
- Friction drag has a gradient with the shear stress between the differential fluid layers being greatest at the surface of the body and least at the outer layer of the boundary layer of fluid affected by the body. It i ⁇ well known that the fluid boundary layer in laminar flow along a body is thinner and thus has less mass or momentum than the boundary layer of turbulent flow. Of course, turbulent flow result ⁇ where a ⁇ mooth laminar flow can no longer be maintained and tiny vortice ⁇ in the fluid are created and propagate down ⁇ tream.
- the point at which the laminar flow of the boundary layer change ⁇ to turbulent flow is important to an understanding of the present invention and varies depending upon numerous parameters such as the size and shape of the body moving through the fluid, the viscosity and velocity of the fluid, the characteristics of the surface on the body, etc.
- the Reynolds Number (Re) is a commonly used dimensionle ⁇ s parameter expressing the ratio of inertia to viscou ⁇ forces used to characterize a fluid in flow.
- the relative effects of skin friction and pressure drag as a function of Re for a cylinder are depicted in Fig. 3. It i ⁇ important to note that at low Re the dominating drag component is skin friction. However, as the Re increase ⁇ the contribution of ⁇ kin friction drag to the overall drag decrea ⁇ es to a minimal amount. By way of example at Re of 1 x 10 3 , approximately 5% of the drag is due to skin friction drag while the remaining contribution, approximately 95%, is due to the pressure drag component.
- the turbulent boundary layer pos ⁇ e ⁇ es more mass and momentum, it resists adverse pres ⁇ ure gradients better and separation of the boundary layer from the body occurs further downstream, resulting in a smaller wake and thus higher average pressure acting on the downstream side of the body, reducing pres ⁇ ure drag.
- Thi ⁇ i ⁇ be ⁇ t illu ⁇ trated in Fig. 4 where the normal movement of a cylinder 20 of circular cro ⁇ - ⁇ ection through a fluid medium i ⁇ seen to create turbulent fluid flow down ⁇ tream of the cylinder and ⁇ eparation of the boundary layer occur ⁇ at about 90° relative to the direction of movement of the fluid medium.
- the turbulence behind the cylinder i ⁇ large and thus, generates a relatively large low pressure zone or wake behind the cylinder.
- FIG. 5 illustrates the amount of turbulence that occurs when the boundary layer is prematurely tripped with a single trip mechani ⁇ m 22 to be described in more detail later. It can therefore be seen that the point of separation of the boundary layer on the side where the trip mechanism is positioned occur ⁇ at about 120° relative to the direction of movement of the fluid medium.
- Fig. 6 is a similar representation with a pair of trip mechanisms 22 in accordance with the present invention and it will be appreciated that the turbulent wake is much smaller yet due to 120° separation on both sides of the cylinder and thus the average fluid pressure acting on the downstream side of the object is increased. A graphic but approximate illustration of this phenomena is shown in Figs. 4A and 6A, respectively.
- Fig. 7 is another graphical representation of the relationship of the diameter of a cylindrical body moving at various velocities and the resultant Reynolds Numbers. This graphic show ⁇ how the Reynold ⁇ Number increa ⁇ es both with relative fluid velocity and the diameter of the cylindrical body.
- the advantageou ⁇ upper and lower limit ⁇ evolving from u ⁇ e of the pre ⁇ ent invention are also illustrated. It should be noted that at a Re of around 3 X IO 5 , for a circular cylinder, the boundary layer becomes turbulent without any tripping mechanism. This, as mentioned previously, is known as the critical Reynolds number. When a trip mechanism is used on a smooth cylinder at Reynolds numbers greater than the critical Re, slight increased drag is observed.
- the boundary layer is prematurely tripped from laminar to turbulent with strategically positioned elongated trip mechanisms on the athlete's body causing the boundary layer to stay attached to the body longer creating a relative increase in the average pres ⁇ ure behind the athlete' ⁇ body.
- the ⁇ e mechani ⁇ ms can either be included in a garment 24B (Figs. 2, 2A and 2B) that the athlete wears or can be adhesively bonded (Figs. 1, IA and IB) to the athlete's body 24A at preselected locations as will be described in more detail later.
