JP2014105633A - Turbine rotor blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbine rotor blade capable of suppressing energy loss of a working fluid due to interference with part of a working fluid passing through a blade tip clearance.SOLUTION: In a turbine rotor blade 34 attached to a rotational shaft 33 and rotating inside a turbine casing 31, flow f flowing from a side of a pressure surface 56 and to a side of a negative pressure surface 57 in a blade tip clearance g between a blade tip 63 of the turbine rotor blade 34 and the turbine rotor blade 34 is decelerated by applying a swirling component f'' at a recess part 64 provided on the blade tip surface 63, and thereby a region A where the flow f flowing in the blade tip clearance g and the mainstream of a working fluid on the side of the negative pressure surface 57 are mixed is controlled, and energy loss of the mainstream is suppressed.

Description

  The present invention relates to a turbine rotor blade.

  The turbine rotor blade is attached to the outer peripheral portion of the rotating shaft to constitute a turbine rotor. This turbine rotor rotates in the casing. Therefore, a gap (hereinafter referred to as a blade tip gap) is interposed between the inner peripheral wall of the casing, which is a stationary body, and the tip surface of the turbine rotor blade facing the casing. A part of the working fluid that moves from the pressure surface side of the turbine blade to the suction surface side through the blade tip gap interferes with the main flow of the working fluid and loses the main flow energy. In view of this, there is a type in which a rib is provided on the tip surface of the turbine blade to seal the blade tip gap (see Patent Document 1, etc.).

JP 2008-51096 A

  However, the configuration in which the blade tip gap is sealed with ribs is effective when the thickness of the turbine blade is large, but the sealing effect is small with a thin turbine blade, and it mixes with the main flow of working fluid through the blade tip gap. The flow velocity of the flow is not sufficiently suppressed. When the flow rate of the working fluid passing through the blade tip clearance is large, the working fluid cannot be rectified, and a vortex (secondary flow) that increases the total pressure loss is generated at the leading edge of the blade. The fluid force acting on the is reduced.

  In addition, when a high-temperature combustion gas is used as a working fluid, the disturbance of the flow field at the blade tip has a considerable influence on the turbine rotor blade. That is, the disturbance of the flow field can increase the heat flow rate from the fluid side to the airfoil, increase the thermal load, and deteriorate the turbine blade.

  The present invention has been made under such a background, and an object thereof is to provide a turbine rotor blade capable of suppressing energy loss of the working fluid due to interference with a part of the working fluid passing through the blade tip clearance. .

  In order to achieve the above object, the present invention provides a turbine rotor blade that is attached to a rotary shaft and rotates inside a turbine casing, wherein the blade tip gap between the blade tip of the turbine rotor blade and the turbine rotor blade is pressurized. The region where the flow flowing from the blade side to the suction surface side is decelerated by applying a swirling component at the recess provided on the blade tip surface to mix the flow flowing through the blade tip gap and the main flow of the working fluid on the suction surface side Suppresses mainstream energy loss.

  ADVANTAGE OF THE INVENTION According to this invention, the energy loss of the working fluid by interference with the one part working fluid which passes a blade tip clearance gap can be suppressed.

