JP2019173617A - Inlet guide vane and compressor - Google Patents

Abstract

To restrict reduction in performance of a compressor.SOLUTION: An inlet guide vane is made such that a first blade surface 71 and a second blade surface 72 facing toward different directions to each other are connected to each other by a front edge end 73 and a rear edge end 74 and there is provided a vane main body 62 extending in a blade height direction. The vane main body 62 at a blade section orthogonal to said blade height direction has a shape showing that a thickness ratio Ts/Tp is in a range of 1.02 to 1.33 where Tp is a first distance ranging from a chord line CL in a direction orthogonal to the chord line CL that is a straight line connecting the front edge end 73 with the rear edge end 74 to the first blade surface 71, and Tz is a second distance ranging from the chord line CL orthogonal to the chord line CL to the second blade surface 72. The thickness ratio Ts/Tp is kept constant at any positions in a blade chord direction D2 where the chord line CL extends.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an inlet guide vane and a compressor.

  For example, some compressors used in turbo refrigerators have an inlet guide vane (movable guide vane) installed at a suction port for sucking refrigerant. The inlet guide vanes are arranged at intervals in the circumferential direction, and a plurality of inlet guide vanes are provided in the suction port. The inlet guide vane has a shape extending from the inner wall of the suction port to the center of the suction port. The angle of the inlet guide vane with respect to the inflowing refrigerant is variable. By adjusting the angle of the inlet guide vane, the amount of refrigerant supplied to the impeller disposed on the downstream side is adjusted.

  As such an inlet guide vane, for example, Patent Document 1 describes a structure in which a part of the vane body is thinned in order to improve assemblability while maintaining performance. In this structure, the airfoil surface along the surface of the virtual airfoil is formed by the other parts excluding the thinned part in order to ensure assemblability.

JP 2017-82622 A

  By the way, in the compressor, it is necessary to increase the maximum flow rate in order to improve the performance. When the maximum flow rate is increased, the flow rate of the refrigerant flowing into the inlet guide vane increases, and the pressure loss in the inlet guide vane increases. As a result, there is a possibility that the performance of the compressor will be lowered due to the inlet guide vanes.

  The present invention has been made to meet the above-described demand, and an object thereof is to provide an inlet guide vane and a compressor capable of suppressing a decrease in the performance of the compressor.

The present invention employs the following means in order to solve the above problems.
An inlet guide vane according to a first aspect of the present invention includes a vane body that extends in the blade height direction, with a first blade surface and a second blade surface that are directed in different directions connected to each other at a leading edge and a trailing edge. The vane body has a first blade from the cord line in a direction perpendicular to a cord line that is a straight line connecting the leading edge and the trailing edge in a cross section perpendicular to the blade height direction. When the distance to the surface is the first distance and the distance from the cord line in the direction orthogonal to the cord line to the second blade surface is the second distance, the second distance relative to the first distance The thickness ratio, which is the distance ratio, is in the range of 1.02 to 1.33, and the thickness ratio is constant at any position in the blade cord direction in which the cord line extends.

  According to such a configuration, when the second blade surface becomes a suction surface, separation of the flow on the second blade surface side can be suppressed and pressure loss can be reduced. Therefore, it is possible to suppress a decrease in peak efficiency when the vane body is rotated so that the second blade surface becomes a suction surface. Thereby, the fall of the peak efficiency of the compressor provided with the inlet guide vane can be prevented.

  In the inlet guide vane according to the second aspect of the present invention, in the first aspect, the vane body may have a shape in which the thickness ratio is in a range of 1.02 to 1.15.

  By adopting such a configuration, not only when the second blade surface is a suction surface, but also almost no decrease in efficiency when the vane body is rotated so that the first blade surface becomes a suction surface. The compressor can be operated. That is, it is possible to suppress a decrease in the peak efficiency of the compressor when the vane body is rotated so that the first blade surface becomes the suction surface.

  In the inlet guide vane according to the third aspect of the present invention, in the first or second aspect, the first blade surface and the second blade surface may have a convex shape with respect to the cord line. .