- test ⁇ have been performed on cylindrical bodies which, of course, are not identical in shape to the components of the human body, but can be used as a basi ⁇ for determining where be ⁇ t to place the wire ⁇ on the human body. Te ⁇ t ⁇ have also been performed on a mannequin leg simulating the human body leg as will be di ⁇ cussed later.
- a single trip mechanism in the form of an elongated protuberance or wire 22 extending longitudinally along the length of the cylindrical body at predetermined angular displacements from a stagnation line 26 and substantially parallel therewith, Figs. 5 and 6, will prematurely trip the boundary layer of fluid from laminar to turbulent flow.
- the stagnation line is an imaginary line running longitudinally along the length of the cylinder along its foremost surface and in direct alignment with the line of movement of the cylinder through the fluid medium.
- a trip mechanism of a dimension to be described later located between 20 degrees and 60 degrees from the stagnation line (optimally 37 degrees) , measuring from the center of the circle, will effectively trip the boundary layer from laminar to turbulent flow and reduce the pressure drag on the cylindrical body.
- the trip mechanism is located at angles les ⁇ than approximately 20 degree ⁇ from the stagnation line, there is virtually no effect on the overall drag and if the trip mechanism is located at angles greater than 60 degrees there is a slight increase in drag.
- the trip mechanism is desirably located (on a perfect circular cylinder) at approximately 37 degrees from the stagnation line. This will provide maneuverability margins on either side of the trip mechanism.
- trip mechanisms 22 (Fig. 6) , one on either side of the stagnation line and within the afore-identified range of 20 degrees to 60 degrees from the stagnation line, provides even better drag reduction.
- trip mechanisms can be placed at +30 degrees and at -30 degrees from the stagnation line and obtain more than twice the drag reduction of a single trip mechanism at 30 degrees to one side or the other from the ⁇ tagnation line.
- the cro ⁇ -sectional size of the trip mechanism i.e., it ⁇ width or diameter, ha ⁇ an effect on the drag reduction. It is preferred that the trip mechanism be sized in cros ⁇ - ⁇ ection to be within the boundary layer of fluid moving across the athlete's body. As mentioned previously, boundary layer varies in depth dependant upon body size and velocity.
- Fig. 12 is a graph plotting boundary layer depth to velocity for various sized cylindrical bodies with the radius of the body being designated "R". From the graph the maximum mechanism diameter can be determined by keeping the mechanism diameter les ⁇ than the boundary layer depth. In other word ⁇ , for a particular athletic event where one can determine the anticipated fluid velocity and the size of .a given body part, the maximum diameter of the trip mechanism to be used can be determined. In addition, large mechanism ⁇ , for example
- the human body doe ⁇ not con ⁇ ist of perfect circular cylinders and, therefore, the placement of trip mechanisms relative to stagnation lines will vary for optimal result ⁇ and will not nece ⁇ sarily follow substantially straight lines as diagrammatically illu ⁇ trated in Fig ⁇ . 1, 2 or 2B.
- the tangential slope at a radius location can be used to convert the optimal position ⁇ identified above for circular cylinder ⁇ to bodie ⁇ of other than ovular configurations.
- the optimal placement of a trip mechani ⁇ m 22 can be determined for differently configured bodie ⁇ such as the arms, legs, or torso of the human body.
- a garment 24B that could be worn by an athlete in accordance with the present invention can be seen to include a torso portion 34, arm portions 36 and leg portions 38 all integrated into a unified suit 39.
- the suit would preferably be skin tight and could be made of Spandex or other similar fabric.
- protuberance ⁇ or trip mechani ⁇ m ⁇ 22 which can ⁇ imply be metal wire ⁇ , fiber cord ⁇ or other protuberance ⁇ that are ⁇ titched or otherwi ⁇ e affixed to the fabric of the ⁇ uit or can be established in the fabric itself by forming ribs in the fabric such as by gathering the fabric along the predetermined trip line locations and stitching the fabric to itself so as to provide an elongated protuberance in the fabric along the trip line location.
- cord ⁇ of a fabric or fiber material are preferably stitched into or onto the fabric so as to extend along the predetermined trip line locations.
- the trip mechanisms 22 do not have to be incorporated into a garment as they can be adhesively bonded or otherwise secured directly to the athlete's skin as shown in Fig. 1.
- the mechanism ⁇ can be ⁇ ecured to ⁇ trip ⁇ 40 of adhe ⁇ ive tape, a ⁇ best shown in Figs. IA and IB, and the strips of tape can be bonded to the skin at the preferred locations for the trip mechanisms.
