JP6159151B2 - Turbine blade - Google Patents

Description

  The present invention relates to a turbine rotor blade.

  In the turbine rotor blade, since a gap exists between a stationary member such as a casing and the blade tip, a leakage flow from the pressure surface of the blade toward the suction surface is generated. The leakage flow interferes with the main flow, so that the total pressure loss increases and the turbine efficiency decreases.

  In order to prevent an increase in the total pressure loss due to the tip leakage flow, various tip shapes have been proposed to reduce the tip leakage flow. One of them is a squealer called a squealer having a structure in which the blade pressure surface and the blade tip surface around the intersection of the suction surface and the blade tip surface are higher than the surroundings.

  There exists Unexamined-Japanese-Patent No. 2009-108834 (patent document 1) as an example of such a structure. This publication describes that “a blade-shaped squealer that forms a recess on the inside is provided, and the back side portion of the squealer has a cutout portion that communicates only with the back side of the turbine blade”. Moreover, there exists Unexamined-Japanese-Patent No. 2010-156325 (patent document 2). This publication includes a wing-shaped squealer formed by a tip wall extending radially outward from a tip plate, and has an angle of 80 to 100 degrees with respect to a wing tip mid chord line (tip center chord line). A rotor blade having ribs is described.

JP 2009-108834 A JP 2010-156325 A

  When the gap between the stationary member and the blade tip is reduced in order to reduce the amount of blade tip leakage flow, the possibility of sliding between the stationary member and the blade tip increases. However, in the conventional structure, frictional heat due to sliding between the casing and the blade tip tends to stay in the recess at the blade tip. In addition, when air for cooling the blade tip is ejected from the blade tip surface, the cooling air flows downstream before sufficiently cooling the blade tip surface, making it difficult to distribute the cooling air over the entire blade tip surface. There was a problem that a part of the end portion became hot.

  Therefore, an object of the present invention is to provide a turbine blade capable of improving turbine efficiency by reducing blade tip leakage flow and improving blade tip surface cooling performance.

The present invention includes a platform portion forming a working gas passage surface, and an airfoil portion extending from the platform portion, the airfoil portion having a concave pressure surface and a convex connecting the leading edge and the trailing edge. A suction surface having a shape and a blade end surface that is a tip side end surface opposite to the platform portion, and has one or more linear grooves or a plurality of linear ribs on the blade end surface. both ends above the groove or plurality said ribs on the suction surface and Majiwa Ri has a hollow portion inside the turbine blade, an opening for introducing a cooling medium to the hollow portion, introduced into the hollow portion A cooling hole for ejecting the cooled cooling medium to the outside of the turbine rotor blade, and the cooling hole is disposed between the groove provided in the blade end surface or between the adjacent ribs. It is characterized by that.

  ADVANTAGE OF THE INVENTION According to this invention, the turbine blade which can improve a turbine efficiency can be provided by the reduction | decrease of a blade tip leakage flow and the improvement of the cooling performance of a blade tip surface.

It is a figure showing the blade tip part and leakage flow of the turbine rotor blade concerning the reference example 1. It is a schematic sectional drawing showing the cross section of a blade tip leak flow direction clearance gap. It is a figure showing the determination method of a groove direction. It is a figure showing the blade tip shape of a cooling turbine moving blade. FIG. 6 is a diagram illustrating a blade tip shape of a turbine blade according to Reference Example 2. FIG. 6 is a diagram illustrating a derived form of a blade tip shape of a turbine rotor blade according to Reference Example 2. FIG. 6 is a diagram illustrating a derived form of a blade tip shape of a turbine rotor blade according to Reference Example 2. It is a diagram illustrating a turbine rotor blade tip shape according to the embodiment. It is a figure showing the blade tip shape of the turbine rotor blade which concerns on an Example . It is the schematic of the gas turbine system for electric power generation. It is a schematic fragmentary sectional view showing the structure of a gas turbine. It is AA sectional drawing of a cooling turbine blade. It is a figure showing the derivative form of the blade tip shape of the turbine rotor blade which concerns on an Example . It is a figure showing the derivative form of the blade tip shape of the turbine rotor blade which concerns on an Example . It is an enlarged view of a turbine rotor blade. It is a figure showing the blade shape of a turbine rotor blade.

