JPH10122192A - Axial flow compressor moving blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a loss by a leakage flow passing through a blade end clearance by gently inclining a blade tip part to the circumferential directional negative pressure side, and setting an inclined part to a specific moving blade height position and an inclination. SOLUTION: A blade tip part 11 (a tip part) of an axial flow compressor moving blade 10 gently inclines to the circumferential directional negative pressure side. According to an analytical result, a loss factor running along a moving blade height L becomes maximum in a position of 95% of the moving blade height L, and becomes a large value in a range not less than 85% around it. Therefore, an inclined part 12 is set not less than at least 10% of the moving blade height L, preferably, about 30%, and is gently inclined. Even it is set not less than 30%, an effect is little, and bending stress by centrifugal force becomes large, and fatigue strength of a moving blade 10 reduces. An inclination αof the inclined part 12 is preferable to be about 20 deg. to about 30 deg.. According to an analytical result, when it is not more than 20 deg., a reducing effect of a loss factor is almost eliminated, and in the case of 30 deg., the loss factor can be sharply reduced. When it exceeds 30 deg., the bending stress becomes large.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blade of an axial compressor for a jet engine or a gas turbine.

[0002]

2. Description of the Related Art FIG. 5 shows a moving blade of a conventional axial flow compressor constituting a jet engine or a gas turbine. In this figure, (A) is a side view, (B) is a view from the tip side of the rotor blade, and (C) is a view from the downstream side. The rotor blade 1 is attached to the hub 2 at a certain interval in the circumferential direction. The blade tip portion 1a is called a tip portion, and the blade root portion 1b is called a root portion. Further, as shown in (B), the blade 1 has a large angle θ at the tip portion 1a with respect to the compressor axis Z,
In the route portion 1b, the angle θ is small. Furthermore,
As shown in (C), the upstream side (left side in the figure) of the rotating blade 1 in the rotational direction is called a positive pressure side (or abdominal side), and the downstream side in the rotational direction (the right side in the figure) is called a negative pressure side (or a back side). The rotation of the moving blade 1 increases the static pressure on the positive pressure side and decreases the static pressure on the negative pressure side.

[0003]

FIG. 6 is a perspective view of a conventional compressor rotor blade viewed from the upstream side (opposite side of FIG. 5C). As schematically shown in this figure, the loss of the compressor rotor blade includes the separation flow A generated at the corner of the root portion 1b, the radial flow B flowing in the radial direction along the blade surface, and the tip portion and the casing 3. There are three types due to the gap flow C flowing through the gap. Among them, the largest loss is caused by the leakage flow C. In the conventional moving blade, the efficiency improvement is hindered by the loss generated by the interference between the leakage flow passing through the blade tip clearance and the high-speed main flow. Was.

The present invention has been made to solve such a problem. That is, an object of the present invention is to provide an axial-flow compressor rotor blade capable of reducing a loss due to a leakage flow passing through a blade tip clearance.

[0005]

Means for Solving the Problems A conventional axial-flow compressor rotor blade has a blade structure which has a small bending from the mounting portion to the blade tip and extends substantially linearly in the radial direction. But,
In such a conventional moving blade, the leakage flow passing through the blade tip gap interferes with the high-speed main flow, so that the loss at the blade tip (tip) increases. In other words, the analysis showed that the conventional rotor blades caused the leakage flow to become vortices that spread inward in the radial direction instead of spreading in the circumferential direction. The result became clear. The present invention is based on such a new finding.

That is, according to the present invention, there is provided an axial compressor blade, wherein the blade tip is gently inclined toward the negative pressure side in the circumferential direction. According to a preferred embodiment of the present invention, the inclined portion has a moving blade height L of 10 to 30.
%, And the inclination angle is preferably about 20 ° or more and about 30 ° or less.

According to the present invention, the leak flow is smoothly diffused in the circumferential direction by inclining the blade tip in the direction opposite to the rotation direction. With this configuration, the leakage flow passes through the tip of the blade in the direction opposite to the rotation direction, and since the tip of the blade is gently inclined in the same direction as the tip, the leakage flow is more smoothly diffused in the circumferential direction. The total amount of leakage flow at the tip of the blade (tip) is almost determined by the size of the gap, and is almost constant regardless of the shape of the blade tip. Therefore, diffusion in the circumferential direction of the leakage flow suppresses radial diffusion. Is done. As a result, the leak flow interferes with the flow in the boundary layer near the inner wall of the casing, which is slower than the main flow in the center, and the loss proportional to the product of the flow velocity can be greatly reduced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In the drawings, common parts are denoted by the same reference numerals. FIG. 1 is a configuration diagram of an axial-flow compressor rotor blade according to the present invention. In this figure, (A) shows an axial compressor moving blade 10 of the present invention, and (B) shows a conventional axial compressor moving blade for comparison. As shown in this figure, the blade tip portion 11 (tip portion) of the axial-flow compressor rotor blade 10 of the present invention is gently inclined toward the negative pressure side in the circumferential direction.

