JP2005299765A - Friction resistance reducing sheet and friction resistance reducing sheet module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet capable of being adopted without remodeling it as a surface layer of various moving bodies and reducing friction resistance on the surface of the moving body caused by action of fluid. <P>SOLUTION: This friction resistance reducing sheet is composed of a flexible sheet 12 and a plurality of circular column bodies 14 buried into the flexible sheet 12. The circular column body 14 protrudes at least a part of a rotation face on one surface of the flexible sheet 12, and at least its lower half part is buried into the flexible sheet 14. The circular column body 14 sets its rotation face along the direction of flow of fluid. Preferably, thickness of the flexible sheet is about 1 mm or less. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a frictional resistance reducing sheet and a frictional resistance reducing sheet module, and more particularly to a sheet structure suitable for reducing resistance generated in an object moving in a gas atmosphere or a liquid atmosphere.

  Conventionally, the shape of the moving body itself has attracted attention as a means for reducing the resistance (drag) received from gas (especially air) and liquid when moving bodies such as airplanes, railways, vehicles, ships, etc. . What is required as the ideal form of the moving body is streamline. A streamline is a long and narrow shape with a rounded tip and a tapered rear end, and is modeled on the shape of a fish.

  The flow field that flows around the object (moving body) can be divided into two fields, the main stream and the boundary layer. The boundary layer is a region close to the object wall where the flow motion is governed by the frictional resistance with the object, and the main flow is a region with little influence of friction that can be assumed to be an ideal fluid flow.

The drag acting on the object, there is a pressure drag D _p and the friction drag D _f, mainstream pressure drag drag due, drag can be a separate and frictional drag due to the influence of the boundary layer, streamlined in particular, the pressure Excellent in reducing drag.

  For this reason, a high-speed moving body is required to have a streamlined shape, and an ultimate shape has been proposed by computer processing. However, even if the shape is obtained as an ideal shape, there are not a few boundary layers around the object (moving body), and therefore it is inevitably affected by frictional drag.

  In ships and the like where the viscosity of the fluid is high and the influence of frictional drag due to the boundary layer is large, attention is paid to the surface structure of the moving body itself, and a surface structure called “riblet structure” has been proposed. The riblet structure is to reduce the sum of frictional drag by intermittently destroying the boundary layer generated on the object wall surface by providing minute irregularities on the surface of the moving body, especially in a liquid atmosphere. It is effective for moving objects.

As a configuration for reducing the resistance of a moving body that moves in a gas atmosphere, an apparatus as in Patent Document 1 has been proposed. The apparatus described in Patent Document 1 is a substrate in which a sphere having a size of about a golf ball is rotatably embedded in a substrate. According to Patent Document 1, by rotating when a sphere receives air resistance, the gas flow can be disturbed and the resistance can be reduced.
JP-A-4-56673

  The riblet structure is particularly effective when the fluid has a relatively high viscosity like a liquid. However, when the viscosity of the fluid is low, such as gas, the effect is small, so that it has not been put to practical use for a moving body that moves in a gas atmosphere. Since the device described in Patent Document 1 has a large sphere that rotates due to the resistance of gas, when it is mounted on the surface of a moving body, it will increase the pressure drag, and the turbulence caused in the flow will also resist the resistance. It may increase. Furthermore, since the structure is large, when it is adopted as a surface layer of an existing moving body, the shape of the moving body itself changes.

As described above, although means for reducing the resistance of the object from the fluid due to the surface structure of the object (moving body) has been proposed, the field of use is limited when the effect is judged at a practical level. End up.
The present invention can be used as a surface layer of various moving bodies and structures without modifying the moving body itself, and friction drag (hereinafter referred to as friction) generated on the surface of the moving body regardless of whether it is in a liquid atmosphere or a gas atmosphere. The object is to provide a sheet capable of reducing resistance).

  In order to achieve the above object, a frictional resistance reducing sheet according to the present invention comprises a flexible sheet and a plurality of rotating bodies that are rotatably embedded in the flexible sheet. At least a portion of the flexible sheet is projected onto one surface of the flexible sheet, and at least the lower half is embedded in the flexible sheet.

In the frictional resistance reducing sheet having the above configuration, the rotating body may be a cylindrical body, and the rotating surface may be set along the flow direction of the fluid flowing along the surface of the flexible sheet.
The rotating body may be a spherical body.

