JPH08121378A - Centrifugal type compressor - Google Patents

Abstract

PURPOSE: To suppress an energy loss at an impeller outlet and a diffuser and to reduce a loss incurring at a flow rate area lower than a proper flow rate by bringing speed distribution of outflow distribution of outflow gas at an impeller outlet into a proper state. CONSTITUTION: In a centrifugal type compressor comprising an impeller 11 to increase energy of gas through centrifugal operation; and a diffuser 17 situated downstream of the flow of gas from the impeller 11 and consisting of two surfaces positioned facing each other, a gas flow straightening means 19 to straighten the flow of gas is arranged on the wall surface of the impeller 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal compressor that compresses gas by the rotary motion of an impeller.

[0002]

2. Description of the Related Art Generally, a centrifugal compressor cannot avoid a decrease in operating efficiency in a region where the amount of gas flowing into the compressor is smaller than an appropriate flow rate, and when operating in this region, loss of impeller and diffuser is caused. There is a demand for higher efficiency through reduction.

A conventional centrifugal compressor is constructed as shown in FIG. In FIG. 9, an impeller 1 is rotatably attached to a rotating shaft 2 with a nut 3. The gas flowing from the inlet portion 4 flows into the impeller 1 in the direction of arrow A, the gas flowing into the impeller 1 is given energy by the centrifugal action of the impeller 1, and the casing 5 and the side plate in the direction of arrow B. It flows into a diffuser 7 formed from 6. In this diffuser 7, the dynamic pressure component of the gas is converted into a static pressure component, and the gas that has passed through the diffuser 7 is scrolled 8
It flows in and is collected.

[0004]

By the way, in the centrifugal compressor shown in FIG. 9, when the amount of gas flowing into the compressor is less than the proper flow rate, a secondary flow is generated in the impeller 1 and the impeller is generated. Separation of the flow occurs at the 1st outlet, increasing the energy loss. Further, there is a problem that the operating efficiency is lowered due to an increase in energy loss due to the mixing in the diffuser 7 due to the uneven velocity distribution at the outlet of the impeller 1.

The present invention has been made in consideration of the above-mentioned circumstances. By optimizing the velocity distribution of the outflow gas at the outlet of the impeller, the energy loss at the outlet of the impeller and the diffuser is suppressed, and the flow rate is less than the proper flow rate. An object of the present invention is to provide a centrifugal compressor that reduces the loss generated in the flow rate range.

[0006]

In order to solve the above-mentioned problems, the first aspect of the present invention provides an impeller for increasing gas energy by centrifugal action, and a downstream side of the gas flow with respect to the impeller. Further, in the centrifugal compressor having a diffuser formed of two surfaces facing each other, gas rectifying means for rectifying a gas flow is provided on a wall surface of the impeller.

A second aspect of the invention is characterized in that the gas rectifying means according to the first aspect is a riblet formed on the wall surface of the impeller. A third aspect of the invention is characterized in that the gas rectifying means according to the first aspect is a groove formed on the wall surface of the impeller. A fourth aspect of the invention is characterized in that the gas rectifying means according to the first aspect is a protrusion formed on the wall surface of the impeller.

[0008]

In the first aspect of the present invention having the above structure, the gas flow rectifying means for rectifying the gas flow is provided on the wall surface of the impeller to optimize the velocity distribution of the outflow gas at the outlet of the impeller. The generation of secondary flow at the impeller outlet and diffuser and the generation of energy loss can be suppressed, and the loss generated at the impeller and diffuser can be reduced,
Highly efficient and stable operation becomes possible. Here, as the gas rectifying means, it is preferable to form riblets, grooves, or protrusions as in claims 2 to 4.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a first embodiment of a centrifugal compressor according to the present invention. As shown in FIG. 1, the impeller 11 is rotatably attached to a rotary shaft 12 with a nut 13. The gas flowing from the inlet portion 14 flows into the impeller 11 in the direction of the arrow A, and the gas flowing into the impeller 11 is given energy by the centrifugal action of the impeller 11, and the arrow B
And flows into the diffuser 17 which is formed by the two surfaces of the casing 15 and the side plate 16 which face each other. In this diffuser 17, the dynamic pressure component of the gas is converted into a static pressure component, and the gas that has passed through the diffuser 17 is scroll 1
It flows into 8 and is collected.

When the amount of gas flowing into the compressor is smaller than the proper flow rate, the temperature distribution of gas flowing out from the impeller 11 is uneven. When the velocity component of this gas is largely biased, the mixing loss in the diffuser 17 increases.

Therefore, in this embodiment, in order to make the velocity component of the gas flowing out of the impeller 11 uniform, a riblet 19 as a gas rectifying means for rectifying the gas flow is formed on the wall surface of the impeller 11. . That is, the riblets 19 are formed on the wall surface of the impeller 11 along the gas flow direction (direction of arrow A) as shown in FIGS. 1 and 2.