  Further, the compressor according to the fourth aspect of the present invention includes an inlet guide vane according to any one of the first to third aspects, a casing formed with a suction port provided with the inlet guide vane, and the suction port. And an impeller for compressing the sucked fluid.

  According to the present invention, it is possible to suppress a decrease in the performance of the compressor.

It is sectional drawing which shows the structure of the compressor which concerns on embodiment of this invention. It is arrow sectional drawing in the II-II line | wire of FIG. It is a graph which shows the relationship between the thickness ratio of a vane main body, and the peak efficiency ratio of a compressor.

  Embodiments of the present invention will be described with reference to the drawings. The compressor 1 according to the present embodiment is a uniaxial multistage (two stages in the present embodiment) centrifugal compressor used for a turbo refrigerator. As shown in FIG. 1, the compressor 1 includes a rotating shaft 10, a plurality (two in this embodiment) of impellers 20, a casing 30, and inlet guide vanes 60.

  The rotation shaft 10 extends around the central axis As and rotates around the central axis As.

  The casing 30 covers the impeller 20 from the outer peripheral side in the radial direction Dr of the rotary shaft 10. A flow path for circulating the refrigerant (fluid) F is formed inside the casing 30. The casing 30 has a casing body 30A and a suction casing 30B. The suction casing 30B is provided on one side of the axial direction Da in which the axial line Ar extends with respect to the casing body 30A. A suction port 31 through which the refrigerant F flows from the outside is formed in the suction casing 30B. Although mentioned later in detail, the inlet guide vane (1st stage IGV) 60 which can change an angle according to a driving | running condition is attached to the inner peripheral side of the suction inlet 31. As shown in FIG. A discharge scroll 32 that discharges the refrigerant F is provided on the other side of the axial direction Da in the casing body 30A. An internal space 33 is formed in the casing body 30A to allow the suction port 31 and the discharge scroll 32 to communicate with each other.

  The impeller 20 is integrally attached to the outer peripheral surface of the rotating shaft 10 and rotates together with the rotating shaft 10. The impeller 20 of the present embodiment is, for example, an open type impeller that does not have a cover. As the impeller 20 of the present embodiment, a first impeller 21 and a second impeller 22 are provided in the internal space 33. The first impeller 21 forms a first compression stage. The second impeller 22 forms a second compression stage. Inside the first impeller 21 and the second impeller 22, an impeller passage 25 through which the refrigerant F can flow is formed. The impeller channel 25 is curved so as to go from the inner side to the outer side in the radial direction Dr as it goes from one side to the other side in the axial direction Da.

  The internal space 33 is an outlet diffuser flow that connects the casing flow path 25 that connects the impeller flow path 25 of the first impeller 21 and the impeller flow path 25 of the second impeller 22, and the impeller flow path 25 and the discharge scroll 32 of the second impeller 22. And a passage 38.

  The casing flow path 34 has an intermediate diffuser flow path 35, a return flow path 36, and a return flow path 37.

  In the intermediate diffuser flow path 35, the refrigerant F discharged from the first impeller 21 flows. The intermediate diffuser channel 35 communicates with the outlet of the impeller channel 25 of the first impeller 21 outside the radial direction Dr of the first impeller 21. The outlet diffuser channel 38 is formed so as to extend from the outlet of the impeller channel 25 toward the outside in the radial direction Dr.

  The return flow path 36 reverses the flow direction of the refrigerant F that has flowed through the intermediate diffuser flow path 35 by 180 degrees. The return flow path 36 is formed continuously with the outside in the radial direction Dr of the intermediate diffuser flow path 35. The return flow path 36 is formed so as to wrap around in a U shape in cross section so as to go from the outer side of the radial direction Dr of the intermediate diffuser flow path 35 to the other side of the axial direction Da and to extend toward the inner side of the radial direction Dr. Yes. A plurality of return vanes 36 </ b> A are arranged radially about the central axis As at a portion of the return flow path 36 extending inward in the radial direction Dr.