Hereinafter, examples will be described with reference to the drawings. First, Reference Example 1 and Reference Example 2 which are the premise of the present invention will be described, and then Examples of the present invention will be described.
<Reference Example 1>

  FIG. 10 is a schematic diagram of a power generation gas turbine system. The power generation gas turbine system mainly includes a compressor 11, a combustor 12, a turbine 13, and a shaft 14. The compressor 11 sucks air and compresses it to generate compressed air. The combustor 12 burns the compressed air and fuel generated by the compressor 11 to generate high-temperature gas. The turbine 13 recovers energy by using this high-temperature gas as a working gas.

  The turbine 13 converts the pressure energy of the working gas into kinetic energy by expanding it, and causes the working gas having the increased kinetic energy to work on the moving blades to generate rotational power. Rotational power generated in the turbine 13 is transmitted to the compressor 11 through the shaft 14, so that a part of the energy recovered by the turbine 13 is used for driving the compressor. The surplus energy recovered by the turbine 13 is used as an output, for example, used for driving a generator to generate electric power.

  FIG. 11 shows a schematic partial cross-sectional view of the gas turbine. The compressor 11 and the turbine 13 are connected through a shaft 14 between which a combustor 12 exists. The turbine rotor blades 21b, 22b, 23b, and 24b extend from the platform portion attached to the turbine rotor in the direction of increasing the radial position, and the turbine stationary blades 21n, 22n, 23n, and 24n are supported on the casing 25 side. . Further, casing shrouds 31, 32, 33, and 34, which are stationary members, are attached to the casing 25 at positions corresponding to the outer circumference in the radial direction of the turbine rotor blades 21b, 22b, 23b, and 24b. There are gaps between the tip portions of the turbine rotor blades 21n, 22n, 23n, and 24n and the casing shrouds 31, 32, 33, and 34, respectively.

  FIG. 15 is an enlarged view of the turbine rotor blade. The turbine rotor blade includes a platform portion 51 that forms a working gas passage surface, an airfoil portion having a blade height of 50 extending from the platform portion 51, a shank portion 52 provided on the base side of the platform portion 51, and the like. Has been. FIG. 16 is a diagram showing the blade shape of the turbine rotor blade. The airfoil portion is formed by a concave pressure surface 1 and a convex suction surface 2 connecting the leading edge and the trailing edge, and the moving blades attached to the turbine rotor form a turbine blade row. It is rotationally driven in the direction of arrow 60 by the working gas. A distance 55 between the blade leading edge and the blade trailing edge represents the axial cord length.

FIG. 1 is a view illustrating a blade tip portion of a turbine rotor blade according to Reference Example 1. FIG. The blade tip portion of the turbine rotor blade is mainly composed of the pressure surface 1 and the suction surface 2 described above, and a blade end surface 3 which is an end surface on the tip side opposite to the platform portion 51 of the airfoil portion. In the gap between the blade tip and the stationary member facing the blade tip, a blade tip leakage flow 5 is generated as indicated by the dashed arrow in the figure. In Reference Example 1 , a linear groove 4 having a groove width 53 is provided on the blade end surface 3 as a configuration for suppressing such blade tip leakage flow 5.

FIG. 2 is an enlarged schematic cross-sectional view of the gap between the blade tip of the turbine rotor blade and the stationary member 6 facing the blade tip. As shown in FIG. 2, the turbine rotor blade of Reference Example 1 has a plurality of grooves 4 formed substantially perpendicular to the flow direction of the leakage flow 5 on the blade end surface 3. According to the configuration of the reference example 1 described above, the flow of the leakage flow 5 can be reduced because the vortex generated in each groove 4 can prevent the flow of the blade tip gap from entering. The working gas corresponding to the reduced leakage flow is used to generate energy by rotating the turbine rotor by applying aerodynamic force to the turbine blades. Therefore, the gas turbine efficiency can be improved by reducing the flow rate of the leakage flow 5.