FIG. 2 shows an analysis result of the loss coefficient along the blade height L in FIG. In this figure, the solid line shows the characteristics of the conventional axial-flow compressor rotor blade, and the broken line shows the characteristics of the axial-flow compressor rotor blade according to the present invention (when the inclination angle is 30 °). As is clear from this figure, the loss coefficient is about 95% of the blade height L.
, And reaches a large value in the range of 85% or more before and after the position. Therefore, the inclined portion 12 is moved to the blade height L.
Is preferably at least 10% or more, preferably about 30%, and the inclination is gentle. In addition, 30%
Even if it is larger than the above, not only the effect is small, but also the bending stress due to the centrifugal force increases, and a problem arises that the fatigue strength of the rotor blade decreases.

It is preferable that the inclination angle α of the inclined portion 12 is about 20 ° or more and about 30 ° or less. Tilt angle 20
At less than 0 °, the analysis shows that there is almost no effect of reducing the loss coefficient, whereas at an inclination angle of 30 °, the loss coefficient at the blade tip 11 (tip) can be significantly reduced as shown in FIG. If the inclination angle α exceeds 30 °, the bending stress increases due to the centrifugal force.

In FIG. 2, the loss coefficient has another maximum value at a position of about 5% of the blade height L. This is due to the separation flow A generated at the corner of the root portion described above.

FIG. 3 is a total pressure distribution diagram between the blades of the axial compressor rotor blade of the present invention, and FIG. 4 is a diagram similar to FIG. 3 of the conventional axial compressor rotor blade. FIGS. 3 and 4 are views of the moving blades viewed from the downstream side. In the moving blades 1 and 10, an intermediate portion from the leading edge to the trailing edge is indicated by a curve without thickness. The closed curves in each figure show isobars. From the comparison between FIG. 3 and FIG. 4, as schematically shown in FIG.
In the axial-flow compressor rotor blade of the present invention, the leakage flow 4 passes through the blade tip 11a in the direction opposite to the rotation direction, and the blade tip 11a is gently inclined in the same direction (circumferential negative pressure side). Therefore, it can be seen that the leak flow 4 diffuses more smoothly in the circumferential direction. The total amount of leakage flow at the blade tip portion 11a (tip portion) is substantially determined by the size of the gap, and is substantially constant regardless of the blade tip shape. Is suppressed. As a result,
Leakage flow 4 is the casing 3 whose speed is slower than the main flow at the center.
As a result, the interference with the flow of the boundary layer near the inner wall of the blade can be reduced, and the loss proportional to the product of the flow velocity can be greatly reduced. As a result, as shown in FIG. ) Can be greatly reduced.

On the other hand, as shown in FIG. 1B, the conventional axial-flow compressor rotor blade 1 has a small curvature from the mounting portion 1b to the blade tip portion 1a, and extends substantially linearly in the radial direction. Structures have been used. However, in such a conventional moving blade 1, the leakage flow 4 passing through the blade tip gap interferes with the high-speed main flow, so that the loss at the blade tip 1a (tip portion) increases. That is, in the conventional rotor blade 1, since the leakage flow 4 becomes a vortex which spreads inward in the radial direction without spreading in the circumferential direction, a large loss occurs due to interference with the main flow having a large flow velocity in the central portion of the flow path. As a result of analysis, it became clear.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the spirit of the present invention.

[0015]

As described above, the axial compressor blade of the present invention has an excellent effect of reducing the loss due to the leakage flow passing through the blade tip clearance.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an axial compressor moving blade according to the present invention.

FIG. 2 is an analysis result of a loss coefficient along a blade height.

FIG. 3 is a total pressure distribution diagram between blades in the axial compressor rotor blade of the present invention.

FIG. 4 is a view similar to FIG. 3 of a conventional axial-flow compressor rotor blade.

FIG. 5 is a schematic view of a conventional axial-flow compressor rotor blade.

FIG. 6 is a perspective view of a conventional compressor rotor blade viewed from an upstream side.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Moving blade 1a Blade tip (tip part) 1b Blade root part (root part) 2 Hub 3 Casing 4 Leakage flow 10 Axial-flow compressor rotor blade 11 Blade tip part (tip part) 12 Slope

Claims (2)

[Claims] 1. An axial compressor blade according to claim 1, wherein the blade tip is gently inclined toward the negative pressure side in the circumferential direction. 2. The inclined portion has a moving blade height L of 10 to 30.
The axial compressor blade according to claim 1, wherein the inclination angle is about 20 ° or more and about 30 ° or less.