JPH09177698A - Structure of vaneless part of compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of the separation phenomenon at a vaneless part by arranging an induction wall projected inwardly along the direction of the inlet air flow at a diffuser on an inner surface of a side wall of the vaneless part which is a connection space between a centrifugal impeller to be driven and the diffuser in a non-rotating condition. SOLUTION: When an induction wall 8 is arranged on side walls 7a, 7b of a vaneless part 7 which is a connection space between a centrifugal impeller l and a diffuser 2, the centrifugal impeller 1 is rotated in the arrow direction, and the air introduced into the centrifugal impeller 1 is compressed mainly due to the centrifugal effect in the deceleration in passing the blades, and fed into the diffuser 2 through the vaneless part 7. In the vaneless part 7, a part of the air flow of the component deviated from the direction of the main flow is induced by the induction wall 8 on the inner surface of the side walls 7a, 7b along the original induction direction of the diffuser 2. Generation itself of the separation flow due to the component in the different direction from that of the main flow is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a vaneless portion of a compressor, and more particularly to suppressing the peeling phenomenon occurring in the vaneless portion of a centrifugal compressor to improve the performance.

[0002]

2. Description of the Related Art FIGS. 3 and 4 show an example of a conventional structure of a centrifugal compressor. The centrifugal compressor has a centrifugal impeller 1 to be rotated, a diffuser 2 in a non-rotating state, and a scroll (volute or spiral casing) 3, and the centrifugal impeller 1 is directed outward by rotation indicated by an arrow. A swirling flow is created, and energy is mainly applied to the gas by centrifugal action so that the dynamic pressure of the outlet gas of the centrifugal impeller 1 is made static by the diffuser 2 and the scroll 3.

As shown in FIGS. 3 and 4, a hub 5 connected to a rotary drive source is provided with a disk 5 for mounting the centrifugal impeller 1 and a disk 5
A shroud (side plate) 6 is arranged at a position facing each other, and a vaneless portion 7 serving as a connection space is arranged between the centrifugal impeller 1 and the diffuser 2.

[0004]

[Problems to be Solved by the Invention] However, the centrifugal impeller 1
When the air flow flowing out from the vaneless portion 7 passes through the vaneless portion 7, the movement of the vaneless portion 7 in the circumferential direction is allowed, so that not all of the airflow is evenly guided to the diffuser 2, and the airflow is not always induced. Side wall 7 of the vaneless portion 7 located inside the bent portion due to a part of the flow in a direction different from the main flow.
A three-dimensional separated flow is generated near the inner surface of a, and the occurrence of this separation becomes a factor that reduces the compression efficiency.

The present invention has been made in view of these problems, and aims to achieve the following objects. To suppress the occurrence of peeling phenomenon itself in the vaneless part. Smoothing the air flow from the centrifugal impeller to the diffuser. To improve the overall compression efficiency of the compressor.

[0006]

In a compressor in which a vaneless portion serving as a connection space is arranged between a centrifugal impeller driven to rotate and a diffuser in a non-rotating state, the vaneless portion is separated in a rotation axis direction. On the inner surface of the side wall that is surrounded by the position, a guide wall that projects inward is arranged along the direction of the inlet air flow in the diffuser. The guide wall is disposed on at least one of the side walls facing each other with the vaneless portion interposed therebetween, and the projecting height is set to be smaller than half of the facing size of the side wall, and the vicinity of the tip of the shroud of the centrifugal impeller is provided. It is desirable to arrange at least one, and one or a plurality of them are arranged between the partition walls of adjacent diffusers.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS.
An embodiment of the structure of the vaneless portion of the compressor according to the present invention will be described.

In the example of FIGS. 1 and 2, a vaneless portion 7 serving as a connection space between the centrifugal impeller 1 which is driven to rotate and the diffuser 2 which is not rotated is arranged. On the inner surfaces of the side walls 7a and 7b of the vaneless portion 7, the inwardly projecting guide wall 8 is arranged.

The guide wall 8 has side walls 7a and 7b surrounding the diffuser 2 at positions separated from each other in the rotation axis direction.
On the inner surface of the diffuser 2 so as to be aligned with the direction of the inlet air flow in the diffuser 2 (the direction in which the air flow is guided).

