JP2023009650A - Axial flow compressor and diffuser for the same - Google Patents

Abstract

To provide an axial flow compressor which inhibits pressure loss in a wide operation range (fluid angle) and achieves improvement of the compressor efficiency.SOLUTION: An axial flow compressor includes: a fluid compression part 20 in which a rotor 22 having rotor vanes is rotationally driven in a center casing 21 having stationary vanes; and a diffuser 30 which guides a compressed fluid discharged from the fluid compression part 20. The diffuser 30 is bent and inverted to the fluid compression part 20 side near an outlet. Further, an annular outer cylinder part 30b extends in a fluid outflow direction and a cylindrical inner cylinder part 30c is arranged parallel to the fluid outflow direction.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to an axial compressor and a diffuser for the axial compressor, and more particularly, to an axial compressor and an axial compressor that suppresses pressure loss in a wide operating range (fluid angle) and improves compressor efficiency. for diffusers.

Conventionally, an axial compressor has been proposed (Patent Document 1). This axial compressor has a fluid compression section.

The fluid compression section compresses gas sucked from the upstream end through the inlet casing and discharges the compressed gas from the downstream end through the diffuser and the outlet casing chamber.

The diffuser is located in the rear part of the axial flow compressor, connects between the outlet of the fluid compression section and the outlet casing chamber, and suppresses the flow velocity of the gas compressed in the fluid compression section.

Japanese Patent No. 5453176

In axial flow compressors, depending on the operating range (fluid angle), pressure loss due to gas boundary layer separation near the outlet of the diffuser becomes a problem. Pressure loss reduces compressor efficiency.

The present invention has been made in view of such conventional circumstances, and provides an axial flow compressor and a diffuser for an axial flow compressor that suppresses pressure loss in a wide operating range (fluid angle) and improves compressor efficiency. The task is to provide

Other objects of the present invention will become clear from the following description.

The above problems are solved by the following inventions.

