JPH09100797A - Impeller of centrifugal compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain generation of a secondary flow in a channel by forming a groove along the flowing direction of fluid on the side of an inflow port of a blade surface and to improve efficiency of an impeller by making it hard to generate a back-flow. SOLUTION: An impeller 1 is constituted of a main plate 2, a blade 3 and a side plate 4, and a through hole 6 to install a drive shaft 5 is formed at the center of the main plate 2. The blade 3 is fixed on the main plate 2 and the side plate 4, and a groove 8 along the fluid flowing direction is formed in length roughly to a central part of the blade 3 on an inner peripheral surface of a channel 7 formed by them. At the time of driving, fluid sucked into the impeller 1 from a suction pipe is introduced to a delivery pipe after it is pressure raised by the rotating impeller 1, but as the groove 8 along the fluid flowing direction is formed on the inner peripheral surface of the channel 7 of the impeller 1 in this flow, the fluid is regulated and comes to be in a streightened state, and generation of a secondary flow in the channel 7 is restrained. Additionally, as a back-flow is hardly generated, peeling of a boundary layer is restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impeller of a centrifugal compressor.

[0002]

2. Description of the Related Art For example, Japanese Patent Laid-Open No. 60-166793 discloses
An improved centrifugal compressor impeller has been proposed. To cite the same publication, in the conventional centrifugal compressor, as shown in FIG. 4, a drive shaft 12 having an impeller 11 attached to an end thereof is rotatable by a bearing and a seal 13 in a compressor body 14. Sealed and supported. A spiral chamber 15 is formed on the outer peripheral portion of the spiral chamber 15, and a portion that forms a diffuser 16 with the main body 14 is provided inside the spiral chamber 15 in the radial direction.
A casing formed with an axial cylindrical portion to which the
18 is attached to the main body 14 and the impeller 11 is provided between the main body 14 and the main body 14.
Is housed.

The main plate side H of the impeller 11 is adjacent to the side plate 19 which supports the bearing of the main body 14 and the seal 13, and the opposite main plate side S is adjacent to the inner wall of the casing 18. Here, the main plate side H refers to the main plate 20 or the hub 21 and the blades 22 in the vicinity thereof in contact with them, and the anti-main plate side S is the side opposite to the main plate side H, that is, the side plate 23 and it if it is a closed type. It refers to the blade 22 near the contact, and in the case of the open type, the blade 22 near the open edge facing the casing 18.

On the opposite main plate side S, a fluid passage (hereinafter referred to as a flow passage) is exposed in the open type impeller, but in the closed type impeller shown in the drawing, a side plate 23 is further provided to allow the flow. The passage is limited to the inside of the side plate 23. A seal 24 is provided between the side plate 23 and the casing 18 to prevent the return flow from the impeller outlet to the impeller inlet.

The fluid sucked in from the suction pipe 17 in the axial direction of the impeller 11 is pressurized by the rotating impeller 11 and given velocity energy, discharged from the impeller 11 in the radial direction, and then enters the diffuser 16. Here, the velocity energy is converted into pressure energy while reaching the outlet of the diffuser 16, and further swirled in the swirl chamber 15 and guided to a discharge pipe (not shown).

In the impeller 11 having the above-mentioned conventional structure, when the compressor shifts to a small flow rate range, the deceleration rate of the fluid on the suction surface of the blade inlet increases, the boundary layer develops, and the collision angle of the collision angle increases. Depending on the size, the flow separates, and in the vicinity of the suction surface, a reverse flow region in which the relative velocities are opposite is generated, which makes the flow significantly different from the ideal flow.Such separation on the blade suction surface causes impeller 11 Therefore, it causes the efficiency of the compressor to decrease, and further increases in the impingement angle at the blade inlet expands the backflow region and develops into the surging of the compressor, further narrowing the operable range of the compressor. .

In order to solve the drawbacks of the conventional impeller 11 as described above, in the impeller of the centrifugal compressor proposed in JP-A-60-166793, the blade suction surface near the impeller inlet is provided. It has been proposed to provide means for suppressing turbulent flow and separation of the boundary layer.

[0008]

By the way, the one proposed in Japanese Patent Laid-Open No. 60-166793 mentioned above is constructed so as to form a turbulent flow by forming grooves intersecting in the fluid flow direction in a blade or the like. Although it is possible to suppress the separation of the boundary layer in the flow path by the generated turbulent flow, a vortex, that is, a secondary flow is always generated in the turbulent flow, so that the efficiency of the impeller is not always sufficiently improved. I can't.

The present invention has been made to solve the above problems, and an object thereof is centrifugal compression capable of suppressing the occurrence of a secondary flow in a flow channel and suppressing the separation of a boundary layer. It provides the impeller of the machine.

