JP2573292B2 - High speed centrifugal compressor - Google Patents

Description

The present invention relates to a high-speed centrifugal compressor, and more 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. 18 and 19 and generates an airflow in a direction indicated by an arrow 2 by rotation of an 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 of the impeller 1 has a large velocity energy, so that the outer peripheral portion of the impeller impinges on the downstream side of the impeller 1. Is provided with a diffuser 3 having stationary blades to convert velocity energy of fluid discharged from the impeller 1 into pressure energy.

As shown in FIG. 19, a plurality of stationary blades 4 constituting the diffuser 3 are radially provided on the outer peripheral portion of the impeller 1, and these stationary blades 4, the side wall 9 on the side plate side, and the The diffuser channel 3 is formed by the side wall 10.

Generally, the flow at the outlet of the centrifugal impeller is distorted in the width direction as shown in FIG. 20, and this tendency is remarkable in a compressor having a pressure ratio per stage of more than 2. The situation of the flow distortion is that the flow direction, that is, the velocity vector 7 is close to the tangential direction 8 of the impeller on the side plate side 9 (the part 5 of the leading edge of the stationary blade 4), while the core plate side 10 (the stationary blade 4 The other portion 6 of the front edge) shows a direction away from the tangential direction compared to the side plate 9.

In such a compressor, as the passing flow rate is increased, chokes are generated in the minimum cross-sectional area of the flow path formed by the stationary vanes and the side walls of the diffuser, and the performance of the compressor is rapidly lowered. Further, under the condition of relatively high speed rotation and low flow rate, a separated flow region is generated on the negative pressure surface of the stationary blade, and a surge phenomenon occurs in which a sufficient pressure increase cannot be obtained.
To solve this problem, a diffuser having an auxiliary wing provided between stationary wings has been proposed.

When the auxiliary wing is provided, it is desirable to make it as thin as possible so as not to reduce the minimum sectional area of the flow path, but a certain thickness is required in terms of strength. For this reason, the number of stationary blades needs to be such that a sufficient flow path cross-sectional area can be secured. However, in this case, the distance between the stationary blades in the flow path near the outer periphery of the stationary blade becomes excessive. As a result, on the suction surface near the trailing edge of the stationary blade 4, the flow does not follow the blade surface and a large separation area is generated. Therefore, the substantial cross-sectional area of the flow is reduced and the flow path of the diffuser is reduced. Diffusion of kinetic energy within the exfoliation zone occurs.

The operating range of such high-speed centrifugal compressors is often limited by the diffuser. That is, on the small flow rate side, it is the stall limit at which the backflow generated in the diffuser reaches the impeller, and on the high flow rate side, it is often the choke limit in the diffuser. Therefore, in order to expand the operating range of the compressor, first, it is necessary to increase the operating range of the diffuser, and several methods have been proposed. At present, a relatively widely used stationary blade 4 is rotatably supported by a spindle parallel to the rotation axis of the impeller 1, and the direction of the stationary blade is changed according to the direction of the flow flowing out of the impeller. Is the way.

In addition, the stationary blade is provided with a boundary layer plate provided by extending the tip (US Pat. No. 3,781,128), and the angle of the inlet of the stationary blade is changed in the blade height direction (US Pat. No. 390431).
No. 2, specification No. 53-162405), and the like.

[Problems to be solved by the invention]

However, the above-mentioned conventional diffuser blades having a movable structure have a complicated structure, and those provided with a boundary layer plate do not have a sufficient effect of the boundary layer plate in a high-speed centrifugal compressor having large impeller outlet flow distortion. . Furthermore, in the case where the angle of the inlet of the stationary blade is changed in the blade height direction, in the conventional case, the operating range is small, or the leading edge of the stationary blade is close to the impeller for expanding the operating range. Although the working range on the small flow side can be expanded, the working range on the large flow side is narrowed because the minimum cross-sectional area of the flow path is reduced, and the strong excitation force due to the aerodynamic interference between the impeller and the stationary blade causes There is a problem that the stationary wing or the impeller may be destroyed after a long-term operation.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high-speed centrifugal compressor having a diffuser having a simple structure, a wide operating range, and a high strength.