(Claim 1)
a fluid compression section in which a substantially cylindrical rotor having moving blades standing on its outer peripheral surface is rotationally driven in a substantially cylindrical central casing having stationary blades standing on its inner peripheral surface;
a diffuser that guides the compressed fluid discharged from the fluid compression part to a flow path formed between the outer cylinder part and the inner cylinder part,
In the vicinity of the outlet of the flow path that is bent and reversed toward the fluid compression section, the outer cylindrical section is annular and extends in the outflow direction of the fluid, and the inner cylindrical section extends in the outflow direction of the fluid. An axial compressor characterized by having parallel cylindrical shapes.
(Claim 2)
An axial flow compressor comprising a fluid compression section for compressing a fluid sucked from an upstream end through an inlet casing and discharging the compressed fluid from a downstream end through a diffuser and an outlet casing chamber,
The fluid compression section is configured such that a substantially cylindrical rotor having moving blades erected on an outer peripheral surface thereof is rotationally driven within a substantially cylindrical central casing having stationary blades erected on an inner peripheral surface thereof. ,
The diffuser comprises a diffuser ring, a substantially conical cylindrical outer cylindrical portion that continues to the downstream end of the inner peripheral surface of the central casing and spreads outward from the downstream end, a support cylindrical member that supports the rotor, and an outlet. It consists of a substantially conical cylindrical inner cylindrical portion which is a part of the casing and spreads outward from the vicinity of the downstream end of the outer peripheral surface of the rotor. A flow path is formed, and the vicinity of the outlet of the flow path is bent and turned toward the fluid compression section, and the fluid is discharged from between the downstream end of the inner peripheral surface of the central casing and the downstream end of the outer peripheral surface of the rotor. directing said compressed fluid through said flow path to said outlet;
The outlet casing chamber includes an outlet casing formed in a hollow annular shape surrounding the outer cylindrical portion of the diffuser, and circulates the fluid that has passed through the outlet of the diffuser in the circumferential direction. discharge from a compressed fluid discharge pipe connected to the outlet casing communicating with the chamber and radially outward;
In the vicinity of the outlet of the diffuser, the outer cylindrical portion of the diffuser is annular and extends in the outflow direction of the fluid, and the inner cylindrical portion is a portion bent and inverted toward the fluid compressing portion. The axial flow compressor is characterized in that the outer peripheral portion of the has a cylindrical shape parallel to the outflow direction of the fluid.
(Claim 3)
3. The inner cylindrical portion has a planar shape parallel to the flow direction of the fluid at a front upstream portion of a portion where the flow path is bent and reversed toward the fluid compression portion side. Axial compressor as described.
(Claim 4)
In the vicinity of the outlet of the flow path, the outer cylindrical portion is annular and extends in the outflow direction of the fluid, and the inner cylindrical portion has a cylindrical shape parallel to the outflow direction of the fluid. 4. The axial flow compressor according to claim 1, wherein separation of a boundary layer of said fluid in said flow path is suppressed by:
(Claim 5)
Between the outer cylinder part and the inner cylinder part, a flow path that is bent and inverted toward the fluid compression section side is formed for guiding the compressed fluid discharged from the fluid compression section, and the flow that is bent and inverted toward the fluid compression section side is formed. In the vicinity of the outlet of the passage, the outer cylindrical portion is annular and extends in the outflow direction of the fluid, and the inner cylindrical portion has a cylindrical shape parallel to the outflow direction of the fluid. Axial compressor diffuser.
(Claim 6)
a substantially conical cylindrical outer cylinder portion which is formed of a diffuser ring and continues to the downstream end of the inner peripheral surface of the substantially cylindrical central casing of the axial flow compressor and spreads outward from the downstream end;
a substantially conical cylindrical inner cylindrical portion consisting of a support cylindrical member that supports the rotor that is rotationally driven in the central casing and a part of the outlet casing, and that spreads outward from the vicinity of the downstream end of the outer peripheral surface of the rotor; become,
A substantially conical tubular channel is formed between the outer cylinder portion and the inner cylinder portion, and the vicinity of the outlet of the channel is bent and turned toward the central casing, and the inner peripheral surface of the central casing is bent. guiding the compressed fluid discharged from between the downstream end and the downstream end of the outer peripheral surface of the rotor to the outlet through the flow path;
In the vicinity of the outlet, the outer cylindrical portion has an annular shape and extends in the outflow direction of the fluid. A diffuser for an axial compressor, characterized in that it has a cylindrical shape parallel to the outflow direction of the air.
(Claim 7)
6. The inner tubular portion has a planar shape parallel to the flow direction of the fluid at a front upstream portion of a portion where the flow path is bent and reversed toward the fluid compression portion. 7. A diffuser for an axial compressor according to 6 above.
(Claim 8)
In the vicinity of the outlet of the flow path, the outer cylindrical portion is annular and extends in the outflow direction of the fluid, and the inner cylindrical portion has a cylindrical shape parallel to the outflow direction of the fluid. 8. The diffuser for an axial flow compressor according to claim 5, wherein boundary layer separation of said fluid in said flow path is suppressed by:

INDUSTRIAL APPLICABILITY The present invention can provide an axial compressor and a diffuser for an axial compressor that suppress pressure loss in a wide operating range (fluid angle) and improve compressor efficiency.

1 is a vertical sectional view schematically showing an axial compressor according to an embodiment of the present invention; FIG. FIG. 2 is a longitudinal cross-sectional view of essential parts showing a diffuser and an outlet casing chamber of the axial compressor; A broken perspective view seen from the downstream side showing the shape of the diffuser ring forming the inner cylindrical portion of the diffuser. A broken perspective view seen from the upstream side showing the shape of the diffuser ring forming the inner cylindrical portion of the diffuser. Cross-sectional view showing an outlet casing chamber of the axial compressor FIG. 2 is a cutaway perspective view seen from the downstream side showing the shapes of the outlet casing and the diffuser ring of the axial compressor; FIG. 2 is a broken perspective view seen from the upstream side showing the shapes of the outlet casing and the diffuser ring of the axial compressor; A diagram showing the flow velocity distribution in the diffuser of the axial compressor Diagram showing the flow velocity distribution in the diffuser of a conventional axial compressor

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a longitudinal sectional view schematically showing an axial compressor according to an embodiment of the invention.

