JPH07253001A - Integral shroud moving blade - Google Patents

Abstract

PURPOSE:To make a complete three-dimensional blade by preventing generation of crack, unstable flow caused by damage or chip, and decrease of efficiency, through a process of eliminating any cut part as well as deceasing bending stress by eccentricity of a shroud during rotation. CONSTITUTION:The side surface, in the circumferential direction T, of a shroud 2 are formed by straight lines 4, 4' in the implanting directions to the rotor of a blade root on the front edge 3 side, and it is formed by bending lines formed in straight lines 6, 6' concentrated on a blade rear edge 5 on the rear edge 5 side, and the straight lines 4, 4' on the side surfaces on the front edge 3 side are deviated from a blade front side 9 to a blade back side 8. Moreover, the shroud 2 on the rear edge 5 side is so formed as to completely shield the rear edge 5. Thereby, the center of gravity G of the shroud is brought close to the radial line of the blade root, and bending tress during rotation can be decreased, and the strength of a moving blade can be increased. Moreover, any generation of crack or damage can be eliminated by eliminating a cut part, moreover turbulence of stream flow is decreased, so as to contribute to improvement of the efficiency of a turbine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shroud cover (hereinafter, simply referred to as shroud) in which blade tips on the blade tip side and the blade root side are provided inclined with respect to the radial direction of rotation and provided on the blade tip in the circumferential direction. Relates to an integral shroud rotor blade with a three-dimensional blade design integrally molded with the wing trunk.

[0002]

2. Description of the Related Art In order to increase the rigidity between rotor blades and to adjust the blade vibration, a shroud provided in the circumferential direction at the blade tip is used as an integral shroud for a turbine rotor blade formed integrally with the blade trunk. Integral Shroud Blade (hereinafter I
SB). FIG. 2 is a plan view of the shroud 01. The shroud 01 formed in a substantially rectangular shape is arranged by machining or forging on the outer circumference of the blade trunk 02 in the circumferential direction T.
It is formed integrally with the wing trunk 02. Further, the blade fixing portion of the blade trunk 02 is formed in an axial entry type to be embedded in a rotor (not shown) in a direction S indicated by an arrow, and the angle formed with the rotor axial direction F on the side surface of the shroud 01 is the direction of this implantation. The angle formed by S and the rotor axial direction F is the same as the implantation angle θ. A straight line connecting the blade leading edge 03 and the blade trailing edge 04, that is, a stagger angle formed by the chord C and the direction of the rotor axis F is referred to as a Stagger angle.

Further, 05 is the ventral side of the wing trunk 02, 06 is the dorsal side, E is the inflow direction of the steam flow, and D is the outflow direction.

Γ is the angle at which the direction of the steam flow changes,
That is, the turning angle is the difference between the inflow angle α and the outflow angle β of the steam flow into the rotating surface of the blade trunk 02. As the turning angle γ increases, the implantation angle θ and Stagger angle ξ
Became larger due to design requirements, and became a so-called high staggered cascade.

Next, in the high-performance reaction blade, reaction control is used, and both the moving and stationary blades are manufactured by the three-dimensional design method.
The secondary flow loss is reduced. However, a secondary flow is generated in the tip at the inner and outer diameter ends and in the boundary layer generated on the base wall surface, and this flows out as a vortex from the trailing edge of the blade, causing a secondary flow loss. This loss is remarkable as the turning angle γ is large. Therefore, in the high-performance reaction blade, the turning angle γ is made small to reduce the secondary flow loss.