[0010]

In order to achieve the above object, an impeller of a centrifugal compressor according to the present invention is formed with a groove along the flow direction of a fluid on an inlet side of a blade surface. Is.

In the impeller of the centrifugal compressor, grooves are formed along the flow direction of the fluid on the surface of the main plate forming the flow passage and on the inlet side of the surface forming the flow passage of the side plate. It may be.

The structure and operation of the present invention will be described in detail below. The flow in the impeller of a centrifugal compressor is originally a turbulent state and has a very large Reynolds number, and the viscous force is extremely smaller than the inertial force, and the viscous force can be generally ignored. This means that the fluid can be treated as a non-viscous fluid, and it is known that the flow of the non-viscous fluid on the object surface follows the direction of the object surface. Therefore, in the present invention, such a characteristic of the flow is utilized, and by forming a groove along the flow direction of the fluid on the inlet side of the blade surface, the fluid flow in a turbulent state is made to flow along the groove. By regulating the flow, a rectified state is obtained. With this, it is possible to suppress the generation of a secondary flow in the flow path, and it is also difficult to generate a backflow, so that it is possible to suppress separation of the boundary layer, and to suppress the centrifugal compressor The efficiency of the impeller can be improved.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 is a front view of an impeller of a centrifugal compressor according to the present invention, FIG. 2 is a cross-sectional view of the upper half of XX in FIG. 1, and FIG. 3 is a blade portion viewed from the Y direction in FIG. FIG.

The impeller 1 is composed of a main plate 2, blades 3 and side plates 4, and a through hole 6 for attaching to a drive shaft 5 is formed at the center of the main plate 2. Further, the blade 3 is fixed to the main plate 2 and, in this example, is also fixed to the side plate 4 to form a closed type. Further, on the inner peripheral surface of the flow path 7 formed by the main plate 2, the blade 3 and the side plate 4, a groove 8 along the fluid flow direction is formed with a length up to almost the central portion of the blade 3.

When the impeller 1 having the above-mentioned structure is used by incorporating it into a compressor, the fluid sucked from the suction pipe into the impeller 1 is boosted by the rotating impeller 1 and gives velocity energy as in the conventional case. After being discharged from the impeller 1 in the radial direction, it enters the diffuser, where it reaches the outlet of the diffuser while converting velocity energy into pressure energy, and is guided to the discharge pipe while swirling in the swirl chamber. Since the groove 8 along the fluid flow direction is formed on the inner peripheral surface of the flow path 7 of the impeller 1, the fluid is regulated by the flow along the groove 8 and is in a rectified state.
Generation of a secondary flow inside is suppressed. Further, since backflow is less likely to occur, separation of the boundary layer can be suppressed, and these can improve the efficiency of the impeller 1 of the centrifugal compressor.

In the above embodiment, the most preferable example is the one in which the grooves 8 are formed in all of the main plate 2, the blades 3 and the side plates 4 forming the flow path 7, but the present invention is limited to this example. The groove 8 may be formed only on the blade 3, or only on the blade 3 and the main plate 2, although the efficiency is slightly lowered. Further, although the closed type is taken as an example, it can be applied to an open type compressor without the side plate 4.

Although the length of the groove 8 is taken as an example up to the substantially central portion of the blade 3, it may be longer than the substantially central portion of the blade 3 where secondary flow or separation easily occurs.

[0018]

As described above, with the impeller of the centrifugal compressor according to the present invention, it is possible to suppress the generation of secondary flow in the flow path, and it is also difficult to generate backflow. Peeling can be suppressed, and the efficiency of the impeller of the centrifugal compressor can be improved.

[Brief description of the drawings]

FIG. 1 is a front view of an impeller of a centrifugal compressor according to the present invention.

2 is a cross-sectional view of the upper half of XX in FIG.

FIG. 3 is a partially enlarged explanatory view of the blade viewed from the Y direction in FIG.

FIG. 4 is a partial cross-sectional view of a conventional centrifugal compressor.

[Explanation of symbols]

1: Impeller 2: Main plate
3: Wing 4: Side plate 5: Drive shaft
6: Through hole 7: Flow path 8: Groove

Claims (4)

[Claims] 1. An impeller of a centrifugal compressor, characterized in that grooves are formed along the flow direction of the fluid on the inlet side of the blade surface. 2. The impeller of a centrifugal compressor according to claim 1, wherein a groove along the flow direction of the fluid is formed on the inlet side of the surface forming the flow path of the main plate. 3. The impeller of a centrifugal compressor according to claim 2, wherein a groove is formed along the flow direction of the fluid on the inlet side of the surface forming the flow path of the side plate. 4. The impeller of a centrifugal compressor according to claim 1, 2 or 3, wherein the length of the groove is such that it reaches substantially the center of the blade.