阅读说明：本技术 旋转叶片以及具备该旋转叶片的离心压缩机 (Rotating blade and centrifugal compressor provided with same ) 是由 林良洋 藤田豊 冈信仁 高桥幸市 西勇人 于 2018-06-11 设计创作，主要内容包括：旋转叶片具备轮毂和设置于轮毂的多个叶片,多个叶片各自包括负压面、压力面、前缘、后缘、叶尖侧缘以及轮毂侧缘,在前缘与后缘之间的任意的翼弦位置处的叶片的截面中,负压面或压力面的至少一方构成为,至少在从前缘到朝向后缘离开的翼弦位置为止的范围内,相对于叶片的叶片高度方向所成的角度从轮毂侧缘到叶尖侧缘在从轮毂侧缘朝向叶尖侧缘的方向上增加。(The rotary blade includes a hub and a plurality of blades provided on the hub, each of the plurality of blades includes a negative pressure surface, a front edge, a rear edge, a tip side edge, and a hub side edge, and at least one of the negative pressure surface and the pressure surface is configured such that an angle formed with respect to a blade height direction of the blade increases from the hub side edge to the tip side edge in a direction from the hub side edge to the tip side edge in a range at least from the front edge to a chord position spaced apart from the rear edge in a cross section of the blade at an arbitrary chord position between the front edge and the rear edge.)

1. A rotary blade comprising a hub and a plurality of blades provided on the hub, wherein,

each of the plurality of blades including a suction surface, a pressure surface, a leading edge, a trailing edge, a tip side edge, and a hub side edge,

in a cross section of the blade at any chord position between the leading edge and the trailing edge, at least one of the negative pressure surface and the pressure surface is configured such that an angle formed with respect to a blade height direction of the blade increases from the hub side edge to the tip side edge in a direction from the hub side edge toward the tip side edge at least in a range from the leading edge to a chord position spaced apart from the trailing edge.

2. The rotary blade according to claim 1,

the at least one of the negative pressure surface or the pressure surface includes: a first region that is a region from the leading edge to a chord position that extends away from the trailing edge, and a second region that is a region closer to the trailing edge than the first region,

in the first region, the angle increases continuously from the hub side edge toward the tip side edge.

3. The rotary blade according to claim 2,

the second region is formed by at least two line segments between the tip side edge and the hub side edge.

4. The rotary blade according to claim 2 or 3,

the first region is a region in a range between the leading edge and a chord position of 5% to 15% from the leading edge.

5. The rotary blade according to any one of claims 1 to 4,

the angle formed by the negative pressure surface or the pressure surface with respect to the blade height direction of the blade increases from the hub side edge to the tip side edge in the direction from the hub side edge toward the tip side edge at least in the range from the leading edge to the chord position spaced apart from the trailing edge, and the other of the negative pressure surface or the pressure surface is configured as a line segment connecting the hub side edge and the tip side edge.

6. A centrifugal compressor comprising the rotary blade according to any one of claims 1 to 5.

Technical Field

The present disclosure relates to a rotary blade and a centrifugal compressor including the same.

Background

In a centrifugal compressor of a turbocharger, the natural frequency of an impeller coincides with the vibration frequency of an exciting force applied by a fluid flowing through the centrifugal compressor, and resonance occurs, and the vibration of the impeller increases, and the impeller may be damaged. In order to improve safety against such resonance, it is conceivable to locally reduce the blade thickness at a portion corresponding to an antinode of the natural mode and to locally increase the blade thickness at a portion corresponding to a node of the natural mode. To achieve such a shape, the blade thickness distribution of the blade needs to be defined stereoscopically.

In patent document 1, in order not to improve safety against resonance but to expand the operating region on the high flow rate side of the centrifugal compressor, the blades of the impeller are divided in the blade height direction into a tip end portion on the tip side, a root portion on the hub side, and a connecting portion located between the tip end portion and the root portion, the blade thickness of the tip end portion is thinner and constant than the blade thickness of the root portion, the blade thickness of the connecting portion is configured to gradually decrease from the root portion toward the tip end portion, and the blade thickness of the root portion is configured to gradually decrease toward the connecting portion.

