JP2000314408A - Drag force reducer for object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce absolute value of the primary gradient of a speed component of fluid by introducing the fluid moving along the surface of an object and providing a recess which rotates in the moving direction in the surface of the object. SOLUTION: A shaft S1 is so formed that straight projecting threads 3 extending in the length direction are integrally provided on the surface of a shaft body 1 at same central-angle intervals with grooves 2 formed between the projecting threads 3. The cross sectional shape of the grooves 2 is set approximately quadrangle, the cross sectional shape of the projecting threads 3 is quadrangle, the angle of the projecting corner is set approximately a right angle, and the outside diameter of the shaft S1 is set larger by the height of the projection 3. The shaft S1 is set to a carbon shaft made of carbon fibers and an epoxy resin compact. This constitution can reduce the fluid frictional drag and the pressure drag.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can reduce fluid resistance generated on an object moving relatively in a fluid.
The present invention relates to a fluid resistance reducing device for the same object.

[0002]

2. Description of the Related Art A conventional object such as a golf club shaft has a cylindrical smooth surface. The suspension rope of the bridge has a cylindrical smooth surface provided with minute projections for promoting turbulent flow transition. Further, a so-called bluff-shaped object having a cliff-like surface whose cross-sectional shape is represented by a quadrangle, for example, a golf club head has a smooth hitting surface.

However, with a shaft, a hanging rope, or a head having such a shape, the velocity distribution of a fluid on a cylindrical smooth surface or a smooth surface when placed in air (fluid) at a certain relative moving speed. The non-slip flow cannot be sufficiently avoided, which causes the shaft, the suspension rope and the head to increase the fluid resistance.

The present invention has been made in order to solve such a conventional problem. The object of the present invention is to change the surface shape of an object so that a separation point of a fluid can be moved downstream of the fluid.
An object of the present invention is to provide a device for reducing fluid resistance of an object, which can reduce fluid resistance by forming a shape in which a velocity distribution of a fluid flowing along the surface of the object does not satisfy a condition of a non-slip flow. .

[0005]

The surface S of an object B
As shown in FIG. 1, the fluid frictional resistance caused by the linear gradient (du / dy) (positive) of the velocity distribution (u) in the fluid flow direction (x) on the surface S of the object B in the vertical direction (у) ,
0, which can be any negative value) multiplied by the viscosity coefficient (μ) of the fluid, and is proportional to the frictional stress (τ) as shown in the following equation.

[0006]

(Equation 1) Therefore, if the absolute value of the primary gradient (du / dy) is reduced or its sign can be changed from the normal positive state shown in FIG. 1 to the negative state, the fluid frictional resistance decreases.

For this purpose, the difference between the velocity components near the surface S of the object B is made closer to 0, or a reverse flow of the fluid is generated on the surface of the object B to make the sign of the primary gradient (du / dy) negative. do it.

Accordingly, in the present invention, as shown in FIG. 2, a dent (Dent) D for introducing a fluid moving along the surface S of the object B and rotating the fluid in the moving direction is formed in the surface S of the object B. Provided.

In this way, as shown in FIG. 2, in the recess D, the fluid rotates in the flow direction,
The backflow R occurs, and the sign of the primary gradient of the velocity component in the flow direction of the fluid becomes negative. Further, the absolute value of the primary gradient of the velocity component of the fluid in the region of the depression D can be reduced. As a result, "slip flow" occurs on the surface of the object.

Although the recess D has a U-shaped cross section in FIG. 2, even if the cross section is L-shaped as shown in FIG. 3, "slip flow" occurs for the same reason.

As described above, when the "slip flow" occurs on the surface of the object B due to the dent D, as shown in FIG. 4, the separation point Q on the fluid upstream side of the object B having no dent is changed as shown in FIGS. As shown in FIG. 6, the fluid moves downstream.

[0012] As a result, the downstream width W ₁ of the object B (FIG. 5, FIG. 6), recess it W ₂ smaller than (FIG. 4) of the object B without the D, vortex fluid made of separation point Q Is pushed downstream away from the object B, and the pressure in the base region K on the downstream end side of the object B increases. At the same time, turbulence does not occur in the fluid flow on the downstream end side of the object B. Therefore, the pressure resistance of the object B decreases.

Further, the pressure at the stagnation point Y of the object B without the dent D shown in FIG.
, The stagnation pressure at the stagnation point Y decreases, and the pressure resistance generated on the object B decreases.

The depression D in the present invention is provided on the entire surface of the object or partially. In addition, long ones can be provided continuously, short ones can be provided intermittently, and long ones and short ones can be provided in any combination.