As shown in FIG. 1, the axial compressor according to the embodiment compresses fluid sucked from an upstream end (front end) through an inlet casing 10, and releases the compressed fluid (also simply referred to as compressed fluid). It is an axial compressor provided with a fluid compression section 20 that discharges fluid from a downstream end (rear end) via a diffuser 30 and an outlet casing chamber 40 .

The axial compressor of this embodiment is used, for example, for supplying air to a blast furnace (iron blast furnace), and the fluid to be compressed is air. However, the axial compressor according to the present invention is not limited to such applications.

The inlet casing 10 is a hollow member into which fluid to be compressed flows, and is formed in an annular (circular or spiral) tubular shape. The fluid that has flowed through the inlet casing 10 is sent to the fluid compression section 20 .

The fluid compression section 20 is configured such that the rotor 22 is rotationally driven within the central casing 21 . The central casing 21 has a substantially cylindrical shape, and has a large number of stationary blades 21a erected on its inner peripheral surface.

The rotor 22 has a substantially columnar shape, and has a large number of moving blades 22a erected on its outer peripheral surface. The rotor 22 is rotationally driven around its axis by a driving force source (not shown). The space between the inner peripheral surface of the central casing 21 and the outer peripheral surface of the rotor 22 narrows from the upstream end to the downstream end of the fluid compressing portion 20, and the volume decreases.

In the fluid compression section 20, when the rotor 22 is rotationally driven, rows of multiple moving blades 22a are rotated while passing between rows of multiple stationary blades 21a. The fluid between the inner peripheral surface of the central casing 21 and the outer peripheral surface of the rotor 22 is rotated around the axis following the rotor blades 22a due to the rotation of the rotor blades 22a. The moving blades 22 a and the stationary blades 21 a are circumferentially arranged so as to guide the fluid rotated between the inner peripheral surface of the central casing 21 and the outer peripheral surface of the rotor 22 toward the downstream end of the fluid compression section 20 . It is slanted. The fluid between the inner peripheral surface of the central casing 21 and the outer peripheral surface of the rotor 22 is compressed by being guided from the upstream end of the fluid compressing portion 20 toward the downstream end. The degree of compression of the compressed fluid can be controlled by driving and controlling the stator vane variable mechanism by a control device (not shown) to change the inclination (fluid angle) of the stator vane 21a. The compressed fluid produced is sent to the diffuser 30 .

FIG. 2 is a vertical cross-sectional view of essential parts showing a diffuser and an outlet casing chamber of the axial compressor according to the embodiment of the present invention.

The diffuser 30 , as shown in FIGS. 1 and 2 , is located in the downstream (rear) portion of the axial flow compressor and connects between the outlet of the fluid compression section 20 and the outlet casing chamber 40 . The diffuser 30 is generally formed in the shape of a divergent duct that widens toward the end in order to suppress the flow velocity of the compressed fluid compressed by the fluid compression section 20 . In the diffuser 30, the velocity energy of the fluid sent from the fluid compression section 20 is converted into static pressure, so the pressure at the outlet 30a of the diffuser 30 is the highest among the axial flow compressors.

The diffuser 30 has an outer cylindrical portion 30b that is continuous with the downstream end of the inner peripheral surface of the central casing 21 and spreads outward from the downstream end, and a front end portion that is near the downstream end of the outer peripheral surface of the rotor 22. and an inner cylindrical portion 30c having a substantially conical cylindrical shape that spreads outward.

FIG. 3 is a broken perspective view seen from the downstream side showing the shape of the diffuser ring forming the inner cylindrical portion of the diffuser.
FIG. 4 is a broken perspective view seen from the upstream side showing the shape of the diffuser ring forming the inner cylindrical portion of the diffuser.

