JP7593863B2 - Bent Pipe - Google Patents

Description

The present invention relates to a bent pipe.

Conventionally, for example, in a curved pipe into which a pipe is inserted, the cross-sectional shape of the curved portion has been made elliptical. In a curved pipe into which a pipe is inserted, the section modulus of the curved portion has been made larger than the section modulus of the straight pipe portion. Bent pipes in which the cross-sectional shape of the curved portion is elliptical or the section modulus of the curved portion is made larger than the section modulus of the straight pipe portion have been disclosed (for example, see Patent Document 1).

Japanese Patent Application Publication No. 08-261383

However, in conventional technology, the cross-sectional shape of the bent portion of the pipe is formed into an elliptical shape. This configuration poses the problem of inviting loss of total pressure due to fluid separation at the bend, and of causing uneven flow velocity at the outlet.
The present invention has been made in consideration of the above-mentioned points, and aims to provide a bent pipe that can suppress fluid separation at the bent section, thereby suppressing loss of total pressure and uneven flow velocity at the outlet flow, thereby allowing fluid to flow efficiently.

In order to achieve the above object, the present invention provides a bent pipe comprising an inlet section formed of a hollow tube, an inlet straight section extending in a straight line from the inlet section, a bent section bent from the inlet straight section, an outlet straight section extending from the bent section toward an outlet side, and an outlet section, wherein the inlet end of the inlet section is formed in a minimum cross-sectional shape of a perfect circle, the inlet straight section is formed in a perfect circle, an ellipse whose major axis passes through a central axis of the inlet straight section, or a shape combining the perfect circle and the ellipse, so that the cross-sectional area gradually increases, the bent section is formed in a modified ellipse shape having a cross-sectional shape larger than that of the inlet straight section and is formed so that the cross-sectional area is maximum at a center of the bent section, and the outlet straight section is formed in a perfect circle, an ellipse whose major axis passes through the central axis of the outlet straight section, or a shape combining the perfect circle and the ellipse, so that the cross-sectional area gradually increases, and is maximum immediately before the outlet section, and the outlet end of the outlet section is formed in the same perfect circle shape as the inlet end.

According to the present invention, it is possible to suppress separation of fluid at the bend in the bent pipe, thereby suppressing loss of total pressure and non-uniformity in the flow rate of the outlet flow, and to allow the fluid to flow efficiently.

1 is a cross-sectional view showing an embodiment of a gas turbine to which a bent pipe according to the present invention is applied; FIG. 2 is a perspective view showing a bent tube in the present embodiment. FIG. 11 is an explanatory diagram showing a cross-sectional shape at the A0 position. FIG. 13 is an explanatory diagram showing a cross-sectional shape at position A1. FIG. 11 is an explanatory diagram showing a cross-sectional shape at position A2. FIG. 13 is an explanatory diagram showing a cross-sectional shape at position A3. FIG. 13 is an explanatory diagram showing a cross-sectional shape at the A4 position. FIG. 13 is an explanatory diagram showing a cross-sectional shape at position A5. FIG. 13 is an explanatory diagram showing a cross-sectional shape at position A6. FIG. 13 is an explanatory diagram showing a cross-sectional shape at position A7. FIG. 13 is an explanatory diagram showing a cross-sectional shape at position A8. 1 is a table showing the cross-sectional shape, cross-sectional area, center point, and length and width dimensions at positions A0 to A8.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[Embodiment]
FIG. 1 is a cross-sectional view showing an embodiment of a gas turbine to which a bent pipe according to the present invention is applied.
As shown in Fig. 1, a gas turbine 10 includes a cylindrical casing 11. Inside the casing 11, a rotating shaft 12 that is rotationally driven by turbine blades (not shown) is rotatably supported by bearings 13.
A rotor 14 is attached to the outer periphery of the rotating shaft 12. A stator 15 is disposed on the outer periphery of the rotor 14, and the rotor 14 and the stator 15 together form a generator 16.
The rotor 14 is rotated inside the stator 15 by the rotational drive of the rotating shaft 12, thereby generating electricity.

