JPH0893691A - Variable inlet guide vanes for centrifugal compressors - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the pressure loss due to the variable inlet guide vanes and promote the downsizing of centrifugal compressors. [Structure] One suction port 2 opened in the casing 1
And an inflow passage 3 for introducing air from a direction substantially orthogonal to the axis of the impeller through the suction port 2, and an inflow passage 3 upstream of the impeller, which is fixed at a predetermined interval in the circumferential direction of the impeller. A plurality of fixed vanes 4, a movable vane 5 which is arranged inside the fixed vanes 4 and is rotatable, and a fixed vane 4 which is arranged between circumferentially arranged positions θ of 0 ° to about 90 °. The angle θ _f formed by the vanes 4a to 4d with respect to the radial direction of the impeller is linearly increased to a predetermined angle θ _f equal to the incident angle of air according to the arrangement position θ in the circumferential direction. Fixed vanes 4e to 4i from about 90 ° to 180 ° in the circumferential direction
Is inclined with respect to the radial direction of the impeller at a predetermined angle θ _f equal to the incident angle of air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a variable inlet guide vane of a centrifugal compressor composed of a fixed vane and a movable vane.

[0002]

2. Description of the Related Art Conventional centrifugal compressors used in gas turbine engines, etc., flow into a centrifugal compressor with movable vanes for adjusting the flow rate and swirling direction of the inflowing air into the centrifugal compressor. A variable inlet guide vane including a fixed vane for rectifying air is provided. As an apparatus of this type, as shown in FIGS. 9 to 11, the suction port 2 opened on the upper surface of the casing 1 in the drawings is an inflow passage. A vertical portion 3 that communicates with an impeller (not shown) through the inflow passage 3 and guides air from the suction port 2 in a direction orthogonal to an axis (not shown) of the impeller.
A and a coaxial portion 3B that guides air along the axis of the impeller, and a hub (not shown) that supports the impeller shaft is coaxially arranged inside the coaxial portion 3B.

In the inflow passage 3 connecting the vertical portion 3A and the coaxial portion 3B, a pair of fixed vanes 94 and movable vanes 5 are radially arranged at predetermined intervals in the circumferential direction on the circumference coaxial with the axis of the impeller. It is arranged. The fixed vane 94 is fixed along the radial direction of the impeller, and the movable vane 5 is rotated by a driving means (not shown) around the rotating shaft 5A on the fixed vane 94 side. After being rectified by the fixed vanes 94, as shown in FIG. 10, a swirling flow corresponding to the turning angle α of the movable vanes 5 is guided to the coaxial portion 3B, and the variable vanes are guided from the fixed vanes 94 and the movable vanes 5. The vanes are configured and the total length of the fixed vanes 94 is generally set to a value less than about 20% of the total length L of the variable inlet guide vanes.

Here, the air flowing in from the suction port 2 side flows as shown by the arrow in FIG. 9, and in the fixed vanes 94 arranged on the suction port 2 side, the difference between the direction of the fixed vanes 94 and the incident angle of air. Although θ _i1 is small, the incident θ _i1 which is the difference between the direction of the fixed vane 94 and the incident angle of air increases toward the bottom of the inflow passage 3 (downward in the figure), and the air flowing in from the vertical portion 3A is fixed. It may separate along the vanes 94 without bending, resulting in increased pressure loss based on this incident.

FIG. 12 shows the result of measuring this pressure loss in the inflow passage 3 downstream of the variable inlet guide vanes. In FIG. 12, when the movable vane 5 has a swirl angle of 0 ° (that is, in the radial direction), the coaxial portion is shown. 3B shows the total pressure distribution measured in FIG. 3B, and the upper, lower, left, and right in the figure show the positions of the inflow passage 3 corresponding to the upper, lower, left, and right in FIG. 9, and the total pressure distribution in the left and right directions greatly differs and the pressure loss increases. . Similarly, the total pressure distribution when the movable vanes 5 are swung to a predetermined swivel angle to swirl the inflowing air is as shown in FIG. 13, and the swirl is guided by the fixed vanes 94 and the movable vanes 5 and swung. Since the total pressure distribution of the air provided with is different between the vertical direction and the horizontal direction of the inflow passage 3, and the loss of the total pressure becomes large in the vertical direction, the pressure loss increases.

