JPH01247798A - High speed centrifugal compressor - Google Patents

Abstract

PURPOSE:To expand a working range on a small flow side and improve capacity control greatly by a method wherein a side plate of a stator blade of a diffuser is extended from a core plate toward an impeller so that the front rim of the stator blade is formed so that it is tilted from the core plate toward the side plate. CONSTITUTION:A front rim 5 on the side of a side plate of a stator blade 4 of a diffuser is located near an exit of an impeller 1. On the other hand, the front rim on the side of a core plate is located farther than the side plate part 5 from the impeller 1. Though velocity vector is close to a tangential direction 8 of the impeller, it is led toward a direction along the stator blade 4 by the front rim which extends to the vicinity of the impeller 1. Since backstreaming of a flow flowing out of the impeller can be thus controlled, the working range of a compressor on the side of a small flow rate can be expanded and capacity control can be greatly improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-speed centrifugal compressor, and particularly to a diffuser for a high-speed centrifugal compressor that requires a wide operating range and high efficiency.

[Conventional technology]

Generally, a high-speed centrifugal compressor has a structure as shown in FIGS. 25 and 26, and generates an air flow in the direction shown by an arrow 2 by the rotation of one impeller 1. In a high-speed centrifugal compressor made to obtain a high pressure ratio in a single stage, the air flow 2 flowing out from one impeller 1 has a large velocity energy, so the outer peripheral part of the impeller on the downstream side of the impeller 1 A diffuser 3 with stationary vanes is provided to convert the velocity energy of the fluid discharged from the impeller 1 into pressure energy.

As shown in FIG. 26, a plurality of stationary blades 4 constituting the diffuser 3 are provided radially around the outer circumference of the impeller 1, and a diffuser flow path 3 is provided between the blades of these stationary blades 4.
is formed.

Generally, the flow at the outlet of the centrifugal impeller is as shown in Figure 3.
This tendency is remarkable in compressors that are distorted in the width direction and have a pressure ratio of more than 2 per stage. The state of flow distortion indicates that the flow direction is close to the tangential direction of the impeller on the side plate side, and is farther away from the tangential direction on the -right center plate side compared to the side plate side.

In such a compressor, as the flow rate increases,
Choking occurs in the smallest cross-sectional area of the flow path formed by the stationary vanes and side walls of the diffuser, and the performance of the compressor sharply decreases. Also.

Under conditions of relatively high rotation speed and low flow rate, a separated flow region occurs on the negative pressure surface of the stationary blade, and a surge phenomenon occurs in which a sufficient pressure increase cannot be obtained. In order to solve this problem, a diffuser in which an aileron is provided between stationary wings has been proposed.

When an aileron is provided, it is desirable to make it as thin as possible so as not to reduce the minimum cross-sectional area of the flow path, but a certain thickness is required for the sake of strength. For this reason, it is necessary to set the number of stationary blades to a level that can ensure a sufficient cross-sectional area of the flow passage, but if this is done, the interval between the stationary blades becomes excessive in the flow passage near the outer periphery of the stationary blade. As a result, the flow does not follow the blade surface on the suction surface 5 near the trailing edge of the stationary y Diffusion of kinetic energy within the separation zone occurs.

The operating range of this type of high speed centrifugal compressor is often limited by the diffuser. That is, on the small flow plate side, this is often the stall limit where the backflow generated in the diffuser reaches the impeller, and on the large flow plate side, it is often the choke limit in the diffuser. Therefore, in order to expand the operating range of the compressor, it is first necessary to expand the operating range of the diffuser, and several methods have been proposed.

Currently, the one that is relatively widely adopted is to rotatably support the stationary blade 4 by a support shaft parallel to the rotation axis of the impeller 1, and change the direction of the stationary blade according to the direction of the flow flowing out from the impeller. It's a method. other.

One in which a boundary layer plate is provided by extending the tip of a stationary blade (US Pat. No. 3,781,128), and one in which the angle of the inlet of a stationary blade is changed in the blade height direction (US Pat. No. 3,904).
312 specification, Utility Model Application Publication No. 53-162405), etc. have been proposed.