A water jacket 17 is disposed on the outer periphery of the stator 15. The water jacket 17 is formed with a cooling water flow passage 18 to which cooling water is supplied.
A bent pipe 20 for draining the cooling water is connected to the water jacket 17 .

Next, an embodiment of the bent pipe 20 according to the present invention will be described.
FIG. 2 is a perspective view of a bent tube 20 according to the present invention.
2, the bent pipe 20 has a shape that is bent at a substantially right angle. The bent pipe 20 is formed of a hollow pipe and includes an inlet section 21, an inlet straight section 22 that extends linearly from the inlet section 21, a bent section 23 that is bent from the inlet straight section 22, an outlet straight section 24 that extends from the bent section 23 to the outlet side, and an outlet section 25.
In the following description, the bent side of the bent tube 20 (the lower side in FIG. 2) is referred to as the inside, and the opposite side (the upper side in FIG. 2) is referred to as the outside.

The inlet end of the inlet portion 21 of the bent pipe 20 is formed into a perfect circular shape with its minimum cross section.
The inlet straight section 22 extending from the inlet section 21 is formed in a perfect circle shape, an elliptical shape whose major axis passes through the central axis of the inlet straight section 22, or a shape that combines a perfect circle shape and an elliptical shape, so that the cross-sectional area gradually increases.
The bent portion 23 has a modified elliptical shape having a larger cross-sectional area than the inlet straight portion 22 , and is formed so that the flow passage cross-sectional area is maximum at the center of the bent portion 23 .
The outlet straight section 24 is formed in a perfect circular shape, an elliptical shape whose major axis passes through the central axis of the outlet straight section 24, or a shape that is a combination of a perfect circular shape and an elliptical shape so that the cross-sectional area gradually increases, and is formed so that the cross-sectional area is maximum just before the outlet section 25.
The outlet end of the outlet portion 25 is formed in the same circular shape as the inlet end.

The center line formed by connecting the center points of the cross-sectional shapes of the inlet section 21, the inlet straight section 22, the bent section 23, the outlet straight section 24, and the outlet section 25 of the bent pipe 20 from the inlet to the outlet is formed so as to be located toward the outside on the inlet and outlet sides of the bent section 23, and to be located toward the inside in the center of the bent section 23.
Here, the irregular oval shape refers to a shape in which an arc on one side of an elliptical shape overlaps with two perfect circular shapes to connect the arcs of the elliptical shape and the perfect circular shape, and the two perfect circular shapes are located inside the bend 23.

Next, the specific shapes of the inlet section 21, the inlet straight section 22, the bent section 23, the outlet straight section 24 and the outlet section 25 will be described.
The cross-sectional shapes of the inlet section 21 at position A0, the inlet straight section 22 at positions A1, A2, and A3, the bent section 23 at position A4, the outlet straight section 24 at positions A5, A6, and A7, and the outlet section 25 at position A8 will be described.
FIG. 3 is an explanatory diagram showing the cross-sectional shape at the A0 position. FIG. 4 is an explanatory diagram showing the cross-sectional shape at the A1 position. FIG. 5 is an explanatory diagram showing the cross-sectional shape at the A2 position. FIG. 6 is an explanatory diagram showing the cross-sectional shape at the A3 position. FIG. 7 is an explanatory diagram showing the cross-sectional shape at the A4 position. FIG. 8 is an explanatory diagram showing the cross-sectional shape at the A5 position. FIG. 9 is an explanatory diagram showing the cross-sectional shape at the A6 position. FIG. 10 is an explanatory diagram showing the cross-sectional shape at the A7 position. FIG. 11 is an explanatory diagram showing the cross-sectional shape at the A8 position. FIG. 12 is a table showing the cross-sectional shape, cross-sectional area, center point, and vertical and horizontal dimensions at the A0 position to the A8 position.

The central axis distance from A0 position to A1 position is 3 mm, the central axis distance from A1 position to A2 position is 22 mm, and the central axis distance from A2 position to A3 position is 30 mm. The A4 position is the center of the bend 23. The central axis distance from A5 position to A6 position is 30 mm, the central axis distance from A6 position to A7 position is 22 mm, and the central axis distance from A7 position to A8 position is 3 mm.

