JPH06137167A - Axial flow fluid machine - Google Patents

Abstract

PURPOSE:To provide an axial flow fluid machine which can be actuated in a flow region of wide range containing a low flow region without decreasing maximum efficiency and partial load efficiency. CONSTITUTION:For instance, in an axial flow compressor having moving blades 3 set up onto the periphery of a hub 2 integrally rotated with a rotary shaft 1, stationary blades 5 set up onto the internal periphery of a casing 4 and an annular flow path 6 constituted between the casing 4 and the hub 2, fluid (B) at a speed higher than fluid (A) 7, flowing in the annular path 6, is jetted toward on a blade surface in a point end part of the moving blade 3 from a jet port 8 via a pressure pipe 10 and an introducing pipe 9 by the compressor 11 when the rotary shaft 1 is rotated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial flow fluid machine, and more particularly to an axial flow compressor and an axial flow blower.

[0002]

2. Description of the Related Art Axial-flow fluid machines have conventionally been required to have a wide range of flow rates, which are highly efficient and can stably operate without causing surging or rotating stall. That is, when surging or turning stall occurs,
Since the flow rate and pressure drop sharply and the original function is lost,
It is necessary to avoid surging and turning stall as much as possible.

When surging or turning stall occurs,
Normally, the method of avoiding damage caused by opening the blow-off valve or the bleeding valve is adopted, but this is a countermeasure for an emergency, and it suppresses the occurrence of surging and turning stall in advance. It is important to suppress the occurrence of surging and turning stall without increasing the maximum efficiency and the partial load efficiency, and to expand the flow rate range in which stable operation is possible.

As a countermeasure, conventionally, a method of varying the angles of the stationary blades and the moving blades and controlling the blade angles according to the change in the flow rate has been widely adopted. However, even if this method is used, there is a limit in expanding the flow rate range in which stable operation is possible without lowering efficiency.

Therefore, conventionally, there has been disclosed a method of expanding the flow rate range in which the blade angle can be made variable and further stable operation is possible. For example, these methods are disclosed in Japanese Utility Model Publication No. 57-95500. There is a casing treatment disclosed in the publication, and an air separator disclosed in JP-A-59-213995. Further, Japanese Patent Publication No. 39-19338 discloses a method in which a slit is provided on the blade surface and a fluid is jetted or sucked from the slit.

[0006]

However, in the above-mentioned prior art, since they act in any part of the entire flow rate range, they may have an adverse effect depending on the flow rate range. For example, in the flow rate region of the highest efficiency point, there is a problem that the highest efficiency is decreased. In addition, there is a problem that the action may reach a portion where the boundary layer separation of the moving blade does not occur, and in this case as well, there is a problem that the partial load efficiency is reduced.

An object of the present invention is to provide an axial flow fluid machine which can be stably operated over a wide range of flow rate without reducing the maximum efficiency and the partial load efficiency.

[0008]

The above object can be achieved as follows.

(1) In an axial flow fluid machine having an annular flow path formed between a casing and a hub, and a rotating shaft having rotor blades attached to the outer peripheral portion of the hub, the annular flow is generated when the rotating shaft rotates. An ejection hole for ejecting the fluid (B) at a higher speed than the fluid (A) is provided upstream of the leading edge of the moving blade in the fluid (A) generated in the passage.

(2) It has an annular flow path formed between the casing and the hub, a stationary blade attached to the inner peripheral portion of the casing, and a rotating shaft having a moving blade attached to the outer peripheral portion of the hub. In an axial fluid machine, the fluid (A) is generated upstream of the leading edge of the vane in the fluid (A) generated in the annular flow passage when the rotating shaft rotates.
Providing ejection holes through which higher-speed fluid (B) is ejected. (3) In (1), the ejection hole is provided toward at least one of the tip portion and the root portion of the moving blade.

(4) In (2), the ejection holes are provided toward at least one of the tip end portion or the root portion of the stationary blade.

(5) In (1) or (2), the jet hole is directed to the downstream side of the fluid (A) in any direction, and the inner peripheral surface of the casing or the outer peripheral surface of the hub is selected. It should be provided on the axial cross section of at least one of the rotating shafts.

(6) In (1) or (2), the ejection hole is provided on the downstream side of the fluid (A) in the longitudinal direction of at least one of the inner peripheral surface of the casing and the outer peripheral surface of the hub. Provide parallel to the axis of rotation of the rotating shaft.