In order to reduce such pressure loss, it is known to increase the size of the casing and dispose a plurality of suction ports to suppress the flow velocity of air, and as shown in FIG. In some cases, the two suction ports 92A and 92B are arranged so as to face each other with the coaxial portion 3B of the inflow passage 3 interposed therebetween. In this case, the incident θ _i2 Is reduced from the above-mentioned incident θ _i1 to reduce the pressure loss.

In addition, Japanese Patent Laid-Open No. 185999/1983 discloses a variable guide vane of this type.

[0008]

However, in such a variable inlet guide vane of the conventional centrifugal compressor,
In order to reduce the pressure loss in the inflow passage and improve the efficiency of the compressor, it is necessary to enlarge the inflow passage by enlarging the casing or providing multiple intake ports. In that case, the piping of the intake system becomes complicated, which leads to an increase in the size of the entire device.For example, in a vehicle-mounted gas turbine engine or a portable generator, there is a limit to the mounting space, and therefore the size of the casing increases. There is a problem that the inflow passage cannot be expanded due to a plurality of suction ports.

Therefore, the present invention has been made in view of the above problems and provides a variable guide vane for a centrifugal compressor capable of reducing the pressure loss in the inflow passage while promoting the downsizing of the centrifugal compressor. The purpose is to provide.

[0010]

SUMMARY OF THE INVENTION A first aspect of the present invention is directed to a suction port opened in a casing, an inflow passage for introducing air from the suction port in a direction substantially orthogonal to the axis of the impeller, and an impeller of the impeller. Centrifugal compression provided with a plurality of fixed blades fixed at a predetermined interval in the circumferential direction of the impeller in an upstream inflow passage, and movable blades respectively arranged inside the fixed blades and rotatable. In the variable inlet guide vanes of the machine, the fixed vanes are inclined with respect to the radial direction of the impeller in accordance with the circumferential arrangement position along the flow of the air flowing into the fixed vanes.

According to the second aspect of the present invention, there is one suction port opened in the casing, an inflow passage through which air is introduced from a direction substantially orthogonal to the axis of the impeller, and an upstream of the impeller. A centrifugal compressor provided with a plurality of fixed blades fixed at a predetermined interval in the circumferential direction of the impeller in an inflow passage, and rotatable blades respectively arranged inside the fixed blades. In the variable inlet guide vanes, the angle θ _f formed by the fixed vanes arranged in the circumferential direction up to about 90 ° from the fixed vanes closest to the suction port is set in the circumferential placement position with respect to the radial direction of the impeller. Linearly to a predetermined value, while the fixed wing closest to the inlet is about 90 ° to 1
The angle θ _f formed by the fixed blades arranged up to 80 ° with the radial direction is set to the predetermined value.

[0012] In a third aspect of the invention, one suction port opened in the casing, an inflow passage through which air is introduced from a direction substantially orthogonal to the axis of the impeller, and an upstream of the impeller are provided. A centrifugal compressor provided with a plurality of fixed blades fixed at a predetermined interval in the circumferential direction of the impeller in an inflow passage, and rotatable blades respectively arranged inside the fixed blades. In the variable inlet guide vanes, the angle θ _f formed by the fixed vanes arranged in the circumferential direction up to about 90 ° from the fixed vanes closest to the suction port is set in the circumferential placement position with respect to the radial direction of the impeller. Linearly to a predetermined value, while the fixed wing closest to the inlet is about 90 ° to 1
The angle θ _f formed by the fixed blades arranged up to 80 ° with the radial direction is set to the incident angle of air according to the arrangement position in the circumferential direction.

A fourth invention is the second or third invention.
In the invention described above, among the fixed blades, the fixed blades closest to the suction port and the fixed blades arranged at the positions farthest from the suction port are fixed along the radial direction of the impeller.

A fifth aspect of the present invention is the above-mentioned first to fourth aspects.
In any one of the inventions, the total length of the fixed blade is set to 30% or more of the total value of the total length of the fixed blade and the movable blade.