Next, the operation of this embodiment will be described.
As shown in FIG. 1, the direction of the gas flowing into the impeller 11 in the direction of the arrow A is bent 90 degrees in the impeller 11 and flows out in the direction of the arrow B. When the amount of gas flowing into the compressor is less than the proper flow rate, a secondary flow occurs in the flow inside the impeller 11, and the loss increases. Further, the gas flowing out from the impeller 11 has a biased velocity distribution, and the diffuser 1 is rotated at an appropriate angle.
Do not flow into 7. If there is a large deviation in the velocity component of the gas, the mixing loss in the diffuser 17 increases.

Therefore, since the riblets 19 having the function of rectifying the flow of gas are formed on the wall surface of the impeller 11,
Generation of a secondary flow of gas flowing in the impeller 11 can be suppressed. Further, since the radial velocity component of the gas flowing out from the impeller 11 can be made uniform, the mixing loss generated in the diffuser 17 can be reduced.

FIG. 3 is a sectional view showing a second embodiment of the centrifugal compressor according to the present invention. The same parts as those in the first embodiment will be described with the same reference numerals. The same applies to the following embodiments. As shown in FIG. 3, in this embodiment, a groove 20 as a gas rectifying means is formed on the wall surface of the impeller 11 along the gas flow direction (direction of arrow A). As shown in FIG. 4, a plurality of grooves 20 are formed on the wall surface of the impeller 11. In this embodiment, the same effect as that of the first embodiment can be obtained. Other configurations and operations are the same as those of the first aspect.
The description is omitted because it is the same as the embodiment.

5 to 7 show a third embodiment of the centrifugal compressor according to the present invention. As shown in FIGS. 5 to 7, in this embodiment, a plurality of projections 21 as gas rectifying means are formed on the wall surface of the impeller 11 along the gas flow direction (direction of arrow A). These protrusions 21 are formed in a semicircular cross section. In this embodiment, the same effect as that of the first embodiment can be obtained. The rest of the configuration and operation are the same as in the first embodiment, so a description thereof will be omitted.

FIG. 8 is a cross-sectional view of essential parts showing a modification of the third embodiment of the centrifugal compressor according to the present invention. In this modified example, a plurality of protrusions 22 having a triangular cross-section as gas rectifying means are formed on the wall surface of the impeller 11 along the gas flow direction. In this modification, the same effect as that of the third embodiment can be obtained.

As the gas rectifying means, the riblets 19 are formed on the wall surface of the impeller 11 in the first embodiment, the grooves 20 in the second embodiment, and the projections 21 in the third embodiment. The cross-sectional shape, the wall height, the depth (in the case of the groove 20), the length, the number, and the pitch thereof are not limited to those in the above-described embodiments as long as they are provided.

[0018]

As described above, according to the first aspect of the present invention.
According to this, by providing the gas rectifying means for rectifying the gas flow on the wall surface of the impeller, it is possible to reduce the loss generated in the impeller and the diffuser, and as a result, it is possible to perform highly efficient and stable operation. A centrifugal compressor can be provided. Further, according to claims 2 to 4, the same effect as that of claim 1 can be obtained by forming the riblets, the grooves or the protrusions as the gas rectifying means.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a centrifugal compressor according to the present invention.

FIG. 2 is a view on arrow in the X direction in FIG.

FIG. 3 is a sectional view showing a second embodiment of the centrifugal compressor according to the present invention.

FIG. 4 is a cross-sectional view of a main part of FIG.

FIG. 5 is a sectional view showing a third embodiment of the centrifugal compressor according to the present invention.

FIG. 6 is a view in the direction of the arrow Y in FIG.

7 is a cross-sectional view of the main parts of FIG.

FIG. 8 is a sectional view of a main part showing a modified example of the third embodiment.

FIG. 9 is a sectional view showing a conventional centrifugal compressor.

[Explanation of symbols]

 Reference Signs List 11 impeller 12 rotating shaft 13 nut 14 inlet 15 casing 16 side plate 17 diffuser 18 scroll 19 riblet (gas rectifying means) 20 groove (gas rectifying means) 21 protrusion (gas rectifying means) 22 protrusion (gas rectifying means)

Claims (4)

[Claims] 1. A centrifugal compressor provided with an impeller for increasing gas energy by centrifugal action, and a diffuser formed by two surfaces facing each other on the downstream side of the gas flow with respect to the impeller. In the centrifugal compressor, a gas rectifying means for rectifying a gas flow is provided on a wall surface of the impeller. 2. The centrifugal compressor according to claim 1, wherein the gas rectifying means is a riblet formed on a wall surface of the impeller. 3. The centrifugal compressor according to claim 1, wherein the gas rectifying means is a groove formed on the wall surface of the impeller. 4. The centrifugal compressor according to claim 1, wherein the gas rectifying means is a protrusion formed on the wall surface of the impeller.