- the size of the trip mechanisms 22 can be identical or varied as can the displacement of the mechanisms from the stagnation line 26. Since large mechanisms appear to reduce drag more efficiently in the range of 20 degrees to 35 degrees from the stagnation line and small mechanisms are more efficient between 35 degrees and 50 degree ⁇ from the ⁇ tagnation line, a large mechanism provided at a 30 degree displacement and/or a small mechanism at a 40 degree displacement might possibly provide for more optimal results. These locations would of course translate into 60° and 50° respectively for the tangent equivalent.
- the trip mechanism ⁇ provide an efficient ⁇ y ⁇ tem for increasing heat transfer from an athlete's body, thereby improving athletic performance.
- any turbulent flow inside the boundary layer along the fabric can be channeled.
- riblets 42 i.e., small parallel ridges in the fabric with the riblets extending preferably parallel to the predominant air flow.
- any turbulent flow inside the boundary layer along the fabric can be channeled.
- riblets channel the turbulent flow and reduce the amount of interference between adjacent vortices and, therefore, reduce energy los ⁇ e ⁇ to di ⁇ organized turbulence and maintain the boundary layer momentum. This allows the flow to remain attached to the body longer which reduces the size of the wake and thus the pre ⁇ ure drag.
- riblets could vary in size and spacing, peak ⁇ of the riblet ⁇ are preferably not greater than .015 inches higher than a valley and the adjacent ridges or peaks protruding outwardly from the surface of the suit are preferably spaced approximately .003 to .007 inches.
- Fig. 2 illustrate ⁇ the location and direction of riblet ⁇ provided on a garment 24B and as will be seen, in the arm portion 36 and leg portion 38, the riblets extend around the limbs in relationship parallel to the fluid flow around the limbs. Riblets may also be provided in the torso region while not being illustrated. The direction of the riblets in the torso region would vary depending on the athletic event and the location of trip mechanisms since the orientation of the athlete's torso varies for different athletic events.
- Fig. 2A illustrate ⁇ a garment or ⁇ uit 24C that can be worn by a ski jumper with additional trip mechanisms 22 located along each shoulder for purpose ⁇ of illu ⁇ tration.
- the ⁇ houlder trip mechani ⁇ ms would extend from the base of the neck to the outermost part of the shoulder and would desirably be placed along a line determined by a 53-degree slope from the stagnation line 26.
- the lift is obtained by moving the point of separation of the air flow rearwardly and changing the direction of the resultant force due to the momentum tran ⁇ fer of the fluid and body.
- Trip mechanisms 22 would also be placed (though not shown in Fig. 2A) on the garment a ⁇ illu ⁇ trated in Fig. 1 so as to allow the body to move more rapidly through the air medium whereby the ski jumper can cover more distance in a given amount of time as when traveling down the in-run of a ski jump and while in the air. Tripping the boundary layer to turbulent will also reduce vortex shedding and therefore provide stability for the jumper.
- Fig. 2B illustrate ⁇ a garment 24D in accordance with the present invention where a net material 46 of crisscrossing protuberances is used on the arm portions to prematurely trip the boundary layer.
- a net material 46 of crisscrossing protuberances is used on the arm portions to prematurely trip the boundary layer.
- Thi ⁇ of cour ⁇ e is true for a skier's arms or helmet.
- a netting material such as found on women's net stocking ⁇ has been found to effectively and prematurely trip the boundary layer for the body parts that do not maintain a fairly constant angular relationship to the air flow and accordingly, such netting material is shown in Fig. 2B used on or for the arm portions of the garment.
- Fig. 2B used on or for the arm portions of the garment.
- netting while not being illustrated could be placed over the athlete's head, helmet or other body parts as well.
- a garment incorporating the trip mechanism ⁇ 22 could be formed, a ⁇ illu ⁇ trated in Fig. 13 in connection with a leg only, with preferably a stretch material 48 such as ⁇ pandex along the ⁇ tagnation line between trip mechani ⁇ m ⁇ 22 and with the remainder of the garment being made of netting 50.
- the netting would be in the regions where air flow is tripped to turbulence providing best heat transfer and would further enhance the tran ⁇ fer of heat from the athlete's body to the ambient environment.
