JPH1077997A - Centrifugal compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce pressure loss of gas flowing through a diffuser by forming loci connecting the center of the radii of curvature of circular arc shaped faces formed at corner parts between a blade face and either one or both of the shroud side wall surface and hub side wall surface, into smooth curves extended along the blade face, and making these loci intersect on the upper reaches of the blade. SOLUTION: A diffuser 40 is composed of the shroud side wall surface 41, the hub side wall surface 42 and a plurality of blades 43, and corner parts between the shroud side wall surface 41 and the pressure face 44 and negative pressure face 45 of the blade 43 are formed into circular arc shaped faces 46, 47 respectively with the radii of curvature ρ. Loci 50, 51 connecting the center 48, 49 of the radii of curvature ρ is formed into smooth curves extended along the pressure face 44 and negative pressure face 45 of the blade 43, and the loci 50, 51 intersect at an upstream point 52 of the blade 43 and meet at a downstream point 55. An angle α1 formed by a blade row line and a crest line formed by the intersection point of the circular arc shaped faces 46, 47 upstream of a blade inlet 53 is made smaller toward the shroud side wall surface 41 from the intermediate part of blade height H, so that an incident angle at the blade inlet 53 can be made small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a centrifugal compressor having a winged diffuser.

[0002]

2. Description of the Related Art An example of a conventional centrifugal compressor of this type is shown in FIG. 2, in which (A) is a schematic longitudinal sectional view, (B) is a sectional view taken along line BB of (A), (C) is a partial perspective view of the wing, (D) is (B),
It is sectional drawing which follows the DD line of (C).

[0003] When the rotating shaft 1 is driven, the impeller 2 rotates, and gas is sucked into the impeller 2 and urged to increase the pressure and the velocity energy. The velocity energy of the gas is converted into pressure in the process of flowing through the diffuser 3 and the scroll 4, and the pressure is further increased to be discharged from a discharge port (not shown).

The diffuser 3 includes a disk-shaped shroud side wall surface 31, a hub side wall surface 32 parallel to the shroud side wall surface, and a plurality of blades 33 provided therebetween. These wings 33 are so-called 2
As shown in FIGS. 2 (B), 2 (C), and 2 (D), the cross-sectional shape of the three-dimensional wing is constant over the entire wing height H of the wing 33 and has a wing shape or a wedge shape.

[0005]

SUMMARY OF THE INVENTION Conventional diffuser 3
FIG. 3 shows changes in the inlet angle α _B of the blade 33 and the flow angle α (the angle formed by the fluid stream line with the cascade line) along the blade height H direction. As is apparent from FIG. 3, the inlet angle α _B is constant over the entire blade height, whereas the flow angle α decreases as the distance from the shroud side wall surface 31 approaches and the small area is wide.

Accordingly, the difference between the flow angle α and the blade inlet angle α _B is:
That is, there is a problem that the pressure loss of the gas is large because the region where the incident angle i is large is wide. Diffuser 3
When the gas flow rate flowing through the diffuser decreases, the incident angle i further increases, and there is a possibility that the stall of the diffuser 3 and the surging may be caused.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its gist is to provide a shroud side wall surface, a hub side wall surface, and a plurality of bridges provided therebetween. In a centrifugal compressor provided with a diffuser including the blades, the corner portion of one or both of the shroud side wall surface and the hub side wall surface and the blade surface of the blade is formed into an arcuate surface, and the arcuate surface of the arcuate surface is formed. A centrifugal compressor is characterized in that a locus connecting the centers of curvature radii forms a smooth curve along the blade surface of the blade and intersects upstream of the blade.

Another feature is that the radius of curvature of the arc-shaped surface is 25 to 60% of the blade height of the blade.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention is shown in FIG. 1, wherein (A) is a partial longitudinal sectional view, (B) is a sectional view taken along line BB of (A), and (C) is a sectional view. Partial perspective view of wing, (D) and (E) are (B)
And (C) are sectional views taken along lines DD and EE.

[0010] Shroud side wall surface 41, hub side wall surface 42,
A diffuser 40 is constituted by a plurality of wings 43 provided between them. The wing surface of the wing 43, that is, the pressure surface 44
In addition, corner portions of the suction surface 45 and the shroud side wall surface 41 are arc-shaped surfaces 46 and 47 having a radius of curvature ρ, respectively.