The rotating body may be arranged such that the distance between the rotation centers is 1.2 to 2 times the outer dimension in the rotating direction of the rotating body.
The flexible sheet may be configured to have a thickness of 1 mm or less (about 1 mm or less).

  Furthermore, in the frictional resistance reducing sheet having the above-described configuration, the rotating body may have an active rotational force. The active rotational force mentioned here means that the rotating body itself rotates, and acts as a frictional resistance reducing sheet in addition to the rotating action. Of course, the rotating body itself has rotational force and rotates. The structure includes a structure in which a rotating body is passively given a rotational force.

  Moreover, the frictional resistance reducing sheet for achieving the above object may be a frictional resistance reducing sheet module configured by arranging a plurality of frictional resistance reducing sheets having the above-described configuration. Note that the frictional resistance reducing sheet module may be configured such that the frictional resistance reducing sheet is affixed side by side on a thin flexible sheet.

  By configuring the frictional resistance reducing sheet as described above, the flexible sheet can be rotated freely by the frictional resistance generated by the action of the fluid flowing through the boundary layer on the surface of the flexible sheet, which is the surface layer of the fluid and the object. The rotating body embedded in the body rotates, and the frictional resistance acting on the object surface can be reduced. Thereby, the boundary layer generated around the object can be reduced, and the resistance that the object receives from the fluid can be reduced.

  Further, since the rotating body is embedded in the flexible sheet, it can be directly installed on the surface of various existing moving bodies and structures. Furthermore, by setting the thickness of the flexible sheet to about 1 mm or less, there is almost no adverse effect on the moving body and the structure due to the grounding of the sheet, and it is easy to bend in accordance with the curved surface.

Moreover, a wide range can be covered regarding one direction of a sheet | seat surface by making a rotary body into a cylindrical body, and the number of structural members can be reduced.
Further, when the rotating body is in a spherical state, it is possible to deal with flows from various directions regardless of the seat installation direction.

  In addition, since the rotating body has a structure having an active rotational force, the rotating body can be spontaneously rotated in the fluid flow direction, and the contact surface between the object and the fluid is simulated in the fluid flow. Since the movement in the direction can be realized, the effect of reducing the resistance that the object receives from the fluid can be amplified. Furthermore, by intentionally increasing the rotation along the fluid flow direction, it is possible to obtain a propulsive force from the fluid that has become a resistance when propelling the object.

  Further, by arranging a plurality of frictional resistance reducing sheets to constitute a frictional resistance reducing sheet module, a sheet that covers the surface of a large moving body such as a vehicle, an aircraft, a railway vehicle, or the like can be configured. In addition, the friction resistance reduction sheet module is configured by arranging the friction resistance reduction sheets on a thin flexible sheet, making it easy to handle large sheets and attaching sheets to a wide range of surfaces at once. Can do.

  Hereinafter, an embodiment according to a frictional resistance reduction sheet of the present invention will be described with reference to the drawings. Note that the following embodiments are some embodiments according to the present invention, and the present invention includes various forms as long as the main part is not changed.

FIG. 1 is a diagram showing a first embodiment according to the frictional resistance reducing sheet of the present invention.
The frictional resistance reducing sheet 10 according to the present embodiment has a basic configuration of a flexible sheet 12 and a plurality of cylindrical bodies 14 which are rotating bodies embedded in the flexible sheet 12 so as to be freely rotatable.

FIG. 2 shows an example of a detailed configuration of the frictional resistance reducing sheet 10 of the present embodiment.
The flexible sheet 12 may be configured by a sheet base 12a and a seat cover 12b. The sheet base 12 a has a plurality of recesses 13 for embedding the cylindrical body 14 on one surface thereof. The concave portion 13 is preferably formed in an arc shape larger than the radius of the cylindrical body 14 and has a depth enough to accommodate the lower half of the cylindrical body 14. Further, the seat cover 12b is provided with an intermittent portion for projecting the rotating surface of the cylindrical body 14 to one surface of the flexible sheet 12, and the intermittent portion corresponds to the concave portion 13 in the sheet base 12a. Provided at the position. In the case of the present embodiment, the recess 13 is provided so that the longitudinal direction is constant and the cylindrical bodies 14 are arranged in a prescribed direction.