  Further, the casing main body 30 </ b> A is provided with an intermediate suction chamber 40 that joins the refrigerant F guided from the outside with the refrigerant F discharged from the first impeller 21 and supplies the refrigerant F to the second impeller 22. The intermediate suction chamber 40 is an annular space surrounding the periphery of the inlet portion of the second impeller 22. A slit-shaped intermediate suction port 41 is provided inside the radial direction Dr of the intermediate suction chamber 40. The intermediate suction port 41 connects the inside of the intermediate suction chamber 40 and a portion extending toward the inside in the radial direction Dr of the return flow path 36.

  The return channel 37 introduces the refrigerant F that has flowed through the return channel 36 into the second impeller 22. The return flow path 37 is formed continuously with the inside of the return flow path 36 in the radial direction Dr. An inner portion of the return channel 37 in the radial direction Dr is curved toward the inlet of the impeller channel 25 of the second impeller 22.

  The return flow path 37 is provided with a movable vane (second stage IGV) 50 capable of changing the angle according to the operating condition. A plurality of movable vanes 50 are arranged at intervals in the circumferential direction Dc with respect to the central axis As. The plurality of movable vanes 50 are driven by the drive unit 51 to change their angles.

  The outlet diffuser flow path 38 allows the refrigerant F discharged from the second impeller 22 to flow to the discharge scroll 32. The outlet diffuser channel 38 communicates with the outlet of the impeller channel 25 of the second impeller 22 outside the radial direction Dr of the second impeller 22. The outlet diffuser channel 38 extends from the outlet of the impeller channel 25 toward the outside in the radial direction Dr, and is formed to be continuous with the discharge scroll 32.

  The inlet guide vane 60 is provided in the suction port 31 so as to be disposed on one side (upstream side) in the axial direction Da with respect to the first impeller 21 in the casing 30. The inlet guide vane 60 adjusts the flow rate of the refrigerant F flowing into the first impeller 21 by adjusting the angle with respect to the flow direction of the refrigerant F flowing through the suction port 31. A plurality of inlet guide vanes 60 are arranged at equal intervals in the circumferential direction Dc centered on the central axis As, along the inner peripheral surface of the suction port 31 having a circular cross section when viewed from the axial direction Da. . The inlet guide vane 60 according to the present embodiment includes a shaft portion 61 and a vane body 62.

  The shaft portion 61 is inserted into an attachment hole 31 </ b> A formed on the inner peripheral surface of the suction port 31. The attachment hole 31 </ b> A is a circular hole centered on an axis Ar that extends in the radial direction Dr with respect to the center axis As. The shaft portion 61 can be rotated around the axis line Ar by a drive device (not shown) while being inserted into the mounting hole 31A. The shaft portion 61 is a member serving as a shaft for rotating the vane body 62 about the axis Ar. The shaft portion 61 is formed integrally with the vane body 62.

  The vane body 62 extends in the blade height direction D1, which is the direction in which the axis Ar extends (radial direction Dr). A shaft portion 61 is provided at the outer end of the vane body 62 in the radial direction Dr (one end in the blade height direction D1). Therefore, the shaft portion 61 protrudes from the vane body 62. The vane main body 62 has a first blade surface 71 and a second blade surface 72 that face different directions when viewed from the radial direction Dr. The vane body 62 has a first blade surface 71 and a second blade surface 72 connected to each other at a leading edge 73 and a trailing edge 74 so that a blade section perpendicular to the axis Ar (cross section viewed from the radial direction Dr) is obtained. Has a wing shape.

  As shown in FIG. 2, the first blade surface 71 and the second blade surface 72 are curved surfaces that are curved so as to form a convex shape with respect to the code line CL. The code line CL is a straight line connecting the leading edge 73 and the trailing edge 74 in the blade cross section of the vane body 62. The direction in which the cord line CL extends is a direction orthogonal to the blade height direction D1, and is referred to as a blade cord direction D2.