[0015]

In the first aspect of the invention, since the fixed blade is inclined with respect to the radial direction of the impeller along the flow of air guided from the suction port to the inflow passage, the air incident on the fixed blade is separated. Since it is guided to the movable blades without causing turbulence and given a predetermined swirl according to the angle of the movable blades, it is possible to make the total pressure distribution inside the inflow passage uniform, and to provide a variable inlet guide. The pressure loss due to the blade can be reduced.

According to the second aspect of the invention, from the fixed blade closest to the intake port, which is a section in which the circumferential velocity component and the radial velocity component of the air incident on the fixed blade under the influence of the intake port are not constant. With fixed blades up to about 90 ° in the circumferential direction,
By inclining so as to linearly increase to a predetermined value according to the arrangement position in the circumferential direction, the air guided by an inclination close to the incident angle of air is guided to the movable blades without causing turbulence, and other By inclining the fixed vanes at a constant angle according to the incident angle of air with respect to the radial direction of the impeller, the total pressure distribution in the inflow passage downstream of the variable inlet guide vanes can be made uniform and It is possible to reduce the pressure loss even when there is only one port.

According to a third aspect of the present invention, the fixed blade closest to the suction port is a section in which the circumferential velocity component and the radial velocity component of the air incident on the fixed blade under the influence of the suction port are not constant. In the fixed blades up to about 90 ° in the circumferential direction, the fixed blades are inclined so as to linearly increase to a predetermined value according to the circumferentially arranged position, while the circumferentially arranged position is fixed at 90 ° to 180 °. Since the blades are inclined at an incident angle of air according to the arrangement position in the circumferential direction with respect to the radial direction of the impeller, by guiding the air to the movable blades without generating turbulence, the variable inlet guide vanes In the inflow passage where the total pressure distribution in the downstream inflow passage can be made uniform and there is one intake port and the circumferential velocity component and the radial velocity component of the air incident on the variable inlet guide vanes are not constant Can also reduce pressure loss The ability.

According to a fourth aspect of the present invention, among the fixed blades, the fixed blades closest to the suction port and the fixed blades arranged at positions farthest from the suction port are fixed along the radial direction of the impeller. As a result, the air guided by the fixed blades near the center line of the suction port can be guided to the movable blades without generating turbulence, and the total pressure distribution downstream of the variable inlet guide vanes is made uniform and pressure loss is reduced. can do.

Further, in the fifth invention, since the total length of the fixed blade is set to 30% or more of the total value of the total length of the fixed blade and the movable blade, the ability of the movable blade to impart swirl to the inflowing air is reduced. It is possible to reduce the pressure loss in the inflow passage downstream of the variable inlet guide vanes.

[0020]

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

As shown in FIGS. 1 to 3, the suction port 2 opened on the upper surface of the casing 1 in the drawing communicates with an impeller of a compressor (not shown) through an inflow passage 3.

This inflow passage 3 has a vertical portion 3A for guiding air from the suction port 2 in a direction substantially orthogonal to the axis of the impeller (in the figure, the axis of the impeller), and a coaxial portion formed substantially coaxially with the axis of the impeller. A hub 10 configured to include the portion 3B and coaxially supporting the shaft of an impeller (not shown) is coaxially disposed inside the coaxial portion 3B.

In the vertical portion 3A, as shown in FIG. 2, a plurality of fixed vanes 4 as fixed blades are provided on a predetermined circumference coaxial with the axis of the impeller at predetermined intervals in the circumferential direction, as will be described later. The fixed vane 4 is fixed to the fixed vane 4, and a movable vane 5 serving as a rotatable movable blade is paired with the fixed vane 4 and is axially supported at a predetermined interval in the circumferential direction. The movable vane 5 constitutes a variable inlet guide vane.
As shown in FIG. 2, the vertical portion 3A is arranged so that the center line of the suction port 2 passes through the axis of the impeller in a cross section orthogonal to the axis of the impeller, and the left and right sides of the center line are different from each other. As will be described later, the symmetric shape is formed so that the circumferential velocity component V _θ and the radial velocity component V _r of the inflowing air are constant.