As shown in FIG. 3 and FIG. 12, the cross-sectional shape at the position A0 is a perfect circle whose center point coincides with the central axis and whose radius is 7.5 mm.
4, the cross-sectional shape at the A1 position is an ellipse whose center point is located at a position shifted from the central axis toward the inside of the bent tube 20 by 0.1 mm. The cross-sectional shape at the A1 position has a radius of 8.2 mm in the vertical direction (from the inside to the outside) from the center point, and a radius of 8.1 mm in the horizontal direction from the center point. That is, the cross-sectional shape at the A1 position is an ellipse whose major axis is located in the vertical direction.

The cross-sectional shape at position A2 is a perfect circle whose center point is shifted 0.2 mm from the central axis toward the outside of the bent tube 20, as shown in Figures 5 and 12. The cross-sectional shape at position A2 is a perfect circle with a radius of 8.5 mm.

6 and 12, the cross-sectional shape at the A3 position is disposed at a position where the center point is shifted from the central axis toward the outside of the bent tube 20 by 0.05 mm. The cross-sectional shape at the A3 position has a part of an ellipse with a radius of 8.4 mm in the vertical direction from the center point (from the inside to the outside) and a radius of 8.7 mm in the horizontal direction from the center point.
The cross-sectional shape at the A3 position is formed by overlapping two perfect circles with a radius of 8 mm horizontally so that their centers are offset by 0.8 mm, and the inner arc shape is a shape connecting the lower arcs of the two perfect circles. The outer arc shape of the cross-sectional shape at the A3 position matches the arc shape of the ellipse described above, and this makes the inner and outer shapes of the bent pipe 20 asymmetrical.

7 and 12, the cross-sectional shape at the A4 position is disposed at a position where the center point is shifted from the central axis toward the inside of the bent tube 20 by 0.6 mm. The cross-sectional shape at the A4 position has a part of a perfect circle with a radius of 8.5 mm.
The cross-sectional shape at the A4 position is formed by overlapping two perfect circles with a radius of 7.5 mm horizontally so that their center points are offset by 1.9 mm, and the inner arc shape is a shape connecting the lower arcs of the two perfect circles. The outer arc shape of the cross-sectional shape at the A4 position matches the arc shape of the perfect circle described above, and this makes the inner and outer shapes of the bent pipe 20 asymmetrical.

8 and 12, the cross-sectional shape at the A5 position is disposed at a position where the center point is shifted from the central axis toward the outside of the bent tube 20 by 0.1 mm. The cross-sectional shape at the A5 position has a part of an ellipse with a radius of 8.4 mm in the vertical direction from the center point (from the inside to the outside) and a radius of 8.3 mm in the horizontal direction from the center point.
The cross-sectional shape at the A5 position is formed by overlapping two perfect circles with a radius of 5.9 mm horizontally so that the center points are offset by 2.6 mm, and the inner arc shape is a shape connecting the lower arcs of the two perfect circles. The outer arc shape of the cross-sectional shape at the A5 position matches the arc shape of the ellipse described above, and this makes the inner and outer shapes of the bent pipe 20 asymmetrical.

The cross-sectional shape at position A6 is an ellipse whose center point is located at a position shifted 0.3 mm from the central axis toward the outside of the bent tube 20, as shown in Figures 9 and 12. The cross-sectional shape at position A6 has a radius of 8.8 mm in the vertical direction (from the inside to the outside) from the center point, and a radius of 8.5 mm in the horizontal direction from the center point. In other words, the cross-sectional shape at position A6 is an ellipse whose major axis is located in the vertical direction.

10 and 12, the cross-sectional shape at the A7 position is a perfect circle whose center point is shifted from the central axis by 0.2 mm toward the outside of the bent tube 20. The radius of the perfect circle is 9.0 mm.
11 and 12, the cross-sectional shape at the position A8 is a perfect circle with a radius of 7.5 mm, with the center point coinciding with the central axis. That is, the cross-sectional shape at the position A8 is the same as the cross-sectional shape at A0 of the inlet portion 21.