(7) In (1) or (2), the ejection holes are provided in parallel with the direction of the axis center line of the rotary shaft.

(8) In (1) or (2), the jet holes are provided so as to be inclined with respect to the axial center line of the rotary shaft toward the rotating direction side of the moving blade or toward the reverse rotating direction side of the moving blade.

(9) In (1) or (2), the fluid
Provide a compressor that supplies (B). (10) In (1) or (2), the axial flow fluid machine is a multi-stage axial flow fluid machine, and the high-pressure working fluid inside the multi-stage axial flow fluid machine is used as a supply source of the fluid (B).

(11) In any one of (1) to (10), the axial fluid machine is an axial compressor or an axial blower.

[0018]

The object of the present invention can be basically achieved if the separation of the boundary layer of the moving blade can be effectively prevented. Therefore,
First, the basic function of preventing separation of the boundary layer of the moving blade in the present invention will be described using an axial flow compressor as an example.

FIG. 5 is an explanatory diagram regarding the blade row and the speed triangle of the axial compressor. FIG. 5 (a) shows two adjoining blades of the blade row of the axial compressor, and here, of these two blades, the upper blade is the object of study. There is. Further, FIG. 5B shows a speed triangle.

In FIG. 5A, 23a and 23b
Shows the flow velocity distribution on the rotor blade 3, of which 23a
Indicates that the boundary layer of the moving blade 3 is not separated, and 23b indicates that the boundary layer of the moving blade 3 is separated. Reference numerals 24a and 24b indicate the outer edges of the boundary layer. Of these, 24a indicates that the boundary layer of the moving blade 3 has not separated, and 24b indicates that the boundary layer of the moving blade 3 has separated. It represents. On the other hand, in the velocity triangle of FIG. 5B, Ca, W, V and β are the axial velocity, the relative velocity, the absolute velocity and the relative inflow angle when the boundary layer of the rotor blade 3 is not separated, Ca ′, W ′, V ′ and β ′ respectively indicate the axial flow velocity, the relative velocity, the absolute velocity and the velocity inflow angle when the boundary layer of the moving blade 3 is separated.
Here, the relative inflow angles β and β ′ are the angles formed by the line connecting the leading edges of the moving blades 3 and the flow direction of the fluid flowing into the moving blades 3, that is, the directions of the axial flow velocities Ca and Ca ′, respectively. Is.

When separation does not occur in the moving blade 3, the relationship between the axial flow velocity Ca, the relative velocity W, the absolute velocity V and the relative inflow angle β is represented by the velocity triangle shown by the solid line in FIG. 5 (b). expressed. In this case, the flow of the fluid on the rotor blade 3 is in the same direction as shown by the flow velocity distribution 23a in FIG. 5 (a), and as can be seen from the outer edge 24a of the boundary layer, the boundary layer is Not peeled off.

However, when the axial flow velocity Ca is decreased, the relative inflow angle β increases and the relative inflow angle β increases.
When a certain angle is reached, the boundary layer on the moving blade 3 separates.

The velocity triangle at the time of separation of the boundary layer is shown by a broken line in FIG. 5 (b). As is clear from this figure, in this case, the axial flow velocity becomes small like the axial flow velocity Ca ′, and the relative inflow angle becomes large like the relative inflow angle β ′ accordingly.

That is, if the axial flow velocity Ca ′ at the time of separation can be changed to a large axial flow velocity from the relative relationship indicated by the velocity triangle, the relative inflow angle β ′ at the time of separation can be accompanied by this.
Can be changed to a small relative inflow angle. Then, if the relative inflow angle β ′ at the time of separation can reach the relative inflow angle β at the time when no separation occurs, the separation of the boundary layer does not occur.

In the present invention, in the low flow rate region where the boundary layer on the rotor blade 3 is easily separated, the fluid (B) which is faster than the fluid (A) generated in the annular flow passage when the axial flow compressor rotates. By ejecting the boundary layer toward a location where the boundary layer easily separates, the angle of the relative inflow angle β ′ when the separation occurs can be reduced, so that the boundary layer can be prevented from separating and the surging can be performed. Alternatively, the occurrence of at least one of the turning stall can be suppressed. The influence range of fluid (B) is
It is limited to the range of the size of the jet of fluid (B),
Furthermore, since the maximum efficiency and the partial load efficiency are obtained regardless of the low flow rate range, the stable operation range of the axial flow compressor is expanded to the low flow rate range without reducing the maximum efficiency and the partial load efficiency. can do.