The outer cylindrical portion 30b of the diffuser 30 consists of a substantially conical cylindrical diffuser ring connected to the downstream end of the central casing 21, as shown in FIGS. The diffuser ring is integrally formed in an axially symmetrical annular shape.

As shown in FIG. 2, the inner cylindrical portion 30c includes a substantially conical cylindrical support member 30f that rotatably supports the outer peripheral surface of the rotor 22 in the vicinity of the downstream end (rear end) thereof, and a support member 30f downstream of the support cylindrical member 30f. and a rear portion of the outlet casing 40b connected to the end (rear end).

The outlet casing 40b is a hollow member into which compressed fluid flows, and is formed in a hollow annular (circular or spiral) tubular shape surrounding the outer cylindrical portion 30b of the diffuser 30 . The outlet casing 40b has a front edge connected to the outer surface near the downstream end (rear end) of the central casing 21, and a rear edge connected to the downstream end (rear end) of the support cylinder member 30f. A portion of the outlet casing 40b behind the outlet 30a of the diffuser 30 is part of the inner cylindrical portion 30c. The outlet casing 40b has an outlet casing chamber 40 in the front portion of the diffuser 30 relative to the outlet 30a.

In the diffuser 30, between the outer tubular portion 30b and the inner tubular portion 30c, a substantially conical tubular flow path 30d is formed. 30 d of flow paths are bent and reversed to the fluid compression part 20 side near the outlet 30a of the diffuser 30. As shown in FIG.

The diffuser 30 directs the compressed fluid discharged from between the downstream end (rear end) of the inner peripheral surface of the central casing 21 and the downstream end (rear end) of the outer peripheral surface of the rotor 22 to the outlet 30a through the flow path 30d. lead. In the vicinity of the outlet 30a of the diffuser 30, the outer cylindrical portion 30b of the diffuser 30 has an annular extension portion 30e extending in the outflow direction of the fluid.

The inner cylinder portion 30c, the outer cylinder portion 30b, and the extension portion 30e forming the diffuser 30 are formed integrally with the diffuser ring in the shape of an axisymmetric body of revolution.

In the diffuser 30, the outer cylindrical portion 30b near the outlet 30a is formed into an annular extension portion 30e extending in the outflow direction of the fluid. This reduces pressure loss over a wide operating range (fluid angle) and improves compressor efficiency.

In the vicinity of the outlet 30a of the diffuser 30, an outer peripheral portion 40a of an outlet casing 40b, which is a part of the inner cylindrical portion 30c, has a cylindrical shape parallel to the outflow direction of the fluid, as shown in FIG. The cylindrical outer peripheral portion 40a, along with the extended portion 30e of the outer cylindrical portion 30b of the diffuser 30, suppresses the occurrence of boundary layer separation of the fluid in the diffuser 30, suppresses pressure loss in a wide operating range (fluid angle), and reduces the pressure loss of the compressor. Improve efficiency.

A rear surface portion 40c of the outlet casing 40b, which is a part of the inner cylindrical portion 30c, is an upstream portion in front of the portion bent and inverted toward the fluid compression portion 20, and has a planar shape parallel to the flow direction of the fluid. . This rear surface portion 40 c also has a planar shape, thereby suppressing boundary layer separation of the fluid within the diffuser 30 .

FIG. 5 is a cross-sectional view showing the outlet casing chamber of the axial compressor according to the embodiment of the invention.
FIG. 6 is a broken perspective view seen from the downstream side showing the shapes of the outlet casing and the diffuser ring of the axial compressor.
FIG. 7 is a broken perspective view seen from the upstream side showing the shapes of the outlet casing and the diffuser ring of the axial compressor.