[Means for solving the problem and its operation]

In order to achieve the above object, the present invention includes a diffuser in which a plurality of stationary blades are arranged on the outer periphery of an impeller and the kinetic energy of fluid discharged from the impeller is converted into pressure energy by the action of the stationary blade. In the high-speed centrifugal compressor, an auxiliary wing having a shorter chord length and a height equal to or less than that of the stationary wing is provided on a side near the inner periphery between the stationary wings of the diffuser, and one wing surface of the auxiliary wing is provided. Only the stationary blade is opposed to the stationary blade, and the side plate side of the leading edge of the auxiliary blade extends in the direction of the impeller from the core plate side.

According to the invention, the auxiliary wing is provided on the side near the inner periphery between the stationary wings, and only one of the auxiliary wings is opposed to the stationary wing,
Since the auxiliary wing does not penetrate the minimum cross-sectional area of the flow path formed by the stationary wing and the side wall, the working range on the small flow rate side can be expanded by bringing the leading edge of the auxiliary wing closer to the impeller. An operating range on the choke side can be secured. In this case, since only a part of the leading edge of the auxiliary wing exists near the impeller, the excitation force due to aerodynamic interference can be greatly reduced, and the strength of the auxiliary wing and the impeller can be relatively increased. When a partition plate extending in the direction along the stationary blade lower than the auxiliary wing is connected to the downstream side of the auxiliary wing, the rigidity is further increased by integrating the auxiliary wing and the partition plate.

According to another aspect of the present invention, in the above aspect, an intermediate wing having a shorter chord length and a height equal to or less than that of the stationary wing is provided on a side closer to the outer periphery between the stationary wings.

According to the above invention, the interval between the stationary blades substantially becomes an appropriate value near the outer peripheral end of the stationary blade, so that a decrease in performance can be prevented.

According to another aspect of the present invention, in the above invention, the auxiliary wing and the intermediate wing are connected by a partition plate, and the partition plate is arranged to be lower than the height of the two wings and extend in a direction along the stationary wing.

According to the above invention, the auxiliary wing, the partition plate, and the intermediate wing are integrated to further increase the rigidity.

〔Example〕

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

1 to 3 show an embodiment of the present invention. In the figure, the same or equivalent parts as those in the conventional example shown in FIGS. 18 to 20 are denoted by the same reference numerals, and description thereof will be omitted. FIG. 1 is a cross-sectional view 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, and FIG. 3 is a plan view of FIG.

In the high-speed centrifugal compressor of the present embodiment, an auxiliary wing 11 is provided on the leading edge side of the stationary wing 4 of the diffuser.

As shown in FIG. 3, the auxiliary wing 11 intersects a circle centering on the rotation axis of the impeller 1 and passing through the leading edge of the stationary wing 4, and has a center of radius of curvature among adjacent stationary wings 4a and 4b. The stationary wing 4a is disposed so as not to intersect with a perpendicular line drawn from the leading edge of the stationary wing 4a to the other stationary wing 4b.

As shown in FIG. 2, the leading edge 11a of the auxiliary wing 11 has a leading edge portion 5 on the side plate side 9 extending in the direction of the impeller 1 from a leading edge portion 6 on the core plate side 10, and The side plate side close to the height b ₁
It consists of the leading edge portion. The dimensions of each part of the leading edge include the radius r _{i of} the impeller and the radial position of the leading edge portion 5 on the side plate side.
r _s, between the radial position r _h of the front edge portion 6 of the heart plate side, 1 <r _s / r
_i ≦ 1.1 <r _h / r _i , and 0.1 <b _i / b <between the average height b _{i of the} leading edge on the side plate side and the height b of the stationary blade.
When there is a relation of 0.6, it is effective in reducing the exciting force caused by aerodynamic interference.

Next, another embodiment of the present invention will be described. The auxiliary wing 11 shown in FIG. 4 and FIG. 5 focuses on the fact that the contribution of the auxiliary wing portion of the high-speed core side 10 is small in expanding the operating range, and the shape without the portion, that is, The height is reduced.

Another embodiment of the present invention will be described. The auxiliary wing 11 shown in FIGS. 6 and 7 has a lower height and is connected to the downstream side thereof, and a partition plate 12 reaching a circle passing the trailing edge of the stationary wing 4 is formed along the stationary wing 4. It was arranged. By providing the partition plate 12 in this manner, the rigidity of the auxiliary wing 11 can be increased.

