JP2004027932A - Centrifugal compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a centrifugal compressor capable of improving efficiency of a diffuser and enlarging an operational range. <P>SOLUTION: In a centrifugal compressor provided with a diffuser 4 composed of a shroud side wall surface 41, a hub side wall surface 42 and a plurality of blades 43 constructed therebetween, inlet angles of the blades 43 are different between a shroud side and a hub side, and the inlet angle α<SB>is</SB>of the shroud side is smaller than the inlet angle α<SB>ih</SB>of the hub side by 5-25 °. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a centrifugal compressor used for a supercharger, a gas turbine, an industrial compressor and the like, and more particularly, to a centrifugal compressor having a bladed diffuser.
[0002]
[Prior art]
An example of a conventional centrifugal compressor of this type is shown in FIG. 6, wherein FIG. 6A is a schematic longitudinal sectional view, FIG. 6B is a sectional view taken along the line BB of FIG. (C) is a partial perspective view of the wing, and (d) is a cross-sectional view taken along the line DD in FIGS. (B) and (c).
[0003]
When the rotating shaft 1 is driven, the impeller 2 rotates, and the gas is sucked into the impeller 2 and energized, so that the pressure and velocity energy increase. The velocity energy of the gas is converted into pressure in the process of flowing through the diffuser 3 and the scroll 4 and is further increased in pressure to be discharged from a discharge port (not shown).
[0004]
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 two-dimensional wings, and their cross-sectional shapes are constant over the entire wing height H of the wing 33 as shown in FIGS. 6 (b), (c) and (d). It is shaped or wedge-shaped.
[0005]
[Problems to be solved by the invention]
FIG. 7 shows changes in the inlet angle α _B of the blade 33 and the flow angle α (the angle between the fluid stream line and the blade row line) along the blade height H direction in the conventional diffuser 3. As is clear from FIG. 7, the inlet angle α _B is constant over the entire blade height H, whereas the flow angle α decreases as the distance from the shroud side wall surface 31 increases and the small area increases.
[0006]
Thus, the difference between the flow angle alpha and the wing inlet angle alpha _B, i.e., because the region of incidence angle i is greater wide by peeling at the inlet of the collision loss and the leading edge, the efficiency is lowered. Further, when the flow rate of the gas flowing through the diffuser 3 decreases, the incident angle i further increases, and there is a possibility that the stall of the diffuser 3 and surging may be caused, and there is a problem that the operating range is also reduced.
[0007]
As a countermeasure for this, a pipe diffuser or the like is used, but it has disadvantages such as a high manufacturing cost, and a simple countermeasure is required. In view of this, the present applicant has proposed a diffuser which can be easily manufactured in Japanese Patent Application No. 8-250895, but the present invention newly proposes a different means.
[0008]
The present invention has been proposed in view of such circumstances, and an object of the present invention is to provide a centrifugal compressor capable of increasing the efficiency of a diffuser and expanding the operating range.
[0009]
[Means for Solving the Problems]
A centrifugal compressor according to the present invention for achieving such an object is a centrifugal compressor including a diffuser including a shroud side wall surface, a hub side wall surface, and a plurality of blades provided therebetween.
The inlet angle of the blade is different between the shroud side and the hub side.
[0010]
Further, the inlet angle on the shroud side is smaller than the inlet angle on the hub side by 5 to 25 °.
[0011]
The chord length on the shroud side is longer than the chord length on the hub side.
[0012]
The chord length on the shroud side is 1.1 to 1.4 times the chord length on the hub side.
[0013]
Further, the inlet angle is different only on the shroud side exceeding 40% of the blade height.
[0014]
Further, the two-dimensional blades having different inlet angles are combined in a blade height direction.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a centrifugal compressor according to the present invention will be described in detail using embodiments with reference to the drawings.
[0016]
[First embodiment]
1A and 1B show a first embodiment of the present invention, in which FIG. 1A is a sectional view of a diffuser portion of a centrifugal compressor, and FIG. 1B is a view taken in the direction of arrows CC in FIG. FIG. 2 is an illustration of different wing shapes.
[0017]
As shown in FIG. 1, a diffuser 4 is provided at a gas outlet portion of the impeller 2, and the diffuser 4 includes a shroud side wall surface 41, a hub side wall surface 42, and a plurality of blades 43 provided between these. It is constituted by.
[0018]
The inlet angle of the blade 43 is different between the shroud side and the hub side. In the illustrated example, the inlet angle α _is on the shroud side _is set to be smaller than the inlet angle α _ih on the hub side by 5 to 25 ° (α _ih −α _is = 5 to 25 °).
[0019]
Further, the chord length on the shroud side is set longer than the chord length on the hub side. In the illustrated example, the chord length of the shroud side _(R o _{-R is)} is set to 1.1 to 1.4 times the chord length of the hub side _{(R o -R ih) (R} o - _{R is / R o -R ih =} 1.1~1.4).
[0020]
The shape of the wing 43 in a side view is appropriately selected from the shapes shown in FIGS. 2A, 2B, 2C, and 2D.
[0021]
With this configuration, the impeller 2 rotates, and gas is sucked into the impeller 2 and urged to increase the pressure and velocity energy. In the process of flowing through the diffuser 4, the velocity energy of the gas is converted into pressure, and the pressure is further increased to be discharged from a discharge port (not shown).
[0022]
At this time, in the present embodiment, in the blade 43 of the diffuser 4, the inlet angle αis on the shroud side _is set to be smaller than the inlet angle _αih on the hub side by 5 to 25 °, so as shown in FIG. By reducing the deviation between the flow of the impeller outlet flowing into the diffuser 4 and the diffuser inlet angle, it is possible to suppress the collision loss at the inlet and the separation at the leading edge, thereby increasing the efficiency of the diffuser 4 and expanding the operating range. .