The radius of curvature ρ is 25 to 60% of the blade height H, and 50% in the illustrated case. A locus 50 connecting the center 48 of the radius of curvature ρ and a locus 51 connecting the center 49 of the radius of curvature ρ are smooth curves along the pressure surface 44 and the suction surface 45 of the wing 43, and these trajectories 50 and 51 They cross at an upstream point 52 and are aligned at a downstream point 55. And the wing entrance 53
The intersection of the arc-shaped surfaces 46 and 47 on the upstream side forms a peak line 54.

The angle α ₁ formed by the peak line 54 with the cascade line becomes smaller as it approaches the shroud side wall 41 as shown in FIG. Thus, the flow angle α changes substantially in the same manner as the conventional one, but the angle α ₁ decreases as the blade height H approaches the shroud side wall surface 41 from the middle, so that the flow angle α and the angle α
₁ , ie, the incident angle i ₁ becomes smaller, and the difference between the inlet angle α ₂ at the blade inlet 53 and the flow angle α, ie, the incident angle i ₂ also becomes smaller.

As a result, the pressure loss of the gas flowing through the diffuser 40 is reduced, and the difference between the surge flow rate and the maximum efficiency point flow rate is also increased, so that the area where the centrifugal compressor can be operated with high efficiency is expanded. I do.

In the above embodiment, the wing surface 44 of the wing 43,
Only the corner between 45 and the shroud side wall surface 41 has an arcuate surface 4
6 and 47, the corner portion with the hub side wall surface 42 can be an arcuate surface, and both the shroud side wall surface 41 and the corner portion with the hub side wall surface 42 can be arcuate surfaces. it can.

[0015]

According to the present invention, the corner portion of one or both of the shroud side wall surface and the hub side wall surface and the blade surface of the blade is formed into an arcuate surface, and the center of the radius of curvature of the arcuate surface is connected. Since the trajectory becomes a smooth curve along the blade surface and intersects at the upstream side of the blade, it is possible to reduce the angle of incidence on the blade, thus reducing the pressure loss of gas flowing through the diffuser and Since the difference between the surge flow rate and the flow rate at the highest efficiency point can be increased, the region where the centrifugal compressor operates with high efficiency can be expanded.

The radius of curvature of the arc-shaped surface is set to 25 to 60 of the blade height.
%, The angle of incidence on the wing can be more effectively reduced.

[Brief description of the drawings]

1 shows an embodiment of the present invention, wherein (A) is a partial longitudinal sectional view, (B) is a sectional view taken along line BB of (A), (C) is a partial perspective view of a wing, (D) and (E) are DD lines of (B) and (C), and E-
It is sectional drawing which follows the E line.

FIG. 2 shows a conventional centrifugal compressor, (A) is a schematic vertical sectional view, (B) is a sectional view taken along the line BB of (A), and (C) is a partial perspective view of a blade. (D) is a sectional view taken along line DD of (B) and (C).

FIG. 3 is a diagram showing changes in a blade inlet angle and a flow angle in a conventional centrifugal compressor.

FIG. 4 is a diagram showing changes in an incident angle and a flow angle in the centrifugal compressor of the present invention.

[Explanation of symbols]

 2 Impeller 40 Diffuser 41 Shroud side wall surface 42 Hub side wall surface 43 Blade 44, 45 Blade surface 46, 47 Arc surface ρ Radius of curvature 48, 49 Center of curvature radius 50, 51 Trajectory

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Katsuyuki Shimauchi 1200, Higashi-Tanaka, Oji, Komaki-shi, Aichi Prefecture Mitsubishi Heavy Industries, Ltd. Nagoya Guidance and Propulsion System Works (72) Inventor Hidehiko Itaka 1-1-1, Akunouramachi, Nagasaki-shi In Nagasaki Shipyard, Mitsubishi Heavy Industries, Ltd.

Claims (2)

[Claims] 1. A centrifugal compressor having a diffuser comprising a shroud side wall surface, a hub side wall surface, and a plurality of blades provided therebetween, wherein one or both of the shroud side wall surface and the hub side wall surface are provided. The corners of the wing and the wing surface are arc-shaped surfaces, and the trajectory connecting the centers of the radii of curvature of these arc-shaped surfaces forms a smooth curve along the wing surface of the wing and intersects on the upstream side of the wing. A centrifugal compressor, characterized in that: 2. The centrifugal compressor according to claim 1, wherein the radius of curvature of the arc-shaped surface is 25 to 60% of the blade height of the blade.