However, this method also has a limit, and recently, as shown in the figure, by providing the blade stem 02 inclined from the rotational radial direction (radial line) R, the vapor flow is made to flow to the tip wall surface 07, and It has come to be attempted to reduce secondary flow loss by pressing against the base wall surface 08 and suppressing the development of vortices on the chip and the base wall surfaces 07 and 08. Such a wing is called a perfect three-dimensional wing. That is, as shown in FIG.
In the complete three-dimensional wing, 2 is formed by a straight line that faces the radial line R direction, but in the case of the complete three-dimensional blade, the vicinity of abutting the tip and the base wall surfaces 04 and 05 is opposite to each other, as shown in FIG. 5 (B). It is inclined to form a continuous curve. Such a wing is Skewed
Also referred to as a wing, or Bow wing, as shown in detail in FIG. 4, which is a perspective view of FIG. 5B, the wing trunk 02 forms a diagonal curve in the radial line direction R, By bowing, the flow of the vapor flow near the tip wall surface 07 and the base wall surface 08 is changed from the direction of the main flow B toward the wall surfaces 07 and 08, respectively, as indicated by arrow AA ′. As a result, the development of the boundary layer on the chip wall surface 07 and the base wall surface 08 is prevented, the generation of the secondary flow is reduced, and the secondary flow loss is reduced.

As described above, it is not always necessary to reduce the turning angle γ in a perfect three-dimensional blade, and a high turning angle γ can be designed for high efficiency. However, in this case, the implantation angle θ and the stagger angle ξ also inevitably increase, and I
In the case of SB, if the stagger angle ξ becomes large, the shroud 0
As shown in FIGS. 2 and 3, the center of gravity position G of
The tip profile of No. 06 shifts from the dorsal side 06 to the ventral side 05. On the other hand, the radial line of the wing trunk 02 is directed to the back side 06 of the chip profile, as shown in FIG. For this reason, in the ISB based on the complete three-dimensional blade design, bending stress is applied due to the eccentricity of the shroud 01 during rotation, which causes a problem in strength.

Further, as shown in FIG. 3, the trailing edge of the blade trunk 02 largely projects from the end face of the shroud 01 to form a cut portion A in the final implant blade, and cracks or damages from this portion occur. There was a problem. Further, in the final implanting blade, the cut portion A is missing, so that the flow becomes unstable, resulting in a decrease in efficiency.

[0009]

Therefore, in the present invention, the shroud provided at the blade tip is formed integrally with the blade trunk, and the blade tip side and the blade root side blade trunk are inclined from the radial line. Integral shroud rotor blades that are installed and are made into a complete three-dimensional blade reduce bending stress due to eccentricity of the shroud during rotation, and eliminate the cut portion to cause flow instability due to crack generation, breakage, or lack. It is an object of the present invention to provide an integral shroud rotor blade that prevents deterioration of efficiency.

[0010]

Therefore, the integral shroud rotor blade of the present invention has the following means. (1) The circumferential side surface of the shroud is formed by a polygonal line that extends toward the trailing edge on the blade leading edge side and toward the trailing edge on the blade trailing edge side. (2) Of the circumferential side surfaces of the shroud, the side surface on the blade leading edge side is arranged so as to be displaced from the blade ventral side to the blade back side.

Another integral shroud rotor blade of the present invention has the following means in addition to the above means. (3) The shroud obscures the trailing edge of the blade tip to eliminate the cut portion protruding from the end surface of the shroud.

[0012]

In the integral shroud rotor of the present invention, which has the above-mentioned means (1) and (2), the center of gravity of the shroud shifts from the ventral side to the dorsal side of the tip profile of the blade trunk, and the radial of the blade trunk is changed. The amount of eccentricity with the line is reduced, bending stress due to eccentricity during rotation is reduced, and the problem of strength is solved.

Further, in the integral shroud moving blade provided with the above-mentioned means (3) of the present invention, in addition to the above-mentioned operation,
The strength of the moving blade is improved, the problem of crack generation or breakage from the cut portion of the final implant blade is eliminated, and the problem of unstable flow due to lack and the problem of reduced efficiency are solved.

[0014]

Embodiments of the integral shroud rotor blade of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing an embodiment of an integral shroud rotor blade of the present invention. Reference numeral 1 denotes a tip profile of the blade, and the blade 1 of the present embodiment is made by a complete tertiary blade design in which the blade tip side and the blade root side are inclined from the radial line as in the case of FIG. 4 described above. ing. The shroud 2 is integrally formed with the tip profile 1 by machining or forging.