Further, the guide wall 8 is the above-mentioned side walls 7a, 7b.
One or a plurality of them are arranged near the tip of the shroud 6 of the centrifugal impeller 1 which is the inside of the bent state, or at least one of them, and between the adjacent partition walls 2a of the diffuser 2.

Further, the protruding height of the guide wall 8 is determined by the side wall 7
It is set to be less than 50% of the facing dimension of a and 7b.

As described above, when the guide wall 8 is provided on both or one of the side walls 7a and 7b of the vaneless portion 7, the centrifugal impeller 1 rotates in the direction shown by the arrow in FIG. The air introduced into No. 1 is compressed mainly by centrifugal action at the time of deceleration when passing between the blades and sent into the diffuser 2 via the vaneless section 7. At that time, in the vaneless section 7, the main flow A part of the air flow of the component deviated from the direction will be guided along the original guiding direction of the diffuser 2 by the guiding wall 8 on the inner surfaces of the side walls 7a and 7b.

Therefore, the generation of the separated flow due to the component in the direction different from the main flow is suppressed, and the diffuser 2 and the scroll 3 are centrifugally guided by guiding the separated flow into the main flow direction. The dynamic pressure of the outlet gas of the impeller 1 can be effectively made static and the compression efficiency can be improved.

The protruding height of the guide wall 8 is set to the side walls 7a, 7
made significantly smaller than the facing range (facing dimension) of b,
For example, the number is less than half, but the reason is that the airflow in the portion of the vaneless portion 7 is provided with freedom in the flow direction, and the increase in frictional resistance during compression is suppressed.

[0015]

The structure of the vaneless portion of the compressor according to the present invention has the following excellent effects. (1) On the inner surface of the side wall of the vaneless portion, since the guide wall in a state of protruding is arranged along the direction of the inlet air flow in the diffuser, the air flow component flowing in a direction different from the main flow of the air flow The secondary flow due to the branched flow or the separated flow can be suppressed, and the compressed air can be smoothly guided. (2) By disposing the guide wall in the vicinity of the tip of the shroud of the centrifugal impeller, a separation flow based on a component different from the air flow is effectively sent between the diffusers to suppress the occurrence of separation phenomenon, and the compression is performed. The compression efficiency of the machine can be improved. (3) By arranging the vaneless portion between the adjacent diffusers, the inductivity of the air flow in the middle portion is improved,
It is possible to effectively suppress the secondary flow due to the branched flow and the separated flow.

[Brief description of the drawings]

FIG. 1 is a plan sectional view showing an embodiment of a structure of a vaneless portion of a compressor according to the present invention, in which a part of the description is omitted.

FIG. 2 is a front cross-sectional view showing an embodiment of the structure of the vaneless portion of the compressor according to the present invention, with a part of the description omitted.

FIG. 3 is a plan sectional view showing an example of a conventional structure of a compressor with a part of the description omitted.

FIG. 4 is a front cross-sectional view showing an example of a conventional structure of a compressor with a part of the description omitted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Centrifugal impeller 2 Diffuser 2a Partition wall 3 Scroll 4 Hub 5 Disk 6 Shroud (side plate) 7 Vaneless part 7a, 7b Side wall 8 Guide wall

Claims (3)

[Claims] 1. In a compressor in which a vaneless portion (7) serving as a connection space is arranged between a centrifugal impeller (1) and a non-rotating diffuser (2), the vaneless portion is separated in a rotation axis direction. A vaneless portion of a compressor, characterized in that a guide wall (8) protruding inward is arranged along the direction of the inlet air flow in the diffuser on the inner surface of the side walls (7a, 7b) surrounded by Structure. 2. The structure of a vaneless portion of a compressor according to claim 1, wherein the guide wall (8) is arranged near the tip of the shroud (6) of the centrifugal impeller (1). 3. The structure of a vaneless portion of a compressor according to claim 1, wherein the guide wall (8) is arranged between the partition walls (2a) of the adjacent diffusers (2).