Disclosure of Invention

Problems to be solved by the invention

However, as is apparent from fig. 4 showing the results of the eigenvalue analysis of the blade by the present inventors, the antinode portion of the primary eigenmode of the blade 100 is located in the range of 50 to 100% of the blade height from the hub side edge 102 toward the tip side edge 103 of the blade 100 on the front edge 101 side of the blade 100. As described above, in the blade thickness distribution of the blade described in patent document 1, even if the blade thickness of the portion corresponding to the antinode of the eigen mode can be locally reduced, the blade thickness of the portion corresponding to the node of the eigen mode cannot be appropriately increased, and there is a possibility that the safety against resonance cannot be improved. Further, since the portion where the blade thickness distribution is concave is formed from the hub side to the blade tip side, the processing method for forming the blade surface is limited.

In view of the above circumstances, an object of at least one embodiment of the present disclosure is to provide a rotary blade having improved safety against resonance, and a centrifugal compressor including the rotary blade.

Means for solving the problems

(1) A rotary blade according to at least one embodiment of the present invention includes a hub and a plurality of blades provided on the hub, wherein,

each of the plurality of blades including a suction surface, a pressure surface, a leading edge, a trailing edge, a tip side edge, and a hub side edge,

in a cross section of the blade at any chord position between the leading edge and the trailing edge, at least one of the negative pressure surface and the pressure surface is configured such that an angle formed with respect to a blade height direction of the blade increases from the hub side edge to the tip side edge in a direction from the hub side edge toward the tip side edge at least in a range from the leading edge to a chord position spaced apart from the trailing edge.

According to the structure of the above (1), in the cross section of the blade at any chord position between the leading edge and the trailing edge, at least one of the negative pressure surface and the pressure surface is configured such that the angle formed with respect to the blade height direction of the blade increases from the hub side edge to the tip side edge in the direction from the hub side edge toward the tip side edge at least in the range from the leading edge to the chord position spaced apart from the trailing edge, and thus the blade thickness at the portion corresponding to the antinode of the eigenmode can be locally made thin and the blade thickness at the portion corresponding to the node of the eigenmode can be made thick, so that the safety against resonance can be improved.

(2) In several embodiments, in the structure of the above (1),

the at least one of the negative pressure surface or the pressure surface includes: a first region that is a region from the leading edge to a chord position that extends away from the trailing edge, and a second region that is a region closer to the trailing edge than the first region,

in the first region, the angle increases continuously from the hub side edge toward the tip side edge.

According to the configuration of the above (2), the first region requires spot cutting, which is associated with an increase in the machining time and manufacturing cost of the blade, but since the first region is a partial region on the leading edge side, an increase in the machining time and manufacturing cost of the blade can be suppressed as compared with the case where spot cutting is performed on the entire blade surface.

(3) In several embodiments, in the structure of the above (2),

the second region is formed by at least two line segments between the tip side edge and the hub side edge.

According to the configuration of the above (3), since the second region can be subjected to the wire-cutting process, even in a configuration in which the angle formed by the first region on the rear edge side with respect to the blade height direction of the blade increases from the hub side edge to the tip side edge in the direction from the hub side edge toward the tip side edge, it is possible to suppress an increase in the processing time and the manufacturing cost of the blade.

(4) In several embodiments, in the structure of the above (2) or (3),

the first region is a region in a range between the leading edge and a chord position from the leading edge to 5% to 15%.

In general, in the range from the leading edge to the position of 5% to 15% of the chord, point cutting is required to form a rounded shape on the leading edge of the blade. According to the configuration of the above (4), by processing the blade surface shape of the first region at the time of processing for forming the rounded shape at the leading edge of the blade, it is possible to suppress an increase in processing time and manufacturing cost of the blade, as compared with the case of performing the spot cutting processing only for processing the blade surface shape of the first region.

(5) In some embodiments, in any of the structures (1) to (4) above,

the angle formed by the negative pressure surface or the pressure surface with respect to the blade height direction of the blade increases from the hub side edge to the tip side edge in the direction from the hub side edge toward the tip side edge at least in the range from the leading edge to the chord position spaced apart from the trailing edge, and the other of the negative pressure surface or the pressure surface is configured as a line segment connecting the hub side edge and the tip side edge.