  The cylindrical body 14 is sandwiched between the concave portion 13 of the seat base 12a and the intermittent portion of the seat cover 12b described above, and in a prescribed direction with a part of the cylindrical side surface protruding from the surface of the flexible sheet 12. Allows to roll. For example, in FIG. 1, when the direction in which the fluid flows is the direction of the arrow A, the cylindrical body 14 rolls in the direction of the arrow B along the flow of the fluid.

  In the frictional resistance reducing sheet 10 having the above-described configuration, the cylindrical body 14 determines the length in the longitudinal direction according to the flexibility of the flexible sheet 12, and the sheet itself is in a bent state. However, it is desirable to constitute so as to function as a rotating body. Also, a plurality of rotation assisting members 16 may be provided between the cylindrical body 14 and the flexible sheet 12 so that the rolling of the cylindrical body 14 is smooth.

  The arrangement interval D of the cylindrical bodies 14 is preferably about 1.2 to 2 times the diameter d of the cylindrical body 14 as the distance of the rotation axis (not shown). Further, the flexible sheet 12 may have a sheet thickness t of about 1 mm or less. By setting it as such sheet | seat thickness, even if an installation surface is a curved surface, a sheet | seat can be bent easily and arrangement | positioning along the shape of an installation surface is attained.

  In the above embodiment, the cylindrical body 14 has a rotating shaft (not shown) like a roller bearing and is configured to be fixed to the flexible sheet 12 by a fixing portion that fixes the rotating shaft. Also good.

ここで、ρは流体の密度であり、δは境界層の厚さであり、ｕは境界層における流体の流速である。数式１は、単位面積あたりの平滑平板５０を、ある位置に固定しておく、あるいは速度Ｕ₀で平板を移動させるために必要な力を示しているので、平滑平板５０の表面と流体との間に境界層が存在する場合、物体を移動させる際の妨げとなることがわかる。このため、図３（Ｂ）に示すように、平面を流体と同じ速度で同じ方向へ移動させることができれば、流体と物体との境界層が発生しなくなり、壁面摩擦せん断応力は生じないものと考えることができる。 The frictional resistance reducing sheet having the above configuration has the following effects.
Theoretically, the wall frictional shear stress τ per unit area caused by the fluid flowing at a uniform flow velocity U ₀ acting on the fixed wall surface (smooth flat plate) 50 can be obtained by Equation 1 (FIG. 3 ( A)).

Here, ρ is the density of the fluid, δ is the thickness of the boundary layer, and u is the flow velocity of the fluid in the boundary layer. Formula 1 shows the force required to fix the smooth flat plate 50 per unit area at a certain position or move the flat plate at a speed U ₀ . It can be seen that when there is a boundary layer between them, it is an obstacle to moving the object. For this reason, as shown in FIG. 3B, if the plane can be moved in the same direction at the same speed as the fluid, the boundary layer between the fluid and the object will not be generated, and the wall frictional shear stress will not occur. Can think.

ここで、ρは流体の密度を示し、νは流体の動粘度を示す。 Here, the flow considered as an example of the surface of the smooth flat 50 for frictional resistance D _f caused by acting on the object surface. The frictional resistance D _f0 generated in the smooth flat plate 50 by the action of the uniform flow velocity U ₀ flowing parallel to the smooth flat plate 50 having the length l as shown in FIG. Can be shown as:

Here, ρ represents the density of the fluid, and ν represents the kinematic viscosity of the fluid.

  On the other hand, the frictional resistance acting on the flat plate 52 having a rotating body as shown in FIG. 4 is such that when all the rotating bodies rotate along the flow, the wall surface is uniform as shown in FIG. It is considered that the frictional resistance can be reduced by moving in the same direction as the flow.