The shape of the cross section of the recess D is not limited as long as the shape can reduce the above-mentioned fluid frictional resistance, that is, the shape of the fluid flowing along the surface of the object does not satisfy the condition of non-slip flow. Absent. A typical sectional shape of the dent D is, for example, a shape as shown in FIGS. 7 to 15. In the figure, arrows indicate the flow direction of the fluid. The fluid is
It may flow in parallel to the surface of the object, flow obliquely to (intersecting with) the surface, or flow in a direction perpendicular to the surface.

The recess D _{1 in} FIG. 7 has a rectangular cross section, and the recess D _{2 in} FIG. 8 has eaves H on the upstream and downstream sides of the fluid.
It is a rectangular section with ₂ provided. Dent D in FIG 9 ₃ is of U-shaped cross section having a curved surface between the bottom and sides. The dent D _{4 in} FIG. 10 is oval in cross section, and FIG.
1 of recess D ₅ is of circular cross-section. 12 to 15
Dent D ₆ of both is of L-shaped cross section.

The object B referred to in the present invention is a pillar-shaped object, a rod-shaped object, a spherical object, an elliptical spherical object, a plate-shaped object,
Various things, such as a cubic thing and a rectangular parallelepiped thing, are included.

The surface of the object B provided with the depressions D _{1 to} D ₆ is:
The surface may be smooth, may be rough, or may have irregularities.

The object B may be a rigid body, a soft body, or an elastic body. Any type can be used as long as the depressions D _{1 to} D ₆ can be provided.

[0020]

(Embodiment 1) FIG. 16 shows Embodiment 1 of the present invention.
FIG. 3 is a side view of the shaft S1 of FIG. ₁ , omitting a display of a groove 2 described later.

The length of the shaft S ₁ is 1170 mm, the outer diameter r ₁ of the distal end E is 9.3 mmφ, and the outer diameter r ₂ of the proximal end G is 1
The outer diameter r ₃ of the intermediate portion F, which is 5.8 mmφ and located 900 mm from the tip end E, is 15.15 mmφ. The range from the intermediate portion F to the distal end portion E is a measurement range of the rotational torque by a rotational torque tester described later.

FIG. 17 is a view showing an enlarged H-H cross section in FIG. 16, H-H cross section, the position of 320mm from the front end portion E of shaft S ₁ in (hereinafter, referred to as H position.) .

As shown in FIG. 17, the shaft S ₁ has the surface of the shaft main body 1 corresponding to the conventional shaft S ₀ having a circular cross section and a wall thickness of 0.8 mm shown in FIG. 19 as a comparative example. In addition, eleven straight ridges 3 extending in the length direction are integrally provided at the same center angle interval, so that eleven grooves 2 are provided between the ridges 3.

The groove 2 at the H position has a width of 1.2 mm and a depth of 0.4 mm, and the cross-sectional shape of the groove 2 is substantially square. The cross-sectional shape of the ridge 3 is quadrangular, and the angle of the protruding corner is almost a right angle. Therefore, the outer diameter of the shaft S _1, speaking in comparison to the shaft S _0, by the height greater than the shaft S ₀ of the convex portion 3.

The shaft S ₁ is a so-called carbon shaft made of a molded product of carbon fiber and epoxy resin, and weighs 65 g.

[0026] (Embodiment 2) FIG. 18 is a sectional view of a shaft S ₂ of Example 2, is a view corresponding to FIG. 17. Length of the shaft S ₂ is 1170 mm, Fig. 18 is an enlarged view showing by cutting at a site corresponding to H position above it.

The shaft S ₂ has four straight ridges 4 extending in the longitudinal direction at the same center angle interval on the surface of the shaft body 1 corresponding to the conventional shaft S ₀ shown in FIG. In this case, a total of three grooves 5 are provided between the projections 4.

The shaft S ₂ has an outer diameter of 10.0 when viewed in a cross-sectional portion (FIG. 18) at a position corresponding to the H position.
the shaft body 1 in the surface of the mm [phi], 4 pieces of the protrusions 4, the range of center angle 90 degrees of the shaft S _2, has a shape which is provided at 1.2mm intervals. The cross-sectional shape of the ridge 4 is quadrangular, and the angle of the protruding corner is almost right. The width of the ridge 4 at the H position is 1.0 mm, the height is 0.4 mm, and the width of the groove 5 is 1.
2 mm, depth 0.4 mm.

The shaft S ₂ is the same carbon shaft as the shaft S ₁ and weighs 62 g.

(Comparative Example) FIG. 19 shows a conventional shaft S ₀ having a circular cross section, which is a comparative example of the shafts S ₁ and S ₂ of the _first and _second embodiments. That is, the shaft S
_1, those listed in order to compare whether the air resistance of S ₂ is how improved.