  FIG. 3 is a view showing the pressure distribution on the blade surface in the blade section near the blade tip of the turbine blade. The horizontal axis represents the position on the blade surface, and the vertical axis represents the pressure. 8a, 8b, 8c, 8d, 8e, and 8f are respectively intersections 8a ′, 8b ′, 8c ′, 8d ′, 8e ′, and 8f ′ of the linear groove 4 and the blade pressure surface 1 or suction surface 2. Represents pressure.

As shown in FIG. 3, in the turbine rotor blade of Reference Example 1 , the pressures at both ends of the linear groove 4, that is, the pressure values of 8a and 8b, 8c and 8d, and 8e and 8f are equal. In this case, since there is almost no pressure gradient in the groove direction, it is difficult for flow to occur in the groove. Therefore, since the groove 4 is provided, the problem that air leaks from the pressure surface toward the suction surface is unlikely to occur. One or more grooves are provided, but the number is not particularly limited. The intervals between the grooves may be equal, but may be unevenly arranged.

  Here, as shown in FIG. 3, the state of the blade surface pressure change is different between the pressure surface side and the suction surface side. The pressure on the suction side changes in such a way that it takes a minimum value in the latter half of the wing, whereas the pressure on the suction side decreases almost monotonously. The pressure difference between becomes larger. Therefore, it is important to suppress the leakage flow in the latter half of the blade.

Therefore, the turbine blade of Reference Example 1 includes a groove 4a whose both ends intersect with the suction surface as one of the grooves 4 provided at the blade end. In the latter half of the blade where the pressure difference between the pressure surface and the suction surface becomes large, the pressure on the suction surface side becomes smaller than the minimum pressure on the pressure surface side. Therefore, in order to reduce the leakage flow by arranging the grooves 4 so that the pressures at both ends are equal in this range, the grooves 4a such that both ends intersect the suction surface, such as 8e 'and 8f', are arranged. It is effective.

According to the configuration of Reference Example 1 including one or more 4a whose both ends intersect with the suction surface, leakage flow in the latter half of the blade where the pressure difference between the pressure surface and the suction surface becomes large can be suppressed. The flow rate of the entire leakage flow can be effectively reduced, and the efficiency of the turbine can be improved.

  Furthermore, the leakage flow can be effectively suppressed by densely arranging the plurality of grooves 4 and 4a in the latter half of the blade where the pressure difference between the pressure surface and the suction surface is large. On the contrary, when the single groove 4a is disposed only in this portion, a high leakage flow suppressing effect can be obtained at a low cost.

  The pressure distribution on the blade surface is maximum near the leading edge and minimum on the suction surface side. However, when the difference between the maximum pressure on the blade surface and the minimum pressure is 9 as the maximum pressure difference, the pressure difference at both ends is By forming the grooves 4 and 4a so as to be 10% or less of the maximum pressure difference 9, the flow in the grooves can be effectively suppressed.

  In addition, when a pressure difference occurs at both ends of the groove due to the design, etc., the groove is arranged so that the pressure at the end located on the rear edge side of both ends is reduced, and the groove pressure distribution is It is desirable to make it smaller as it goes to the trailing edge side. By setting in this way, a flow from the leading edge side to the trailing edge side is induced in the groove, and the flow in the groove is discharged from the blade pressure surface or the blade suction surface. Therefore, the increase in loss can be avoided.