It is a fragmentary sectional side view of the example of 1 structure of the gas turbine to which the turbine rotor blade concerning this invention is applied. 1 is a perspective view of a turbine rotor blade according to a first embodiment of the present invention. It is arrow sectional drawing by the III-III line in FIG. It is sectional drawing of the turbine rotor blade which concerns on the 1st Embodiment of this invention cut | disconnected by the surface orthogonal to a turbine central axis. It is the figure which looked at the blade tip surface of the turbine rotor blade concerning a 1st embodiment of the present invention from the turbine radial direction outside. The blade surface Mach at the outer edge of the blade tip surface of the turbine rotor blade according to the first embodiment of the present invention when the influence of the working fluid moving from the pressure surface side to the suction surface side through the blade tip gap is not considered It is the figure which showed the number. The blade surface Mach at the outer edge of the blade tip surface of the turbine rotor blade according to the first embodiment of the present invention in consideration of the influence of the working fluid passing through the blade tip gap and moving from the pressure surface side to the suction surface side It is the figure which showed the number. It is sectional drawing of the turbine rotor blade which concerns on a comparative example. It is a figure showing the turbine stage containing the turbine bucket which concerns on the 2nd Embodiment of this invention. It is sectional drawing of the turbine rotor blade which concerns on the 2nd Embodiment of this invention cut | disconnected by the surface orthogonal to a turbine central axis. It is the figure which looked at the blade front end surface of the turbine rotor blade concerning the 2nd Embodiment of this invention from the turbine radial direction outer side. It is the figure which overlapped and illustrated the area | region A on illustration of FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
1. Gas Turbine FIG. 1 is a partial sectional side view of a structural example of a gas turbine to which a turbine blade according to the present invention is applied.

  The gas turbine shown in the figure includes a compressor 10, a combustor 20, and a turbine 30. The compressor 10 includes a compressor casing 11 and a compressor rotor 12. The compressor rotor 12 is configured by providing a plurality of moving blade cascades each including a plurality of compressor moving blades 14 in the axial direction on the outer peripheral portion of the rotating shaft 13. Further, on the inner peripheral wall of the compressor casing 11, a plurality of stator blade cascades composed of a plurality of compressor stator blades 15 are provided in the axial direction so as to be positioned upstream of each rotor blade cascade. A stationary blade cascade and a moving blade cascade downstream thereof constitute one paragraph. The turbine 30 includes a turbine casing 31 and a turbine rotor 32. The turbine rotor 32 is configured by providing a plurality of rows of moving blade cascades including a plurality of turbine rotor blades 34 in the axial direction on the outer peripheral portion of the rotating shaft 33. Further, a plurality of stationary blade cascades including a plurality of turbine stationary blades 35 are provided on the inner peripheral wall of the turbine casing 31 in the axial direction so as to be located upstream of each rotor blade cascade. A stationary blade cascade and a moving blade cascade downstream thereof constitute one paragraph. The compressor rotor 12 and the turbine rotor 32 constitute an integral rotor 40 in which the rotary shafts 13 and 33 are connected coaxially. A load device (not shown) such as a generator is connected to the compressor rotor 12 or the turbine rotor 32.

  In the gas turbine configured as described above, the air sucked into the compressor 10 is compressed by the compressor 10 and flows into the combustor 20. The compressed air from the compressor 10 is combusted with fuel in the combustor 20. The hot working fluid (combustion gas) generated in the combustor 20 flows into the turbine 30 and drives the turbine rotor 32. The rotational power thus obtained by the turbine 30 is transmitted to a load device (not shown) to drive the load device.

2. Turbine Blade (1) Airfoil Part FIG. 2 is a perspective view of the turbine blade 34, and FIG. 3 is a cross-sectional view taken along line III-III in FIG.

  The turbine rotor blade 34 includes a tab tail-shaped blade root portion 50, a platform portion 51, and an airfoil portion 53 that extends outward from the upper surface 52 of the platform portion 51 in the turbine radial direction. The tab tail blade root 50 is a part for attaching the turbine blade 34 to the turbine rotor 32. The upper surface 52 of the platform 51 is formed so as to be line symmetric with respect to the turbine central axis as viewed from the outside in the turbine radial direction. As shown in FIG. 3, if a plane passing through an intermediate point between the concave pressure surface 56 and the convex negative pressure surface 57 in the cross section of the airfoil portion 53 is a blade center surface 58, the airfoil portion 53 has the blade center surface. A thickness is increased from the blade leading edge 54 to the center along the blade 58, and becomes thinner from the center toward the blade trailing edge 55.