- an athlete's performance when related to speed, lift or heat transfer can be enhanced with the teachings of the present invention, i.e., through the use of strategically placed trip mechanism and riblets and/or netting on the athlete's body. Both the ⁇ peed of movement of the athlete' ⁇ body through the fluid medium and the ability of that body to travel longer through the fluid medium are both enhanced thereby providing considerable improvement to an athlete's performance in any athletic endeavor that involves speed and/or endurance.
- various test ⁇ were made in a wind tunnel where the condition ⁇ of the air movement could be controlled.
- cylinder ⁇ having a 4.2 inch diameter as well as a mannequin full-length leg were placed in the wind tunnel with variou ⁇ modification ⁇ in accordance with the present invention and in varied wind velocities.
- the 4.2 inch diameter cylinder was placed in the wind tunnel in a vertical orientation to determine the drag force on the cylinder at varying wind velocities thereby defining a Baseline from which to compare other data.
- the other data was derived after modifying the cylinder in variou ⁇ way ⁇ but in accordance with the pre ⁇ ent invention in attempt ⁇ to reduce the drag force.
- the cylinder was initially placed in the wind tunnel with no modifications and the result ⁇ of tho ⁇ e tests plotting wind velocity against drag force are defined as the Baseline.
- the Baseline test ⁇ showed the largest drag force on the cylinder and by adding a small mesh to the cylinder where the fibers were approximately 1/100" in diameter and criss-cros ⁇ ing to define openings wherein the mesh openings were approximately 3/8" square, a small improvement or reduction in drag force was obtained.
- Fig. 18 is a graph illustrating the variations in drag force resulting from various angular displacement ⁇ of a ⁇ ingle trip mechanism from the stagnation line of a cylinder with a constant wind velocity of 45 mph. It will be appreciated that a radical drop in drag force is obtained at approximately 17° displacement from the stagnation line and that a sub ⁇ tantial increa ⁇ e i ⁇ observed at approximately 59°.
- a mannequin leg with a ski boot but without trip mechanism ⁇ was also tested in a wind tunnel to form a Baseline from which other data could be compared.
- the percentage change in drag force from the Baseline data for the mannequin leg is illustrated in Fig. 21 for various modifications to the mannequin leg.
- a mesh 52 having the dimension of the aforementioned large mesh, was placed on the leg of the mannequin, as shown in Fig. 14, there was an improvement of 8-12% over the Baseline.
- Fig. 19 is a graph comparing the Baseline mannequin leg to the mannequin leg with a mesh having the dimension ⁇ mentioned previou ⁇ ly in connection with the large me ⁇ h. It can there be appreciated that the me ⁇ h improves the drag force on a blunt body such as a leg.
- the above-noted test ⁇ ⁇ how that drag force i ⁇ reduced, to ⁇ ome degree, by placing me ⁇ h on a leg and to a greater degree with the u ⁇ e of two ⁇ paced trip mechani ⁇ m ⁇ at 35° di ⁇ placement ⁇ on either ⁇ ide of the ⁇ tagnation line.
- FIG. 20 Another graph, ⁇ hown in Fig. 20, compare ⁇ the Baseline mannequin leg with the use of single and double trip mechanism ⁇ a ⁇ ⁇ hown in Fig ⁇ . 16 and 17, re ⁇ pectively.
- the reference is to single trip mechanism ⁇ po ⁇ itioned one on each ⁇ ide of the stagnation line. It can there be seen that the single trip mechani ⁇ m at a 35° di ⁇ placement from the ⁇ tagnation line provides some improvement over the Baseline mannequin leg while the double trip mechanism at plus and minus 35° from the stagnation line provides even more improvement.