  At the turbine rotor blade tip, the leakage flow generated from the pressure surface toward the suction surface peels off once at the position where the pressure surface and the blade end surface intersect, and then reattaches. The thickness of the peeled area is about 0.4% of the blade height. Therefore, if the groove depth is about 0.4 %% of the blade height and the groove width is about 0.4 %% of the shaft cord length, the generation of vortices due to separation occurring at the position of each groove will cause blade tip leakage. Since the flow is prevented, the tip leakage flow can be reduced more effectively. On the other hand, when the depth and width of the groove are increased more than necessary, it is necessary to reduce the area of the blade surface, and there is a risk that sufficient turbine efficiency cannot be expected. Therefore, the groove depth is preferably set within a range of 1% or less of the blade height 50, and the groove width is set within a range of 1% or less of the shaft cord length 55.

  Further, the groove may be a straight line or a curved line. Furthermore, it may be a polygonal line. In addition, as shown in FIG. 14, by setting the curve so that the groove protrudes to the upstream side, the pressure at the groove ends 8a '' and 8b '' becomes lower than that at the center of the groove, and the mainstream air into the groove Inflow can be suppressed. Naturally, even when the groove is formed in a polygonal line shape, the same effect can be obtained by setting a polygonal line protruding in the upstream side.

Further, since the groove 4 is opened at a position where it intersects the blade pressure surface or the suction surface, the problem is that the fluid heated by the frictional heat with the casing stays at the blade tip and heats the blade tip. Therefore, it is possible to reduce the amount of cooling air, thereby improving the turbine efficiency.
<Reference Example 2>

FIG. 5 is a configuration diagram illustrating a blade tip shape of a turbine rotor blade in Reference Example 2. In Reference Example 2 , a linear rib 10 having a width of 54 is provided instead of providing a linear groove as means for making the blade end surface uneven. If there are multiple protrusions almost perpendicular to the leakage flow direction, vortices are generated by each protrusion to prevent the flow of the tip clearance and to reduce the flow rate of the tip leakage flow. It is.

As described in Reference Example 1, if there is almost no pressure gradient in the direction of the rib, a flow along the direction of the rib is less likely to occur in the recess between the ribs. Therefore, the problem that air leaks from the pressure surface to the suction surface through the concave portion between the ribs is unlikely to occur.

Further, as in Reference Example 2 , when one or more linear ribs 10a each having both ends of the rib intersect with the suction surface are provided, the pressure difference between the pressure surface and the suction surface becomes large. The flow can be suppressed, and the flow rate of the entire leakage flow can be effectively reduced. Therefore, like the groove 4a of Reference Example 1, the turbine efficiency can be improved.

  At the turbine rotor blade tip, the leakage flow generated from the pressure surface toward the suction surface peels off once at the position where the pressure surface and the blade end surface intersect, and then reattaches. The thickness of the peeled area is about 0.4% of the blade height. Therefore, if a rib height of about 0.4% of the blade height 50 and a rib width of about 0.4% of the shaft cord length 55 are secured, the generation of vortices due to separation occurring at the positions of the ribs is caused. By preventing the leakage flow, the tip leakage flow can be effectively reduced. On the other hand, when the height and width of the rib are increased more than necessary, it is necessary to reduce the area of the blade surface, and there is a possibility that sufficient improvement in turbine efficiency cannot be expected. Therefore, the rib height is preferably set within a range of 1% or less of the blade height 50, and the rib width is set within a range of 1% or less of the shaft cord length 55.

When the tip clearance changes and the blade tip contacts the casing, only the rib portion contacts the casing, so adopting Reference Example 2 reduces the contact area with the casing compared to Reference Example 1. In addition, it is possible to suppress heat generation at the blade tip portion due to wear of the casing and sliding with the casing. Therefore, it is possible to reduce the amount of cooling air, thereby improving the turbine efficiency.

  In addition, if the arc-shaped rib 15 as shown in FIG. 6 or the triangular rib 16 as shown in FIG. 7 is adopted as the rib shape, the contact area with the casing can be further reduced. It becomes possible to reduce. The rib may be a straight line or a curved line. Furthermore, it may be a polygonal rib 35 as shown in FIG.

