JP2005233140A - Turbine blade - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a turbine blade improving durability and reliability by suppressing high temperature gas flowing into a gap between a stator blade and a moving blade. <P>SOLUTION: A front edge adjacent wall surface (hub surface) of the moving blade which is a downstream side blade is heaped up in relation to the stator blade which is an upstream side blade of turbine drive gas. In embodiment, a heaping up part 6a is provided on a platform 6 adjacent to the front edge of the moving blade 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention, in the turbo machine such as a gas turbine, to a structure of the turbine blade.

  Conventionally, a turbomachine including a gas turbine has a structure in which a gap is formed between an end wall on which a stationary blade and a moving blade are disposed. FIG. 5 is a longitudinal sectional view schematically showing an example of a basic structure of a blade portion in a gas turbine which is a kind of such a conventional turbomachine. As shown in the figure, a blade portion in a conventional gas turbine is constituted by a stage of a stationary blade 1 and a moving blade 2 disposed behind the stationary blade 1. The stationary blade 1 is disposed between a shroud 4 and a casing 5 that form an annular combustion gas passage 3 as a working fluid passage.

  The rotor blade 2 is implanted in the outer periphery of the turbine disk (not shown), the platform 6 and the outer peripheral side of the casing 7 a little apart from the tip side of the hub side, communicating from the stage of the stationary blade 1 A combustion gas flow path 3 is formed. The rotor blades 2 and the turbine disk are rotationally driven by the combustion gas flow generated by the combustor (not shown) and deflected by the stationary blades 1.

  In such a gas turbine, a gap 8 is inevitably set between the shroud 4 and the platform 6 in order to enable rotation of the turbine disk. At this time, as shown by the arrow A in the figure, when the combustion gas stream is brought into contact with the moving blade 2, called horseshoe vortices, etc., partially caused a phenomenon that the flow flows back, combustion gases (turbine driven gas) It may flow into the gap 8.

  In this way, the hot combustion gases flowing through the combustion gas flow path 3, and enters through the gap 8 into the interior of the shroud 4 and the platform 6, by the center-side combustion gases inside the structure member or turbine disk Shuuraudo 4 Problems such as heating, deterioration, and reduced durability occur. For this reason, a seal portion (not shown) for preventing inflow of combustion gas is formed in the gap 8.

  Further, secondary air having a pressure higher than that of the combustion gas is supplied from the compressor side (not shown) to the inside of the shroud 4 and the platform 6 to cool the components and the turbine disk inside the shroud 4 and As shown by an arrow B, the gas is allowed to flow out from the gap 8 to the combustion gas flow path 3, thereby enhancing the sealing effect and completely preventing the combustion gas from flowing into the gap 8.

However, this way, in the like to flow out into the combustion gas flow path 3 constituting the secondary air from the gap 8, there is a problem that the pressure loss causes the efficiency reduction occurs. Therefore, to enable improved efficiency while preventing flowing into inner (shroud 4 and the platform 6 in this embodiment) inner circumferential casing of the combustion gas by the secondary air, paragraph sealing part structure of a gas turbine is disclosed (For example, refer to Patent Document 1). Also, to enable the clearance control seal portion, the gas turbine seal apparatus is disclosed to reduce the leakage amount of air (e.g., see Patent Document 2).
JP 11-324608 A Japanese Patent Laid-Open No. 11-6446

  However, the high temperature of recent gas turbine combustion gases, with the transition from 1350 ° C. Examples to 1500 ° C., with only seal structure as described in the above patent documents has become insufficient. Further, new problems such as a decrease in durability and reliability of a portion around the gap have arisen due to such high-temperature gas flowing into the gap where cooling measures are not sufficiently taken. In view of such problems, an object of the present invention is to provide a turbine blade in which high temperature gas is prevented from flowing into a gap between a stationary blade and a moving blade, and durability and reliability are improved.