As shown in FIG. 3, the fixed vane 4 and the movable vane 5 are paired to constitute one blade, and the fixed vane 4 forms the leading edge of the blade, while the movable vane 5 is Form the trailing edge of the wing.

Letting the total value of the total length L ₁ of the fixed vanes 4 and the total length L ₂ of the movable vanes 5 be the total length L of the variable inlet guide vanes, the total length L ₁ of the fixed vanes 4 is the total length L of the variable inlet guide vanes.
Is set to a predetermined value between 30% and 50%, for example, 30%.

The movable vane 5 is rotatable about a shaft 5A provided on the fixed vane 4 side, and the plurality of movable vanes 5 are synchronously rotated by a driving means (not shown).

The movable vanes 5 are in a radial position along the radial direction of the impeller when the swirl angle is 0 °, and the air taken into the inflow passage 3 in accordance with the increase in the swivel angle rotates clockwise or in FIG. It is given a counterclockwise turn.

Here, as shown in FIG. 2, when the fixed vane 4 is disposed at a position θ = 0 ° on the center line of the suction port 2 around the axis of the impeller, θ = clockwise and counterclockwise.
In the circumferential direction between 0 ° and 180 °, the fixed vane 4 is inclined with respect to the radial direction of the impeller at a mounting angle θ _f according to the installation position θ.

The plurality of fixed vanes 4 are arranged symmetrically with respect to the center line of the suction port 2, and the fixed vanes 4a to 4j arranged clockwise on the circumference of the right half will be described.

Both the fixed vane 4a closest to the suction port 2 and the fixed vane 4j arranged at the farthest position from the suction port 2 have a mounting angle θ _f = 0 °, that is, along the radial direction of the impeller. It is fixed. Here, the fixed vane 4j is arranged at an arrangement position of θ = 180 °, while the fixed vane 4a is arranged at a position closest to the arrangement position θ≈0 °.

Then, the mounting angle θ of the fixed vanes 4b to 4d included in the arrangement position θ = 0 ° to about 90 °.
_f increases linearly from 0 ° to θ _f0 along the air flow corresponding to the installation position θ as shown in FIG.
The predetermined mounting angle θ _f0 is a value obtained from the circumferential velocity component V _θ and the radial velocity component V _{r of} the air incident on the fixed vane 4 based on the following equation.

Θ _f0 = tan ⁻¹ (V _θ / V _r ) ... (1) Here, the vertical portion 3 A of the inflow passage 3 is at least the installation position θ of the fixed vane 4 θ = θ _e (corresponding to the fixed vane 4 _e The cross-sectional shape is set so that the circumferential velocity component V _θ and the radial velocity component V _r are substantially constant between the arrangement position (about 90 °) to 180 °. The mounting angle θ _f0 obtained in step 1 is equal to the incident angle of the air flowing into the fixed vane 4.

The fixed vanes 4b to 4d are fixed to be inclined with respect to the radial direction of the impeller so that the front edge is directed to the suction port 2 side at a mounting angle θ _f that linearly increases according to the installation position θ. To be done.

Next, the mounting angle θ of the fixed vanes 4e to 4i between the disposition position θ = about 90 ° to 180 ° is set to the predetermined mounting angle θ _f0 calculated by the above equation (1) and fixed. The vanes 4e to 4i have their leading edges directed toward the suction port 2 and
It has an inclination of a predetermined angle θ _f0 with respect to the radial direction of the impeller.

In this way, the fixed vanes 4 arranged on the circumference coaxial with the impeller have a predetermined mounting angle θ _f0 depending on the mounting position θ in the section from the mounting position θ = 0 to about 90 °. While increasing the mounting angle θ _f linearly, approximately 90 ° to 180
The fixed vane 4a closest to the inlet 2 and the fixed vane 4j farthest from the inlet 2 are inclined with respect to the radial direction of the impeller at a constant installation angle θ _f0 in the section up to ° and the radial direction of the impeller It is fixed radially along the.