  The reference position of the vane body 62 is a state in which the code line CL is parallel to the flow direction of the refrigerant F (the code line CL and the central axis As are parallel). When the flow rate of the refrigerant F flowing into the first impeller 21 is increased, the vane body 62 is rotated so that the first blade surface 71 is directed upstream from the reference position. The side on which the vane body 62 is rotated so that the first blade surface 71 faces the upstream side with respect to the reference position is referred to as an excessive opening degree side. When the vane body 62 is rotated to the excessive opening degree side, the first blade surface 71 becomes a suction surface and the second blade surface 72 becomes a pressure surface.

  When reducing the flow rate of the refrigerant F flowing into the first impeller 21, the vane body 62 is rotated so that the second blade surface 72 is directed upstream from the reference position. The side on which the vane body 62 is rotated so that the second blade surface 72 faces the upstream side with respect to the reference position is referred to as a throttle side. When the vane body 62 is rotated to the throttle side, the first blade surface 71 becomes a pressure surface and the second blade surface 72 becomes a negative pressure surface.

  Here, the direction perpendicular to the blade height direction D1 and the blade cord direction D2 and perpendicular to the code line CL is referred to as a blade thickness direction D3. In the blade cross section of the vane body 62, the distance from the code line CL to the first blade surface 71 in the blade thickness direction D3 is referred to as a first distance Tp. In the blade cross section of the vane body 62, the distance from the code line CL to the second blade surface 72 in the blade thickness direction D3 is referred to as a second distance Ts. That is, the sum of the first distance Tp and the second distance Ts is the length of the vane body 62 in the blade thickness direction D3.

  The vane body 62 has a shape in which a thickness ratio Ts / Tp, which is a ratio of the second distance Ts to the first distance Tp, is in the range of 1.02 to 1.15. The thickness ratio Ts / Tp is preferably a shape that falls within the range of 1.02 to 1.15, and more preferably a shape that falls within the range of 1.02 to 1.33. The thickness ratio Ts / Tp is constant at any position in the blade cord direction D2. Therefore, the blade cross section of the vane main body 62 has a cord line so that the region on the second blade surface 72 side with respect to the cord line CL is slightly larger than the region on the first blade surface 71 side with respect to the cord line CL. It has a similar shape based on CL. Further, the thickness ratio Ts / Tp is determined within the above range regardless of the rotational speed of the compressor 1 (during rated operation).

  According to the inlet guide vane 60 as described above, the vane body 62 is formed so that the thickness ratio Ts / Tp is in the range of 1.02 to 1.33, so that the vane body 62 is placed on the throttle side. When rotated, separation of the flow on the second blade surface 72 side that becomes the suction surface can be suppressed, and the pressure loss can be reduced. Specifically, as shown in FIG. 2, in the inlet guide vane 60, a state in which the vane body 62 is disposed so that the code line CL is parallel to the flow direction of the refrigerant F is 100% opening. To do. As shown in FIG. 3, when the opening degree is 100%, the peak efficiency ratio of the compressor 1 tends to decrease slightly as the thickness ratio Ts / Tp increases, but the effect of the thickness ratio Ts / Tp is almost the same. I understand that I do not receive. On the other hand, when the vane body 62 is rotated to the throttle side (for example, when the opening degree is 40%), the peak efficiency ratio of the compressor 1 becomes 1 or less because the thickness ratio Ts / Tp is less than 1.02. , Begins to decline significantly. Moreover, the peak efficiency ratio of the compressor 1 will be 1 or less because thickness ratio Ts / Tp exceeds 1.33. Therefore, when the thickness ratio Ts / Tp is in the range of 1.02 to 1.33, the second blade surface 72 has little influence on the peak efficiency of the compressor 1 when the opening degree is 100%. It is possible to suppress a decrease in peak efficiency when the vane body 62 is rotated toward the throttle side so that the pressure surface becomes a negative pressure surface. Thereby, the fall of the peak efficiency of the compressor 1 provided with the inlet guide vane can be prevented, and the performance can be suppressed from being lowered.