[Problem to be solved by the invention]

However, the structure of the conventional diffuser blades that are movable is complicated, and the effect of the boundary layer plate is not sufficient in high-speed centrifugal compressors where the impeller outlet flow is highly distorted. .

Furthermore, in the case of a device that changes the inlet angle of a stationary blade in the blade height direction, the expansion of the operating range is small with conventional types, and if the leading edge of the stationary blade is brought closer to the impeller in order to expand the operating range, Although it is possible to expand the operating range on the small flow rate side, the operating range on the large flow rate side becomes narrower due to the decrease in the minimum cross-sectional area of the flow path, and due to the strong excitation force due to aerodynamic interference between the impeller and the stationary blade, There were problems such as the possibility that the stationary blades or impeller would be destroyed after long-term operation.

An object of the present invention is to provide a high-speed centrifugal compressor having a simple structure, a wide operating range, and a diffuser with high strength.

[Means for Solving the Problems and Their Effects] In order to achieve the second object, the present invention arranges a plurality of stationary blades around the outer periphery of an impeller, and utilizes the kinetic energy of the fluid discharged from the impeller. In a high-speed centrifugal compressor equipped with a diffuser that converts pressure energy through the action of stationary blades, the side plate side of the diffuser stationary blade extends from the core plate side toward the impeller, so that the leading edge of the stationary blade faces the core plate side. The shape is inclined from the side toward the side plate.

According to the above invention, since the side plate side of the leading edge of the diffuser stationary vane is located close to the impeller, it is possible to strongly guide a flow close to the tangential direction in the direction of the stationary vane, making it difficult for backflow to occur and for surges to occur. The critical flow rate can be reduced.

In addition, since the core plate side of the leading edge of the stationary blade is farther from the impeller than the side plate side, the minimum cross-sectional area of the flow path can be made sufficiently large without any difficulty, so the choke in the diffuser can reduce the operating range on the high flow side of the compressor. It will no longer be narrowed down.

Furthermore, since only a portion of the leading edge of the stationary blade is located near the impeller, the excitation force due to aerodynamic interference can be significantly reduced.

Still another invention is that in the above invention, a side closer to the inner circumference between the stationary blades of the diffuser has a chord length shorter than that of the stationary blades;
and an aileron of equal or lower height is provided, only one wing surface of the aileron faces the stationary wing, and the side plate side of the leading edge of the aileron extends from the core plate side toward the impeller. The shape is similar to that of the original.

According to the above invention, when the aileron is provided on the side near the inner circumference between the stationary blades and only one of the aileron blades faces the stationary blade, the minimum cross-sectional area of the flow path formed by the stationary blade and the side wall is Since the aileron does not penetrate, by bringing the leading edge of the aileron closer to the impeller, it is possible to expand the operating range on the small flow rate side and secure the operating range on the choke side. In this case as well, since only a portion of the front of the aileron exists near the impeller, the excitation force due to aerodynamic interference can be greatly reduced, and the strength of the aileron and impeller can be relatively increased. If a partition plate extending in a direction along the stationary blade, which is lower in height than the aileron, is connected to the downstream side of the aileron, the aileron and the partition plate become integrated, and the rigidity is further increased.

Another aspect of the present invention is that, in the above invention, an intermediate blade having a chord length shorter than that of the stationary blade and a height equal to or lower than the stationary blade is provided on the side closer to the outer periphery between the stationary blades.

According to the above invention, the distance between the stationary blades is substantially at an appropriate value near the outer peripheral end of the stationary blades, thereby preventing performance deterioration.

Another invention is that in the above invention, the aileron and the intermediate blade are connected by a partition plate, and the partition plate is installed lower than the height of the two wings and extends in a direction along the stationary blade.

According to the above invention, the aileron, the partition plate, and the intermediate blade are integrated, and the rigidity is further increased.

〔Example〕

An embodiment of a high-speed centrifugal compressor according to the present invention will be described below with reference to the drawings.

An embodiment of the present invention is shown in FIGS. 1 to 3.

In the figures, parts that are the same or equivalent to those of the conventional example shown in FIGS. 25 and 26 are denoted by the same reference numerals, and explanations thereof will be omitted. FIG. 1 is a cross section including the rotating shaft of an impeller of a high-speed centrifugal compressor to which the present invention is applied.

