Patent Application
20230175525
The present disclosure relates to a scroll casing and a centrifugal compressor including the scroll casing.
A centrifugal compressor used in a compressor part or the like of a turbocharger for an automobile or a ship imparts kinetic energy to a fluid through rotation of an impeller and discharges the fluid outward in the radial direction, thereby achieving a pressure increase of the fluid by utilizing the centrifugal force. Such a centrifugal compressor is provided with various features to meet the need to improve the pressure ratio and the efficiency in a broad operational range.
Generally, a centrifugal compressor includes an impeller and a scroll casing rotatably housing the impeller. This scroll casing includes a scroll portion forming a spiral scroll passage, and a diffuser portion forming a diffuser passage for introducing a fluid having passed through the impeller to the scroll passage (for example, Patent Document 1).
Patent Document 1: WO2018/179112A
According to the inventors' knowledge, as shown in
If the thickness T of the diffuser outlet jaw portion 054 is decreased as shown in
In view of the above, an object of at least one embodiment of the present disclosure is to provide a scroll casing and a centrifugal compressor whereby it is possible to suppress the reduction in the efficiency of the centrifugal compressor and the reduction in the operating range.
A scroll casing according to the present disclosure is a scroll casing for a centrifugal compressor, including: a diffuser portion forming a diffuser passage of the centrifugal compressor; and a scroll portion forming a scroll passage of the centrifugal compressor, in which a relationship of Tb/Ta≥1.0 is satisfied in a range of an angular position around a scroll center of the scroll passage from 180 degrees to 360 degrees, where Ta is a passage width of the diffuser passage along an axial direction of the centrifugal compressor, Tb is a shortest distance from a start position which is a connection position with a hub-side passage surface of the diffuser passage on an inner peripheral surface of the scroll portion to a virtual arc that touches an end position which is a position opposite to the start position on the inner peripheral surface, and the angular position is defined so that the angle gradually increases from a merging position between a scroll start and a scroll end of the scroll passage of 60 degrees to a downstream side of the scroll passage.
A centrifugal compressor according to the present disclosure includes the above-described scroll casing.
At least one embodiment of the present disclosure provides a scroll casing and a centrifugal compressor whereby it is possible to suppress the reduction in the efficiency of the centrifugal compressor and the reduction in the operating range.
Embodiments of the present disclosure will be described below with reference to the accompanying drawings. It is intended, however, that unless particularly identified, dimensions, materials, shapes, relative positions, and the like of components described in the embodiments shall be interpreted as illustrative only and not intended to limit the scope of the present disclosure.
For instance, an expression of relative or absolute arrangement such as “in a direction”, “along a direction”, “parallel”, “orthogonal”, “centered”, “concentric” and “coaxial” shall not be construed as indicating only the arrangement in a strict literal sense, but also includes a state where the arrangement is relatively displaced by a tolerance, or by an angle or a distance whereby it is possible to achieve the same function.
For instance, an expression of an equal state such as “same” “equal” and “uniform” shall not be construed as indicating only the state in which the feature is strictly equal, but also includes a state in which there is a tolerance or a difference that can still achieve the same function.
Further, for instance, an expression of a shape such as a rectangular shape or a cylindrical shape shall not be construed as only the geometrically strict shape, but also includes a shape with unevenness or chamfered corners within the range in which the same effect can be achieved.
On the other hand, an expression such as “comprise”, “include”, “have”, “contain” and “constitute” are not intended to be exclusive of other components.
The same features can be indicated by the same reference numerals and not described in detail.
As shown in
The centrifugal compressor 1 can be applied to, for example, turbochargers 10 for automobiles, ships, or power generation, or other industrial centrifugal compressors, blowers, or the like. In the illustrated embodiment, the centrifugal compressor 1 is mounted in a turbocharger 10. As shown in
In the illustrated embodiment, as shown in
Hereinafter, for example as shown in
In the illustrated embodiment, as shown in
As shown in
The turbocharger 10 rotates the turbine rotor 13 by the exhaust gas introduced from an exhaust gas generation device (not shown, e.g., internal combustion engine such as engine) into the turbine casing 14 through the exhaust gas introduction port 141. Since the impeller 2 is mechanically connected to the turbine rotor 13 via the rotational shaft 12, the impeller 2 rotates in conjunction with the rotation of the turbine rotor 13. By rotating the impeller 2, the turbocharger 10 compresses the fluid introduced into the scroll casing 3 through the fluid introduction port 31 and sends it to a supply destination (e.g., internal combustion engine such as engine) through the fluid discharge port 32.