  As shown in FIG. 10, the cooling air is acquired by extracting a part of the air in the compressor and guided to the turbine blade. Since bypass air extracted as cooling air contributes little to work in the turbine, an increase in cooling air leads to a decrease in gas turbine performance.

  The gas turbine rotor blade may have an airfoil portion formed so as to have a hollow portion therein and to flow a cooling medium in the hollow portion to cool the blade from the inside. FIG. 4 shows the blade tip shape of a turbine blade whose inside is hollow for cooling. FIG. 12 is a cross-sectional view taken along the line AA of the turbine rotor blade shown in FIG.

  The cooling air guided from the compressor is introduced into the turbine blades through the openings 36 and 37, and flows through the hollow portions (cooling flow paths) inside the turbine blades in the directions of arrows 38 and 39, respectively. At that time, the blade metal temperature is reduced by absorbing heat from the turbine blade. The cooling air that has flowed through the cooling flow path inside the turbine blade is then ejected from a plurality of cooling holes 40 arranged at the blade leading edge to cool the blade leading edge or the blade trailing edge nozzle By ejecting from 42 or ejecting from the cooling hole 7 disposed at the blade tip, the gas is discharged into the gas path.

A part of the cooling air is ejected from the cooling hole 7 provided in the blade tip groove 4 as indicated by an arrow 41. FIG. 9 is an example of a configuration diagram showing the blade tip shape in the present embodiment . When the groove is provided as in Reference Example 1, the cooling hole 7 is provided in the groove 4 as shown in FIG. 9, and the cooling air is ejected therefrom. On the other hand, when the rib is provided as in Reference Example 2, the cooling hole 7 is provided in the blade end surface 3 corresponding to the region between the adjacent ribs as shown in FIG.

Unlike the squealer blades, the turbine blades described in Reference Example 1 and Reference Example 2 are open at the positions where the grooves or ribs and the concave spaces between the ribs intersect with the blade pressure surface or the suction surface. The problem is that the fluid heated by the frictional heat stays at the blade tip and heats the blade tip. In addition, due to the presence of the grooves and ribs, the cooling air ejected from the cooling holes 7 tends to stay in the grooves having the cooling holes or between the ribs and the ribs. Therefore, by adjusting the amount of cooling air ejected from each cooling hole, the metal temperature in the groove to which each cooling hole belongs or between the ribs can be controlled. While increasing the cooling hole diameter in the high temperature part to increase the cooling air volume, reducing the cooling air volume by reducing the cooling hole diameter in the part where the temperature is not so high, the thermal load can be kept within the allowable range over the entire blade end face. It becomes possible to suppress to. In addition, it is not necessary to eject only a minimum amount of cooling air, which contributes to a reduction in the amount of cooling air.

  Some examples are shown below. In FIG. 8, the refracted portion of the U-shaped concave portion 3 has the highest pressure in the groove, and if the cooling hole 7 is provided there, the cooling air can flow along the groove. A similar effect can be expected in the case of a curve as shown in FIG. Alternatively, the pressure value 8a at the position of intersection with the upstream blade surface is set to be higher in the range of 0% to 10% of the total pressure width 9 than the pressure value at the intersection position 8b with the downstream blade surface. If the cooling hole is provided near the highest pressure 8a in the groove as shown in FIG. 13, the cooling air flows in the groove from 8a to 8b, and the vicinity of the groove can be effectively cooled.

  Note that the above embodiments can also be applied to steam turbines, jet engines, and the like.