(2) Blade Tip Surface FIG. 4 is a cross-sectional view of the turbine blade 34 cut along a plane orthogonal to the turbine central axis, and FIG. 5 is a view of the blade tip surface 63 of the turbine blade 34 as viewed from the outside in the turbine radial direction. . 4 corresponds to a partial cross-sectional view taken along line IV-IV in FIG.

  In FIG. 4, the flow of a part of the working fluid moving from the pressure surface 56 side to the negative pressure surface 57 side through the gap between the blade tip surface 63 of the turbine rotor blade 34 and the turbine casing 31 (hereinafter referred to as blade tip gap g). Is indicated by a thick arrow. The R axis is a coordinate axis taken in the turbine radial direction, and the direction toward the radially outer side is positive. The X axis is a coordinate axis parallel to the turbine central axis, and the direction from upstream to downstream in the flow direction of the main flow of the working fluid is positive. The θ axis is a coordinate axis taken in the turbine rotation direction.

  As shown in FIGS. 4 and 5, the blade tip surface 63 includes a flat portion 67 formed in an annular shape along the outer edge of the blade tip surface 63, and a concave portion 64 inside the flat portion 67. The blade tip surface 63 is a surface on the outer side in the turbine radial direction of the airfoil portion 53 and is a surface facing the inner peripheral surface of the turbine casing 31.

  In the concave portion 64, the deepest portion 65 where the depth taken from the flat portion 67 inward in the turbine radial direction is the deepest is located on the pressure surface 56 side with respect to the blade center surface 58. Further, when taking the axis in the cord length direction and setting the position of the blade leading edge 54 to 0% and the position of the blade trailing edge 55 to 100%, the deepest portion 65 (if the deepest portion 65 has an area, at least one of them). Part) is located in the range of 30% -80%. Even in the vicinity of the blade leading edge 54 and the blade trailing edge 55, the flat portion 67 is necessary at the outer edge portion of the blade tip surface 63, and therefore the existence range of the deepest portion 65 in the cord length direction is in the range of 30% -80%. Is appropriate.

  The depth of the concave portion 64 monotonously decreases across the blade center plane 58 from the deepest portion 65. Therefore, the blade tip gap g takes the maximum value gmax on the pressure surface 56 side relative to the blade center surface 58 and becomes smaller toward the negative pressure surface 57 side. Since the bottom surface of the concave portion 64 is inclined and intersects with the blade center surface 58 so that the concave portion 64 becomes shallower toward the suction surface 57 side, the intersecting portion 66 of the bottom surface of the concave portion 64 with the blade center surface 58 is It is shallower than the deepest portion 65. In the present embodiment, as shown in FIG. 4, the bottom surface of the concave portion 64 is formed from a convex portion on the inner side in the turbine radial direction toward the negative pressure surface 57 starting from the deepest portion 65, and a convex portion on the inner side. It has a shape in which convex portions are smoothly continued outward in the turbine radial direction toward the negative pressure surface 57 side. That is, the bottom surface of the concave portion 64 has a shape that monotonously increases from the deepest portion 65 toward the negative pressure surface 57 via the inflection point. Further, the bottom surface of the concave portion 64 closer to the pressure surface 56 than the deepest portion 65 has a convex shape inward in the turbine radial direction from the deepest portion 65 toward the pressure surface 56 side.

  4, Rtip indicates the radial position on the R axis of the inner peripheral wall of the turbine casing 31, and R′tip indicates the radial position of the deepest portion 65 of the recess 64.

3. Comparative Example FIG. 6 is a view showing the blade surface Mach number of the outer edge of the blade tip surface of the turbine rotor blade when the influence of the working fluid that passes through the blade tip gap g and moves from the pressure surface side to the suction surface side is not considered. FIG. 7 is a diagram showing the blade surface Mach number of the outer edge of the blade tip surface of the turbine rotor blade when the influence of the working fluid moving from the pressure surface side to the suction surface side through the blade tip gap g is considered. FIG. 8 is a cross-sectional view of a turbine blade according to a comparative example. FIG. 8 is shown corresponding to FIG.