As shown in
In the illustrated embodiment, as shown in
Each of the intake passage 70, the diffuser passage 40, and the scroll passage 50 is formed in the scroll casing 3. The scroll passage 50 is disposed outward of the impeller 2 in the radial direction. The intake passage portion 7 has an inner wall surface 71 forming the intake passage 70 and extending along the axial direction X. The fluid introduction port 31 is formed at the front side XF end of the inner wall surface 71. The scroll portion 5 has an inner peripheral surface 51 forming the scroll passage 50.
The diffuser portion 4 has a shroud-side passage surface 41 forming a front side XF section of the diffuser passage 40, and a hub-side passage surface 42 disposed on the rear side XR of the shroud-side passage surface 41 so as to face the shroud-side passage surface 41 and forming a rear side XR section of the diffuser passage 40. In a cross-section along the axis CA as shown in
The diffuser portion 4 is disposed between the shroud portion 6 and the scroll portion 5. In the illustrated embodiment, the scroll casing 3 internally forms an impeller chamber 60 housing the impeller 2. The shroud surface 61 forms a front side XF section of the impeller chamber 60. The scroll casing 3 has an impeller chamber forming surface 33 disposed on the rear side XR of the shroud surface 61 and forming a rear side XR section of the impeller chamber 60.
The inlet of the diffuser passage 40 communicates with the impeller chamber 60, and the outlet of the diffuser passage 40 communicates with the scroll passage 50. In the illustrated embodiment, the upstream end of the shroud-side passage surface 41 is smoothly connected to the downstream end of the shroud surface 61. The upstream end of the hub-side passage surface 42 is connected to the outer peripheral end of the impeller chamber forming surface 33 via a stepped surface 34, and the downstream end of the hub-side passage surface 42 is smoothly connected to one end of the inner peripheral surface 51 of the scroll portion 5.
The fluid introduced into the scroll casing 3 through the fluid introduction port 31 flows through the intake passage 70 to the rear side XR and then is sent to the impeller 2 (impeller chamber 60). The fluid having passed through the impeller 2 flows through the diffuser passage 40 and the scroll passage 50 in this order, and then is discharged to the outside of the scroll casing 3 through the fluid discharge port 32.
As shown in
The start position P1 is the rear side XR end of the inner peripheral surface 51 in the axial direction X, where the curvature radius changes from infinite (straight line) to finite. Further, the end position P2 is positioned on the one-direction UD side of the start position P1. Here, the one-direction UD is the counterclockwise direction centered at the center SC of the scroll passage 50 in a cross-section along the axis CA of the centrifugal compressor 1 (on the outer side of the center SC in the radial direction Y, a direction from the rear side XR to the front side XF in the circumferential direction around the center SC, and on the inner side of the center SC in the radial direction Y, a direction from the front side XF to the rear side XR in the circumferential direction around the center SC), and the one-direction UD side is the downstream side.
In the embodiments shown in
The shape of the inner peripheral surface 51 is not limited to the illustrated embodiments. For example, the inner peripheral surface 51 may be formed so that its curvature continuously decreases toward the one-direction UD side.
As shown in
As shown in
The swirling flow SF flows downstream of the diffuser outlet jaw portion 54 along the virtual arc VC. The cross-sectional shape of the scroll casing 3 shown in
The cross-sectional shape of the scroll casing 3 shown in
As shown in
If the value of Tb/Ta is too small (if the relationship of Tb/Ta<1.0 is satisfied), the outlet flow DF of the diffuser passage 40 and the swirling flow SF in the scroll passage 50 interfere with each other, so that the resistance of the fluid passing through the diffuser passage 40 increases, which may induce diffuser stall. When the diffuser stall is induced, the efficiency of the centrifugal compressor 1 is extremely reduced, and surge is induced due to the diffuser stall, resulting in a reduction in the operating range of the centrifugal compressor 1. In order to avoid this, it is preferable to satisfy the relationship of Tb/Ta≥1.0. With the above configuration, since the scroll casing 3 satisfies the relationship of Tb/Ta≥1.0 in the range of the angular position θ from 180 degrees to 360 degrees (downstream range RD), the interference between the outlet flow DF of the diffuser passage 40 and the swirling flow SF in the scroll passage 50 can be suppressed in the downstream range RD. As a result, since the blockage of the diffuser passage 40 can be suppressed, it is possible to suppress the reduction in the efficiency of the centrifugal compressor 1 and the reduction in the operating range.