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU69693/96A AU6969396A (en) | 1995-09-08 | 1996-09-06 | Reducing drag on bodies moving through fluid mediums |
JP9511425A JPH10513510A (en) | 1995-09-08 | 1996-09-06 | Method and system for reducing drag and increasing heat transfer for movement of a bluff body through a flowing medium |
EP96930753A EP0914046A1 (en) | 1995-09-08 | 1996-09-06 | Reducing drag on bodies moving through fluid mediums |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US340095P | 1995-09-08 | 1995-09-08 | |
US60/003,400 | 1996-02-02 | ||
US08/580,121 US5836016A (en) | 1996-02-02 | 1996-02-02 | Method and system for reducing drag on the movement of bluff bodies through a fluid medium and increasing heat transfer |
US08/580,121 | 1996-02-02 |
Publications (1)
Publication Number | Publication Date |
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WO1997008966A1 true WO1997008966A1 (en) | 1997-03-13 |
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Application Number | Title | Priority Date | Filing Date |
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PCT/US1996/014362 WO1997008966A1 (en) | 1995-09-08 | 1996-09-06 | Reducing drag on bodies moving through fluid mediums |
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EP (1) | EP0914046A1 (en) |
JP (1) | JPH10513510A (en) |
AU (1) | AU6969396A (en) |
WO (1) | WO1997008966A1 (en) |
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WO2004098327A1 (en) * | 2003-05-05 | 2004-11-18 | Vives Vidal, Vivesa, Sa | Sports garment |
US10238156B2 (en) | 2015-01-13 | 2019-03-26 | Under Armour, Inc. | Suit for athletic activities |
US10548358B2 (en) | 2016-08-16 | 2020-02-04 | Under Armour, Inc. | Suit for athletic activities |
US10709181B2 (en) | 2016-09-28 | 2020-07-14 | Under Armour, Inc. | Apparel for athletic activities |
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US5106331A (en) * | 1989-05-26 | 1992-04-21 | Jairo Lizarazu | Apparatus for body surfing and method of making the same |
-
1996
- 1996-09-06 AU AU69693/96A patent/AU6969396A/en not_active Abandoned
- 1996-09-06 JP JP9511425A patent/JPH10513510A/en not_active Ceased
- 1996-09-06 EP EP96930753A patent/EP0914046A1/en not_active Withdrawn
- 1996-09-06 WO PCT/US1996/014362 patent/WO1997008966A1/en not_active Application Discontinuation
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US5052053A (en) * | 1988-12-05 | 1991-10-01 | O'neill, Inc. | Garment for aquatic activities having increased elasticity and method of making same |
US5106331A (en) * | 1989-05-26 | 1992-04-21 | Jairo Lizarazu | Apparatus for body surfing and method of making the same |
US5033116A (en) * | 1989-07-24 | 1991-07-23 | Descente Ltd. | Clothing for reducing fluid resistance |
Non-Patent Citations (2)
Title |
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PRITCHARD, WILLIAM G. and PRITCHARD, JONATHAN K., "Mathematical Models of Running", AMERICAN SCIENTIST MAGAZINE, Vol. 82, November-December 1994, pages 546-553. * |
See also references of EP0914046A4 * |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2000045658A1 (en) * | 1999-02-08 | 2000-08-10 | Gierveld Beheer B.V. | Cloth for sportswear, use of said cloth in producing sportswear, and also said sportswear |
AU762207B2 (en) * | 1999-04-27 | 2003-06-19 | Toray Industries, Inc. | Racing swimsuit |
EP1127500A2 (en) * | 2000-02-24 | 2001-08-29 | adidas International B.V. | Full body swimsuit |
EP1127500A3 (en) * | 2000-02-24 | 2003-09-10 | adidas International B.V. | Full body swimsuit |
WO2004098327A1 (en) * | 2003-05-05 | 2004-11-18 | Vives Vidal, Vivesa, Sa | Sports garment |
US10238156B2 (en) | 2015-01-13 | 2019-03-26 | Under Armour, Inc. | Suit for athletic activities |
US11812800B2 (en) | 2015-01-13 | 2023-11-14 | Under Armour, Inc. | Suit for athletic activities |
US10548358B2 (en) | 2016-08-16 | 2020-02-04 | Under Armour, Inc. | Suit for athletic activities |
US10709181B2 (en) | 2016-09-28 | 2020-07-14 | Under Armour, Inc. | Apparel for athletic activities |
US11547163B2 (en) | 2016-09-28 | 2023-01-10 | Under Armour, Inc. | Apparel for athletic activities |
USD928456S1 (en) | 2017-08-16 | 2021-08-24 | Under Armour, Inc. | Athletic suit |
Also Published As
Publication number | Publication date |
---|---|
EP0914046A4 (en) | 1999-05-12 |
EP0914046A1 (en) | 1999-05-12 |
JPH10513510A (en) | 1998-12-22 |
AU6969396A (en) | 1997-03-27 |
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