The side surface of the shroud 2 in the circumferential direction T is formed by straight lines 4 and 4'which coincide with the blade implantation direction S on the blade leading edge 3 side, and extends on the blade trailing edge 3 side toward the trailing edge 5. 6,6 '
And a straight line 7 connecting both straight lines 4, 4 ′, 6, 6 ′ and straight line 4 ′ on the back side 8 and straight line 6 ′.

The straight line 7 is not always necessary, and like the broken line formed by the straight lines 4 and 6 on the abdominal side 9, a straight line connected by an extension line of the straight line 4'and the straight line 6'on the back side. You may do it.

The straight line 4 on the ventral side 9 in the wing implantation direction S on the front edge 3 side is narrower than the distance between the straight line 4'on the back side 8 and the back side 8 and is provided close to the ventral side 9. That is, the shroud 2 is provided so as to be displaced from the side surface 9 in the circumferential direction T on the blade leading edge 3 side to the back side 8. Therefore, the shroud 2 is a high staggered blade row having a large turning angle γ, a large implantation angle θ, and a large stagger angle ξ, like the moving blade shown in FIG. The position shown in FIG. 3 shifts to the back side 8 of the chip profile 1. Also,
Polygonal lines 6, 6'that form a side surface in the circumferential direction T on the trailing edge 5 side
Extend to the trailing edge 5, which is shroud 2
Occluded by.

Since this embodiment is constructed as described above, the amount of eccentricity of the shroud with respect to the radial line of the blade trunk 1 at the center of gravity G of the shroud decreases, and the bending stress associated with the eccentricity during rotation decreases. The problems that have occurred with conventional blades are eliminated.

Further, in the conventional ISB, since the trailing edge is obscured by the shroud provided on the outer circumference of the adjacent blade stem, the cut portion which is always generated in the final implant blade is the same as that of this embodiment. So you can get rid of it,
Conventionally, it is possible to reduce the occurrence of cracks or breakage, which often occur from the cut portion, and to solve the problem of the unstable flow caused by the lack of the cut portion and the turbine efficiency reduction accompanying this.

[0020]

As described above, according to the integral shroud rotor blade of the present invention, the following effects can be obtained with the configuration shown in the claims. (1) The eccentric stress due to the shroud is reduced, and the blade strength is increased. (2) The trailing edge portion protruding from the shroud is eliminated, and the blade strength at that portion is improved. (3) The cut portion at the trailing edge of the final implant blade is eliminated, and unstable flow is prevented, improving efficiency.

That is, a remarkable effect is obtained in improving reliability and thermal efficiency. It should be noted that the present invention is particularly effective when applied to the production of moving blades used in upstream stages of high-, medium-pressure turbines, and low-pressure turbines having a small blade height.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of an integral shroud rotor blade of the present invention.

FIG. 2 is a plan view showing a conventional integral shroud rotor blade.

FIG. 3 is a plan view showing a conventional high stagger integral shroud rotor blade.

FIG. 4 is a perspective view of a complete three-dimensional wing.

FIG. 5 is a conceptual diagram showing a flow in a blade row, FIG. 5 (A) is a flow in a blade row formed by a straight line in a radial line direction, and FIG. 5 (B) is a blade row in a complete three-dimensional blade. Shows the flow of.

[Explanation of symbols]

 1 Tip profile of the wing 2 Shroud 3 (Wing) Leading edge 4,4 'Leading edge side 5 Trailing edge 6,6' Trailing edge side 8 (Wing) dorsal side 9 (Wing) ventral G Shroud's Center of gravity S (Wing) implantation direction T Circumferential direction

Claims (2)

[Claims] 1. An integral shroud rotor blade in which a wing tip side and a wing root side of a wing trunk are provided so as to be inclined from a radial line, and a shroud provided in a circumferential direction of the wing tip is integrally formed with the wing trunk. The circumferential side surface of the blade is formed by a polygonal line composed of a straight line on the blade leading edge side in the blade implantation direction and a straight line on the blade trailing edge side in the blade trailing edge direction, and the blade leading edge side surface is formed from the blade vent side to the blade back side. Integral shroud blade characterized by being shifted to. 2. The integral shroud rotor blade according to claim 1, wherein the shroud is provided so as to cover the trailing edge of the blade tip.