As shown in FIG. 12 , the cross-sectional area from A1 to A4 is 208.6 mm2 at position A1 of the inlet straight section 22, 227.0 mm2 at position A2 of the inlet straight section 22, and 231.4 mm2 at position A3 of the inlet straight section 22, and is formed so that the cross-sectional area of the inlet straight section 22 gradually increases from the inlet section 21 towards the outlet.
In addition, the cross-sectional area from A5 to A7 is 221.6 mm2 at position A5 of the outlet straight section 24, 235.6 mm2 at position A6 of the outlet straight section 24, and 254.5 mm2 at position A7 of the outlet straight section 24, so that the cross-sectional area of the outlet straight section 24 gradually increases toward the outlet.

In addition, the cross-sectional area at the A4 position of the bent section 23 is 232.4 mm2, which is larger than the 231.4 mm2 at the A3 position of the inlet straight section 22 and the 221.6 mm2 at the A5 position of the outlet straight section 24.

The cross-sectional area at the A0 position and the A1 position is 176.7 mm2 at the A0 position of the inlet portion 21 and 208.6 mm2 at the A1 position of the inlet straight portion 22, and the inlet portion 21 is formed into a throttle shape with a small diameter.
Similarly, the cross-sectional area at positions A7 and A8 is 254.5 mm2 at position A7 of the outlet straight section 24 and 176.7 mm2 at position A8 of the outlet section 25, and the outlet section 25 is formed into a throttle shape with a small diameter.

Furthermore, a center line formed by connecting the center points of the flow path cross sections of the inlet section 21, the inlet straight section 22, the bent section 23, the outlet straight section 24, and the outlet section 25 from the inlet to the outlet is formed to be located outside on the inlet and outlet sides of the bent section 23 and located inside at the center of the bent section 23. Specifically, the center point at position A3 is located at a position shifted 0.05 mm in the outward direction of the bent pipe 20 from the central axis, and the center point at position A5 is located at a position shifted 0.1 mm in the outward direction of the bent pipe 20 from the central axis.
The center point at position A4 is located at a position shifted 0.6 mm inward from the central axis of the bent tube 20.

Next, the operation of this embodiment will be described.
In this embodiment, the cross-sectional shape of the bent pipe 20 is formed into a perfect circle, an ellipse, or a shape that is a combination of a perfect circle and an ellipse, and the inlet straight section 22 and the outlet straight section 24 are formed so that their cross-sectional areas gradually increase. The center line formed by connecting the center points of the flow path cross section from the inlet section 21 to the outlet section 25 is positioned toward the outside at the inlet and outlet sides of the bent section 23, and toward the inside at the center of the bent section 23. This makes it possible to suppress fluid separation at the bent section 23 of the bent pipe 20, and to suppress loss of total pressure and uneven flow velocity at the outlet.
This makes it possible to obtain an efficient piping shape.

Cooling water was made to flow at a flow rate of 5 (l/min) through a bent pipe 20 having the cross-sectional shape of this embodiment shown in Figs. 3 to 11 described above and a bent pipe (comparative example) having a circular cross-sectional shape with a diameter of 18 mm, and the total pressure loss coefficient of the bent pipe 20 was measured.
As a result, in the comparative example, the total pressure loss coefficient was 0.551.
In contrast, in the bent pipe 20 of this embodiment, the total pressure loss coefficient is 0.086, and it has been found that the loss is reduced to 1/6.

The bent pipe 20 of this embodiment can be manufactured, for example, by integrally molding a resin material using molded parts or layered molding with a 3D printer or the like.

As described above, in this embodiment, the inlet end of the inlet section 21 is formed in a smallest cross-sectional shape of a perfect circle, the inlet straight section 22 is formed in a perfect circle shape, an ellipse shape whose major axis passes through the central axis of the inlet straight section 22, or a shape combining a perfect circle shape and an ellipse shape, so that the cross-sectional area gradually increases, the bent section 23 is formed in a deformed ellipse shape having a cross-sectional area larger than that of the inlet straight section 22 and is formed so that the cross-sectional area is maximum at the center of the bent section 23, and the outlet straight section 24 is formed in a perfect circle shape, an ellipse shape whose major axis passes through the central axis of the inlet straight section 22, or a shape combining a perfect circle shape and an ellipse shape, so that the cross-sectional area gradually increases, and is formed so that the cross-sectional area is maximum just before the outlet section 25, and the outlet end of the outlet section 25 is formed in the same perfect circle shape as the inlet end.
This makes it possible to suppress separation of the fluid at the bent portion 23 of the bent pipe 20, suppress loss of total pressure and non-uniform flow velocity at the outlet flow, and allow the fluid to flow efficiently.