FIGS. 8 to 17 show an embodiment of a high-speed centrifugal compressor in which an auxiliary blade is provided on the leading edge side of the stationary blade and an intermediate blade is provided on the trailing edge side.

The embodiment shown in FIGS. 8 and 9 uses the auxiliary wing shown in FIG.
In the diffuser having 11, an intermediate blade 13 having the same height as the stationary blade 4 is disposed on the trailing edge side of the stationary blade 4.
The intermediate wing 13 passes through the midpoint of a perpendicular 14 extending from the outer peripheral end of the stationary wing 4 to the inner peripheral side of the adjacent stationary wing 4, and the outer peripheral end of the intermediate wing 13 The length of the intermediate wing 13 reaching the circle passing through the end and inside the midpoint of the perpendicular 14 is not more than 20% of the total length of the intermediate wing 13.

The shape of the entire intermediate wing 13 is virtually included in the stationary wing 4 when the intermediate wing 13 is rotationally moved around the rotation axis of the impeller 1. By the way, it is desirable to make the inner peripheral side auxiliary wing 11 as thin as possible, but a certain thickness is required in terms of strength. For this reason, the number of stationary blades needs to be such that a sufficient flow path cross-sectional area can be ensured. However, in this case, the distance between the stationary blades 4 in the flow path near the outer periphery of the stationary blade 4 becomes excessive, and the performance becomes poor. On the side closer to the outer periphery between the stationary blades 4, the intermediate blade 13 extends so as to pass through the midpoint of a perpendicular drawn from the outer peripheral end of the stationary blade 4 to the blade surface of the adjacent stationary blade 4. Therefore, in the vicinity of the outer peripheral end of the stationary blade 4, the interval between the stationary blades 4 becomes substantially an appropriate value, and a decrease in performance can be prevented.

The embodiment shown in FIGS. 10 and 11 uses the auxiliary wing shown in FIG.
In the diffuser having 11, an intermediate wing 13 having the same height as the stationary wing 4 is disposed on the trailing edge side of the stationary wing 4, and the one shown in FIGS. 14 and 15 is shown in FIG. 10. Aileron
The side plate side 9 is connected between the stationary blade 4 and the stationary blade 4 by a partition plate 15 having a height sufficiently lower than the height of the auxiliary wing 11.

The embodiment shown in FIGS. 12 and 13 uses the auxiliary wing shown in FIG.
In the diffuser having the intermediate blade 11, an intermediate wing 13 lower than the stationary wing 4 is disposed on the trailing edge side of the stationary wing 4,
FIG. 17 shows the auxiliary wing 11 shown in FIG.
The side plate 9 between the intermediate wing 13 and the intermediate wing 13 is connected by a partition plate 15 having a height sufficiently lower than the height of the auxiliary wing 11. Thereby, the rigidity of the auxiliary wing 11 and the intermediate wing 13 is increased.

〔The invention's effect〕

As described above, according to the present invention, in the high-speed centrifugal compressor, the auxiliary blade is provided on the inner peripheral side of the stationary blade constituting the diffuser, and the leading edge of the auxiliary blade is formed based on the speed vector of the impeller. In addition, the backflow occurring on the side plate side at the time of a small flow rate can be suppressed, and the operating range on the small flow rate side can be expanded. Further, since the auxiliary wing and the intermediate wing are arranged between the stationary wings and the leading edge of the auxiliary wing has the above-mentioned shape, the operating range of the diffuser is further expanded, and the capacity control is dramatically improved.

Further, since the partition plate is provided between the trailing edge of the auxiliary wing or the auxiliary wing and the intermediate wing, the stiffness of the wing is increased, and stable performance is ensured for a long period of time.