This shaft S₀Is the length of the shaft
S₁, S_Two1170 mm, which is the same as Referring to FIG.
In other words, the outer diameter r of the tip E₁Is 8.5mmφ, base end G
Outer diameter r _TwoIs 15.0mmφ, 900mm from tip E
Outer diameter r of the intermediate portion F_ThreeIs 14.35mmφ, and the wall thickness is
0.8 mm.

FIG. 20 shows the shafts S ₁ and S _{1 of the first} and second embodiments.
Shaft S ₀ of the comparative example the rotational torque of the S ₂ (air resistance)
3 is a graph shown in comparison with that of FIG.

Each shaft S₀, S₁, S_TwoRotating torque
(Air resistance) was measured by the rotational torque tester shown in FIG.
Measured. That is, as shown in FIG.
Arm 2 vertically attached to a rotating shaft 22 driven by
Shaft S for 3₀, S₁ , S _TwoAre installed separately and each chassis is
The rotational torque (kg · m) with respect to the
It was measured with a total meter 24. The measurement range is the rotation center of the shaft.
From 691mm to 1591mm, ie the shaft
The range from the tip E to the middle F is 900 mm.
Shaft S₀, S₁, S_TwoThe rotation direction of
In the direction indicated by the arrow. The Reynolds number at the time of measurement
Is 10^FourRange.

As is apparent from FIG. 20, the rotational torque (air resistance) of the shaft S ₁ of the first embodiment is about 20 times smaller than that of the conventional shaft S ₀ at a tip speed of 40 m.
% Smaller. Also, the shaft S2 of the _second embodiment is similarly reduced by about 20%.

As described above, the shaft S of the first and second embodiments is used.
_1, S _2, since the air resistance of the shaft is reduced, the golf club using this, when the same other conditions other than the shaft can be swung faster than conventional golf club. Since the swing is faster, the head speed is faster, and the flight distance of the ball is longer than that of a golf club using a conventional shaft.

Although not shown, instead of the grooves 2 and 5 of the first and second embodiments, for example, a ridge having a width of 1.2 mm and a depth of 0.5 mm may be spirally provided on the entire surface of the shaft. Is the same as that of the first and second embodiments.

(Embodiment 3) FIG. 22 shows a case where the diameter (R) is 90 m.
m, circular edge of cylindrical body E (not shown) with length (L) of 50 mm
Part is cut out stepwise, and the ridge is an annular recess with an L-shaped cross section.
Object B provided with only 6 ₁Flows in the direction of its central axis C.
Same object B when placed in the flow of body 7₁Departs around
The behavior of the generated fluid 7 is schematically shown based on actual measurement.
It is. In the figure, the arrow X indicates the flow direction of the fluid.

The recess 6 is a groove having an L-shaped cross section. The width of the wall surface forming the groove is 5% of the diameter (R), that is, 4.
5 mm.

The lower graph of this schematic diagram shows the pressure distribution generated on the center axis of the object B ₁ C.
In this pressure distribution, the lower the pressure value on the base surface K behind the object, the greater the pressure resistance.

[0040] In the graph, the solid line indicates the flow resistance of the object B _1, dashed line for comparison, does not form a recess 6 shows the pressure distribution of the cylinder E.

The pressure distribution was measured in the following manner.

That is, the Navier-Stokes equation capable of describing the motion of a fluid was converted into a discrete equation by a difference method, and the numerical solution was calculated by a computer to measure the pressure distribution.

As is apparent from FIG. 22, the separation point Q of the fluid 7 flowing on the surface of the object B ₁ is on the downstream side of the fluid, and the vortex 8 of the fluid formed at the separation point Q is located on the downstream side far from the object B. Pushed to the side.

As a result, as is clear from the graph, the fluid resistance of the object B ₁ is smaller than that of the cylindrical body E as a comparative example, and the addition of the decrease in the area where the stagnation pressure is applied on the front surface of the object B ₁ It can be seen that it has been reduced by about 20%.

With respect to the objects B _{2 to} B ₇ of Examples 4 to 9 shown in FIGS. 23 to 28, the fluid resistance was measured in the same manner as in the case of the object B ₁ . In each figure, an arrow X is the flow direction of the fluid, C is the center axis of each object B ₂ .about.B _7, respectively.

(Embodiment 4) The object B _{2 in} FIG. 23 has an annular recess 9 having an L-shaped cross section at the peripheral edge of a disk. The reduction rate of the fluid resistance differs depending on the inclination angle of the fluid 7 with respect to the flow direction. Approx. 35% for zero tilt angle
(FIG. 9A), about 15% at 15 ° (FIG. 9B), and about 30% at about 16% (FIG. 9C).

(Embodiment 5) The object B _{3 in} FIG. 24 is a streamlined cylindrical body having flat front and rear ends and provided with an annular recess 10 having an L-shaped cross section. The reduction rate of the fluid resistance was about 55%.