With the above construction, the operation will be described.

The air sucked from the suction port 2 into the inflow passage 3 is made to flow through the fixed vanes 4 and the movable vanes 5 while keeping the circumferential velocity component V _θ and the radial velocity component V _r substantially constant according to the shape of the vertical portion 3A. The air flows into the coaxial portion 3B through the swirl, and the inflow air is swirled according to the swirl angle of the movable vane 5.

In FIG. 2, the arrangement position θ = about 90 ° to 1
The fixed vanes 4e to 4i between 80 ° have their leading edges directed toward the suction port 2 and are inclined with respect to the radial direction of the impeller at a predetermined mounting angle θ _f0 that is equal to the incident angle of air, so that the inflow passage 3 The air that has entered the fixed vanes 4e to 4i from the vertical portion 3A is guided to the movable vane 5 without causing the incident loss as in the conventional example.

Here, since the radial velocity component V _r of the inflowing air is 0 at the disposition positions θ = 0 ° and 180 ° because it is located at the center of the suction port 2, the disposition position θ = 180 °.
It can be disposed along the air flowing together by a mounting angle θ _f = 0 ° the fixed vanes 4a to be fixed vanes 4j and disposed position theta ≒ theta _e located.

On the other hand, between the installation position θ = 0 ° and about 90 °, the shape of the vertical portion 3A of the inflow passage 3 is influenced by the suction port 2 so that the circumferential velocity component V _θ and the radial velocity component V _{r are formed.} Is difficult to form so that the arrangement position θ =
Only above θ _e , the circumferential velocity component V _θ and the radial velocity component V _r become constant.

Therefore, the fixed vanes 4 included in this section
As shown in FIG. 4, the mounting angles θ _{f of} b to 4 _d are inclined with respect to the radial direction by the mounting angle θ _f that increases according to the installation position θ, so that the influence of the suction port 2 is reduced. The fixed vanes 4b to 4d can be arranged in the direction of the flow of the received air.

Since the fixed vanes 4a to 4j are arranged so as to substantially follow the flow of the air flowing in from the suction port 2, the air flowing into the variable inlet guide vanes is smoothly separated from the fixed vanes 4. Since it is guided, it is possible to reduce the incident loss as in the conventional example, and it is possible to reduce the pressure loss and improve the efficiency of the compressor without enlarging the casing 1 or increasing the number of suction ports. Can be done.

FIG. 5 shows the result of measuring the total pressure distribution in the coaxial portion 3B downstream of the variable inlet guide vanes for this pressure loss. In FIG. 5, the movable vane 5 has a swirl angle of 0 ° (that is, along the radial direction). Radial positions), and the upper and lower and left and right sides in the drawing show the positions of the coaxial portion 3B of the inflow passage 3 corresponding to the upper, lower, left and right in FIG. In FIG. 12, the total pressure distribution in the left-right direction is significantly different and the pressure loss is remarkable, whereas in the present embodiment, the total pressure distribution can be made almost uniform, and the incident loss in the fixed vane 4 can be reduced. It was confirmed by an experiment by the inventor of the present application that

Similarly, the total pressure distribution when the movable vane 5 is rotated to give a swirl to the inflowing air is as shown in FIG. 6 according to an experiment conducted by the inventor of the present application. In Fig. 13, the total pressure loss was large in the vertical direction of the inflow passage 3, whereas in the present embodiment, as shown in Fig. 6, there is a large difference in the total pressure distribution according to the swirling of air, which is large. The loss of total pressure is suppressed, and the loss of total pressure as in the conventional example can be improved. In addition,
The tip side in the figure means the wall surface side of the inflow passage 3 (the same applies hereinafter).

In order to expect such a rectifying effect of the inflow air by the fixed vanes 4, as shown in FIG. 3, the total length L ₁ of the fixed vanes 4 is the total length L of the variable inlet guide vanes, that is, the fixed vanes. It is necessary to set 30 to 50% of the total value L of the total length L _{1 of No.} 4 and the total length L ₂ of the movable vane 5.