The compressed fluid that has passed through the diffuser 30 has rotational energy given by the rotation R of the rotor 22 in the fluid compression section 20, as shown in FIGS. The fluid that has passed through the outlet 30a circulates in the circumferential direction. In the outlet casing chamber 40, the compressed fluid is discharged from a compressed fluid discharge pipe 50 that communicates with the outlet casing chamber 40 and is connected to the outlet casing 40b radially outward. The compressed fluid discharge pipe 50 is a cylindrical pipe, is connected to the outlet casing 40b, and discharges the compressed fluid sent from the outlet casing chamber 40 to the radially outer side of the outlet casing 40b. Since the outlet casing chamber 40 does not require a horn-shaped member used in a conventional axial flow compressor, the manufacturing cost can be reduced. Moreover, since the diffuser ring used in the present invention has an axially symmetrical shape, it is possible to reduce the manufacturing cost.

The outlet casing 40b may have a smooth circular shape, or may have a shrimp tube shape in which a plurality of U-shaped members are arranged and connected in the circumferential direction. By making the outlet casing of the shrimp tube type, the outlet casing can be manufactured only by connecting each shrimp tube, and the manufacturing cost can be reduced.

The effect of the present invention is illustrated by showing the flow velocity distribution in the diffuser of the axial flow compressor according to the present invention and the flow velocity distribution in the diffuser of the conventional axial flow compressor.
FIG. 8 is a diagram showing the flow velocity distribution inside the diffuser of the axial compressor.
FIG. 9 is a diagram showing a flow velocity distribution inside a diffuser of a conventional axial compressor.

In the diffuser 30 of the axial flow compressor of the embodiment, as shown in FIG. 8, the flow velocity distribution changes substantially uniformly from upstream to downstream, and boundary layer separation does not occur.

On the other hand, in the diffuser of the conventional axial flow compressor, boundary layer separation 300d of the fluid occurs in the diffuser 300 as shown in FIG. ing.

In the diffuser 30 of the axial flow compressor of the embodiment, as shown in FIG. Since the outer peripheral portion 40a of the outlet casing 40b, which is a part of the cylindrical portion 30c, has a cylindrical shape parallel to the outflow direction of the fluid, boundary layer separation of the fluid in the flow path 30d of the diffuser 30 is suppressed. , pressure loss is suppressed in a wide operating range (fluid angle), and compressor efficiency is improved.

The diffuser for an axial compressor according to the present invention can also be used by replacing the diffuser section of an existing axial compressor. As a result, even in existing axial flow compressors, boundary layer separation of the fluid in the flow path of the diffuser is suppressed, pressure loss is suppressed over a wide operating range (fluid angle), and compressor efficiency is improved. You can get the effect of

Various specifications shown in the above-described embodiments are examples and do not limit the present invention. The invention is not to be construed as being limited to these.

REFERENCE SIGNS LIST 10 inlet casing 20 fluid compression section 21 central casing 21a stationary blade 22 rotor 22a moving blade 30 diffuser 30a outlet 30b outer cylindrical section 30c inner cylindrical section 30d flow path 30e extension 30f support cylindrical member 40 outlet casing chamber 40a outer peripheral portion 40b outlet casing 40c rear surface portion 50 compressed fluid discharge pipe

Claims (8)