According to the configuration of the above (5), by processing only either the negative pressure surface or the pressure surface such that the angle formed with respect to the blade height direction of the blade increases from the hub side edge to the tip side edge in the direction from the hub side edge toward the tip side edge, it is possible to suppress an increase in the processing time and manufacturing cost of the blade as compared with the case where the above-described processing is performed on both the negative pressure surface and the pressure surface. Further, since the other of the suction surface and the pressure surface is a plane connecting the hub side edge and the tip side edge, it is possible to reliably realize a blade thickness distribution in which the blade thickness is locally reduced at a portion corresponding to the antinode of the natural mode and the blade thickness is increased at a portion corresponding to the node of the natural mode.

(6) A centrifugal compressor according to at least one embodiment of the present invention includes the rotary blade according to any one of (1) to (5) above.

According to the configuration of the above (6), safety against resonance can be improved.

Effects of the invention

According to at least one embodiment of the present disclosure, in a cross section of the blade at any chord position between the leading edge and the trailing edge, at least one of the negative pressure surface and the pressure surface is configured such that an angle formed with respect to the blade height direction of the blade increases from the hub side edge to the tip side edge in a direction from the hub side edge toward the tip side edge at least in a range from the leading edge to the chord position spaced apart from the trailing edge, and thus the blade thickness at a portion corresponding to an antinode of the eigenmode can be locally made thin and the blade thickness at a portion corresponding to a node of the eigenmode can be made thick, and therefore, safety against resonance can be improved.

Drawings

Fig. 1 is a partial sectional view of a centrifugal compressor including a rotary blade according to an embodiment of the present disclosure.

Fig. 2 is a sectional view taken along line II-II of fig. 1.

Fig. 3 is a sectional view taken along the line III-III of fig. 1.

Fig. 4 is a diagram showing the result of analysis of the eigenvalues of the blade by the present inventors.

Detailed Description

Hereinafter, several embodiments of the present invention will be described with reference to the drawings. However, the scope of the present invention is not limited to the following embodiments. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the following embodiments are not intended to limit the scope of the present invention to these, and are merely illustrative examples.

The rotary vane according to several embodiments of the present disclosure shown below is described by taking as an example a rotary vane (impeller) provided in a centrifugal compressor of a turbocharger. However, the centrifugal compressor in the present disclosure is not limited to the centrifugal compressor of the turbocharger, and may be any centrifugal compressor that operates alone. Although not specifically described, the rotary vane of the present disclosure includes a rotary vane used in a turbine or an axial flow pump.

As shown in fig. 1, a centrifugal compressor 1 includes a casing 2 and an impeller 3 provided in the casing 2 so as to be rotatable about a rotation axis L. The impeller 3 has a plurality of blades 4 (only one blade 4 is shown in fig. 1) having a streamlined shape and provided on the hub 5 at predetermined intervals in the circumferential direction. Each blade 4 includes a front edge 4a, a rear edge 4b, a tip (tip) side edge 4c facing the casing 2, and a hub side edge 4d connected to the hub 5.

The negative pressure surface 10 of the blade 4 is divided into a first region 11, which is a region from the leading edge 4a to a chord position spaced apart from the trailing edge 4b, and a second region 12, which is a region closer to the trailing edge 4b than the first region 11. Although not shown in fig. 1, the pressure surface of the blade 4 is similarly divided into the first region 11 and the second region 12.

Fig. 2 shows a cross section (cross-sectional line omitted) obtained by cutting the blade 4 at an arbitrary chord position in the first region 11 of each of the suction surface 10 and the pressure surface 20 of the blade 4. Both the negative pressure surface 10 and the pressure surface 20 have a line segment L connecting the tip side edge 4c and the hub side edge 4d in the cross section₁₀And L₂₀Is in a convexly curved shape.