と表すことができる。一方、図５（Ｂ）に示すように、回転体が一定速度で回転している場合には、回転体に流体の流れ方向と反対方向の回転トルクＴ₁が生じていることとなる。回転トルクＴ₀とＴ₁との関係は、動摩擦と静止摩擦との大小関係により、

となる。従って、回転状態の回転体に作用する局所摩擦ｆ₁も同様に、停止状態の回転体に作用する局所摩擦ｆ₀より小さいものとなる。 This is demonstrated below. First, consider that each rotating body rotates along a uniform flow. As shown in FIG. 5, assuming that the local friction f ₀ acts on only one upper point in a rotating body with a radius r, as shown in FIG. A rotational torque T ₀ is generated in the body in a direction different from the fluid flow direction. The rotational torque T ₀ is

It can be expressed as. On the other hand, as shown in FIG. 5B, when the rotating body rotates at a constant speed, a rotating torque T _{1 in the} direction opposite to the fluid flow direction is generated in the rotating body. The relationship between rotational torque T ₀ and T ₁ is based on the magnitude relationship between dynamic friction and static friction.

It becomes. Accordingly, the local friction f ₁ acting on the rotating body in the rotating state is also smaller than the local friction f ₀ acting on the rotating body in the stopped state.

で求めることができる（ｎは平板に設けられた回転体の数）。 Based on the above relationship, assuming that all the rotating bodies provided on the flat plate rotate at the same speed, the sum of the frictional resistance acting on each rotating body is as follows:

(N is the number of rotating bodies provided on the flat plate).

と表すことができる。このため、平板に対して作用する摩擦抗力Ｄ_f0とＤ_f1との関係には、

が成り立つこととなり、回転体を平板５２の長さｌに対して充分に小さくした場合には、流体の作用によって生じる平板表面の摩擦抵抗を低減することができるということがいえる。 Here, when the radius r of the rotating body can be made sufficiently small with respect to the length l of the flat plate 52, the frictional resistance acting on the stopped rotating bodies arranged in a plurality on the flat plate 52 is The frictional resistance acting on the fixed smooth flat plate 50 can be regarded as the same. Therefore, the frictional resistance D _f0 acting on the smooth flat plate 50 in the fixed state is

It can be expressed as. For this reason, the relationship between the frictional drag D _f0 and D _f1 acting on the flat plate is

Thus, it can be said that when the rotating body is sufficiently small with respect to the length l of the flat plate 52, the frictional resistance of the flat plate surface caused by the action of the fluid can be reduced.

In the frictional resistance reduction sheet 10 as in the present embodiment, by arranging the arrangement interval of the cylindrical bodies 14 to be about 1.2 to 2 times the diameter d of the cylindrical bodies 14, as shown in FIG. formed circulation flows between the cylindrical body 14, a stagnation point between the uniform flow flowing in U ₀ occurs. As a result, the flow separated at the rear part of the cylindrical body 14 does not cause entrainment, the fluid flow slides on the surface of the cylindrical body 14, and the surface of the object in which a plurality of rotating bodies are arranged on a uniform wall surface. It can be mimicked and can help to reduce the resistance the object receives from the fluid.

  As shown in FIG. 1, the frictional resistance reducing sheet 10 having the above-described configuration regards the frictional resistance reducing sheet 10 that is minutely formed as one unit, and disposes a plurality of the units, thereby reducing the frictional resistance reducing sheet module ( Hereinafter, it is referred to as a module) 100. By setting it as such a structure, it can be set as the sheet | seat which can also cover the surface of the mobile body with a large surface area. Further, when configuring the module 100, the individual frictional resistance reducing sheets 10 as the units are preferably arranged and pasted on a separately prepared flexible thin sheet. With such a configuration, it is easy to handle a large sheet, and the sheet can be attached to a wide range of surfaces at once. In addition, when setting it as such a structure, it is good to determine the magnitude | size of the one frictional resistance reduction sheet | seat 10 according to the curvature of the surface which affixes the module 100. FIG.

  Since the frictional resistance reducing sheet 10 or the module 100 as described above is flexible, it can be easily mounted on a curved surface such as the surface of a moving body such as a vehicle, an aircraft, or a railway as shown in FIG. (FIG. 7 shows the case of a frictional resistance reducing sheet module). When the frictional resistance reduction sheet 10 according to the present embodiment is mounted on the surface of the moving body as described above, the cylindrical body 14 rotates corresponding to the speed of the fluid passing through the surface of the moving body, Generation / growth of a boundary layer generated / grown with the surface of the moving body can be suppressed, and frictional resistance generated on the surface of the moving body can be reduced.