  In FIG. 6, the blade surface Mach number from the leading edge of the blade tip surface to the trailing edge of the blade on the suction surface side is indicated by Ms, and the blade surface from the leading edge of the blade tip surface to the trailing edge of the blade on the pressure surface side is shown. The Mach number is indicated by Mp. As shown in the figure, the blade surface Mach number Ms of the suction surface becomes the maximum blade surface Mach number Mmax at the intermediate portion between the blade leading edge and the blade trailing edge, and decreases from the intermediate portion to the blade trailing edge. On the other hand, the blade surface Mach number Mp of the pressure surface becomes the minimum blade surface Mach number Mmin at the intermediate portion between the blade leading edge and the blade trailing edge, and increases from the intermediate portion to the blade trailing edge. Due to the difference in blade surface Mach number between the suction surface and the pressure surface, a pressure difference between the pressure surface and the suction surface is generated, and the main fluid force of the working fluid acts on the airfoil portion to drive the rotor to rotate.

  However, in practice, a part of the working fluid moves from the high pressure surface side to the low pressure surface side through the blade tip gap g, so that the maximum blade surface Mach number of the suction surface is as shown in FIG. It decreases from Mmax to M'max, and the pressure difference between the pressure surface and the suction surface decreases. Part of the working fluid that has passed through the blade tip gap g interferes with the main flow of the working fluid that passes between the blades, so that the energy of the main flow of the working fluid is lost and the expansion of the main flow is hindered. This is because the total pressure loss at the front end surface increases.

  Specifically, as shown in FIG. 8, a part of the working fluid f acting on the pressure surface flows into the blade tip gap g, passes through the blade tip gap g, and is rolled down at a point a on the suction surface side. A secondary flow f ′ is formed along the suction surface. This secondary flow f 'interferes with the main flow of the working fluid and partially obstructs the flow of the main flow, and is mixed with the main flow, leading to energy loss of the working fluid. This is a so-called blockage effect. That is, as the region A in which the energy of the working fluid is reduced by mixing the secondary flow f 'with the main flow of the working fluid is larger, the rate at which the energy of the working fluid is converted into the rotational energy of the turbine rotor is reduced.

4). In the present embodiment, as shown in FIGS. 4 and 5, the recess 64 gradually becomes shallower from the deepest portion 65 on the pressure surface 56 side to the negative pressure surface 57 with respect to the blade center surface 58. By providing the surface 63, the working fluid flowing into the blade tip gap g is decelerated by adding a swirling component f "at an early stage, and further flows through the blade tip gap g with the remaining stroke of the blade tip gap g. And the secondary flow f ′ can be weakened by jetting it toward the suction surface 57. This makes it possible to reduce the region A where the secondary flow f ′ is mixed with the main flow of the working fluid. , The energy loss of the main flow of the working fluid due to the interference with a part of the working fluid passing through the blade tip gap g is suppressed, and the rate at which the working fluid energy is converted into the rotational energy of the turbine rotor 32 by the turbine rotor blade 34 is increased. It can be.

  Further, since the blockage effect at the blade tip portion can be reduced, deviation due to the radial position of the airfoil portion 53 of the thermal expansion work of the working fluid can be suppressed.

  Further, unlike the configuration in which the blade tip gap is sealed, the generation of a secondary flow in the vicinity of the blade leading edge 54 or the pressure surface 56 of the blade tip surface 63 is not facilitated. Reduction can also be suppressed.

  Further, by reducing the area A, it is possible to suppress the heat flow velocity flowing from the main flow of the working fluid into the airfoil portion 53, and thus suppress the deterioration of the turbine rotor blade 34.