This is because it is necessary to secure the total length L ₂ of the movable vanes 5 in order to impart swirl to the inflowing air, which is the original purpose of the variable inlet guide vanes, and only the total length L ₁ of the fixed vanes 4 is If it is increased, the ability of the movable vane 5 to generate the swirling flow is reduced.

Assuming that the swirl flow generation capability of the movable vane 5 is Δθ, which is the difference between the set angle of the movable vane 5 and the swirl angle to which the inflow air is applied, the ratio of the fixed vane 4 to the total length L of the variable inlet guide vanes is Accordingly, Δθ changes as shown in FIG. 8 according to the experiment by the inventor of the present application, and the total length L _{1 of the} fixed vanes 4 is
Is greater than 50% of the total length L of the variable inlet guide vanes, the swirl flow generation capability of the movable vane 5 decreases, so the maximum value of the total length L ₁ of the fixed vanes 4 is set to 50% or less of the total length L of the variable inlet guide vanes. It is something to set.

On the other hand, the ratio of the total length L ₁ of the fixed vanes 4 to the total length L of the variable inlet guide vanes, and the coaxial portion 3 of the inflow passage 3.
The relationship with the total pressure loss ΔP in B is as shown in FIG. 7 according to the experiment by the inventor of the present application. When the total length L ₁ of the fixed vanes 4 is less than 30% of the total length L of the variable inlet guide vanes, the fixed vanes are fixed. Four
Movable vane 5 without disturbing the turbulence of the air flowing into
Since the total pressure loss ΔP to flow into the coaxial portion 3B increases with a decrease of the overall length L ₁ of the stationary vanes 4, the overall length L ₁ of the stationary vanes 4 of the total length L of the variable inlet guide vanes 30
Must be set to% or higher.

In this way, the arrangement position θ = 0 ° to about 9
The fixed vanes 4b to 4d between 0 ° have a mounting angle θ _f that increases to θ _f0 according to the mounting position θ, and the mounting position θ = about 90
The fixed vanes 4e to 4i between 0 ° to 180 ° have their leading edges directed toward the suction port 2 and inclined with respect to the radial direction of the impeller at a predetermined mounting angle θ _f0 equal to the incident angle of air, while the suction ports are The fixed vane 4j and the fixed vane 4a having the arrangement position θ = 0 ° or 180 ° near the center line of 2 are arranged along the radial direction of the impeller with the mounting angle θ _f = 0 °, respectively. Since the total length L ₁ of _No. 4 is set to 30 to 50% of the total length L of the variable inlet guide vanes, it is possible to reduce the pressure loss even with one suction port 2 and downsize the centrifugal compressor. It is possible to improve the efficiency of the compressor while promoting

In the above embodiment, the circumferential velocity component V _θ and the radial velocity component V _r are constant when the position θ of the fixed vane 4 is at least the position θ _e corresponding to the fixed vane 4e. Vertical part 3A of the inflow passage 3
However, the vertical portion 3A cannot be formed in this way due to the size and shape restrictions of the casing 1, and the circumferential velocity component V _θ and the radial velocity component V _r change depending on the arrangement position θ. To do so, the following settings should be made.

Fixed vanes 4 in the section of 0 ° <θ <about 90 °
For b to 4d, similar to the casing 1 in which the circumferential velocity component V _θ and the radial velocity component V _r are constant,
The mounting angle θ _f is linearly changed from 0 ° to θ _f0 according to the installation position θ, and at this time, the value of θ _{f 0} is the fixed vane 4e at the position of θ = 90 ° (the installation position θ _From V _θ and V _r in _e ), it is _calculated by the following equation.

Θ _f0 = tan ⁻¹ {V _θ (θ _e ) / V _r (θ _e )} (2) On the other hand, for the fixed vanes 4 _{f to 4 i} , the mounting angle θ _f
Is not a constant value, but is an incident angle θ _V 'of air that changes according to the installation position θ. This incident angle θ _V ′ is calculated by the following equation.