In some embodiments, as shown in
In order to suppress the interference between the outlet flow DF of the diffuser passage 40 and the swirling flow SF in the scroll passage 50, it is preferable that Tb/Ta≥1.0 is satisfied even in the range of the angular position θ of the scroll casing 3 from 60 degrees to 180 degrees (upstream range RU). However, since the cross-sectional area A of the scroll passage 50 decreases toward the scroll start 501 of the scroll passage 50, it may be difficult to satisfy the relationship of Tb/Ta≥1.0 in the upstream range RU. With the above configuration, the relationship of Tb/Ta≥0.5 is satisfied in the range of the angular position θ from 60 degrees to 180 degrees (upstream range RU). In this case, the interference between the outlet flow DF of the diffuser passage 40 and the swirling flow SF in the scroll passage 50 can be suppressed in the upstream range RU. As a result, since the blockage of the diffuser passage 40 can be suppressed, it is possible to suppress the reduction in the efficiency of the centrifugal compressor 1 and the reduction in the operating range. In some embodiments, the scroll casing 3 may be formed so as to satisfy the relationship of Tb/Ta≥1.0 in the upstream range RU and the downstream range RD. In this case, the interference between the outlet flow DF and the swirling flow SF can be effectively suppressed.
In some embodiments, as shown in
If the value of Tb/Ta is too large (if the relationship of Tb/Ta>1.75 is satisfied), as the thickness T of the diffuser outlet jaw portion 54 increases, the above-described region WA expands, and the wake loss increases, which may lead to a reduction in the efficiency of the centrifugal compressor 1. With the above configuration, the relationship of Tb/Ta≤1.75 is satisfied in the range of the angular position θ from 180 degrees to 360 degrees (downstream range RD). In this case, it is possible to suppress the reduction in the efficiency of the centrifugal compressor 1 due to the wake loss in the downstream range RD. In some embodiments, the scroll casing 3 satisfies the relationship of Tb/Ta≤1.75 in the upstream range RU and the downstream range RD. In this case, it is possible to suppress the reduction in the efficiency of the centrifugal compressor 1 due to the wake loss in the upstream range RU and the downstream range RD.
In the above-described embodiments, the distance ratio Tb/Ta is used as the parameter value related to the shape of the scroll casing 3, but in other embodiments, the intersection angle α may be used as the parameter value. As the intersection angle α increases, the inclination angle of the swirling flow SF downstream of the diffuser outlet jaw portion 54 with respect to the outlet flow DF increases according to the intersection angle α. When the inclination angle increases, the degree of interference between the swirling flow SF and the outlet flow DF increases, and the degree of blockage of the outlet flow DF of the diffuser passage 40 increases. For this reason, in order to suppress the blockage of the outlet flow DF, it is preferable to make the intersection angle α small. The scroll casing 3 preferably satisfies a relationship of intersection angle α≤70°, and more preferably satisfies a relationship of intersection angle α≤50°.
As shown in
If the intersection angle α is too large, the outlet flow DF of the diffuser passage 40 and the swirling flow SF in the scroll passage 50 interfere with each other, so that the resistance of the fluid passing through the diffuser passage 40 increases, which may induce diffuser stall. When the diffuser stall is induced, the efficiency of the centrifugal compressor 1 is extremely reduced, and surge is induced due to the diffuser stall, resulting in a reduction in the operating range of the centrifugal compressor 1. In order to avoid this, it is preferable to satisfy the relationship of α≤50°. With the above configuration, since the scroll casing 3 satisfies the relationship of α≤50° in the range of the angular position θ from 180 degrees to 360 degrees (downstream range RD), the interference between the outlet flow DF of the diffuser passage 40 and the swirling flow SF in the scroll passage 40 can be suppressed in the downstream range RD. As a result, since the blockage of the diffuser passage 40 can be suppressed, it is possible to suppress the reduction in the efficiency of the centrifugal compressor 1 and the reduction in the operating range. The present embodiment can be implemented independently.
