JPH08121389A - Stationary blade structure for compressor - Google Patents

Abstract

PURPOSE: To reduce the occurrence of a gap vortex and to prevent the occurrence of separation on the rear edge side of a stationary vane by arranging a blade end plate at the tip of a blade. CONSTITUTION: A stationary blade 1 is attached in a cantilever state to a casing 2, and the blade end plate 10 is attached to the blade tip throughout a range of approximate 60% of a front edge. A gap 4 is provided between the blade end plat 10 and a hub 3 rotating at a high speed and the stationary blade is prevented from making contact with the hub even by thermal expansion of the stationary blade 1 and the hub 3 and a centrifugal force generated at the hub 3. The magnitude of a gap vortex 7 is increased to a pressure difference between the belly surface (a pressure surface) and the back (a negative pressure surface) of the stationary blade 1. In such a way that the blade end plate 10 is arranged in a range of approximate 60% from the front edge where the pressure difference is high, the occurrence of the gap vortex 7 is eminently suppressed. Further, since even when the gap vortex 7 is generated, it is constrained at the vicinity of a hub surface, diffusion to a main flow is reduced and incurring of a mixture loss owing to diffusion is also reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airfoil structure of a stationary blade used in an axial flow compressor.

[0002]

2. Description of the Related Art In an axial flow compressor, moving blades planted in a hub and stationary blades planted in a casing are arranged alternately in the axial direction. A gap is provided between the tip of the moving blade and the casing and between the tip of the stationary blade and the hub, and the moving blade rotates with the hub. Such a gap has the minimum size that allows the rotor blade and the hub to rotate without any trouble.

[0003]

FIG. 3 (a) is a transverse sectional view at a position where the vane 1 is provided, and FIG. 3 (b) is an XX sectional view of (a). The stationary vanes 1 are attached to the inner surface of the casing 2, and are arranged with a hub 3 rotating at high speed and a gap 4. Since a pressure higher than that on the blade back surface 6 acts on the blade belly surface 5 of the stationary blade 1, a flow passing through the gap 4 is generated, and a clearance gap 7 is generated, which causes a loss.

FIG. 4 shows a structure in which the tip of the vane 1 is connected by a shroud 8, (a) is a cross-sectional view, and (b) shows an engagement between the vane 1 and the shroud 8. By connecting the tip of the stationary blade 1 with the shroud 8, it is possible to prevent the generation of the clearance gap 7 described in FIG. However, on the trailing edge side of the stationary blade 1, in the range indicated by the hatched portion 9 in (b), the slow fluid gathers on the shroud 8 due to the pressure exerted from the blade belly surface 5 toward the blade back surface 6, and separation occurs. It occurs and causes a loss.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a vane structure that reduces the clearance gap and prevents separation on the trailing edge side of the vane.

[0006]

In order to achieve the above object, a blade tip of a compressor which has a gap with a rotating hub and is cantilevered on the inner surface of a casing having the same axial center as the hub and a large diameter. In the stationary blade structure, a blade plate is provided at the tip of the blade.

Further, the blade plate is provided on the back side of the stationary blade.

The blade tip plate is provided over a range of approximately 60% of the chord length from the blade leading edge.

[0009]

By providing a blade plate at the tip of the stationary blade, the effect close to the effect of connecting the blade ends with a shroud is obtained, so that the occurrence of clearance gaps is reduced and loss is reduced.

If the tip plate is also provided on the ventral side of the vane, the vane receives a force that bends to the back side due to the pressure difference between the ventral surface and the back side of the vane. There is a risk of approaching and contacting the hub. For this reason, it is recommended that the wing tip plate only be on the back side.

Since the pressure difference between the ventral side and the back side of the blade is large in the range of about 60% from the leading edge, the blade end plate is provided in this range. If the blade end plate is provided on the trailing edge side of the blade, the boundary layer between the blade and the blade end plate separates and a loss occurs as described with reference to FIG. 4B. Therefore, the blade end plate is provided on the trailing edge side of the blade. It is better not to.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B are views showing a configuration of an embodiment, FIG. 1A is a cross-sectional view at a stationary blade position, and FIG. 1B is a view taken along the line YY of FIG. The stationary blade 1 is attached to the casing 2 in a cantilevered manner, and a blade end plate 10 is attached to the blade tip over a range of 60% from the front edge. A gap 4 is provided between the blade end plate 10 and the hub 3 that rotates at a high speed so that the vane 1 and the hub 3 do not come into contact with each other due to the thermal expansion of the vane 1 and the centrifugal force generated in the hub 3.

