JPH1162506A - Moving blade for axial flow turbo machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moving blade of an axial flow turbo machine which has low clearance loss and high efficiency by increasing a code length of a chip cross section. SOLUTION: An axial flow turbo machine moving blade rotated by a working fluid 10 entering from a stationary blade is implanted on an outer circumference of a rotor, and a cord length of a tip cross section (CTIP) of a moving blade 1 is made to be equal to or longer than a length of a cross section of a blade shape part 4 other than the chip (CMED). Thereby, a flow rate 11 of leakage from the tip clearance σ can be decreased to reduce the clearance loss and improve the efficiency of the turbo machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a moving blade of a steam turbine, a moving blade of another axial flow turbomachine, and particularly to a moving blade of a gas turbine. Reduce leakage of working fluid flowing out,
The present invention relates to an axial-flow turbomachine rotor blade having improved turbine efficiency.

[0002]

2. Description of the Related Art A rotor blade of a conventional axial-flow turbomachine, for example,
The moving blades of the gas turbine, which are implanted in the circumferential direction on the outer periphery of the rotor, are spouted from the stationary blades, and are rotated by a working fluid adapted to pass between the blades to generate power, are configured as shown in FIG. Have been.

[0003] That is, the moving blades 01 are fitted on the outer periphery of the rotor (not shown), and are provided outside the blade root portion 02, where the moving blades 01 are arranged at equal pitches in the circumferential direction of the rotor. A platform 03 forming a flow path bottom of the working fluid 010 passing between the blades, a working fluid ejected from a stationary blade (not shown) provided to protrude outward from the platform 03 and installed upstream of the moving blade 01 010 acts to form the airfoil portion 04 for rotating the rotor in the circumferential direction by the fluid force of the working fluid 010, and the tip cross section 05 formed on the outer peripheral end of the airfoil portion 04.

[0004] Since the rotor blade 01 operates while being housed in a state of being enclosed in the chip casing 06 including the rotor, it rotates around the inner peripheral surface of the stationary chip casing 06 and the rotor. Tip cross section 05 of moving blade 01
, It is necessary to provide a chip clearance δ.

Therefore, a part of the working fluid 010 ejected from the stationary blade and flowing into the upstream side of the moving blade 01 becomes a leakage flow 011, which leaks from the tip clearance δ, and
And hardly contributes to the generation of power of the rotor blades 01. The increase in the leakage flow 011 causes a reduction in the efficiency of the gas turbine.

For this reason, the outer peripheral surface of an outer shroud (not shown) or the like, in which the blades 01 provided adjacent to the tip cross section 05 are connected to reduce vibration generated in the rotor blades 01, or Attempts have been made to reduce the leakage flow 011 by reducing the chip clearance δ by projecting fins from the inner peripheral surface of the chip casing 06 into the chip clearance δ.

[0007] However, as shown in the drawing, the moving blade 01 of the conventional gas turbine is provided with a taper in which the cord length is reduced in the blade height direction, and as shown in FIG. Since the code length C _TIP of the tip cross section 05 is usually shorter than the code length C _{MED of the} cross section of the airfoil portion 04 other than the tip cross section 05 shown in FIG.
Chip clearance δ and code length C of chip cross section 05
_TIP ratio δ / C _TIP increases, the amount of working fluid 011 leaking from the tip clearance δ increases, and so-called clearance loss CL increases.

That is, as shown in FIG. 3, δ / C _TIP
And the clearance loss CL have a substantially linear relationship,
When a taper is provided in the blade height direction as in the case of the conventional rotor blade 01 shape so that the cord length C _TIP of the chip cross section 05 is reduced, the distance between the inner peripheral surface of the chip casing 06 and the chip cross section 05, so-called, Since the chip clearance δ must be kept at a predetermined size inevitably due to other factors such as torsional vibration of the rotor and the amount of thermal expansion of the rotor blade 01, as shown by a black circle in FIG. Parameter δ / C consisting of clearance δ and code length C _TIP of chip cross section 05
_{The TIP} increases, and the clearance loss CL, which fluctuates substantially in proportion to the value of the parameter δ / C _TIP , increases, resulting in a problem that the turbine efficiency decreases.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a gas turbine.
Above conventional axial-flow turbomachine rotor blades,
Formed on the tip of the rotor blade in order to solve the problems described above
Wing-shaped cord length C _TIPAs large as possible
And the chip clearance δ and the code length C of the chip cross section
_TIPRatio δ / C_TIPIs as small as possible
To reduce the clearance loss CL
Flow turbine blades that can improve the efficiency of
The task is to provide.

[0010]

For this reason, the moving blade of the axial-flow turbomachine of the present invention has the following means. In the moving blade of the axial flow turbomachine, which is implanted on the outer periphery of the rotor and rotates the rotor with the working fluid flowing from the stationary blade, a code length of a tip section of the moving blade is smaller than that of an airfoil portion other than the tip section. The length was made equal to or longer than the cord length in the cross section.

[0011] The cord length is the length of a straight line connecting the leading edge and the trailing edge of a blade formed in an airfoil.

Further, as long as the cord length of the cross section of the airfoil other than the tip is shorter than the cord length of the tip cross section, the cord length of the airfoil from the blade root to the tip cross section like a tapered blade. Does not need to be gradually reduced.

According to the axial flow turbomachine rotor of the present invention, the code length C _{TIP of the} cross section of the tip and the code length C _MED of the cross section of the airfoil section are set to C _TIP > C _MED by the above-mentioned means, _Is increased under the condition that the chip clearance δ is constant by increasing the code length C _TIP of
The parameter defined by / C _TIP can be reduced.

