JPH06257597A - Cascade structure of axial compressor - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a cascade structure of an axial flow compressor, which achieves high flow rate and high efficiency of the compressor. A blade of an axial compressor 5 in which a plurality of blades 3 are arranged at predetermined intervals along the circumferential direction between an inner flow passage wall 2 and an outer flow passage wall 1 which are annularly arranged. In the column structure,
On the inner flow passage wall 2, a recess 1 for expanding the flow passage cross-sectional area by being located at the throat portion 9 where the flow passage cross-sectional area between the three rows of blades is minimized.
1 is formed, and a smooth convex portion 12 that is positioned on the downstream side of the concave portion 11 and that suppresses deceleration of the fluid flowing through the blade back side root portion 7 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vane structure of a stationary blade or a moving blade of an axial compressor used in a jet engine or the like, and particularly to an axial compressor having a high flow rate and high efficiency. Related to the cascade structure.

[0002]

2. Description of the Related Art An outline of an axial flow compressor is shown in FIG. As shown in the drawing, a plurality of blades 3 are arranged at predetermined intervals along the circumferential direction between the outer flow path wall 1 (outer cylinder) and the inner flow path wall 2 (inner cylinder) arranged in an annular shape. It is provided. These wings 3
Consists of a stationary blade 3a fixed to the inner surface of the outer cylinder 1 and a moving blade 3b fixed to the rotor 4 in the inner cylinder 2. The moving blade 3b and the stationary blade 3a are alternately arranged in the axial direction of the compressor 5. It is arranged in multiple stages.

The rotor 4 is connected to a downstream turbine (not shown) and is rotationally driven by the turbine. When the rotor 4 rotates, the rotor blade 3b also rotates and the compressor 5
The upstream air is sequentially compressed while passing through the moving blades 3b and the stationary blades 3a, and is sent to a combustion chamber (not shown) downstream of the compressor 5.

[0004]

By the way, such an axial flow compressor 5 has the following problems.

.. Since the moving and stationary blades 3a and 3b rows of the axial flow compressor 5 are designed according to a certain design point, if the flow rate is significantly increased outside the design point, the flow path disconnection between the blade rows shown in FIG. Choking occurs in the minimum area portion 9 (throat portion 9), and the flow rate cannot be increased any further. Therefore, the utilization range of the compressor 5 cannot be expanded to the flow rate increasing side.

[0006] Further, during compression, the fluid flowing on the back side 6 of the blade 3 is first accelerated and then gradually decelerated as shown by the solid line in FIG. 4, but is easily separated from the blade back side 6 in the deceleration process. In particular, as shown in FIG. 3, at the root portion 7 on the back side 6 of the blade 3, a separation region 8 is generated over a wide area in combination with a complicated flow phenomenon between the moving blade 3b and the stationary blade 3a, and Due to the turbulence, the pressure loss of the flow at the blade root 7 is significantly increased. Therefore, the efficiency of the compressor 5 could not be increased.

An object of the present invention, which was devised in view of the above circumstances, is to provide a blade cascade structure for an axial flow compressor, which achieves a high flow rate and high efficiency of the compressor.

[0008]

In order to achieve the above-mentioned object, the present invention provides a plurality of annular inner wall walls and outer wall walls that are spaced at predetermined intervals in the circumferential direction. In the blade row structure of the axial flow compressor in which the blades are arranged, a recess is formed in the inner flow passage wall to widen the flow passage cross sectional area by locating the throat portion where the flow passage cross sectional area between the blade rows is minimized. Along with the formation of the concave portion, a smooth convex portion is formed which is located on the downstream side of the concave portion and suppresses the deceleration of the fluid flowing through the blade back side root portion.

[0009]

According to the above construction, the concave portion provided in the inner flow passage wall increases the flow passage cross-sectional area of the throat portion (minimum flow passage cross-sectional area portion) between the blade rows. The choke flow rate at the throat increases. Therefore, the flow rate of the compressor can be increased.

Further, the flow passage after the throat portion is narrowed by the convex portion provided on the downstream side of the concave portion, and flows due to the nozzle effect and the characteristics of the fluid flowing along the convex surface. The fluid is accelerated. Therefore, the deceleration of the fluid flowing on the back side of the blade is weakened, and the separation point shifts to the wake side. Therefore, the pressure loss is reduced, and the efficiency of the compressor can be improved.

[0011]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a partial side view of a rotor blade 3b of an axial flow compressor 5 used in a jet engine. The rotor blade 3b is
As shown in FIG. 5, a plurality of ring-shaped outer flow passage walls 1 and inner flow passage walls 2 are arranged at predetermined intervals along the circumferential direction, and are arranged in the axial direction of the compressor 5. Along the vanes 3
It is provided in multiple stages alternately with a.

A partial perspective view of the moving blade 3b is shown in FIG.
As shown in the drawing, each of the moving blades 3b is erected on the inner flow path wall 2 with a predetermined space therebetween, and the tip 10 thereof is very close to the outer flow path wall 1 (not shown). . In the figure, the inner flow path wall 2 is shown as a flat plate for the sake of convenience, but in actuality, it has a ring shape as shown in FIG. A rotor 4 that rotationally drives the inner flow path wall 2 and the moving blades 3b is provided further inside the inner flow path wall 2.