(Embodiment 6) The object B ₄ shown in FIG. 25 has a shape in which a disk 12 is attached to a disk 11 having a circular arc surface, and a cross section formed by the two plates 11 and 12. Stepped annular recess 13 is provided. The reduction rate of the fluid resistance was about 30%.

The object B ₅ (Example 7) FIG. 26 is obtained by providing an annular recess 14 in which the L-shaped cross section on the peripheral edge portion of the cylindrical body. The reduction rate of the fluid resistance was about 40%.

(Embodiment 8) The object B ₆ shown in FIG. 27 has a shape in which a cylindrical body is attached to a disk, and is provided with an annular recess 15 having a stepped cross section formed by the both. The reduction rate of the fluid resistance was about 28%.

(Embodiment 9) The object B _{7 in} FIG. 28 has a hemispherical surface provided with an annular recess 16 having an L-shaped cross section. The reduction rate of the fluid resistance was about 5%.

[0052]

As described above, according to the present invention, since the surface of the object is provided with the recess for causing the slip flow of the fluid, the fluid resistance generated in the object, that is, the fluid frictional resistance and the pressure resistance are effectively reduced. Can be reduced. Therefore, according to the present invention, a golf club shaft,
Fluid friction resistance and pressure resistance generated in suspension ropes of bridges, yacht sails, electric cables, pantograph columns, golf club heads, and the like can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a velocity distribution shape of a fluid generated near a surface of an object.

FIG. 2 is a diagram showing a dent provided on a surface of an object and a velocity distribution shape of a fluid generated near the dent.

FIG. 3 is a diagram showing the behavior of a fluid generated in a dent provided on the surface of an object and in the vicinity thereof;

FIG. 4 is a diagram showing the behavior of a fluid generated on the surface of an object.

FIG. 5 is a diagram showing the behavior of a fluid generated on the surface of an object having a concave surface.

FIG. 6 is a diagram showing the behavior of a fluid generated on the surface of an object having a concave surface.

FIG. 7 is a sectional view of a recess that can be employed in the present invention.

FIG. 8 is a sectional view of a recess that can be employed in the present invention.

FIG. 9 is a sectional view of a recess that can be employed in the present invention.

FIG. 10 is a sectional view of a recess that can be employed in the present invention.

FIG. 11 is a sectional view of a recess that can be employed in the present invention.

FIG. 12 is a sectional view of a recess that can be employed in the present invention.

FIG. 13 is a sectional view of a recess that can be employed in the present invention.

FIG. 14 is a sectional view of a recess that can be employed in the present invention.

FIG. 15 is a sectional view of a recess that can be employed in the present invention.

FIG. 16 is a side view of the shaft according to the first embodiment.

17 is a sectional view taken along the line HH in FIG. 16;

FIG. 18 is a sectional view of a shaft according to the second embodiment.

FIG. 19 is a sectional view of a conventional shaft shown as a comparative example.

FIG. 20 is a graph showing the rotational torque of the shafts of Examples 1 and 2 and the shaft of the comparative example.

FIG. 21 is a configuration diagram of a rotation torque tester used for measurement of rotation torque.

FIG. 22 is a diagram illustrating a behavior of a fluid generated near an object according to the third embodiment.

FIG. 23 is a side view of the object of the fourth embodiment.

FIG. 24 is a side view of the object of the fifth embodiment.

FIG. 25 is a side view of the object of the sixth embodiment.

FIG. 26 is a partial longitudinal side view of the object of the seventh embodiment.

FIG. 27 is a partial longitudinal side view of the object of the eighth embodiment.

FIG. 28 is a side view of the object of the ninth embodiment.

[Explanation of symbols]

B _{1 to} B ₇ Object x Flow direction of fluid S Surface D, D _{1 to} D ₆ Depression R Backflow Q Separation point Y Stagnation point K Base area L Stagnation line S ₀ , S ₁ , S ₂ Shaft 1 Shaft body 2, 5 Groove 6 Recess 7 Fluid 8 Eddy flow 9, 10, 13, 14, 15, 16 Recess 21 Motor 22 Rotation shaft 23 Rotation arm

Claims (3)

[Claims] 1. A device for reducing fluid resistance generated on an object relatively moving in a fluid, provided on a surface of the object, introducing a fluid moving along the surface of the object, and rotating the fluid in the moving direction. An apparatus for reducing fluid resistance of an object, characterized in that the apparatus comprises a recess. 2. The fluid resistance reducing device for an object according to claim 1, wherein the object is a cylindrical object, and the recess is a groove. 3. An object having a cliff-like surface,
2. The apparatus for reducing fluid resistance of an object according to claim 1, wherein the recess is a groove provided in a peripheral portion of the cliff-like surface.