Such jetting of the fluid (B) occurs when the jet holes are located upstream of the moving blades, but even when the jet holes are located upstream of the stator blades, Since the separation of the boundary layer can be prevented, the separation of the boundary layer of the moving blade caused by the turbulence of the flow of the fluid (A) due to the separation of the boundary layer of the stationary blade can be prevented. Further, since it is possible to suppress the generation of at least one of the surging and the rotating stall, it is possible to obtain the same effect as in the case where the ejection hole is located on the upstream side of the moving blade.

The location of the jet holes and the direction of the jet holes differ depending on the location where boundary layer separation is likely to occur in the moving blade and the flow direction of the fluid (A). Since it is provided so as to be most effective in preventing peeling, the boundary layer can be efficiently prevented from peeling.

When the fluid (B) is generated by a separate compressor, the flow velocity of the fluid (B) can be adjusted by the flow rate adjusting valve, so that the fluid at the flow velocity most effective for preventing separation of the boundary layer is used.
Further, (B) can be ejected, and high pressure in the latter stage of the multi-stage axial compressor can be used. In this case, therefore, the cost required for installing the compressor separately installed can be saved.

As described above, the operation of the axial flow fluid machine has been described by using the axial flow compressor as an example. However, since the axial flow compressor and the axial flow blower are in principle the same mechanism, The action of the flow compressor can be directly applied to the axial blower.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the drawings. 1A and 1B are explanatory views of the main part of the axial compressor of the first embodiment, FIG. 1A is a vertical cross-sectional view of the main part, and FIG. 1B is FIG. 1A. FIG.

A large number of moving blades 3 are arranged on the outer peripheral surface of the hub 2 which rotates integrally with the rotating shaft 1, and a large number of stationary blades 5 are arranged on the inner peripheral surface of the casing 4.

The annular flow path 6 formed between the casing 4 and the hub 2 has a fluid (A) 7 when the axial compressor is rotated.
Is generated, the introduction pipe 9 is attached through the casing 4 at a position corresponding to the upstream side of the leading edge of the moving blade 3 in the flow of the fluid (A) 7, and the fluid (B) 13 is ejected. Hole 8
Are provided so as to be parallel to the flow direction of the fluid (A) 7 and at the same radial position of the rotating shaft 1 as the tip of the moving blade 3. Further, the fluid (B) 13 is generated by the compressor 11.

That is, the fluid generated by the compressor 11
The flow rate of (B) 13 is adjusted by the pressure adjusting valve 12, is ejected from the ejection hole 8 via the pressure pipe 10 and the introduction pipe 9, and passes over the blade surface at the tip of the moving blade 3.

In this case, since the fluid (B) 13 is faster than the fluid (A) 7, the moving blade 3 through which the fluid (B) 13 passes.
The relative inflow angle on the blade surface at the tip of is smaller than in the case of the fluid (A) 7, and the boundary layer separation does not occur on the moving blade 3 through which the fluid (B) 13 passes.

That is, the boundary layer is liable to be separated in the moving blade 3 on the blade surfaces of the tip and the root, but in this embodiment, the boundary layer is prevented from being separated. By preventing this peeling, it is possible to suppress the occurrence of at least one of surging and turning stall.

Further, the fluid (B) 13 is ejected from the ejection hole 8 only in the low flow rate region where at least one of surging or stall is likely to occur, and the fluid (B) 13 is also ejected. Affects only the range of the size of the ejection hole 8.

Further, since the maximum efficiency and the partial load efficiency are efficiencies not related to the low flow rate region, it is necessary to expand the stable working flow rate region of the axial flow compressor without lowering the maximum efficiency and the partial load efficiency. Became possible.

A second embodiment of the present invention will be described with reference to the drawings. 2A and 2B are explanatory views of the main part of the axial flow compressor of the second embodiment, FIG. 2A is a vertical cross-sectional view of the main part, and FIG. 2B is FIG. 2A. FIG. 6 is a development view in the circumferential direction of the BB cross section of FIG. Further, the reference numerals in FIG. 2 that are the same as those in FIG. 1 have the same functions as those.

In this embodiment, the jet holes 8 are provided at the root of the vane 5.
And is connected to the pressure pipe 10 via the introduction pipe 9. The outlet of the ejection hole 8 is at the trailing edge of the stationary blade 5, and the direction of the fluid (B) 13 ejected from the ejection hole 8 is the same as the direction of the fluid (A) 7 flowing into the moving blade 3. There is.