  To achieve the above object, the present invention, the upstream-side blade which is disposed upstream of the turbine driving gas, in a more composed turbine blades and downstream blades disposed on the downstream side, abuts the downstream blade wherein as turbine drive gas does not flow into the gap of reflux to said upstream blade and the downstream blades, and is characterized in that a raised portion in proximity to the leading edge hub surface of said downstream wing.

  Further, either one of the upstream blade and the downstream blade is stationary blade, and the other is a moving blade.

Further, the following conditional expression is satisfied.
120 ° ≦ theta ≦ 0.99 ° However, theta is the angle between L1 and L2,
L1: A straight line through which the trailing edge hub point of the upstream wing and the hub surface downstream end point of the upstream wing pass L2: A straight line through which a point on the hub surface upstream of the downstream wing and a point on the hub surface upstream of the downstream blade leading edge passes through the downstream side The point on the hub surface upstream of the side blade leading edge is the farthest point on the turbine outer diameter side between the upstream surface of the hub surface of the downstream blade and the straight line passing through the front edge hub point of the downstream blade.

  Further, the hub surface upstream end point of the downstream blade is located on the turbine inner diameter side from the L1.

Further, there is a turbine outer diameter side than the L1 is a point on the downstream blade leading edge upstream of the hub surface, and satisfies the following conditional expression.
D> 0.25Tmax
Or D> 0.05 Rht
However,
D: distance between a point and L1 on the downstream blade leading edge upstream of the hub surface Tmax: maximum blade thickness of the downstream-side blade Rht: a gas path height downstream wing.

  Further, the point on the hub surface of the downstream blade leading edge upstream the leading edge hub point of the downstream blade, the distance of the turbine drive gas flow direction, the downstream blade leading smaller than edge arc radius or elliptic minor axis radius and it features.

  In addition, a raised portion is provided on the tip surface near the leading edge of the downstream blade.

  According to the present invention, it is possible to provide a suppressing flow into the gap between the vanes and the rotor blades of the high-temperature gas turbine blade having improved durability and reliability.

  Specifically, as abutting turbine drive gas on the downstream side blade does not flow into the gap between the upstream blade and the downstream-side blade and reflux, to a structure provided with raised portions in proximity to the leading edge hub surface of the downstream-side blade Accordingly, achieving penetration reduction of hot gas into the rotor blade hub front cavity and the stationary blade hub front cavity or the like, can be reduced turbine disks and turbine rotors, or the high temperature oxidation of the vane shroud upstream end face Become.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, a concept for suppressing the above-described backflow of combustion gas will be described. Figure 1 is a diagram schematically showing the concept of such a backflow inhibiting. FIG. 2A shows a conventional configuration, and FIG. 2B shows a configuration applied to the present invention.

  First, it is assumed that there is a shielding object 12 such as a cylinder extending upward from the wall surface 11 as shown in FIG. According to the boundary layer theory, the gas flow toward the shield 12 has a low flow velocity in the vicinity of the wall surface 11 and a high speed in the distance, as indicated by an arrow C. For this reason, as shown by the arrow D, the flow in contact with the shielding object 12 is swirled, and as a result, the flow in the vicinity of the wall surface 11 flows backward.

  In order to reduce this back flow region E, as shown in FIG. (B), the front vicinity of the shield 12, raise as the wall 11 by an appropriate height 11a. As a result, the upward flow of gas is induced as indicated by the arrow Da, the vortex near the wall surface is reduced, and as a result, the distance from the shield 12 at the upstream end of the reverse flow region E is suppressed to be short.

  FIG. 2 is a vertical cross-sectional view schematically showing a main part of the turbine blade according to the first embodiment of the present invention. In this embodiment, in accordance with the concept of combustion gas backflow inhibition as described above, with respect to the stationary blade on the upstream side blades of the turbine driving gas, the rotor blade leading edge near the wall rotate (hub side) of the turbine radius is the downstream-side blade The configuration is raised outward in the direction. Specifically, the raised portion 6a is provided on the platform 6 near the leading edge of the rotor blade 2. Note that after stationary blade 1 edge and 1a, has a moving blade 2 leading edge and 2a. However, the upstream blade may be a moving blade and the downstream blade may be a stationary blade. This configuration will be described later. Each point and each line in the figure are defined as follows.