In some embodiments, as shown in
In order to suppress the interference between the outlet flow DF of the diffuser passage 40 and the swirling flow SF in the scroll passage 50, it is preferable that the relationship of α≤50° is satisfied even in the range of the angular position θ of the scroll casing 3 from 60 degrees to 180 degrees (upstream range RU). However, since the cross-sectional area A of the scroll passage 50 decreases toward the scroll start 501 of the scroll passage 50, it may be difficult to satisfy the relationship of α≤50° in the upstream range RU. With the above configuration, the relationship of α≤70° is satisfied in the range of the angular position θ from 60 degrees to 180 degrees (upstream range RU). In this case, the interference between the outlet flow DF of the diffuser passage 40 and the swirling flow SF in the scroll passage 50 can be suppressed in the upstream range RU. As a result, since the blockage of the diffuser passage 40 can be suppressed, it is possible to suppress the reduction in the efficiency of the centrifugal compressor 1 and the reduction in the operating range. In some embodiments, the scroll casing 3 may be formed so as to satisfy the relationship of α≤50° in the upstream range RU and the downstream range RD. In this case, the interference between the outlet flow DF and the swirling flow SF can be effectively suppressed.
In the above-described embodiments, either one of the distance ratio Tb/Ta or the intersection angle α is used as the parameter value related to the shape of the scroll casing 3, but in other embodiments, both the distance ratio Tb/Ta and the intersection angle α may be used as the parameter values.
In some embodiments, the scroll casing 3 satisfies the relationship of Tb/Ta≥1.0 and α≤50° in the range of the angular position θ from 180 degrees to 360 degrees, i.e., in the downstream range RD.
With the above configuration, since the scroll casing 3 satisfies not only Tb/Ta≥1.0 but also α≤50° in the range of the angular position θ from 180 degrees to 360 degrees (downstream range RD), compared to the case where only Tb/Ta≥1.0 is satisfied, the interference between the outlet flow DF of the diffuser passage 40 and the swirling flow SF in the scroll passage 50 can be suppressed in the downstream range RD more effectively. As a result, since the blockage of the diffuser passage 40 can be effectively suppressed, it is possible to effectively suppress the reduction in the efficiency of the centrifugal compressor 1 and the reduction in the operating range.
In some embodiments, the scroll casing 3 satisfies the relationship of Tb/Ta≥0.5 and α≤70° in the range of the angular position θ from 60 degrees to 180 degrees, i.e., in the upstream range RU.
With the above configuration, since the scroll casing 3 satisfies not only Tb/Ta≥0.5 but also α≤70° in the range of the angular position θ from 60 degrees to 180 degrees (upstream range RU), compared to the case where only Tb/Ta≥0.5 is satisfied, the interference between the outlet flow DF of the diffuser passage 40 and the swirling flow SF in the scroll passage 50 can be suppressed in the upstream range RU more effectively. As a result, since the blockage of the diffuser passage 40 can be effectively suppressed, it is possible to effectively suppress the reduction in the efficiency of the centrifugal compressor 1 and the reduction in the operating range.
In some embodiments, as shown in
Normally, the length T along the axial direction of the centrifugal compressor 1 between the end position P2 and the downstream end 43 of the shroud-side passage surface 41 of the diffuser passage 40 is set uniformly in the circumferential direction of the centrifugal compressor 1. In this case, if Tb/Ta and the intersection angle α satisfy the above-described relationship at every angular position θ, the shape of the scroll passage 50 in the vicinity of the scroll end 502 becomes inappropriate, which may lead to a reduction in the efficiency of the centrifugal compressor 1. With the above configuration, since the length T2 of the scroll casing 3 at the angular position θ2 is longer than the length T1 at the angular position θ1, while maintaining the above-described relationship of Tb/Ta and the intersection angle α at every angular position θ, the scroll passage 50 can be shaped appropriately at every angular position θ. Thus, it is possible to suppress the reduction in the efficiency of the centrifugal compressor 1.