(Second Embodiment)
FIG. 9 is a view showing a turbine stage including a turbine blade according to the second embodiment of the present invention, FIG. 10 is a cross-sectional view of the turbine blade cut along a plane orthogonal to the turbine central axis, and FIG. It is the figure which looked at the blade front end surface 63 of the blade | wing 34 from the turbine radial direction outer side. In FIG. 9, the turbine rotor blade 34 is represented by a cross-sectional view taken along the blade center plane 58. 10 corresponds to a partial cross-sectional view taken along the line XX in FIG.

  This embodiment is different from the first embodiment in that the turbine rotor blade 34 has cooling air passages 71 and 72 inside, and the cooling air is allowed to flow through the cooling air passages 71 and 72. This is a configuration in which the turbine rotor blade 34 is cooled from the inside.

  The thick arrow in FIG. 9 indicates the flow of the cooling air, and the block arrow indicates the main flow of the working fluid. The cooling air flow paths 71 and 72 are provided with fins for effective heat exchange between the cooling air and the turbine rotor blades 34. However, the structure that promotes heat exchange can be replaced by convection cooling or other cooling means. The cooling air flowing through the cooling air flow paths 71 and 72 is extracted from the compressor 10 (see FIG. 1) and guided through a center hole (not shown) provided at the rotation center of the rotor 40.

  The cooling air flow path 71 penetrates a portion on the blade leading edge 54 side of the airfoil portion 53 in the turbine radial direction, and the terminal end is open to the blade tip surface 63, and the cooling air is discharged from the blade tip surface 63. In the present embodiment, as shown in FIG. 11, the cooling air flow path 71 opens in the flat portion 67 on the blade leading edge 54 side of the recess 64, but a configuration in which it opens in the recess 64 may be used. The cooling air flow path 72 is a serpentine flow path formed inside a portion of the airfoil portion 53 on the blade trailing edge 55 side, and operates the cooling air through a plurality of discharge holes provided in the blade trailing edge 55 portion. Release into the main stream of fluid. In the present embodiment, as shown in FIG. 10, a stepped portion 73 is provided at the edge of the flat surface 67 on the negative pressure surface 57 side of the blade tip surface 63.

  Other configurations are the same as those of the first embodiment, and portions similar to those of the first embodiment are denoted by the same reference numerals as in the first embodiment in FIGS. To do.

  In the above configuration, the cooling air fc1 is discharged from the cooling air flow path 71 to the blade tip gap g, mixed with a part of the working fluid f passing through the blade tip gap g, and flows toward the negative pressure surface 57 to be the main flow of the working fluid. To mix. At this time, in the present embodiment, the cooling air fc1 exiting from the cooling air passage 71 flows into the recess 64 along the blade tip surface 63 and is decelerated by mixing with the swirling component f ″ in the recess 64. As a result, the flow velocity is decreased by flowing toward the negative pressure surface 57. By this effect, even if the cooling air fc1 flows through the blade tip gap g, the region A where the fluid flowing through the blade tip gap g and the main flow of the working fluid are mixed is kept small. And the same effects as those of the first embodiment can be obtained.

  FIG. 12 is a diagram showing the region A superimposed on the illustration of FIG. In the same figure, in order to clearly show the region A, cross-sectional hatching is omitted.

  A part of the working fluid f flowing through the blade tip gap g is mixed with the cooling air fc1 to be cooled and mixed with the main flow of the working fluid flowing on the negative pressure surface 57 side in the region A shown in FIG. When viewed from the rotational direction, the region A becomes wider on the inner side in the radial direction of the turbine than the upstream side in the flow direction of the main flow as shown in the figure due to mixing with the main flow of the working fluid. As described above, the spread of the region A is suppressed by providing the concave portion 64.