X: coordinate shows the turbine axis R: coordinates indicating the radial direction of the turbine (X1, R1): trailing hub point of the stationary blade 1 (X2, R2): hub surface downstream end points of the stationary blade 1 (X3, R3 ): Hub surface upstream end point of moving blade 2 (X4, R4): Leading edge hub point of moving blade 2 (X0, R0): Point on the hub surface upstream of moving blade 2 leading edge (X3, R3) And the straight line connecting (X4, R4) is the farthest point on the turbine outer diameter side L1: A straight line passing through (X1, R1) and (X2, R2) L2: (X3, R3) and (X0, R0) straight line θ: Angle formed by L1 and L2

Here, it is desirable to satisfy the following conditions.
1.120 ° ≦ θ ≦ 150 ° (X3, R3) is on the turbine inner diameter side from L1.
3. (X0, R0) is in the turbine outer diameter side than L1, to satisfy the following condition.
D> 0.25Tmax
Or D> 0.05 Rht
However,
D: (X0, R0) and the distance between L1 Tmax: maximum blade thickness of the blade 2 Rht: a gas path height of the blade 2.
4). (X4-X0) <(moving blade 2 the leading edge arc radius, or elliptical minor axis radius)

  Condition 1. And condition 4. Is a condition for the raised portion 6a in the vicinity of the leading edge of the rotor blade 2 to be in an appropriate position. Condition 2 Is a condition for making it difficult for the combustion gas to enter the gap 8 directly. Furthermore, Condition 3 Is a condition for making the raised portion 6a higher than the boundary layer height of the combustion gas. The gas path height Rht here is the height from the leading edge hub point of the rotor blade 2 to the casing 7 (see FIG. 5).

  The above condition 4. It is intended to determine the swelling position of the blade leading edge near, as shown in FIG. 3, in the plane section of the blade 2, is to a circle or the reference diameter of the ellipse inscribing the front edge. That is, the radius r of the circle inscribed in the leading edge is set as the reference length as shown in FIG. 10A, or the major axis a is along the longitudinal direction of the blade as shown in FIG. of the ellipse inscribed, half the length of the minor axis b and the reference length.

  At this time, as shown by the broken line in the figure, the apex of the swelled portion 6a may be arranged within the reference length range on the combustion gas upstream side from the leading edge of the moving blade 2, but as shown by the broken line in FIG. In addition, the apex of the raised portion 6a may be distributed two-dimensionally along the front edge. In this case, the two-dimensional distribution range may be an angle range formed by the center O of a range in which a circle or an ellipse is inscribed in the front edge.

  Now, in this embodiment, as shown in FIG. 2, the stationary blade from an upstream side of the combustion gases, placed at the rotor blades of the order, the raised portion 6a provided on the platform 6 of the front edge portion of the neighboring blades 2 As a result, entry of high-temperature gas from the gap 8 into the rotor blade front cavity and the like is reduced, thereby reducing high-temperature oxidation of the turbine disk and the turbine rotor.

  On the other hand, contrary to the case of FIG. 2, the moving blades and the stationary blades are arranged in this order from the upstream side of the combustion gas, and a raised portion is provided on the shroud in the vicinity of the leading edge portion of the stationary blades. It is possible to reduce the high temperature gas intrusion into the cavity or the like, thereby reducing the high temperature oxidation of the upstream end face of the stationary blade shroud. This configuration can also be applied to the following examples.