In addition, since the inertial force in the rotation direction acts on the rotating body, it is considered that the effect of reducing the frictional resistance can be enhanced as the speed of the moving body increases. Furthermore, the reduction of the frictional resistance on the surface of the moving body can improve the fuel consumption, which is economical and also useful for environmental protection from the viewpoint of CO ₂ reduction and the like. Of course, it also contributes to speeding up the moving body.

  In addition, the frictional resistance reducing sheet 10 according to the present embodiment is mounted on an existing moving body as well as a newly manufactured moving body by setting the thickness of the flexible sheet 12 to about 1 mm or less. Even if you do, it will not change its appearance. As a result, it is possible to employ the moving body designed as an ideal shape as it is.

Next, a second embodiment according to the frictional resistance reducing sheet of the present invention will be described with reference to FIG.
The configuration of the frictional resistance reducing sheet according to the present embodiment is substantially the same as that of the first embodiment except for the shape of the rotating body. Therefore, portions having the same function are denoted by the same reference numerals as those in the first embodiment, and description thereof is omitted.

In the present embodiment, the spherical body 114 is employed as the rotating body. By using the spherical body 114 as the rotating body, it is possible to cope with a flow in an arbitrary direction regardless of the installation direction of the rotating body. For this reason, it is not necessary to select the seat attachment position, and it is not necessary to pay attention to the attachment direction.
Other functions and effects are the same as those in the first embodiment.

  In the said 2nd Embodiment, although it has shown so that the spherical body 114 may be installed in matrix form in FIG. 8, the installation form is not restricted to this. For example, you may arrange | position in a stone wall shape so that the clearance gap between rotary bodies may decrease.

  Moreover, in the said embodiment, although the rotary body described only two, a cylindrical body and a spherical body, if the rotary body which concerns on this invention is a rotatable shape, it will not be limited to these. For example, a cylindrical body may be subdivided and a disk-shaped thing may be used as a rotating body, and a thing like a Soroban pearl may be arranged as a rotating body.

  In the friction resistance-reducing sheet of the present invention, it is preferable that the thickness of the flexible sheet is preferably about 1 mm or less, but the sheet thickness is increased as long as flexibility is not lost. Even if it is a case, it is included by this invention.

  In the above-described embodiment, it is described that the rotating body is provided directly in the recess 13 of the seat base 12a or via the rotation auxiliary member 16. However, when the rotating body is provided in the recess 13, a floating type with the recess 13 as a magnetic bearing and the rotating body as an axis may be used. Thereby, the friction loss by rotation is reduced, the rotating body can be efficiently rotated along the flow of the fluid, and the effect of reducing the frictional resistance can be improved.

  In the above-described embodiment, the description has been given on the assumption that the rotating body is passively rotated by the resistance received from the fluid. However, the rotating body in the above embodiment may have a structure having an active rotational force. The active rotational force may be applied by, for example, electrical means, magnetic means, or the like. Specific examples of the structure include a general motor, a magnetically levitated rotary motor, and the like. Of course, you may make it provide the mechanism which generate | occur | produces a rotational force inside a rotary body. In such a structure, if the friction loss generated when rotating the rotating body itself can be sufficiently reduced, the rotation applied from the flexible sheet to the rotating body rotates the rotating body. It is also possible to be only at the initial stage of movement when the torque is most required. Of course, rotation may be intermittently applied.

  By configuring the rotating body as described above, the rotating body can be spontaneously rotated in the fluid flow direction, and the contact surface between the object and the fluid is moved in the fluid flow direction in a pseudo manner. Therefore, the effect of reducing the resistance that the object receives from the fluid can be amplified. Furthermore, it is considered that a propulsive force can be obtained from the fluid that has become a resistance when propelling the object by intentionally increasing the rotation along the fluid flow direction.

  The frictional resistance reducing sheet of the present invention can obtain the same effect by adopting not only a moving body that moves in a gas atmosphere but also a ship that moves in a liquid atmosphere. In a liquid with high fluid viscosity, it is considered that a good effect can be obtained even if the outer dimension of the rotating body is made larger than that in the gas.

  In addition, the frictional resistance reducing sheet according to the present invention can obtain a high lift by being provided on the upper surface of a wing part of an aircraft or the like by promoting the flow of fluid on the surface of the moving body (object). Conceivable.