As a result, as shown in FIG. 3, the clearance loss can be reduced substantially linearly in accordance with the decrease in δ / C _TIP , and the efficiency of the turbomachine can be improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an axial flow turbomachine blade according to the present invention will be described below with reference to the drawings. FIG.
FIGS. 1A and 1B are diagrams showing a blade of a gas turbine as a first embodiment of an axial-flow turbomachine blade of the present invention. FIG. 1A is a side view, FIG. (C) is a sectional view of an airfoil section.

As shown in the drawing, the moving blade 1 is fitted to a fitting portion provided on the outer periphery of the rotor, and the blade root portion 2 is provided with the moving blade 1 implanted in the circumferential direction of the rotor and arranged at an equal pitch. A platform 3, which is provided at the outer diameter of the blade root portion 2 and forms a flow path bottom of the working fluid 10 passing between the blades, is provided so as to protrude from the platform 3 in the outer diameter direction, and is installed upstream of the moving blade 01. In addition, a working fluid 1 which is accelerated by a stationary blade not shown and whose flow direction is determined and is ejected acts thereon, and the fluid force of the working fluid 10 causes the rotor to rotate in the circumferential direction to generate power. The shape portion 4 is formed from a tip section 5 formed at the outermost end of the airfoil portion 4.

The rotor blades 1 arranged on the outer periphery of the rotor (not shown) operate while being housed in the chip casing 6 together with the rotor. As described above, since the gas turbine rotor blade 1 is configured to rotate inside the stationary chip casing 6, the gas turbine rotor blade 1 is positioned between the outermost end tip section 5 and the inner peripheral surface of the chip casing 6. Needs to provide a chip clearance δ. That is, the working fluid 10 ejected from the stationary blade and flowing into the moving blade 1 is
The rotor is rotated while passing between the blades of the airfoil portion 4, and a part of the leakage flow 11 leaks from the tip clearance δ.
As a result, a flow that passes through the outer peripheral edge of the moving blade 1 and hardly contributes to the generation of power of the moving blade 01 is formed.

For this reason, the outer peripheral surface of the outer shroud (not shown), which connects the adjacent moving blades 1 to the tip section 5 so as to reduce vibration generated in the moving blade 01, Alternatively, the fins are made to protrude from the inner peripheral surface of the casing 6 to reduce the tip clearance δ and reduce the amount of the leakage flow 11.

As shown in FIG. 1A, the airfoil 4
1 is formed in a blade height direction so as to have a substantially straight cord length from the blade root portion 2 toward the chip cross section 5.
As shown in (b), the code length C _TIP of the airfoil shape of the tip cross section 5 is the code of the airfoil shape of the horizontal cross section at an arbitrary blade height position of the airfoil portion 4 shown in FIG. C _TIP > C _MED , which is longer than the length C _MED .

As described above, the taper having a larger cord length in the blade height direction is provided without providing a taper in which the cord length becomes smaller in the blade height direction of the rotor blade 1. By increasing the length C _TIP , the distance between the inner peripheral surface of the chip casing 6 and the chip cross section 5 is inevitably set to a predetermined value due to the torsional vibration of the rotor, the thermal expansion of the rotor blade 1, and the like. In other words, the chip clearance δ needs to be substantially constant according to the specifications of the gas turbine.
_The parameter δ / C _TIP determined from the _TIP becomes smaller, and is reduced from the black circle position shown in FIG. 3 to the white circle position parameter δ / C _TIP in the moving blade 01 of the conventional gas turbine.

By reducing this parameter δ / C _TIP ,
The clearance loss CL also decreases substantially linearly, the leakage flow rate 11 decreases, and the turbine efficiency improves.

In the embodiment, the cord length in the blade height direction of the airfoil portion 4 is the same, but it may be longer in the outer diameter direction. is there.

[0023]

As described above, the axial-flow turbomachine rotor blade of the present invention is implanted on the outer periphery of the rotor, and rotates the rotor with the working fluid flowing from the stationary blade. In the moving blade of the machine, the cord length of the cross section of the tip of the moving blade is equal to or greater than the cord length of the cross section of the airfoil other than the tip.

[0024] In this manner, the code length in the code length and the airfoil section of the tip section and C _{TI P>} C _MED, by having an increased code length of chip cross section, the tip clearance under certain conditions Thus, the parameter defined by δ / C _TIP can be reduced, and the leakage flow from the tip clearance can be reduced, the clearance loss can be reduced, and the efficiency of the turbomachine can be reduced in accordance with the decrease in the parameter. Can be improved.

[Brief description of the drawings]

FIG. 1 is a view showing a gas turbine rotor blade as a first embodiment of an axial-flow turbomachine rotor blade of the present invention, wherein FIG. 1 (a) is a side view, FIG. 1 (c) is a cross-sectional view of the airfoil at an arbitrary height,

FIG. 2 is a view showing a conventional gas turbine rotor blade.
2A is a side view, FIG. 2B is a cross-sectional view of a chip, FIG.
(C) is a sectional view of the airfoil at an arbitrary height,

FIG. 3 is a diagram illustrating a relationship between a ratio of a chip clearance δ to a code length of a chip cross section and a clearance loss.

[Explanation of symbols]

1,01 Blade 2,02 Blade root 3,03 Platform 4,04 Airfoil 5,05 Chip section 6,06 Chip casing 10,010 Working fluid 11,011 Leakage flow δ Chip clearance C _TIP Chip section cord length Cord length in C _MED airfoil section CL Clearance loss

Claims (1)

[Claims] 1. A moving blade of an axial turbomachine, which is implanted on the outer periphery of a rotor and rotates with a working fluid flowing from a stationary blade, a cord length of a blade section of a tip section of the moving blade is a tip section. An axial-flow turbomachine rotor blade having a length equal to or greater than a cord length of a cross-section airfoil in an airfoil other than the above.