In the cross section shown in fig. 2, the convex curvature in the first region 11 of the suction surface 10 has the following shape: the angle formed with respect to the blade height direction of the blade 4 increases from the hub side edge 4d to the tip side edge 4c in the direction from the hub side edge 4d toward the tip side edge 4 c. That is, the angle formed by the position a closer to the hub side edge 4d than the tip side edge 4c with respect to the blade height direction of the blade 4 is represented by θ₁An angle formed by a position B closer to the tip side edge 4c than the position a with respect to the blade height direction of the blade 4 is represented by θ₂When theta is greater than theta₁<θ₂。

In the cross section shown in fig. 2, the convex curvature in the first region 11 of the pressure surface 20 likewise has the following shape: the angle formed with respect to the blade height direction of the blade 4 increases from the hub side edge 4d to the tip side edge 4c in the direction from the hub side edge 4d toward the tip side edge 4 c. That is, the angle formed by the position C closer to the hub side edge 4d than the tip side edge 4C with respect to the blade height direction of the blade 4 is represented by θ₃An angle formed by a position D closer to the tip side edge 4C than the position C with respect to the blade height direction of the blade 4 is represented by θ₄When theta is greater than theta₃<θ₄。

Fig. 3 shows a cross section (cross-sectional line omitted) obtained by cutting the blade 4 at an arbitrary chord position in the second region 12 of each of the suction surface 10 and the pressure surface 20 of the blade 4. The negative pressure surface 10 has three line segments L connected in sequence in the cross section₁₁、L₁₂、L₁₃And the shape of the structure. The pressure surface 20 also has three line segments L which are connected in succession in the cross section₂₁、L₂₂、L₂₃And the shape of the structure. As a result, the negative pressure surface 10 and the pressure surface 20 are formedBecomes a phase comparison line segment L₁₀And L₂₀And (4) protruding.

In the cross section shown in FIG. 3, the line segment L is drawn₁₁、L₁₂、L₁₃The angle formed by each of the blades 4 with the blade height direction is θ₁₁、θ₁₂、θ₁₃At this time, the second region 12 of the negative pressure surface 10 becomes θ₁₁<θ₁₂<θ₁₃The shape of (2). That is, similarly, the angle formed by the second region 12 of the negative pressure surface 10 with respect to the blade height direction of the blade 4 increases from the hub side edge 4d to the tip side edge 4c in the direction from the hub side edge 4d toward the tip side edge 4c, but is not continuous but is stepwise.

In the cross section shown in FIG. 3, the line segment L is drawn₂₁、L₂₂、L₂₃The angle formed by each of the blades 4 with the blade height direction is θ₂₁、θ₂₂、θ₂₃In this case, the second region 12 of the pressure surface 20 is θ₂₁<θ₂₂<θ₂₃The shape of (2). That is, the angle formed by the second region 12 of the pressure surface 20 with respect to the blade height direction of the blade 4 similarly increases from the hub side edge 4d to the tip side edge 4c in the direction from the hub side edge 4d toward the tip side edge 4c, but is not continuous but is stepwise.

As described above with reference to fig. 2 and 3, both the negative pressure surface 10 and the pressure surface 20 are configured such that the angle formed with respect to the blade height direction of the blade 4 increases in the direction from the hub side edge 4d to the tip side edge 4c toward the tip side edge 4c from the hub side edge 4d, so that the blade thickness in the vicinity of the tip side edge 4c, which is a portion corresponding to the antinode of the natural mode, can be made thin, and the natural value can be secured, and the blade thickness in the vicinity of a position of about 50% of the blade height can be made thick from the hub side edge 4d toward the tip side edge 4c, so that the strength of the portion corresponding to the node of the natural mode can be increased, and therefore, the safety against resonance that may occur during operation of the centrifugal compressor 1 (see fig. 1) can be improved.

As shown in fig. 3, the blade surface shape of the second region 12 having a cross section formed by cutting the blade 4 at an arbitrary chord position and including a plurality of line segments can be processed by wire cutting, but as shown in fig. 2, the blade surface shape of the first region 11 having a structure in which the cross section formed by cutting the blade 4 at an arbitrary chord position and continuously curving is not formed by wire cutting, and point cutting is necessary. The machining time and cost of the spot cutting machining become larger than those of the line cutting machining, but the first region 11 is limited to a partial region in the vicinity of the leading edge 4 a. Therefore, as compared with the case where the entire blade surface is formed into the blade surface shape of the first region 11, the increase in the processing time and the manufacturing cost of the blade 4 can be suppressed.