As shown in
In some embodiments, as shown in
Normally, the length d along the radial direction of the centrifugal compressor 1 from the axis CA of the centrifugal compressor 1 to the downstream end 43 of the shroud-side passage surface 41 of the diffuser passage 40 is set uniformly in the circumferential direction of the centrifugal compressor 1. In this case, if Tb/Ta and the intersection angle α satisfy the above-described relationship at every angular position θ, the shape of the scroll passage 50 in the vicinity of the scroll end becomes inappropriate, which may lead to a reduction in the efficiency of the centrifugal compressor 1. With the above configuration, since the length d2 of the scroll casing 3 at the angular position θ4 is longer than the length d1 at the angular position θ3, while maintaining the above-described relationship, the scroll passage 50 can be shaped appropriately at every angular position θ. Thus, it is possible to suppress the reduction in the efficiency of the centrifugal compressor 1.
In the embodiment shown in
The centrifugal compressor 1 according to some embodiments includes the above-described scroll casing 3. In this case, the scroll casing 3 can suppress the interference between the outlet flow DF of the diffuser passage 40 and the swirling flow SF in the scroll passage 50. As a result, since the blockage of the diffuser passage 40 can be suppressed, it is possible to suppress the reduction in the efficiency of the centrifugal compressor 1 and the reduction in the operating range.
The present disclosure is not limited to the embodiments described above, but includes modifications to the embodiments described above, and embodiments composed of combinations of those embodiments.
The contents described in the above embodiments would be understood as follows, for instance.
1) A scroll casing (3) according to at least one embodiment of the present disclosure is a scroll casing (3) for a centrifugal compressor (1), including: a diffuser portion (4) forming a diffuser passage (40) of the centrifugal compressor (1); and a scroll portion (5) forming a scroll passage (50) of the centrifugal compressor (1), in which a relationship of Tb/Ta≥1.0 is satisfied in a range (downstream range RD) of an angular position (θ) around a scroll center (O) of the scroll passage (50) from 180 degrees to 360 degrees, where Ta is a passage width of the diffuser passage (40) along an axial direction of the centrifugal compressor (1), Tb is a shortest distance from a start position (P1) which is a connection position with a hub-side passage surface (42) of the diffuser passage (40) on an inner peripheral surface (51) of the scroll portion (5) to a virtual arc (VC) that touches an end position (P2) which is a position opposite to the start position (P1) on the inner peripheral surface (51), and the angular position (θ) is defined so that the angle gradually increases from a merging position (P) between a scroll start (501) and a scroll end (502) of the scroll passage (50) of 60 degrees to a downstream side of the scroll passage (50).
If the value of Tb/Ta is too small (if the relationship of Tb/Ta<1.0 is satisfied), the outlet flow (DF) of the diffuser passage and the swirling flow (SF) in the scroll passage interfere with each other, so that the resistance of the fluid passing through the diffuser passage (40) increases, which may induce diffuser stall. When the diffuser stall is induced, the efficiency of the centrifugal compressor (1) is extremely reduced, and surge is induced due to the diffuser stall, resulting in a reduction in the operating range of the centrifugal compressor (1). In order to avoid this, it is preferable to satisfy the relationship of Tb/Ta≥1.0. With the above configuration 1), since the scroll casing (3) satisfies the relationship of Tb/Ta≥1.0 in the range of the angular position (θ) from 180 degrees to 360 degrees (downstream range RD), the interference between the outlet flow (DF) of the diffuser passage and the swirling flow (SF) in the scroll passage can be suppressed in the downstream range. As a result, since the blockage of the diffuser passage (40) can be suppressed, it is possible to suppress the reduction in the efficiency of the centrifugal compressor (1) and the reduction in the operating range.
2) In some embodiments, in the scroll casing (3) described in 1), a relationship of Tb/Ta≥0.5 is satisfied in a range of the angular position (θ) from 60 degrees to 180 degrees (upstream range RU).
With the above configuration 2), the relationship of Tb/Ta≥0.5 is satisfied in the range of the angular position (θ) from 60 degrees to 180 degrees (upstream range RU). In this case, the interference between the outlet flow (DF) of the diffuser passage and the swirling flow (SF) in the scroll passage can be suppressed in the upstream range (RU). As a result, since the blockage of the diffuser passage (40) can be suppressed, it is possible to suppress the reduction in the efficiency of the centrifugal compressor (1) and the reduction in the operating range.