  In the above embodiment, it has been described that the frictional resistance reducing sheet of the present invention is particularly effective in reducing the frictional resistance generated by the action of fluid on the surface of the moving body. However, the frictional resistance reducing sheet of the present invention can also be applied to the case where the frictional resistance generated when a heavy object is conveyed is reduced. In this case, the frictional resistance reducing sheet of the present invention may be provided on the floor surface on which the heavy object is moved, or may be provided on the bottom surface of the heavy object itself as necessary. Since the thickness of the frictional resistance-reducing sheet of the present invention is much thinner than that of conventional rollers or carts, it can be placed on the sheet with almost no lifting. In addition, when it is provided on the floor surface, it is only necessary to arrange the sheets on a path through which a heavy object slides, and no large-scale construction or the like is required. Since the friction resistance reducing sheet of the present invention has a structure in which a plurality of minute rotating bodies are provided on a flexible sheet, even when a heavy object is transported, it moves smoothly with almost no vibration. Can be made. For this reason, it is also effective for carrying precision instruments. When the rotating body of the frictional resistance reducing sheet used for such an application has an active rotational force, there is a power assist effect. It is possible to push up with force, and it is considered that braking can be applied arbitrarily if it is a downward slope. Of course, even when it is used not only as a heavy object but also as a rail such as a sliding window or a fence, it is considered that a good effect can be obtained without deteriorating the scenery.

  In addition, when the rotating body has an active rotational force, the frictional resistance reducing sheet can serve as a conveyor, so it is considered that it can be adopted as a product conveying means in various factories. When employed in such applications, it is considered that not only can installation and maintenance costs be reduced, but it is also possible to take a curvilinear conveyance path that is difficult with conventional conveyors.

In addition, as a wide range of use of the frictional resistance reducing sheet of the present invention, it is considered that it can be used for practice such as skiing and skating by providing it on the floor surface of the playground.
As described above, it can be said that the frictional resistance reducing sheet of the present invention can be applied to various fields for the purpose of reducing the frictional resistance.

It is a figure which shows 1st Embodiment which concerns on the frictional resistance reduction sheet | seat of this invention. It is a figure which shows an example of the detailed structure of a frictional resistance reduction sheet | seat. It is a figure which shows the theory of the fluid which flows through an object surface. It is a figure which shows the theory of the fluid which flows through the surface of the frictional resistance reduction sheet | seat of this invention. It is a figure which shows the effect | action which a rotary body exerts on a flow. It is an enlarged view which shows the theory of the fluid which flows through the surface of the frictional resistance reduction sheet | seat of this invention. It is a figure which shows the example of application of the frictional resistance reduction sheet | seat of this invention. It is a figure which shows 2nd Embodiment which concerns on the frictional resistance reduction sheet | seat of this invention.

Explanation of symbols

10 ......... Friction resistance reducing sheet, 12 ......... Flexible sheet, 12a ......... Seat base, 12b ......... Seat cover, 13 ......... Recess, 14 ......... Cylinder, 16 ......... Rotation Auxiliary member, 100... Friction resistance reducing sheet module (module), 114.

Claims (7)

  It consists of a flexible sheet and a plurality of rotating bodies embedded rotatably in the flexible sheet, the rotating body protruding at least part of the rotating surface to one surface of the flexible sheet, A frictional resistance reducing sheet characterized in that at least the lower half is embedded in the flexible sheet.   The frictional resistance reducing sheet according to claim 1, wherein the rotating body is a cylindrical body, and a rotating surface is set along a flow direction of a fluid flowing along the surface of the flexible sheet.   The frictional resistance reducing sheet according to claim 1, wherein the rotating body is a spherical body.   4. The rotating body according to claim 1, wherein the rotating body is disposed such that the distance between the rotation centers is 1.2 to 2 times the outer dimension in the rotating direction of the rotating body. The frictional resistance reducing sheet according to 1.   The frictional resistance reducing sheet according to any one of claims 1 to 4, wherein a thickness of the flexible sheet is set to 1 mm or less.   The frictional resistance reducing sheet according to claim 1, wherein the rotating body has an active rotational force. A frictional resistance reducing sheet module comprising a plurality of the frictional resistance reducing sheets according to any one of claims 1 to 6.

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