a fluid compression section in which a substantially cylindrical rotor having moving blades standing on its outer peripheral surface is rotationally driven in a substantially cylindrical central casing having stationary blades standing on its inner peripheral surface;
a diffuser that guides the compressed fluid discharged from the fluid compression part to a flow path formed between the outer cylinder part and the inner cylinder part,
In the vicinity of the outlet of the flow path that is bent and reversed toward the fluid compression section, the outer cylindrical section is annular and extends in the outflow direction of the fluid, and the inner cylindrical section extends in the outflow direction of the fluid. An axial compressor characterized by having parallel cylindrical shapes. An axial flow compressor comprising a fluid compression section for compressing a fluid sucked from an upstream end through an inlet casing and discharging the compressed fluid from a downstream end through a diffuser and an outlet casing chamber,
The fluid compression section is configured such that a substantially cylindrical rotor having moving blades erected on an outer peripheral surface thereof is rotationally driven within a substantially cylindrical central casing having stationary blades erected on an inner peripheral surface thereof. ,
The diffuser comprises a diffuser ring, a substantially conical cylindrical outer cylindrical portion that continues to the downstream end of the inner peripheral surface of the central casing and spreads outward from the downstream end, a support cylindrical member that supports the rotor, and an outlet. It consists of a substantially conical cylindrical inner cylindrical portion which is a part of the casing and spreads outward from the vicinity of the downstream end of the outer peripheral surface of the rotor. A flow path is formed, and the vicinity of the outlet of the flow path is bent and turned toward the fluid compression section, and the fluid is discharged from between the downstream end of the inner peripheral surface of the central casing and the downstream end of the outer peripheral surface of the rotor. directing said compressed fluid through said flow path to said outlet;
The outlet casing chamber includes an outlet casing formed in a hollow annular shape surrounding the outer cylindrical portion of the diffuser, and circulates the fluid that has passed through the outlet of the diffuser in the circumferential direction. discharge from a compressed fluid discharge pipe connected to the outlet casing communicating with the chamber and radially outward;
In the vicinity of the outlet of the diffuser, the outer cylindrical portion of the diffuser is annular and extends in the outflow direction of the fluid, and the inner cylindrical portion is a portion bent and inverted toward the fluid compressing portion. The axial flow compressor is characterized in that the outer peripheral portion of the has a cylindrical shape parallel to the outflow direction of the fluid. 3. The inner cylindrical portion has a planar shape parallel to the flow direction of the fluid at a front upstream portion of a portion where the flow path is bent and reversed toward the fluid compression portion side. Axial compressor as described. In the vicinity of the outlet of the flow path, the outer cylindrical portion is annular and extends in the outflow direction of the fluid, and the inner cylindrical portion has a cylindrical shape parallel to the outflow direction of the fluid. 4. The axial flow compressor according to claim 1, wherein separation of a boundary layer of said fluid in said flow path is suppressed by: Between the outer cylinder part and the inner cylinder part, a flow path that is bent and inverted toward the fluid compression section side is formed for guiding the compressed fluid discharged from the fluid compression section, and the flow that is bent and inverted toward the fluid compression section side is formed. In the vicinity of the outlet of the passage, the outer cylindrical portion is annular and extends in the outflow direction of the fluid, and the inner cylindrical portion has a cylindrical shape parallel to the outflow direction of the fluid. Axial compressor diffuser. a substantially conical cylindrical outer cylinder portion which is formed of a diffuser ring and continues to the downstream end of the inner peripheral surface of the substantially cylindrical central casing of the axial flow compressor and spreads outward from the downstream end;
a substantially conical cylindrical inner cylindrical portion consisting of a support cylindrical member that supports the rotor that is rotationally driven in the central casing and a part of the outlet casing, and that spreads outward from the vicinity of the downstream end of the outer peripheral surface of the rotor; become,
A substantially conical tubular channel is formed between the outer cylinder portion and the inner cylinder portion, and the vicinity of the outlet of the channel is bent and turned toward the central casing, and the inner peripheral surface of the central casing is bent. guiding the compressed fluid discharged from between the downstream end and the downstream end of the outer peripheral surface of the rotor to the outlet through the flow path;
In the vicinity of the outlet, the outer cylindrical portion has an annular shape and extends in the outflow direction of the fluid. A diffuser for an axial compressor, characterized in that it has a cylindrical shape parallel to the outflow direction of the air. 6. The inner tubular portion has a planar shape parallel to the flow direction of the fluid at a front upstream portion of a portion where the flow path is bent and reversed toward the fluid compression portion. 7. A diffuser for an axial compressor according to 6 above. In the vicinity of the outlet of the flow path, the outer cylindrical portion is annular and extends in the outflow direction of the fluid, and the inner cylindrical portion has a cylindrical shape parallel to the outflow direction of the fluid. 8. The diffuser for an axial flow compressor according to claim 5, wherein boundary layer separation of said fluid in said flow path is suppressed by:

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