3) In some embodiments, in the scroll casing (3) described in 1) or 2), a relationship of Tb/Ta≤1.75 is satisfied in a range of the angular position (θ) from 180 degrees to 360 degrees (downstream range RD).
If the value of Tb/Ta is too large (if the relationship of Tb/Ta>1.75 is satisfied), as the thickness (T) of the diffuser outlet jaw portion (54) increases, the wake loss increases, which may lead to a reduction in the efficiency of the centrifugal compressor (1). With the above configuration 3), the relationship of Tb/Ta≤1.75 is satisfied in the range of the angular position (θ) from 180 degrees to 360 degrees (downstream range RD). In this case, it is possible to suppress the reduction in the efficiency of the centrifugal compressor (1) due to the wake loss in the downstream range (RD).
4) In some embodiments, in the scroll casing (3) described in any one of 1) to 3), a relationship of α≤50° is satisfied in a range of the angular position (θ) from 180 degrees to 360 degrees (downstream range RD), where a is an intersection angle between a virtual tangent line (VT) that touches the end position (P2) of the inner peripheral surface (51) of the scroll portion (5) and a radial direction (Y) of the centrifugal compressor (1).
With the above configuration 4), since the scroll casing (3) satisfies not only Tb/Ta≥1.0 but also α≤50° in the range of the angular position (θ) from 180 degrees to 360 degrees (downstream range RD), compared to the case where only Tb/Ta≥1.0 is satisfied, the interference between the outlet flow (DF) of the diffuser passage and the swirling flow (SF) in the scroll passage can be suppressed in the downstream range (RD) more effectively. As a result, since the blockage of the diffuser passage (40) can be effectively suppressed, it is possible to effectively suppress the reduction in the efficiency of the centrifugal compressor (1) and the reduction in the operating range.
5) In some embodiments, in the scroll casing (3) described in 4), a relationship of α≤70° is satisfied in a range of the angular position (θ) from 60 degrees to 180 degrees (upstream range RU).
With the above configuration 5), the relationship of α≤70° is satisfied in the range of the angular position (θ) from 60 degrees to 180 degrees (upstream range RU). In this case, the interference between the outlet flow (DF) of the diffuser passage and the swirling flow (SF) in the scroll passage can be suppressed in the upstream range (RU). As a result, since the blockage of the diffuser passage (40) can be suppressed, it is possible to suppress the reduction in the efficiency of the centrifugal compressor (1) and the reduction in the operating range.
6) A scroll casing (3) according to at least one embodiment of the present disclosure is a scroll casing (3) for a centrifugal compressor (1), including: a diffuser portion (4) forming a diffuser passage (40) of the centrifugal compressor (1); and a scroll portion (5) forming a scroll passage (50) of the centrifugal compressor (1), in which a relationship of α≤50° is satisfied in a range of an angular position (θ) around a scroll center (O) of the scroll passage from 180 degrees to 360 degrees, where a is an intersection angle between a virtual tangent line (VT) that touches an end position (P2) of an inner peripheral surface (51) of the scroll portion (5) and a radial direction (Y) of the centrifugal compressor (1), the end position (P2) being a position opposite to a start position (P1) which is a connection position with a hub-side passage surface (42) of the diffuser passage (40) on the inner peripheral surface (51) of the scroll portion (5), and the angular position (θ) is defined so that the angle gradually increases from a merging position (P) between a scroll start (501) and a scroll end (502) of the scroll passage (50) of 60 degrees to a downstream side of the scroll passage (50).
If the intersection angle α is too large, the outlet flow (DF) of the diffuser passage and the swirling flow (SF) in the scroll passage interfere with each other, so that the resistance of the fluid passing through the diffuser passage (40) increases, which may induce diffuser stall. When the diffuser stall is induced, the efficiency of the centrifugal compressor (1) is extremely reduced, and surge is induced due to the diffuser stall, resulting in a reduction in the operating range of the centrifugal compressor (1). With the above configuration 6), since the scroll casing (3) satisfies the relationship of α≤50° in the range of the angular position (θ) from 180 degrees to 360 degrees (downstream range RD), the interference between the outlet flow (DF) of the diffuser passage and the swirling flow (SF) in the scroll passage can be suppressed in the downstream range (RD). As a result, since the blockage of the diffuser passage (40) can be suppressed, it is possible to suppress the reduction in the efficiency of the centrifugal compressor (1) and the reduction in the operating range.