  In addition, since the vane body 62 is formed so that the thickness ratio Ts / Tp is in the range of 1.02 to 1.15, the vane body 62 is rotated not only on the throttle side but also on the over-opening side. The compressor 1 can be operated with almost no decrease in efficiency. Specifically, as shown in FIG. 3, when the vane body 62 is rotated to the excessive opening degree (for example, when the opening degree is 130%), the thickness ratio Ts / Tp exceeds 1.15. The peak efficiency ratio of the compressor 1 becomes 1 or less and starts to decrease. Moreover, the peak efficiency ratio of the compressor 1 will be 1 or less because thickness ratio Ts / Tp is less than 1.02. Therefore, when the thickness ratio Ts / Tp is in the range of 1.02 to 1.15, the peak when the vane body 62 is rotated to the over-opening side so that the first blade surface 71 becomes a negative pressure surface. A decrease in efficiency can be suppressed. Thereby, the performance of the compressor 1 provided with the inlet guide vane can be further suppressed from decreasing.

  Further, as can be seen from FIG. 3, by setting the thickness ratio Ts / Tp in the vicinity of 1.15, the vane body 62 is maximized while the peak efficiency ratio of the compressor 1 when the vane body 62 is rotated to the throttle side is maximized. A large decrease in the peak efficiency ratio when the 62 is rotated to the over-opening side can also be suppressed.

(Other variations of the embodiment)
Although the embodiments of the present invention have been described in detail with reference to the drawings, the configurations and combinations of the embodiments in the embodiments are examples, and the addition and omission of configurations are within the scope not departing from the gist of the present invention. , Substitutions, and other changes are possible. Further, the present invention is not limited by the embodiments, and is limited only by the scope of the claims.

  In the above embodiment, the two-stage compression compressor 1 including the two impellers 20 has been described as the compressor 1 provided with the inlet guide vanes 60. However, the number of stages of the compressor 1 in which the inlet guide vanes 60 are provided is not limited to this, and may be, for example, three stages or four stages or more.

DESCRIPTION OF SYMBOLS 1 ... Compressor F ... Refrigerant 10 ... Rotating shaft As ... Center axis Da ... Axial direction Dr ... Radial direction Dc ... Circumferential direction 20 ... Impeller 21 ... First impeller 22 ... Second impeller 25 ... Impeller flow path 30 ... Casing 30A ... Casing body 30B ... Suction casing 31 ... Suction port 31A ... Mounting hole 32 ... Discharge scroll 33 ... Inner space 34 ... Casing flow path 35 ... Intermediate diffuser flow path 36 ... Return flow path 36A ... Return vane 37 ... Return flow path 38 ... Outlet Diffuser flow path 40 ... Intermediate suction chamber 41 ... Intermediate suction port 50 ... Movable vane 51 ... Drive unit 60 ... Inlet guide vane 61 ... Shaft portion Ar ... Axis 62 ... Vane body 71 ... First blade surface 72 ... Second blade surface 73 ... Lead edge 74 ... Rear edge CL ... Cord line D1 ... Wing height direction T p ... first distance Ts ... second distance D2 ... blade cord direction D3 ... blade thickness direction Ts / Tp ... thickness ratio

Claims (4)

A first blade surface and a second blade surface facing in different directions are connected to each other at a leading edge and a trailing edge, and include a vane body extending in the blade height direction,
The vane body has a first blade surface from the cord line in a direction orthogonal to a cord line that is a straight line connecting the leading edge and the trailing edge in a cross section perpendicular to the blade height direction. The second distance relative to the first distance when the distance from the cord line in the direction perpendicular to the cord line to the second blade surface is the second distance. The thickness ratio, which is the ratio of, is a shape that falls within the range of 1.02-1.33,
The inlet guide vane in which the thickness ratio is constant at any position in the blade cord direction in which the cord line extends.   The inlet guide vane according to claim 1, wherein the vane body has a shape in which the thickness ratio is in a range of 1.02 to 1.15.   The inlet guide vane according to claim 1 or 2, wherein the first blade surface and the second blade surface are convex with respect to the code line. The inlet guide vane according to any one of claims 1 to 3,
A casing formed with a suction port provided with the inlet guide vane;
And an impeller for compressing the fluid sucked from the suction port.

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