DESCRIPTION OF SYMBOLS 1 Rotating blade pressure surface 2 Rotating blade suction surface 3 Rotating blade blade end surface 4 Blade end groove 5 Blade end leakage flow 6 Static member 7 Cooling air injection hole 9 Pressure difference 10 Blade end rib 11 Compressor 12 Combustor 13 Turbine 14 Shaft 15 Arc-shaped rib 16 Triangular rib 21n First stage stationary blade 21b First stage stationary blade 22n Second stage stationary blade 22b Second stage stationary blade 23n Third stage stationary blade 23b Third stage stationary blade 24n Fourth stage stationary blade 24b Fourth stage Rotor 25 casing 36 opening (front edge side)
37 opening (rear edge side)
50 Turbine blade height 51 Platform portion 52 Shank portion 53 Slit groove width 54 Rib width 55 Shaft cord length 60 Direction of rotation

Claims (10)

A turbine rotor blade comprising a platform portion forming a working gas passage surface and an airfoil portion extending from the platform portion;
The airfoil portion includes a concave pressure surface and a convex suction surface connecting the leading edge and the trailing edge, and a blade end surface serving as a tip side end surface opposite to the platform portion,
The tip surface has a linear groove 1 or more, Ri both ends of the groove than one is Majiwa and the negative pressure surface,
The turbine rotor blade has a hollow portion, and includes an opening for introducing a cooling medium into the hollow portion, and a cooling hole for ejecting the cooling medium introduced into the hollow portion to the outside of the turbine rotor blade. ,
The turbine rotor blade according to claim 1, wherein the cooling hole is disposed in the groove provided in the blade end face . A turbine rotor blade comprising a platform portion forming a working gas passage surface and an airfoil portion extending from the platform portion;
The airfoil portion includes a concave pressure surface and a convex suction surface connecting the leading edge and the trailing edge, and a blade end surface serving as a tip side end surface opposite to the platform portion,
The tip plurality have a linear rib surface, Ri across a plurality of said ribs is Majiwa and the negative pressure surface,
The turbine rotor blade has a hollow portion, and includes an opening for introducing a cooling medium into the hollow portion, and a cooling hole for ejecting the cooling medium introduced into the hollow portion to the outside of the turbine rotor blade. ,
The turbine rotor blade according to claim 1, wherein the cooling hole is disposed between the adjacent ribs provided on the blade end face . The turbine rotor blade according to claim 1 ,
The groove is arranged such that both ends of the groove intersect the pressure surface or the suction surface and the blade surface pressures at the intersections with the pressure surface or the suction surface are equal. . The turbine rotor blade according to claim 2 , wherein
The rib is disposed such that both ends of the rib intersect the pressure surface or the suction surface and the blade surface pressures at the intersections with the pressure surface or the suction surface are equal. . The turbine rotor blade according to claim 1 ,
Said groove has its both ends intersecting the pressure surface or the suction side, the difference between the minimum value of the pressure at the maximum value and the previous Kimake surfaces of the pressure in the positive pressure surface is taken as 100%, the positive pressure surface Alternatively, the turbine blade according to claim 1, wherein a pressure difference on the blade surface at an intersection with the suction surface is within a range of 10% or less. The turbine rotor blade according to claim 2 , wherein
The rib has its ends intersects with the pressure surface or the suction side, the difference between the minimum value of the pressure at the maximum value and the previous Kimake surfaces of the pressure in the positive pressure surface is taken as 100%, the positive pressure surface Alternatively, the turbine blade according to claim 1, wherein a pressure difference on the blade surface at an intersection with the suction surface is within a range of 10% or less. The turbine rotor blade according to claim 1, 3 or 5 ,
The turbine blade according to claim 1, wherein the depth of each of the grooves is 1% or less of the blade height. The turbine rotor blade according to claim 2, 4 or 6 ,
A turbine rotor blade characterized in that the height of each rib is 1% or less of the blade height. The turbine rotor blade according to claim 1, 3, 5, or 7 ,
The turbine rotor blade according to claim 1, wherein the width of each groove is 1% or less of the axial code length of the blade. The turbine rotor blade according to claim 2, 4, 6 or 8 ,
The turbine rotor blade according to claim 1, wherein the width of each rib is 1% or less of the axial cord length of the blade.