7) In some embodiments, in the scroll casing (3) described in 6), a relationship of α≤70° is satisfied in a range of the angular position (θ) from 60 degrees to 180 degrees (upstream range RU).
With the above configuration 7), the relationship of α≤70° is satisfied in the range of the angular position (θ) from 60 degrees to 180 degrees (upstream range RU). In this case, the interference between the outlet flow (DF) of the diffuser passage and the swirling flow (SF) in the scroll passage can be suppressed in the upstream range (RU). As a result, since the blockage of the diffuser passage (40) can be suppressed, it is possible to suppress the reduction in the efficiency of the centrifugal compressor (1) and the reduction in the operating range.
8) In some embodiments, in the scroll casing (3) described in any one of 1) to 7), a relationship of T1<T2 is satisfied, where T1 is a length along an axial direction of the centrifugal compressor (1) between the end position (P2) and a downstream end (43) of a shroud-side passage surface (41) of the diffuser passage (40) at a position where the angular position is θ1, and T2 is a length along the axial direction between the end position (P2) and the downstream end (43) of the shroud-side passage surface (41) at a position where the angular position is θ2 that is larger than θ1.
Normally, the length (T) along the axial direction of the centrifugal compressor (1) between the end position (P2) and the downstream end (43) of the shroud-side passage surface (41) of the diffuser passage (40) is set uniformly in the circumferential direction of the centrifugal compressor (1). In this case, if Tb/Ta and the intersection angle α satisfy the above-described relationship at every angular position (θ), the shape of the scroll passage (50) in the vicinity of the scroll end (502) becomes inappropriate, which may lead to a reduction in the efficiency of the centrifugal compressor (1). With the above configuration 8), since the length T2 of the scroll casing (3) at the angular position θ2 is longer than the length T1 at the angular position θ1, while maintaining the above-described relationship of Tb/Ta and the intersection angle α at every angular position (θ), the scroll passage (50) can be shaped appropriately at every angular position (θ). Thus, it is possible to suppress the reduction in the efficiency of the centrifugal compressor (1).
9) In some embodiments, in the scroll casing (3) described in any one of 1) to 8), a relationship of d1>d2 is satisfied, where d1 is a length along a radial direction (Y) of the centrifugal compressor (1) from an axis (CA) of the centrifugal compressor (1) to a downstream end (43) of a shroud-side passage surface (41) of the diffuser passage (40) at a position where the angular position is θ3, and d2 is a length along the radial direction (Y) from the axis (CA) to the downstream end (43) of the shroud-side passage surface (41) at a position where the angular position is θ4 that is larger than θ3.
Normally, the length (d) along the radial direction (Y) of the centrifugal compressor (1) from the axis (CA) of the centrifugal compressor (1) to the downstream end (43) of the shroud-side passage surface (41) of the diffuser passage (40) is set uniformly in the circumferential direction of the centrifugal compressor (1). In this case, if Tb/Ta and the intersection angle α satisfy the above-described relationship at every angular position (θ), the shape of the scroll passage (50) in the vicinity of the scroll end becomes inappropriate, which may lead to a reduction in the efficiency of the centrifugal compressor (1). With the above configuration 9), since the length d2 of the scroll casing (3) at the angular position θ4 is longer than the length d1 at the angular position θ3, while maintaining the above-described relationship of Tb/Ta and the intersection angle α at every angular position (θ), the scroll passage (50) can be shaped appropriately at every angular position (θ). Thus, it is possible to suppress the reduction in the efficiency of the centrifugal compressor (1).
10) A centrifugal compressor (1) according to at least one embodiment of the present disclosure includes the scroll casing (3) described in any one of 1) to 9).
With the above configuration 10), the scroll casing (3) can suppress the interference between the outlet flow (DF) of the diffuser passage and the swirling flow (SF) in the scroll passage. As a result, since the blockage of the diffuser passage (40) can be suppressed, it is possible to suppress the reduction in the efficiency of the centrifugal compressor (1) and the reduction in the operating range.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/020032 | 5/21/2020 | WO |