In addition, in this embodiment, the irregular oval shape is formed by overlapping an arc on one side of an elliptical shape with two perfect circles and connecting the tangents to the elliptical shape and the perfect circles, and the two perfect circular shapes are formed in a shape that is located inside the bend 23.
As a result, in the bending width region including the center of bending portion 23, an arc on one side of the elliptical shape and two perfect circles are overlapped and the tangents to the elliptical shape and the perfect circles are connected, thereby suppressing the flow resistance of the fluid inside bending portion 23 and reducing losses.

In addition, in this embodiment, the bend 23 has a bent shape in which the inlet straight section 22 and the outlet straight section 24 each extend at a right angle, and a center line formed by connecting the center points of the flow path cross sections of the inlet section 21, the inlet straight section 22, the bend 23, the outlet straight section 24, and the outlet section 25, from the inlet to the outlet, is located outside on the inlet and outlet sides of the bend 23, and is located inside at the center of the bend 23.
As a result, the center line formed by connecting the center point from the inlet to the outlet is positioned closer to the outside at the inlet and outlet sides of the bend 23, and closer to the inner circumference at the center of the bend 23, so that the curvature of the piping for the fluid flowing through the bend 23 can be made gentle and smooth and continuous, and the flow resistance of the fluid can be suppressed.

In this embodiment, the shape from the inlet section 21 to the inlet straight section 22 and the shape from the outlet section 25 to the outlet straight section 24 are each formed into a tapered shape with a smaller diameter on the inlet side and the outlet side, respectively.
This allows the flow path to be expanded over a short distance while ensuring the rigidity of the inlet portion 21 and the outlet portion 25 of the bent pipe 20, thereby ensuring the flow path area.

In this embodiment, the components are integrally molded by molding or lamination.
As a result, the bent pipe 20 is integrally molded by molding or lamination molding, so that it is possible to mold complex piping shapes that are difficult to achieve by conventional pipe bending molding.

The present invention is not limited to the configuration of the above embodiment, and can be implemented in various forms without departing from the spirit of the invention.

[Configuration supported by the above embodiment]
The above embodiment supports the following configurations.

(Configuration 1) A bent pipe having an inlet portion formed of a hollow tube, an inlet straight portion extending in a straight line from the inlet portion, a bent portion bent from the inlet straight portion, an outlet straight portion extending from the bent portion toward an outlet side, and an outlet portion, wherein an inlet end of the inlet portion is formed in a minimum cross-sectional shape of a perfect circle, the inlet straight portion is formed in a perfect circle shape, an ellipse shape whose major axis passes through a central axis of the inlet straight portion, or a shape combining the perfect circle and the ellipse, so that a cross-sectional area gradually increases, the bent portion is formed in a deformed ellipse shape having a cross-sectional shape larger than that of the inlet straight portion and is formed so that the cross-sectional area is maximum at a center of the bent portion, and the outlet straight portion is formed in a perfect circle shape, an ellipse shape whose major axis passes through the central axis of the inlet straight portion, or a shape combining the perfect circle and the ellipse, so that a cross-sectional area gradually increases, and is maximum immediately before the outlet portion, and the outlet end of the outlet portion is formed in the same perfect circle shape as the inlet end.
According to this configuration, separation of the fluid at the bent portion of the bent pipe is suppressed, and loss of total pressure and non-uniformity in the flow velocity of the outlet flow are suppressed, making it possible to flow the fluid efficiently.

(Configuration 2) The bent pipe described in Configuration 1, wherein the deformed oval shape is formed by overlapping an arc on one side of an ellipse shape with two perfect circles and connecting the tangents to the ellipse shape and the perfect circles, and the two perfect circles are formed in a shape that is located inside the bent portion.
According to this configuration, in the bend width region including the center of the bend, an arc on one side of the elliptical shape and two perfect circles are overlapped to form a shape connecting the arcs of the elliptical shape and the perfect circle shape, thereby suppressing the flow resistance of the fluid inside the bend and reducing losses.