  Since the cooling air fc2 flowing through the serpentine cooling air flow path 72 rises in the process of flowing through the cooling air flow path 72, the cooling efficiency of the airfoil portion 53 by the cooling air fc2 decreases as it approaches the blade trailing edge 55. On the other hand, a part of the working fluid f flowing through the blade tip gap g is mixed with the cooling air fc1 discharged from the cooling air flow channel 71 on the blade leading edge 54 side to lower the temperature, and the recess 64 is provided. As a result, since the spread of the region A toward the inner side in the turbine radial direction is suppressed, the inflow of heat from the main flow of the working fluid to the airfoil portion 53 can be more effectively suppressed in the region A. In the region A, the blade trailing edge 55 side is wider in the turbine radial direction than the blade leading edge 54 side. Therefore, the cooling effect by the cooling air fc1 is as described above due to the temperature rise of the cooling air fc2 flowing through the cooling air flow path 72. It can play a role of suppressing a decrease in cooling efficiency on the blade trailing edge 55 side.

(Other)
The above embodiment is merely one embodiment of the present invention, and the design of the turbine rotor blade of the present invention can be changed as appropriate without departing from the technical idea of the present invention. For example, the turbine rotor blade 34 can be applied to all the stages of the turbine 30, but can also be applied to at least one of a plurality of stages. In addition, although the single-shaft turbine is illustrated in FIG. 1 as an example, the present invention can be applied to a two-shaft turbine having a high-pressure turbine and a low-pressure turbine in which the rotation shafts are separated from each other. In the case of a two-shaft turbine, a compressor rotor and a load device are usually connected to the high-pressure turbine and the low-pressure turbine, respectively, and the low-pressure turbine is driven by the combustion gas that has driven the high-pressure turbine. The present invention can be applied to at least one stage of the turbine rotor blade in at least one of the high-pressure turbine and the low-pressure turbine of the two-shaft turbine. If necessary, the present invention can be applied to a turbine rotor blade of a steam turbine.

DESCRIPTION OF SYMBOLS 10 Compressor 20 Combustor 30 Turbine 31 Turbine casing 33 Rotating shaft 34 Turbine rotor blade 53 Airfoil part 54 Blade front edge 55 Blade rear edge 56 Pressure surface 57 Negative pressure surface 58 Blade center surface 63 Blade tip surface 64 Recess 65 Deepest part 71 Cooling air hole

Claims (6)

A turbine blade attached to a rotating shaft and rotating inside a turbine casing,
Having a recess in the blade tip surface facing the turbine casing of the airfoil,
The deepest part where the depth taken inside the turbine radial direction of the recess is the deepest is located on the pressure surface side than the blade center surface which is the center of the pressure surface and the suction surface,
The turbine rotor blade according to claim 1, wherein the depth of the concave portion monotonously decreases from the deepest portion toward the suction surface across the blade center surface. The turbine rotor blade according to claim 1,
The turbine rotor blade according to claim 1, wherein a bottom surface of the recess is inclined outward in the turbine radial direction from the deepest portion toward the suction surface side and intersects the blade center surface. The turbine rotor blade according to claim 1,
A turbine rotor blade having a cooling air hole passing through the inside of the airfoil portion and opening in the blade tip surface. The turbine rotor blade according to claim 1,
Taking the axis in the cord length direction, the deepest part is located in the range of 30% -80% when the blade leading edge position is 0% and the blade trailing edge position is 100%. Turbine blade. A compressor for compressing the sucked air;
A combustor for combusting compressed air compressed by the compressor together with fuel;
A turbine driven by combustion gas generated in the combustor,
A gas turbine comprising the turbine rotor blade according to claim 1.   In the turbine blade that is attached to the rotating shaft and rotates inside the turbine casing, the flow that flows from the pressure surface side to the suction surface side through the blade tip gap between the blade tip portion of the turbine blade and the turbine blade, By applying a swirling component in the recess provided on the blade tip surface and decelerating, the region where the flow flowing through the blade tip gap and the main flow of the working fluid on the suction surface side are suppressed, and the energy loss of the main flow is reduced. A method for improving the efficiency of a turbine, comprising suppressing the turbine.

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