In addition, the first region 11 is preferably a region in the range between the leading edge 4a and the position of the chord from the leading edge 4a to 5% to 15%. In general, in the range from the leading edge 4a to the position of 5% to 15% of the chord, point cutting is required to form a rounded shape on the leading edge 4a of the blade 4. By machining the blade surface shape of the first region 11 at the time of machining the leading edge 4a of the blade 4 into the rounded shape, it is possible to suppress an increase in machining time and manufacturing cost of the blade 4 as compared with the case where the spot cutting machining is performed only for machining the blade surface shape of the first region 11.

In the above embodiment, the second region 12 has a shape in which three line segments are connected in order in a cross section obtained by cutting the blade 4 at an arbitrary chord position, but the present invention is not limited to this embodiment. The second region 12 may have a shape formed by connecting two line segments or four or more line segments in sequence.

In the above embodiment, the blade surface shapes of the first region 11 and the second region 12 are formed in the same manner for both the suction surface 10 and the pressure surface 20, but the present invention is not limited to this manner. The ranges of the first regions 11 of the negative pressure surface 10 and the pressure surface 20 may be different. In this case, the range of the first region 11 of the negative pressure surface 10 is preferably larger than the range of the first region 11 of the pressure surface 20. This is because the boundary layer of the pressure surface 20 is thinner than the boundary layer of the negative pressure surface 10, and peeling is less likely to occur with respect to a change in curvature of the wall surface, and thus improvement in performance can be expected.

In the above embodiment, the negative pressure surface 10 and the pressure surface 20 are providedThe blade surface shapes of the first region 11 and the second region 12 are formed on both sides, but the present invention is not limited to this embodiment. The blade surface shape of the first region 11 and the second region 12 may be formed on either the suction surface 10 or the pressure surface 20, and the other of the suction surface 10 or the pressure surface 20 may be a plane (corresponding to the line segment L in fig. 2 and 3) connecting the hub side edge 4d and the blade tip side edge 4c₁₀Or L₂₀Are equivalent in shape). In this case, it is preferable that the pressure surface 20 has a blade surface shape of the second region 12 and the negative pressure surface 10 is a plane connecting the hub side edge 4d and the tip side edge 4 c. This is because the boundary layer of the pressure surface 20 is thinner than the boundary layer of the negative pressure surface 10, and peeling is less likely to occur with respect to a change in curvature of the wall surface.

By forming the blade surface shapes of the first region 11 and the second region 12 only on one of the suction surface 10 and the pressure surface 20, it is possible to suppress an increase in the processing time and the manufacturing cost of the blade 4, as compared with the case where the blade surface shapes as described above are formed on both the suction surface 10 and the pressure surface 20. Further, since the other of the suction surface 10 and the pressure surface 20 is a plane connecting the hub side edge 4d and the tip side edge 4c, it is possible to reliably realize a blade thickness distribution in which the blade thickness is locally reduced at a portion corresponding to an antinode of the natural mode and the blade thickness is increased at a portion corresponding to a node of the natural mode.

In the above embodiment, the negative pressure surface 10 and the pressure surface 20 include both the first region 11 and the second region 12, respectively, but it is sufficient to include at least the first region 11. Even when the second region 12 is included, the second region 12 may not be included in the entire region from the first region 11 to the trailing edge 4b, or may be included in a range from the first region 11 to a chord position distant from the trailing edge 4 b.

In the above embodiment, the blade 4 has been described as a solid blade, but the present invention is not limited to this embodiment. The blade 4 may also be a splitter blade arranged between two solid blades.

Description of the reference numerals

1 centrifugal compressor

2 casing

3 impeller (rotating vane)

4 blade

4a leading edge

4b trailing edge

4c tip side edge

4d hub side edge

5 wheel hub

10 negative pressure surface

11 first region

12 second region

20 pressure surface

L axis of rotation

L₁₀Line segment

L₁₁Line segment

L₁₂Line segment

L₁₃Line segment

L₂₀Line segment

L₂₁Line segment

L₂₂Line segment

L₂₃Line segment

θ₁Angle of rotation

θ₂Angle of rotation

θ₃Angle of rotation

θ₄Angle of rotation

θ₁₁Angle of rotation

θ₁₂Angle of rotation

θ₁₃Angle of rotation

θ₂₁Angle of rotation

θ₂₂Angle of rotation

θ₂₃Angle of rotation