FIG. 2 is an enlarged view of the diffuser portion of FIG. 1. The leading edge portion 5 on the side plate side of the stationary vane 4 of the diffuser is located near the one-blade table outlet. On the other hand, the front edge portion 6 on the core plate side
is further away from the impeller than the side plate side portion 5. FIG. 3 shows the stationary wing section, together with the velocity vector 7 of the flow entering the stationary wing. The velocity vector on the side plate side is close to the tangential direction 8 of the impeller, but it is guided in the direction along the stationary blade 4 by the leading edge portion 5 of the stationary blade that extends close to the impeller, so the flow flowing out of the impeller flows backward. By being controlled,
The operating range of the low flow side of the compressor can be expanded.

The minimum cross-sectional area of the flow path formed by the diffuser stationary blade 4, the side wall 9 on the side plate side, and the side wall 10 on the core plate side is determined by the shape of the stationary blade 4, etc., but if the leading edge of the stationary blade 4 is far from the impeller, , since the circumference that passes through all the leading edges becomes longer,
This minimum cross-sectional area can be easily increased. Since the front part 6 on the core plate side of the stationary blade 4 is far from the impeller, it can be enlarged to the above-mentioned minimum cross-sectional area and width compared to the case where the leading edge part is close to the impeller. It also becomes possible to expand the operating range.

FIGS. 4 and 5 are diagrams showing other embodiments of the present invention.

FIG. 4 is a view of the impeller 1 and the diffuser stationary blade 4 viewed from the direction of the rotation axis of the impeller 1, and FIG. 5 is an enlarged view of the stationary blade. The feature of this embodiment is that the blade angle βS on the side plate side of the leading edge of the stationary blade is configured to be larger than the blade angle βh on the core plate side. According to this embodiment, although the shape of the stationary blade becomes complicated, the minimum cross-sectional area of the diffuser flow path can be increased, so that the operating range on the high flow rate side can be expanded more effectively.

FIG. 6 and FIG. 7 are diagrams showing other embodiments of the present invention, and FIG.
The figure shows a simplified version of the stationary wing with a stepped leading edge. FIG. 7 shows a simplified version of the embodiment shown in FIG. 1 by constructing the front edge with a straight line. In this embodiment as well, the effect can be enhanced by distributing the angle of the leading edge of the stationary blade as in the embodiment shown in FIGS. 4 and 5.

FIG. 8 is a diagram explaining the most effective dimensional relationship of each part of the leading edge, where the radius r+ of the impeller and the radial position r of the edge-resistant portion 5 on the side plate side are shown.
s, radial position 1!1 r h of the leading edge portion 6 on the core plate side, the relationship of γS/γ1≦1.1≦γb/γ□, and the average of the leading edge portion on the side plate side. The effect is high when there is a relationship of 0.1<bl/b<0°6 between the height b and the height b of the stationary wing.

9 to 14 show an embodiment of a high-speed centrifugal compressor in which an auxiliary vane is provided on the leading edge side of a stationary vane.

As shown in FIG. 10, the aileron 11 intersects a circle that is centered on the rotation axis of the impeller 1 and passes through the leading edge of the stationary blade 4, and is located at the center of the radius of curvature of the adjacent stationary blades 4a and 4b. It is arranged so as not to intersect the perpendicular line drawn from the leading edge of the stationary blade 4a on one side to the stationary blade 4b on the other side.

As shown in FIG. 9, the leading edge 11a of the aileron 11 is a leading edge portion where the side plate side extends in the direction of the impeller from the core plate side, and the side plate side closest to the impeller is elevated. It is configured.

Next, a modified example of the aileron will be explained. The aileron shown in Figure 11 has a shape that does not include the aileron part on the core plate side, where the speed is faster, that is, the height is lowered, focusing on the fact that the contribution of the aileron part on the core plate side, where the speed is high, is small in expanding the operating range. It is.

The aileron shown in FIG. 13 has a reduced height and has a partition 12 extending from the downstream side to a circle that passes through the trailing edge of the stationary blade 4 along the stationary blade.