The feature of this embodiment is that a recess 11 is formed in the inner flow passage wall 2 to widen the flow passage cross-sectional area by locating it in the throat portion 9 where the flow passage cross-sectional area between the blade rows is minimized. The point is that a smooth convex portion 12 that is formed on the downstream side of the concave portion 11 and that suppresses deceleration of the fluid flowing through the blade back side root portion 7 is formed. As shown in FIG. 2, the concave portion 11 and the convex portion 12 are formed in the inner flow path wall 2 in an annular shape along the circumferential direction thereof. In addition, the concave portion 11 and the convex portion 12 are, as shown in FIG.
It is formed so that the flow passage cross-sectional area between the two smoothly changes. Therefore, the fluid passing therethrough smoothly flows along the flow path walls 1 and 2.

The operation of this embodiment having the above configuration will be described.

Due to the recess 11 formed in the inner flow passage wall 2, the flow passage cross-sectional area of the throat portion 9 (minimum flow passage cross-sectional area portion) between the blade rows increases. Therefore, the choke flow rate of the throat portion 9 increases as the area increases. That is, this recess 1
In the conventional cascade structure without 1, the choking phenomenon occurs in the throat portion 9 between the cascades as the flow rate increases.
According to the present cascade structure shown in FIG. 1, since the flow passage cross-sectional area of the throat portion 9 is widened by the concave portion 11, the choke flow rate increases and the choke margin increases accordingly. Therefore, the flow rate of the compressor 5 can be increased, and the usage range of the compressor 5 can be widened toward the flow rate increasing side as shown in FIG.

Further, the convex portion 12 provided on the inner flow path wall 2
Therefore, the throat portion 9 that minimizes the flow passage cross-sectional area between the blade rows
The subsequent channels are narrowed. Therefore, due to the nozzle effect and the characteristics of the fluid flowing along the convex surface, the convex portion 1
The fluid flowing over the surface of 2 is accelerated. That is, the convex portion 1
In a general blade cascade structure having no 2 as shown by the solid line in FIG. 4, the fluid flowing on the blade back side 6 peaks in the vicinity of the throat portion 9 and then is decelerated. It is re-accelerated and the deceleration of the fluid after the throat portion 9 is weakened as shown by the broken line. The fact that the speed on the blade back side 6 is once reduced is due to the diffuser effect of the concave portion 11 formed in the inner channel wall 2.

In this way, the deceleration point of the fluid flowing on the blade back side 6 shifts to the wake side, and accordingly, the separation point of the fluid flowing on the blade back side 6 also shifts to the wake side. Therefore, as shown in FIG. 3, the separation area that has spread over a wide area in the conventional blade root portion 7 is narrowed, and the pressure loss of the flow having a direct correlation with the area of the separation area is significantly reduced as shown by the broken line. Therefore, higher efficiency can be promoted as shown in FIG.

That is, in this embodiment, the concave portion 11 widens the flow passage cross-sectional area of the throat portion 9 to increase the passing flow rate, and at the same time, the convex portion 12 weakens the deceleration of the fluid after the throat portion 9 and leaves the separation point behind. Pressure loss is reduced by shifting to the flow side. As a result, both high flow rate and high efficiency of the compressor 5 can be reasonably compatible with each other.

In this embodiment, the moving blade 3b of the axial compressor 5 is used.
Although the example applied to the above is shown, of course, it may be applied to the stationary blade 3a.

[0021]

As described above, according to the "blade cascade structure of the axial flow compressor" of the present invention, it is possible to achieve a high flow rate and high efficiency of the compressor.

[Brief description of drawings]

FIG. 1 is a partial side view of a blade cascade structure of an axial compressor showing an embodiment of the present invention.

FIG. 2 is a partial perspective view of the blade row structure.

FIG. 3 is a diagram showing a difference in separation area and a difference in loss distribution between the blade row structure and a conventional blade row structure.

FIG. 4 is a diagram showing a difference in velocity distribution between the blade row structure and a conventional blade row structure.

FIG. 5 is a diagram showing a difference in performance characteristics between the blade row structure and a conventional blade row structure.

FIG. 6 is a side sectional view of an axial flow compressor.

[Explanation of symbols]

 1 Outer Flow Path Wall 2 Inner Flow Path Wall 3 Blade 3a Stator Blade 3b Moving Blade 5 Axial Flow Compressor 6 Dorsal 7 Root 9 Throat 11 Recess 12 Convex

Claims (1)

[Claims] 1. A blade row structure for an axial compressor, wherein a plurality of blades are arranged at predetermined intervals along a circumferential direction between an inner flow passage wall and an outer flow passage wall that are annularly arranged. In the above-mentioned inner flow passage wall, a recess is formed in the throat portion where the flow passage cross-sectional area between the blade rows is minimized to widen the flow passage cross-sectional area, and the blade is placed on the downstream side of the recess. A blade cascade structure for an axial flow compressor, characterized in that a smooth convex portion is formed to suppress deceleration of fluid flowing through a root portion on the back side.