(Configuration 3) The bent pipe described in Configuration 1 or Configuration 2, characterized in that the bent portion has a bent shape in which the inlet straight portion and the outlet straight portion each extend at a right angle, and a center line formed by connecting the center points of the flow path cross section of the inlet portion, the inlet straight portion, the bent portion, the outlet straight portion, and the outlet portion from the inlet to the outlet is located outside on the inlet and outlet sides of the bent portion and is located inside at the center of the bent portion.
With this configuration, the center line formed by connecting the center point from the inlet to the outlet is positioned closer to the outside at the inlet and outlet sides of the bent section, and closer to the inner circumference at the center of the bent section, so that the curvature of the piping for the fluid flowing through the bent section can be made gentle and smooth and continuous, thereby suppressing the flow resistance of the fluid.

(Configuration 4) A bent pipe as described in any one of Configurations 1 to 3, characterized in that a shape from the inlet portion to the inlet straight portion and a shape from the outlet portion to the outlet straight portion are formed into a tapered shape in which the inlet side and the outlet side are smaller in diameter, respectively.
According to this configuration, the flow path can be expanded over a short distance while ensuring the rigidity at the inlet and outlet of the bent pipe, and the flow path area can be ensured.

(Configuration 5) The bent pipe according to any one of Configurations 1 to 4, characterized in that it is integrally molded by molding or lamination molding.
According to this configuration, since the bent pipe is integrally molded by molding or lamination molding, it is possible to mold complex piping shapes that are difficult to achieve by conventional pipe bending molding.

REFERENCE SIGNS LIST 10 Gas turbine 11 Casing 12 Rotating shaft 13 Bearing 14 Rotor 15 Stator 16 Generator 17 Water jacket 18 Cooling water flow path 20 Bent pipe 21 Inlet section 22 Inlet straight section 23 Bent section 24 Outlet straight section 25 Outlet section

Claims (4)

A bent pipe having an inlet portion formed of a hollow pipe, an inlet straight portion extending straight from the inlet portion, a bent portion bent from the inlet straight portion, an outlet straight portion extending from the bent portion to an outlet side, and an outlet portion,
The inlet end of the inlet portion is formed into a minimum cross-sectional shape of a perfect circle,
The inlet straight section is formed in a perfect circle shape, an ellipse shape whose major axis passes through a central axis of the inlet straight section, or a shape combining the perfect circle and the ellipse so that the cross-sectional area gradually increases,
The bent portion has a deformed elliptical shape having a cross-sectional shape larger than that of the inlet straight portion, and is formed so that the cross-sectional shape is maximized at a center of the bent portion,
the outlet straight section is formed to have a perfect circle shape, an ellipse shape whose major axis passes through a central axis of the outlet straight section, or a shape that is a combination of the perfect circle and the ellipse, so that the cross-sectional area gradually increases, and is formed so that the cross-sectional area is maximum immediately before the outlet section,
A bent pipe, wherein the outlet end of the outlet portion is formed in the same perfect circular shape as the inlet end. The bent pipe according to claim 1, characterized in that the irregular oval shape is formed by overlapping an arc on one side of an ellipse with two perfect circles to connect the arcs of the ellipse and the perfect circle, and the two perfect circles are formed in a shape that is located inside the bent portion. The bent portion has a bent shape in which the inlet straight portion and the outlet straight portion each extend at a right angle,
3. The bent pipe according to claim 1, wherein a center line formed by connecting center points of the flow path cross section of the inlet section, the inlet straight section, the bent section, the outlet straight section, and the outlet section from the inlet to the outlet is located outside on the inlet and outlet sides of the bent section, and is located inside at the center of the bent section. 4. The bent pipe according to claim 3, wherein a shape from the inlet section to the inlet straight section and a shape from the outlet section to the outlet straight section are formed into a tapered shape in which the inlet side and the outlet side are made smaller in diameter, respectively.

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