Θ _V ′ = tan ⁻¹ {V _θ (θ) / V _r (θ)} (3) Note that V _θ (θ) represents the circumferential velocity component that changes according to the installation position θ. , V _r (θ) is a value indicating a radial direction velocity component that also changes according to the installation position θ, and V _θ (θ
Similarly, _e ) and V _r (θ _e ) are velocity components that change according to the installation position θ _e with respect to the fixed vane 4.

The fixed vanes 4a and 4j are directed in the radial direction, that is, toward the mounting angle θ _f = 0 ° in the same manner as the casing 1 in which the circumferential velocity component V _θ and the radial velocity component V _r are constant. You can leave it.

[0055]

As described above, according to the first aspect of the invention, the fixed blade is inclined with respect to the radial direction of the impeller so as to follow the flow of the air guided from the suction port to the inflow passage. Since the air that has entered the inlet is given a predetermined swirl by the movable blades without causing turbulence such as separation, the total pressure distribution inside the inflow passage can be made uniform, and the pressure by the variable inlet guide blades can be made uniform. The loss can be reduced and the efficiency of the centrifugal compressor can be improved.

According to the second aspect of the invention, from the fixed blade closest to the suction port, which is a section in which the circumferential velocity component and the radial velocity component of the air incident on the fixed blade under the influence of the suction port are not constant. With fixed blades up to about 90 ° in the circumferential direction,
By inclining so as to linearly increase to a predetermined value according to the arrangement position in the circumferential direction, it is possible to guide the guided air to the movable blades without causing turbulence in the guided air due to the inclination close to the incident angle of air, By tilting the other fixed blades with respect to the radial direction of the impeller at a predetermined angle according to the incident angle of air, it is possible to make the total pressure distribution in the inflow passage downstream of the variable inlet guide vane uniform. Even if there is only one suction port, it is possible to reduce the pressure loss without enlarging the inflow passage, and it is possible to improve the efficiency while promoting the downsizing of the centrifugal compressor.

In the third aspect of the invention, the fixed blade closest to the suction port, which is a section in which the circumferential velocity component and the radial velocity component of the air incident on the fixed blade under the influence of the suction port are not constant, The fixed vanes up to about 90 ° in the circumferential direction are inclined with respect to the radial direction of the impeller so as to linearly increase to a predetermined value according to the circumferential placement position, while the fixed vanes are arranged in the circumferential direction. Since the fixed blades having an angle of 90 ° to 180 ° are inclined with respect to the radial direction of the impeller at an incident angle of air that changes according to the arrangement position in the circumferential direction, the movable blades are not disturbed in the air to be guided. It is possible to make the total pressure distribution in the inflow passage downstream of the variable inlet guide vane uniform, and to have one suction port and the circumferential velocity component of the air incident on the variable inlet guide vane. Flow in which the radial velocity component is not constant Even if it is a passage, it is possible to reduce the pressure loss without expanding the inflow passage, which can improve the efficiency while promoting the downsizing of the centrifugal compressor, and the degree of freedom in design. Can be extended.

According to a fourth aspect of the present invention, among the fixed blades, the fixed blades closest to the suction port and the fixed blades arranged at positions farthest from the suction port are fixed along the radial direction of the impeller. As a result, the air guided by the fixed blades near the center line of the suction port can be guided to the movable blades without generating turbulence, and the total pressure distribution downstream of the variable inlet guide vanes is made uniform and pressure loss is reduced. Therefore, the efficiency of the centrifugal compressor can be improved.

Further, in the fifth invention, the total length of the fixed blade is set to 30 to 50% of the total value of the total length of the fixed blade and the movable blade, so that the ability of the movable blade to impart swirl to the inflowing air is reduced. The pressure loss in the inflow passage downstream of the variable inlet guide vane can be reduced without performing the above, and the pressure loss in the inflow passage can be reduced while surely adjusting the swirling flow or the flow rate of the air by the movable blade. Therefore, it is possible to promote downsizing of the centrifugal compressor and improvement of efficiency.

[Brief description of drawings]

FIG. 1 is a sectional view of a variable inlet guide vane showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view showing a fixed vane and a movable vane.

[Fig. 4] Similarly, the circumferential position of the fixed vane and the mounting angle θ
It is a figure which shows the relationship with _f .