That is, even when the ejection holes 8 are located on the upstream side of the stationary blade 5, the boundary layer separation of the stationary blade 5 is prevented, and the boundary layer separation of the moving blade 3 caused by the disturbance due to the separation is prevented. Therefore, it is possible to obtain the same effect as in the case of the moving blade 3 described above.

Further, in this embodiment, since the fluid (B) 13 is jetted from the trailing edge of the stationary blade 5, the aerodynamic resistance of the stationary blade is reduced, and the effect of increasing the adiabatic efficiency per stage can be obtained.

In FIG. 2B, the direction of the stationary blade 5 is the moving blade 3
However, even if the directions of the stationary blade 5 and the moving blade 3 are the same, the direction of the stationary blade 5 can be changed by opening the ejection holes 8 at the trailing edge of the stationary blade 5. It is possible to obtain the same effect as in the case where the direction is opposite to that of 3.

A third embodiment of the present invention will be described with reference to the drawings. FIG. 3 is an explanatory diagram of a main part of the multi-stage axial compressor of the present invention. Reference numerals in the figure that are the same as those in FIGS. 1 and 2 have functions equivalent to those.

The hub 2 is provided with a hub-side suction hole 15 on the rear side of the compressor and a hub-side ejection hole 17 on the front side thereof. The hub-side suction hole 15 and the hub-side ejection hole 17 are separated from each other. ,
Communication is made by a hub side communication pressure pipe 16. Also,
Reference numeral 14 is a moving blade on the rear stage side, and 18 is a stationary blade on the rear stage side.

On the other hand, at the position on the upstream side of the moving blade 3, the ejection hole 8 is formed on the axial section of the rotary shaft 1 so as to face the downstream side and be inclined in the direction of the rotary shaft 1. Yes, spout hole 8
Communicates with the compressor 11 via the introduction pipe 9 and the pressure pipe 10. A large number of ejection holes 8 are formed on the circumference of the casing 4.

In the case of this embodiment, the operation of ejecting the fluid (B) 13 at a higher speed than the fluid (A) 7 to prevent the boundary layer on the rotor blade 3 from separating is the same as in the first and second embodiments. The same as in each case of the embodiment, but since the ejection holes 8 are obtained by boring the casing 4, it is effective in reducing the number of parts.

Further, on the hub 2 side, the working fluid in the annular flow passage 6 of the rear stage is sucked from the hub side suction hole 15 by utilizing the pressure difference between the rear stage and the front stage, and is ejected from the hub side ejection hole 17. Since this working fluid is high speed,
The same effects as in the case of jetting the fluid (B) 13 in the embodiment and the second embodiment are obtained, and there is an advantage that the compressor 11 need not be installed.

A fourth embodiment of the present invention will be described with reference to the drawings. 4A and 4B are explanatory views of a main part of the axial flow compressor of the present invention, FIG. 4A is a vertical cross-sectional view of the main part, and FIG. 4B is a C of FIG. 4A. FIG. Further, the same reference numerals as those in FIG. 1 in these figures have the same functions as those.

The casing 4 on the upstream side of the rotor blade 3 has a ring-shaped ejection hole 19 having a slit 20. The ring-shaped ejection holes 19 are provided for several ring-shaped ejection holes arranged in the circumferential direction. It communicates with the compressor 11 via the pipe 21, the ring-shaped ejection hole pressure branch pipe 22 and the pressure pipe 10.

In this embodiment, the fluid (B) 13 generated by the compressor 11 is branched by the pressure branch pipe 22 for the ring-shaped ejection hole through the pressure pipe 10 and the branch pipe 21 for the ring-shaped ejection hole. It is ejected from the slit 20 in parallel with the axial center line direction of the rotary shaft 1.

The effect of ejecting the fluid (B) 13 from the slit 20 is basically the same as that of the first to third embodiments, but the ring-shaped ejection hole 19 having the slit 20 is used. Therefore, uniform ejection of the fluid (B) 13 is realized in the circumferential direction, and compared with the case where the ejection of the fluid (B) 13 has a distribution in the circumferential direction as in the first to third embodiments. Therefore, the boundary layer on the moving blade 3 can be more reliably prevented from peeling off, and the effect of preventing the occurrence of surging and turning stall can be further enhanced. Further, there are advantages that the number of parts is small and that adjustment of the ejection direction is unnecessary. Each of the above-described embodiments of the axial compressor can be applied to the axial blower as it is, and the same effect as that of the axial compressor can be obtained.

