JP3132944B2 - Three-dimensional design turbine blade - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional design blade for an axial gas turbine, a steam turbine or the like.

[0002]

2. Description of the Related Art FIGS. 4 and 5 are an external view of a conventional three-dimensionally designed turbine blade and a stacking diagram of a trailing edge line in a blade height direction, respectively. As shown in these figures, in the three-dimensional design of the turbine blade 1, the pressure surface 1 a of the blade 1 is inclined with respect to the suction surface 1 b on the wall side 3 with respect to the radial stacking 2 having a linear distribution in the radial direction. Perform bow stacking 4.

As described above, in the bow stacking 4, by tilting the wing 1, the wing force 5 is applied to the suction surface 1 a of the wall 3.
Acts to press the flow, thereby suppressing accumulation of low-energy fluid on the suction surface 1a and improving blade performance.

[0004]

By the way, in a conventional three-dimensional design blade, as shown by a solid line 6 in FIG. 1, the gauging distribution (throat width / pitch) of the blade is lowered rightward in the blade height direction. The distribution is determined so as to be a distribution or an upper right distribution (not shown). However, in the actual flow, as shown by the solid line 6a in FIG. 2, in the conventional blade, the outflow angle distribution is larger than the gauging angle 6 on the base and tip side and smaller than the gauging angle 6 on the mean side due to the three-dimensional effect.

FIG. 6 shows a loss distribution in the blade height direction. In the distribution 8 of the conventional blade, a vortex core 8a due to the secondary flow generated near the wall develops, resulting in a large loss, and a two-dimensional loss near the mean. A profile loss 8b showing the target performance can be seen.

On the other hand, in the distribution 9 of the three-dimensional design wing, although the loss near the wall decreases, the profile loss tends to increase near the mean. As shown in FIG. 3, this increase in profile loss is considered to be caused mainly by an increase in the ratio of the wake 11 of the blade to one pitch 12 due to a decrease in the outflow angle (13b → 13a). .

As described above, in the conventional three-dimensionally designed turbine blade, the secondary flow loss on the wall side is reduced, while the profile loss near the mean is increased, and depending on the design, the overall cascade performance is deteriorated. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and suppresses an increase in the profile loss of the mean cross section while maintaining the effect of reducing the secondary flow loss by the three-dimensional effect. It is an object of the present invention to provide a three-dimensionally designed turbine blade capable of improving overall cascade performance.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a three-dimensionally designed turbine blade such as an axial flow turbine or a steam turbine. The gauging value is maximized in the mean section and minimized in the tip or base section.

[0010]

According to the above means, the gauging distribution of the three-dimensional design turbine blade is maximized in the mean cross-section and minimized in the tip or base cross-section, whereby the profile loss caused by the decrease of the outflow angle in the mean cross-section due to the three-dimensional effect. By suppressing the increase and reducing the gauging in the cross section of the tip and the base, the acceleration in the blade passage can be improved and the secondary flow loss can be reduced.

[0011]

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

According to the present invention, as shown by a dashed line 7 in FIG. 1, in a three-dimensional design turbine blade such as an axial flow turbine or a steam turbine, the gauging distribution 7 in the blade height direction is formed to have an upwardly convex shape. Gauging value is maximum in mean cross section,
Further, it is designed to be minimum in a chip or base section (chip section in this embodiment). In the present embodiment, the gauging value in the blade height direction is increased by a relative value of 10 to 20% in the mean cross section with respect to the linear distribution (conventional example: gauging distribution of the control vortex design) 6 applied from the base to the tip. , And 1 on the tip and base cross section
The gauging distribution 7 is set such that the relative value becomes 0 to 20% and becomes smaller.

The dashed line 7a in FIG. 2 shows the outflow angle distribution of the three-dimensionally designed turbine blade according to the present invention. By making the gauging smaller in the base and chip cross sections than in the conventional outgoing angle distribution 6a and larger in the mean cross section, the outflow angle distribution 7a becomes almost equal to the gauging angle distribution 6.

In this case, in order to prevent the deterioration of the performance of the mean cross section while maintaining the effect of reducing the secondary flow loss on the wall side by the three-dimensional effect, the amount of change in gauging with respect to the conventional distribution is 10 to 20 in the base and chip cross sections. % (Relative value)
In addition, good performance can be obtained by designing the mean cross section larger by 10 to 20% (relative value).

The dashed line 10 in FIG. 6 shows the loss distribution in the blade height direction in the three-dimensionally designed turbine blade according to the present invention. According to the loss distribution 10 of the present invention, the effect of reducing the secondary flow loss near the wall is obtained as compared with the loss distribution 8 of the conventional example, and the profile performance in the mean cross section is equal to or higher than that of the conventional example.

[0016]

As described above, according to the present invention, in a three-dimensional design turbine blade such as an axial flow turbine or a steam turbine, the gauging distribution in the blade height direction is made to have an upwardly convex shape, and the gauging value is obtained. Is maximized in the mean cross-section and minimized in the tip or base cross-section to properly control the outflow angle and prevent the reduction in the profile performance of the mean cross-section while maintaining the secondary flow loss reduction effect by the three-dimensional effect. This has the effect of improving the overall cascade performance.

[Brief description of the drawings]

FIG. 1 is a diagram showing gauging distributions of a three-dimensionally designed turbine blade according to one embodiment of the present invention and a conventional three-dimensionally designed turbine blade.

FIG. 2 is a diagram showing the outflow angle distributions of a three-dimensionally designed turbine blade according to an embodiment of the present invention and a conventional three-dimensionally designed turbine blade, respectively.

FIG. 3 is a diagram showing a change in a wake outflow direction due to a three-dimensional effect.

FIG. 4 is an outline view of a conventional three-dimensionally designed turbine blade.

FIG. 5 is a stacking diagram of a blade height direction trailing edge line of a conventional three-dimensionally designed turbine blade.

FIG. 6 is a diagram showing blade height direction loss distributions of a three-dimensionally designed turbine blade according to one embodiment of the present invention and a conventional three-dimensionally designed turbine blade.

[Description of Signs] 6 Gauging distribution of conventional example (linear distribution) 7 Gauging distribution of the present invention

Continuation of front page (56) References JP-A-6-81603 (JP, A) JP-A-2-271002 (JP, A) JP-A-3-267506 (JP, A) JP-A-2-271002 (JP) , A) Japanese Utility Model Application No. 5-27201 (JP, U) Japanese Utility Model Application No. 57-68103 (JP, U) Japanese Utility Model Application No. 62-156085 (Japanese Utility Model Application No. 1-61401) (JP, U) (58) Field of investigation (Int. Cl. ⁷ , DB name) F01D 5/14

Claims (2)

(57) [Claims] In a three-dimensional design turbine blade such as an axial flow turbine or a steam turbine, a gauging distribution in a blade height direction is formed to have an upwardly convex shape, a gauging value is maximized in a mean cross section, and a tip or base cross section is obtained. Then, a three-dimensional design turbine blade characterized by minimizing. 2. The three-dimensionally designed turbine blade according to claim 1, wherein the gauging value in the blade height direction is a relative value with respect to a linear distribution from the base to the tip in a mean cross section of 10%.
20% larger and 1 in tip and base cross section
A three-dimensional design turbine blade characterized by being reduced by 0 to 20%.