15 to 23 show an embodiment of a high-speed centrifugal compressor in which an auxiliary blade is provided on the leading edge side of a stationary blade and an intermediate blade is provided on the trailing edge side.

What is shown in FIG. 15 is a diffuser having the ailerons shown in FIG. 10, in which an intermediate blade 13 having the same height as the stationary blade is disposed on the trailing edge side of the stationary blade 4. The intermediate wing is
It passes through the midpoint of the perpendicular line 14 drawn from the outer circumferential edge of the stationary wing 4 to the inner circumference and side extension of the adjacent stationary wing, and the outer circumferential edge of the intermediate wing reaches a circle passing through the outer circumferential edge of the stationary wing. , and perpendicular line 14
The length of the intermediate blade inside the midpoint is 2 of the total length of the intermediate blade.
It is set at 0% or less.

Further, the shape of the entire intermediate blade is configured such that when the intermediate blade is virtually rotated around the rotation axis of the impeller, it is included inside the stationary blade. By the way, it is desirable to make the inner peripheral side aileron as thin as possible, but a certain thickness is required for the sake of strength. For this reason, it is necessary to set the number of stationary blades to a level that can ensure a sufficient cross-sectional area of the flow path.
If this is done, the space between the stationary blades will be too large in the flow path near the outer periphery of the stationary blades, resulting in poor performance. Since it extends so as to pass through the midpoint of the perpendicular line drawn to the blade surface of the stationary blade, the spacing between the stationary blades is essentially at an appropriate value near the outer peripheral edge of the stationary blade, preventing performance degradation. .

The diffuser shown in FIG. 17 has the ailerons shown in FIG. 11, but has an intermediate blade 13 on the trailing edge side of the stationary blade 4 having the same height as the static IL blade. In what is shown, the side plate side between the aileron and the stationary wing is connected by a partition 15 whose height is sufficiently lower than the height of the aileron.

The diffuser shown in FIG. 19 has the ailerons shown in FIG. 11, except that an intermediate blade 13 having the same height as the stationary blade is disposed on the trailing edge side of the stationary blade 4, and the diffuser shown in FIG. The side plate side between the aileron and the intermediate wing is connected by a partition 15 whose height is sufficiently lower than the height of the aileron.

〔Effect of the invention〕

As described above, according to the present invention, since the leading edge of the stationary blade or the auxiliary blade has a shape based on the speed vector of the impeller 12, it is possible to suppress the backflow that occurs on the side plate side when the flow rate is small.
The operating range on the small flow rate side can be expanded. Further, since the aileron and the intermediate wing are arranged between the stationary blades, and the leading edge of the aileron has the shape described above, the operating range of the diffuser is further expanded, and capacity control is dramatically improved.

Furthermore, since a partition plate is provided at the trailing edge of the aileron or between the aileron and the intermediate wing, the rigidity of the wing is increased and stable performance is guaranteed over a long period of time.