  Further, as shown in FIG. 2, by setting the inclination of L1 to be positive, that is, by setting the hub surface on the downstream side of the stationary blade 1 to the turbine outer diameter side, the boundary layer of the combustion gas is reduced, and the above-mentioned The effect of reducing the entry of high-temperature gas into the rotor blade front cavity or the like is more remarkable. Alternatively, unlike FIG. 2, a zero inclination of L1, namely by a hub surface of the stationary blade 1 downstream and horizontal, blade shape of the upstream side becomes the present invention can be applied without changing, Cost can be reduced. Or, when it is necessary to widen the gas path toward the downstream, contrary to FIG. 2, it is necessary that the inclination of L1 is negative, that is, the hub surface on the downstream side of the stationary blade 1 is lowered to the turbine inner diameter side. is there.

  In addition, FIG. 2 shows the structure on the hub side of each wing, but the tip side can also have the same structure. That is, the high temperature oxidation of the shroud and blade ring on the tip side can be reduced by providing the tip side with the hub side structure turned upside down.

  Note that, as shown in FIG. 4 described above, it is possible to prevent inflow into the gap between the blades arranged in the turbine circumferential direction by adopting a configuration in which the rising portions are distributed two-dimensionally. . Further, when this configuration is used for a moving blade, it is possible to reduce high-temperature oxidation of the circumferential end surface of the platform, and when used for a stationary blade, the shroud.

The figure which shows typically about the concept of backflow suppression. Longitudinal sectional view schematically showing a main portion of a turbine blade according to a first embodiment of the present invention. Plan sectional view showing a raised portion of the blade leading edge near. The plane sectional view showing signs that a rising part is distributed two-dimensionally. Longitudinal sectional view schematically showing an example of the basic structure of the blade portion in a gas turbine.

Explanation of symbols

1 stationary blade 2 moving blade 3 the combustion gas passage 4 shroud 5 casing 6 platform 7 casing 8 Clearance

Claims (7)

  The upstream-side blade which is disposed upstream of the turbine driving gas, in a more composed turbine blades and downstream blades disposed on the downstream side, the upstream blade the turbine drive gas in contact with the said downstream wing flows back the so prevented from flowing into the gap between the downstream blade, a turbine blade, characterized in that the raised portion is provided in proximity to the leading edge hub surface of said downstream wing with.   2. The turbine blade according to claim 1, wherein one of the upstream blade and the downstream blade is a stationary blade, and the other is a moving blade. Turbine blade according to claim 1 or claim 2, characterized by satisfying the following conditional expression.
120 ° ≦ θ ≦ 150 ° However, θ is an angle formed by L1 and L2.
L1: A straight line through which the trailing edge hub point of the upstream wing and the hub surface downstream end point of the upstream wing pass L2: A straight line through which a point on the hub surface upstream of the downstream wing and a point on the hub surface upstream of the downstream blade leading edge passes through the downstream side The point on the hub surface upstream of the side blade leading edge is the farthest point on the turbine outer diameter side between the upstream surface of the hub surface of the downstream blade and the straight line passing through the front edge hub point of the downstream blade.   4. The turbine blade according to claim 3, wherein a hub surface upstream end point of the downstream blade is located on a turbine inner diameter side from the L <b> 1. The downstream blade leading there than the points on the hub surface of the edge upstream L1 to the turbine outer diameter side, the turbine blade according to claim 3 or claim 4, characterized by satisfying the following conditional expression.
D> 0.25Tmax
Or D> 0.05 Rht
However,
D: distance between a point and L1 on the downstream blade leading edge upstream of the hub surface Tmax: maximum blade thickness of the downstream-side blade Rht: a gas path height downstream wing.   Of a point on the hub surface of the downstream blade leading edge upstream the leading edge hub point of the downstream blade, the distance of the turbine drive gas flow direction, and wherein the downstream blade leading smaller than edge arc radius or elliptic minor axis radius The turbine blade according to any one of claims 3 to 5.   Turbine blade according to claim 1, characterized in that the raised portion is provided in proximity to the leading edge tip surface of the downstream blade.

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