[0023]
Further, since the chord length of the shroud side _(R o _{-R is)} is set to 1.1 to 1.4 times the chord length of the hub side _(R o _{-R ih),} turning the wings 43 The blade strength on the shroud side with a large angle can be sufficiently provided.
[0024]
[Second embodiment]
FIG. 3 is a cross-sectional view of a diffuser portion showing a second embodiment of the present invention.
[0025]
This is because the inlet angle of the shroud side exceeding 40% of the blade height b of the blade 43 in the first embodiment is different from that of the first embodiment in the same manner as in the first embodiment, and the angle is constant at 40% or less (the range of the mesh in the figure). This is an example in which a two-dimensional wing is formed.
[0026]
According to this, as shown in FIG. 5, the difference between the flow of the impeller outlet flowing into the diffuser 4 and the diffuser inlet angle can be reduced to suppress the collision loss at the inlet and the separation at the leading edge, and the diffuser 4 has an advantage that the blade shape can be changed to the minimum necessary while improving the efficiency and expanding the operation range.
[0027]
[Third embodiment]
FIG. 4 is a cross-sectional view of a diffuser section showing a third embodiment of the present invention.
[0028]
This is an example in which the blades 43 in the first embodiment are combined (butted) with the two-dimensional blades 43a and 43b having different entrance angles in the blade height direction. Although the two-dimensional blades 43a and 43b have different chord lengths in the illustrated example, the two-dimensional blades 43b on the shroud side may have the same chord length.
[0029]
According to this, as shown in FIG. 5, the difference between the flow of the impeller outlet flowing into the diffuser 4 and the diffuser inlet angle can be reduced to suppress the collision loss at the inlet and the separation at the leading edge, and the diffuser 4 has an advantage that the two-dimensional blades 43a and 43b can be easily manufactured while improving the efficiency and expanding the operation range.
[0030]
It is needless to say that the present invention is not limited to the above embodiment, and various changes can be made without departing from the spirit of the present invention.
[0031]
【The invention's effect】
As described above in detail based on the embodiments, the invention according to claim 1 of the present invention includes a diffuser including a shroud side wall surface, a hub side wall surface, and a plurality of blades provided therebetween. In the centrifugal compressor, since the inlet angle of the blade is different between the shroud side and the hub side, it is possible to reduce the deviation between the flow of the impeller outlet flowing into the diffuser and the diffuser inlet angle, thereby increasing the efficiency of the diffuser. The working range can be expanded.
[0032]
According to the second aspect of the invention, since the inlet angle on the shroud side is smaller by 5 to 25 degrees than the inlet angle on the hub side, the same operation and effect as those of the first aspect can be obtained.
[0033]
In the invention according to claim 3, since the chord length on the shroud side is longer than the chord length on the hub side, the blade strength on the shroud side where the turning angle of the blade is large can be sufficiently provided.
[0034]
In the invention according to claim 4, the chord length on the shroud side is 1.1 to 1.4 times the chord length on the hub side, so that the same operation and effect as in claim 3 can be obtained.
[0035]
In the invention according to claim 5, since the inlet angle is made different only on the shroud side exceeding 40% of the blade height, the blade shape can be changed to the minimum necessary.
[0036]
In the invention according to claim 6, since the two-dimensional blades having different entrance angles are combined in the blade height direction, manufacture is easy.
[Brief description of the drawings]
FIG.
1A and 1B show a first embodiment of the present invention, in which FIG. 1A is a cross-sectional view of a diffuser portion of a centrifugal compressor, and FIG. 1B is a view taken along the line CC in FIG. 1A.
FIG. 2 is an illustration of different wing shapes.
FIG. 3 is a cross-sectional view of a diffuser unit according to a second embodiment of the present invention.
FIG. 4 is a cross-sectional view of a diffuser section showing a third embodiment of the present invention.
FIG. 5 is a diagram showing changes in a blade inlet angle and a flow angle in the centrifugal compressor of the present invention.
6 (a) is a schematic longitudinal sectional view, FIG. 6 (b) is a sectional view taken along the line BB of FIG. 6 (a), and FIG. FIG. 2D is a partial perspective view of the wing, and FIG. 2D is a cross-sectional view taken along line DD of FIGS. 1B and 1C.
FIG. 7 is a diagram showing changes in a blade inlet angle and a flow angle in a conventional centrifugal compressor.
[Explanation of symbols]
1 impeller 4 diffuser 41 the shroud side wall surface 42 of the hub-side wall surface 43 blade alpha inlet angle of the _is the shroud side of the inlet angle alpha _ih hub side _R o _-R chord length of the _is the shroud side _R o _{-R ih} hub-side blade chord Long

Claims (6)

In a centrifugal compressor including a diffuser including a shroud side wall surface, a hub side wall surface, and a plurality of blades spanned therebetween,
A centrifugal compressor, wherein an inlet angle of the blade is different between a shroud side and a hub side. The centrifugal compressor according to claim 1, wherein the inlet angle on the shroud side is smaller than the inlet angle on the hub side by 5 to 25 °. 3. The centrifugal compressor according to claim 1, wherein a chord length on the shroud side is longer than a chord length on the hub side. The centrifugal compressor according to claim 3, wherein the chord length on the shroud side is 1.1 to 1.4 times the chord length on the hub side. The centrifugal compressor according to claim 1, 2, 3, or 4, wherein the inlet angle is different only on the shroud side exceeding 40% of the blade height. 6. The centrifugal compressor according to claim 1, wherein the two-dimensional blades having different inlet angles are combined in a blade height direction.

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