Also, since only a part of the leading edge of the aileron exists near the impeller, the effect of the excitation force due to aerodynamic interference is reduced,
The strengths of the stationary blade and the auxiliary blade impeller are relatively increased, and high reliability is ensured.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a high-speed centrifugal compressor provided with a diffuser having an auxiliary wing according to an embodiment of the present invention, and FIG.
3 is a plan view of FIG. 2, FIG. 4 is a longitudinal sectional view showing another embodiment of the present invention, and FIG. 5 is a sectional view showing a main part of FIG. FIG. 6, FIG. 6 is a longitudinal sectional view showing another embodiment of the present invention, FIG. 7 is a three-dimensional layout showing main parts of FIG. 6, and FIG. 8 is another embodiment of the present invention. 9 is a vertical sectional view of a high-speed centrifugal compressor provided with a diffuser having an intermediate wing, FIG. 9 is a plan view of FIG. 8, FIG. 10 is a vertical sectional view showing another embodiment of the present invention, and FIG. FIG. 10 is a three-dimensional view showing the main parts of FIG. 10, FIG. 12 is a longitudinal sectional view showing another embodiment of the present invention, FIG. 13 is a three-dimensional view showing the main parts of FIG. 12, and FIG. In another embodiment of the invention, a longitudinal sectional view of a high-speed centrifugal compressor provided with a diffuser in which an auxiliary wing and an intermediate wing are connected by a partition plate, FIG. 15 is a three-dimensional arrangement diagram showing a main part of FIG. 14, FIG. FIG. Longitudinal sectional view showing a 施例, 17
FIG. 18 is a three-dimensional layout showing the main parts of FIG. 16, FIG. 18 is a longitudinal sectional view showing a conventional high-speed centrifugal compressor, and FIG.
FIG. 20 is a diagram showing a cross section taken along line -B, and FIG. 20 is a diagram showing a velocity vector of an air flow at an impeller outlet of the high-speed centrifugal compressor. DESCRIPTION OF SYMBOLS 1 ... Impeller, 2 ... Flow direction of fluid, 3 ... Diffuser, 4 ... Stationary blade, 9 ... Side wall on side plate side, 10 ... Side wall on core plate side, 11 ... Auxiliary wing, 12, 15 ... divider, 13 ... middle wing.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yoshiaki Abe 603, Kandamachi, Tsuchiura-shi, Ibaraki Pref.Hitachi, Ltd. Tsuchiura Plant, Hitachi, Ltd. (56) References JP-A-61-182495 (JP, A) JP-A-60-135797 (JP, A) JP-A-59-231199 (JP, A) JP-A-61-38198 (JP, A)

Claims (4)

(57) [Claims] A high-speed centrifugal compressor having a diffuser having a plurality of stationary blades arranged on the outer periphery of an impeller and converting kinetic energy of fluid discharged from the impeller into pressure energy by the action of the stationary blade. On the side near the inner periphery of the stationary wing of the diffuser, an auxiliary wing having a shorter chord length than the stationary wing and having the same height or less is provided, and only one wing surface of the auxiliary wing is opposed to the stationary wing. Wherein the side plate side of the leading edge of the auxiliary wing extends in the direction of the impeller from the core plate side, and the leading edge of the auxiliary wing is inclined from the core plate side to the side plate side. Centrifugal compressor. 2. The diffuser according to claim 1, wherein a partition plate having a height lower than that of said auxiliary wing and extending in a direction along the stationary wing is connected to a downstream side of said auxiliary wing. Centrifugal compressor. 3. A high-speed centrifugal compressor having a diffuser having a plurality of stationary blades arranged on the outer periphery of an impeller and converting kinetic energy of fluid discharged from the impeller into pressure energy by the action of the stationary blade. On the side closer to the inner periphery of the stationary wing, an auxiliary wing having a shorter chord length than the stationary wing and having the same height or less is provided, and only one wing surface of the auxiliary wing is opposed to the stationary wing. The side plate side of the leading edge of the auxiliary wing extends in the direction of the impeller from the core plate side so that the front edge of the auxiliary wing is inclined from the core plate side to the side plate side, and between the plurality of stationary blades. A high-speed centrifugal compressor characterized in that a chord length shorter than the stationary blade and an intermediate blade having a height equal to or less than that of the stationary blade are provided on a side close to the outer periphery. 4. The diffuser according to claim 3, wherein the auxiliary wing and the intermediate wing are connected to each other by a partition plate having a height lower than that of each of the auxiliary wing and the intermediate wing and extending in a direction along the stationary wing. A high-speed centrifugal compressor characterized by the following.