5 is a total pressure distribution diagram in the BB cross section of FIG. 1 when the movable vane is fixed at a turning angle of 0 °.

6 is a total pressure distribution diagram in the BB cross section of FIG. 1 when a movable vane is rotated.

FIG. 7 is a diagram showing the relationship between the ratio of the total length of the fixed vanes to the total length of the vanes and the total pressure loss ΔP.

FIG. 8 is a diagram showing the relationship between the ratio of the total length of the fixed vanes to the total length of the vanes, the difference Δθ between the angle of the movable vanes and the swirling angle of the inflowing air.

FIG. 9 is a sectional view of a variable inlet guide vane showing a conventional example.

FIG. 10 is a sectional view showing the arrangement of fixed vanes and movable vanes.

FIG. 11 is an enlarged sectional view showing a fixed vane and a movable vane.

FIG. 12 is a total pressure distribution diagram downstream of the movable vane when the movable vane is fixed in the radial direction.

FIG. 13 is a total pressure distribution diagram downstream of the movable vane when the movable vane is rotated.

FIG. 14 is a cross-sectional view of a variable inlet guide vane showing a conventional example having two suction ports.

[Explanation of symbols]

 1 casing 2 suction port 3 inflow passage 4 fixed vane 5 movable vane

Claims (5)

[Claims] 1. An inlet opening to a casing, an inflow passage through which air is introduced from a direction substantially orthogonal to an axis of the impeller, and an inflow passage upstream of the impeller, around the impeller. In a variable inlet guide vane of a centrifugal compressor, which comprises a plurality of fixed vanes fixed at predetermined intervals in a predetermined direction, and movable vanes respectively arranged inside the fixed vanes and rotatable. A variable inlet guide vane for a centrifugal compressor, characterized in that fixed vanes are inclined with respect to a radial direction of an impeller in accordance with a circumferential arrangement position along the flow of air flowing into the vanes. 2. An impeller in an inlet opening to the casing, an inflow passage through which air is introduced from a direction substantially orthogonal to the axis of the impeller, and an inflow passage upstream of the impeller. In a variable inlet guide vane of a centrifugal compressor, which is provided with a plurality of fixed vanes fixed at a predetermined interval in the circumferential direction of, and movable vanes respectively arranged inside the fixed vanes and rotatable. The angle θ _f formed by the fixed blades arranged in the circumferential direction up to about 90 ° from the fixed blades closest to the suction port with the radial direction of the impeller is set to a predetermined value depending on the arrangement position in the circumferential direction. While increasing linearly, the angle θ _f formed by the fixed blades arranged in the radial direction of the impeller about 90 ° to 180 ° in the circumferential direction from the fixed blade closest to the suction port.
Is set to the predetermined value. A variable inlet guide vane for a centrifugal compressor. 3. An intake port opened to the casing, an inflow passage for introducing air from the intake port in a direction substantially orthogonal to the axis of the impeller, and the impeller in the inflow passage upstream of the impeller. In a variable inlet guide vane of a centrifugal compressor, which is provided with a plurality of fixed vanes fixed at a predetermined interval in the circumferential direction of, and movable vanes respectively arranged inside the fixed vanes and rotatable. The angle θ _f formed by the fixed blades arranged in the circumferential direction up to about 90 ° from the fixed blades closest to the suction port with the radial direction of the impeller is set to a predetermined value depending on the arrangement position in the circumferential direction. While increasing linearly, the angle θ _f formed by the fixed blades arranged in the radial direction from the fixed blade closest to the suction port at about 90 ° to 180 ° in the circumferential direction is set to the circumferential position. The centrifugal compressor is characterized by setting the incident angle of air according to Inlet guide vanes. 4. The fixed blades, which are closest to the suction port and farthest from the suction port, of the fixed blades are fixed along the radial direction of the impeller. The variable inlet guide vane of the centrifugal compressor according to claim 2 or 3. 5. The centrifugal compression according to any one of claims 1 to 4, wherein the total length of the fixed blade is set to 30% or more of the total value of the total length of the fixed blade and the movable blade. Variable inlet guide vanes of the machine.