In addition, since only part of the leading edge of the stationary wing or aileron exists near the impeller, the influence of excitation force due to aerodynamic interference is reduced, and the strength of the stationary wing or aileron impeller is relatively increased. This ensures high reliability.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a high-speed centrifugal compressor according to an embodiment of the present invention;
Fig. 2 is a vertical cross-sectional view of the main parts of the embodiment shown in Fig. 1, Fig. 3 is a three-dimensional layout diagram showing the main parts of Fig. 2, and Fig. 4 is a cross-sectional view of a high-speed centrifugal compressor of another embodiment. Figures 5 and 5 are three-dimensional layout diagrams showing the main parts of Figure 4, Figures 6 and 7 are longitudinal sectional views of the main parts of other embodiments, and Figure 8 is a diagram explaining the dimensional relationship. FIG. 9 is a longitudinal cross-sectional view of a high-speed centrifugal compressor equipped with a diffuser having aileron blades, which is another embodiment of the present invention.
The figure is a plan view of FIG. 9, FIG. 11 is a vertical sectional view showing another embodiment of the aileron, FIG. 12 is a three-dimensional layout diagram showing the main parts of FIG. 11, and FIG. 14 is a vertical sectional view showing an example of the embodiment, FIG. 14 is a three-dimensional layout diagram showing the main parts of FIG.
FIG. 15 is a longitudinal sectional view of a high-speed centrifugal compressor equipped with a diffuser having an aileron and an intermediate blade, which is another embodiment of the present invention, FIG. 16 is a plan view of FIG. 15, and FIG. FIG. 18 is a vertical sectional view showing another embodiment of the aileron shown in the figure, and FIG. 18 is a three-dimensional layout diagram showing the main parts of FIG. 17. FIG. L9 is a longitudinal sectional view showing another embodiment of the intermediate blade shown in FIG. 17, FIG. 20 is a three-dimensional layout diagram showing the main parts of FIG. 19, and FIG. 21 is another embodiment of the present invention. A longitudinal sectional view of a high-speed centrifugal compressor equipped with a diffuser in which a certain aileron and intermediate blades are connected by a partition plate, FIG. 22 is a three-dimensional layout diagram showing the main parts of FIG. 21, and FIG. 24 is a vertical cross-sectional view of a high-speed centrifugal compressor equipped with a diffuser in which an aileron whose height is lower than that of a stationary blade and an intermediate blade are connected by a partition plate. FIG. 24 is a three-dimensional diagram showing the main parts of FIG. Layout, No. 25
The figure is a longitudinal cross-sectional view showing a conventional high-speed centrifugal compressor, and FIG. 26 is a cross-sectional view taken along line B-13 in FIG. 25. DESCRIPTION OF SYMBOLS 1... Impeller, 2... Fluid flow direction, 3... Diffuser, 4... Stationary blade, 11... Aileron, 12
．． 15... Partition plate, 13... Intermediate wing.

Claims (1)

[Claims] 1. A high-speed centrifugal compressor equipped with a diffuser in which a plurality of stationary blades are arranged around the outer periphery of the impeller and converts the kinetic energy of the fluid discharged from the impeller into pressure energy by the action of the stationary blades. In the high-speed centrifugal device, the side plate side of the stationary blade of the diffuser extends from the core plate side toward the impeller, and the leading edge of the stationary blade is inclined from the core plate side to the side plate side. compressor. 2. A high-speed centrifugal compressor according to claim 1, wherein the inlet angle of the leading edge of the stationary blade on the side plate side (the angle formed with the radial direction of the impeller) is larger than the inlet angle on the core plate side. 3. A high-speed centrifugal compressor equipped with a diffuser in which a plurality of stationary blades are arranged around the outer circumference of the impeller and converts the kinetic energy of the fluid discharged from the impeller into pressure energy by the action of the stationary blades. An aileron having a chord length shorter than that of the stationary wing and having a height equal to or less than the stationary wing is provided on the side close to the inner circumference of the stationary wing, and only one wing surface of the aileron faces the stationary wing, and A high-speed centrifugal compressor characterized in that the side plate side of the leading edge of the aileron blade extends from the core plate side toward the impeller, and the leading edge of the aileron blade is inclined from the core plate side to the side plate side. . 4. A high-speed centrifugal compressor according to claim 3, further comprising a partition plate that is lower in height than the aileron blades and extends in a direction along the stationary blades, and is connected to the downstream side of the aileron blades. . 5. A high-speed centrifugal compressor equipped with a diffuser in which a plurality of stationary blades are arranged around the outer periphery of the impeller and converts the kinetic energy of the fluid discharged from the impeller into pressure energy by the action of the stationary blades. An aileron whose chord length is shorter than the stationary wing and whose height is equal to or less than the stationary wing is provided on the side near the inner circumference of the stationary wing, and only one wing surface of the aileron faces the stationary wing, and the auxiliary wing The side plate side of the leading edge of the blade extends from the core plate side toward the impeller, and the leading edge of the aileron blade is inclined from the core plate side to the side plate side, and is close to the outer periphery between the plurality of stationary blades. A high-speed centrifugal compressor characterized in that an intermediate blade having a chord length shorter than the stationary blade and having a height equal to or less than the stationary blade is provided on the side thereof. 6. The diffuser according to claim 5, wherein the aileron and the intermediate blade are connected by a partition plate that is lower in height than both the aileron and the intermediate blade and extends in a direction along the stationary blade. High-speed centrifugal compressor.