JPH06272504A - Three dimensional design turbine blade - Google Patents

Abstract

PURPOSE:To maintain secondary flow loss reducing effect by three dimensional effect and to suppress increase of a profile loss in a mean cross section at the same time. CONSTITUTION:In a three dimensional design turbine blade such as an axial flow turbine and a steam turbine, a gauging distribution 7 in the blade height direction is formed into an upward projecting shape, and a gauging value takes the maximum value in a mean cross section while takes the minimum value in a tip cross section or in a base cross section. Suitably, the gauging value in the blade height direction is increased by 10-20% in the mean cross section as a relative value, while reduced by 10-20% in the tip cross section and in the base cross section in comparison to the linear distribution from the base to the tip.

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 axial flow gas turbines, steam turbines and the like.

[0002]

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

As described above, in the bow stacking 4, by tilting the blade 1, the blade force 5 is applied to the suction surface 1a on the wall side 3.
By acting to press the flow, the accumulation of the low energy fluid on the suction surface 1a can be suppressed and the blade performance can be improved.

[0004]

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

FIG. 6 shows the loss distribution in the blade height direction. In the distribution 8 of the conventional blade, the vortex core 8a due to the secondary flow generated near the wall develops and becomes a large loss, and two-dimensional near the mean. You can see the profile loss 8b which shows the dynamic performance.

On the other hand, in the distribution 9 of the three-dimensional design blade, although the loss near the wall decreases, the profile loss tends to increase near the mean. It is considered that the increase in the profile loss is caused mainly by the increase in the ratio of the wing 11 of the blade to the pitch 12 per one pitch 12 (13b → 13a) as shown in FIG. .

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

The present invention has been made in order to solve the problems of the prior art as described above, and suppresses the profile loss increase of the mean cross section while maintaining the effect of reducing the secondary flow loss due to the three-dimensional effect. It is an object of the present invention to provide a three-dimensional design turbine blade capable of improving the blade cascade performance as a whole.

[0009]

In order to solve the above problems, the present invention provides a three-dimensional design turbine blade such as an axial flow turbine, a steam turbine, etc., in which the gauging distribution in the blade height direction is convex upward. And 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, so that the profile loss due to the decrease of the outflow angle in the mean cross section due to the three-dimensional effect is achieved. By suppressing the increase and reducing the gauging in the tip and base cross sections, it is possible to improve the acceleration in the blade passage and reduce the secondary flow loss.

[0011]

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

In the present invention, as indicated by a chain 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 convex upward, The gauging value is maximum in the mean section,
The cross section of the chip or the base (the cross section of the chip in this embodiment) is minimized. Then, in this embodiment, the gauge value in the blade height direction is set to a relative value of 10 to 20% relative to the straight line distribution (conventional example: gauging distribution of controlled vortex design) 6 obtained by multiplying the base from the tip to increase the relative value. , And 1 on the reverse of the tip and base cross sections
The gauging distribution 7 is set so that the relative value is reduced to 0 to 20%.

The alternate long and short dash line 7a in FIG. 2 shows the outflow angle distribution of the three-dimensional design turbine blade according to the present invention. The outflow angle distribution 7a becomes substantially equal to the gauging angle distribution 6 by making the gauging angle distribution 6a smaller in the base and chip cross sections than in the conventional example and larger in the mean cross section.

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 due to the three-dimensional effect, the variation of gauging with respect to the conventional distribution is 10 to 20 in the base and chip cross sections. % (Relative value)
Also, good performance can be obtained by designing the mean cross section to be larger by 10 to 20% (relative value).

The alternate long and short dash line 10 in FIG. 6 shows the loss distribution in the height direction of the three-dimensional design turbine blade according to the present invention. The loss distribution 10 of the present invention has an effect of reducing the secondary flow loss in the vicinity of the wall as compared with the loss distribution 8 of the conventional example, and the profile performance in the mean cross section is the same as 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 upward convex shape, and its gauging value is obtained. Is maximized in the cross section of the mean and minimized in the cross section of the tip or the base to properly control the outflow angle and maintain the secondary flow loss reduction effect due to the three-dimensional effect while preventing the profile performance of the cross section of the mean from decreasing. There is an effect that the cascade performance as a whole is improved.

[Brief description of drawings]

FIG. 1 is a diagram showing gauging distributions of a three-dimensional design turbine blade according to an embodiment of the present invention and a conventional three-dimensional design turbine blade, respectively.

FIG. 2 is also a diagram showing outflow angle distributions of a three-dimensional design turbine blade according to an embodiment of the present invention and a conventional three-dimensional design 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-dimensional design turbine blade.

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

FIG. 6 is a diagram showing blade height loss distributions of a three-dimensional design turbine blade according to an embodiment of the present invention and a conventional three-dimensional design turbine blade, respectively.

[Explanation of symbols]

 6 Gauging distribution of conventional example (linear distribution) 7 Gauging distribution of the present invention

Claims (2)

[Claims] 1. 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 maximized in the mean section, and the tip or base section is used. The three-dimensional design turbine blade is characterized by being the smallest. 2. The three-dimensional design turbine blade according to claim 1, wherein a gauging value in a blade height direction is a relative value with respect to a straight line distribution from a base to a tip and is 10 in a mean section.
~ 20% larger and 1 for chip and base cross section
A three-dimensionally designed turbine blade that is 0-20% smaller.