FIG. 2 is a diagram showing a loss coefficient distribution between the casing 2 and the hub 3 of the stationary blade 1 of this embodiment. The horizontal axis indicates the loss coefficient, and the vertical axis indicates the stationary blade 1 between the casing 2 and the hub 3.
The span of is displayed in%. The large loss coefficient in the span close to the casing 2 is due to the loss described in FIG. That is, on the trailing edge side of the stationary blade 1, a boundary layer between the stationary blade 1 and the casing 2 causes a range where the flow velocity is slow, where separation occurs and a large loss occurs. The loss is small at the center of the span of the vane 1 and increases as it approaches the hub 3. This is because even if the wing tip plate 10 is provided, some clearance gap 7 is generated as shown in FIG.
This is due to the generation of the gap waste 7 in the remaining 40% range where the gap is not provided. The broken line shows the loss coefficient of the conventional example shown in FIG. 3A, which is much smaller than that of the conventional example.

The strength of the clearance gap 7 increases according to the pressure difference between the belly surface (pressure surface) and the back surface (negative pressure surface) of the stationary blade 1. By providing the blade end plate 10 within a range of 60% from the leading edge where the pressure difference is large, the generation of the clearance gap 7 can be significantly suppressed. Further, even if the clearance gap 7 is generated, it is restrained in the vicinity of the hub surface, so that the diffusion into the main flow is reduced and the mixing loss due to the diffusion is also reduced.

In the present embodiment, the range of the wing tip plate 10 is set to 60% from the leading edge, but it may be changed in the range of 50 to 80%. However, if it is provided near the blade trailing edge, loss due to separation of the boundary layer between the stationary blade 1 and the blade end plate 10 occurs as described with reference to FIG. It is necessary to determine the range of the wing tip plate 10 in consideration of the decrease of Although the wing tip plate 10 is provided on the wing rear surface side, it may be provided on the wing ventral surface side. However, in this case, as described above, the tip end portion 10 provided on the blade flank side is the hub because the tip end portion of the vane receives a bending force to the back side due to the pressure difference between the blade flank surface 5 and the blade back surface 6. The structure of the vane 1 is designed so that it does not come in contact with 3.

[0016]

As is apparent from the above description, according to the present invention, the tip of the vane is provided with the blade end plate to suppress the generation of the clearance gap and reduce the loss. Further, the blade end plate is provided on the blade back surface so that the blade tip plate does not come into contact with the hub even if the blade tip receives a force to bend the blade tip toward the blade back surface side. In addition, the blade tip plate has a pressure difference between the pressure surface and the suction surface of the blade that is approximately 60 from the leading edge of the blade.
% To reduce the occurrence of voids. Since no blade end plate is provided on the trailing edge side of the stationary blade, loss due to separation of the boundary layer between the stationary blade and the blade end plate does not occur. It should be noted that, in the future, as the load of the compressor is increased and the peripheral speed is increased, the clearance gap of the hub side blade tip of the stationary blade increases, but the clearance gap can be reduced by the present invention, and the efficiency of the compressor is improved. Can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention, in which (a) is a partial cross-sectional view at a vane position, (b) is YY of (a).
It is an arrow view.

FIG. 2 is a loss coefficient distribution diagram of an example.

3A and 3B are diagrams showing a configuration of a conventional vane portion, FIG. 3A is a partial cross-sectional view at a vane position, and FIG. 3B is an XX cross-sectional view of FIG.

FIG. 4 shows a structure in which a tip of a conventional vane is connected with a shroud, (a) is a partial cross-sectional view at a vane position, and (b) is a boundary layer formed in the vicinity of a joint between the vane and the shroud. It is a figure which shows the range where loss occurs by peeling.

[Explanation of symbols]

 1 Static Blade 2 Casing 3 Hub 4 Gap 5 Blade Vent Surface 6 Blade Back Surface 7 Gap Uz 8 Shroud 9 Diagonal Area 10 Blade End Plate

Claims (3)

[Claims] 1. A vane structure of a compressor, wherein the vane tip has a gap with a rotating hub, and is cantilevered on an inner surface of a casing having the same axial center as that of the hub and having a large diameter. A stator vane structure for a compressor, characterized by being provided with. 2. The stator vane structure for a compressor according to claim 1, wherein the vane end plate is provided on the back side of the vane. 3. The wing tip plate has a chord length of approximately 6 from the leading edge of the wing.
The vane structure of the compressor according to claim 1 or 2, wherein the vane structure is provided over a range of 0%.