[0052]

According to the present invention, boundary layer separation on a moving blade is prevented, and stable operation is possible over a wide range of flow rates including a low flow rate range without lowering the maximum efficiency and the partial load efficiency. An axial fluid machine can be provided.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an axial flow compressor according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an axial flow compressor according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of an axial flow compressor according to a third embodiment of the present invention.

FIG. 4 is an explanatory diagram of an axial flow compressor according to a fourth embodiment of the present invention.

FIG. 5 is an explanatory diagram of blade rows and velocity triangles.

[Explanation of symbols]

1 ... Rotation axis, 2 ... Hub, 3 ... Moving blade, 4 ... Casing, 5
... Static vanes, 6 ... annular flow path, 7 ... fluid (A), 8 ... jet holes, 9
... Introduction pipe, 10 ... Pressure pipe, 11 ... Compressor, 12 ... Pressure adjusting valve, 13 ... Fluid (B), 14 ... Last stage moving blade, 1
5 ... Hub side suction hole, 16 ... Hub side communication pressure pipe, 17 ...
Hub-side ejection hole, 18 ... Last stage stationary vane, 19 ... Ring-shaped ejection hole, 20 ... Slit, 21 ... Ring-shaped ejection hole introducing pipe,
22 ... Ring branch pressure branch pipe, 23a ... Velocity distribution when boundary layer is not separated, 23b ... Velocity distribution when boundary layer is separated, 24a ... Boundary layer when boundary layer is not separated Outer edge, 24b ... Outer edge of the boundary layer when the boundary layer is peeled off. Ca ... Axial flow velocity, W ... Relative velocity, V ... Absolute velocity, β ... Relative inflow angle (when the boundary layer is not separated). Ca '... axial flow velocity, W' ... relative velocity, V '
… Absolute velocity, β '… Relative inflow angle (in both cases when the boundary layer is separated).

Claims (11)

[Claims] 1. An axial flow fluid machine having an annular flow path formed between a casing and a hub, and a rotary shaft having rotor blades attached to an outer peripheral portion of the hub, wherein the rotary shaft rotates when the rotary shaft rotates. An axial flow characterized in that a jet hole for jetting a fluid (B) at a higher speed than the fluid (A) is provided upstream of the leading edge of the moving blade in the fluid (A) generated in the annular flow path. Fluid machinery. 2. An annular flow path formed between a casing and a hub, a stationary blade attached to an inner peripheral portion of the casing, and a rotary shaft having a moving blade attached to an outer peripheral portion of the hub. In the axial fluid machine having the above, the fluid (B) having a higher speed than the fluid (A) is jetted to the upstream side of the leading edge of the vane in the fluid (A) generated in the annular flow passage when the rotary shaft rotates. An axial flow fluid machine characterized in that it is provided with a jetting hole. 3. The axial fluid machine according to claim 1, wherein the jet holes are provided toward at least one of a tip portion and a root portion of the moving blade. 4. The axial fluid machine according to claim 2, wherein the jet holes are provided toward at least one of a tip portion and a root portion of the vane. 5. The rotary shaft of at least one of the inner peripheral surface of the casing or the outer peripheral surface of the hub, with the ejection hole directed toward the downstream side of the fluid (A) in an arbitrary direction. The axial flow fluid machine according to claim 1 or 2, wherein the axial flow fluid machine is provided on the axial section. 6. The rotation is performed by directing the ejection hole to a downstream side of the fluid (A) in parallel with a longitudinal direction of at least one of an inner peripheral surface of the casing and an outer peripheral surface of the hub. The axial flow fluid machine according to claim 1 or 2, wherein the axial flow fluid machine is provided on an axial section of the shaft. 7. The axial flow fluid machine according to claim 1, wherein the jet holes are provided in parallel with a direction of an axial center line of the rotary shaft. 8. The jet hole according to claim 1, wherein the jet hole is provided so as to be inclined with respect to an axial center line of the rotary shaft toward a rotation direction side of the moving blade or a reverse rotation direction side of the moving blade. Axial fluid machinery. 9. The axial fluid machine according to claim 1, further comprising a compressor for supplying the fluid (B). 10. The high-pressure working fluid inside the multi-stage axial fluid machine is used as the supply source of the fluid (B), wherein the axial fluid machine is a multi-stage axial fluid machine. The described axial flow fluid machine. 11. The axial flow fluid machine according to claim 1, wherein the axial flow fluid machine is an axial flow compressor or an axial flow blower.