JPH0988505A - Turbine blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce non-steady heat stress which is generated during the operation of a turbine blade made of fiber reinforced ceramics by orienting fiber for reinforcement in the direction of the thickness of the blade or in the direction of rotation of a turbine. SOLUTION: A platform on a basic end side of a moving blade 11 made of fiber reinforcing ceramics is fitted and attached in a groove formed on outer periphery of a disc 10. Fiber 13 for reinforcement to be embedded in a matrix section 12 is oriented in the direction of the thickness of the blade as well as the direction of radius of a turbine (Z direction). The direction of the thickness of the blade means the orthogonal direction to an outer peripheral face of the blade, namely, the direction of normal. The orientation amount in the direction of the thickness of the blade of the fiber 13 for reinforcement is set to 50 to 100%, of the orientation amount in the direction of radius of the turbine (Z direction). Since the fiber 13 for reinforcement is oriented in the direction of the thickness of the blade as well as the direction of radius of the turbine, heat transfer rate of a heat flow passage in the direction of the thickness of the blade which is the closest to an outer surface of the blade is increased comparatively, and heat transfer in this direction becomes easy. Accordingly, it is possible to relax temperature distribution at the non-steady time and reduce heat stress greatly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbine blade, and more particularly to a turbine blade made of fiber reinforced ceramics.

[0002]

2. Description of the Related Art Recently, turbine blades made of FRC (fiber reinforced ceramics) have been developed because they are excellent in heat resistance and strength. The orientation of the reinforcing fibers when the turbine blade is manufactured by FRC corresponds to such a centrifugal stress because a large tensile stress is generated in the radial direction of the turbine due to the centrifugal force during the rotation, and therefore the orientation is shown in FIG. Generally, the Z direction is used, and the YZ direction, in which two-dimensional fabrics are laminated as shown in FIG. 7, is used.

Here, in FIGS. 6 and 7, X is a turbine rotation direction, Y is a turbine axis direction, and Z is a turbine radial direction, which are orthogonal to each other. In these figures, F represents a reinforcing fiber. Further, in the turbine vane, a laminated material having a YZ two-dimensional woven fabric in the fiber direction is often used because of the ease of manufacturing the thick FRC.

[0004]

By the way, in general, F
Since RC has a large decrease in the thermal conductivity of the matrix due to the presence of voids, the distribution of fibers in each direction causes thermodynamic anisotropy. Therefore, in the conventional fiber orientation of turbine blades, the thermal conductivity in the blade thickness direction or the turbine rotation direction (X direction) is the same as that in the turbine radial direction and the chord length or the turbine axial direction (Y direction). Compared to a large decrease In particular, in a shape such as a turbine blade where the wall thickness changes greatly, when the fiber orientation described above is used, the heat quantity of the thick wall portion has a low thermal conductivity in the blade thickness direction with a short distance. Because of the long distance in the chord length direction, which has high conductivity, it becomes difficult to move, and the central portion of the blade cannot follow the temperature change of the outer surface, and a large temperature gradient is generated between this portion and the outer surface portion. The thermal stress generated by such a mechanism may be about twice the centrifugal stress.

FIG. 8 shows the fiber orientation of a turbine blade made of FRC having a general shape with the fiber orientation in the turbine radial direction (Z direction).
It shows the results of unsteady thermal stress analysis in the case of using only. In the case of this blade, the centrifugal stress is 130 MPa, whereas the thermal stress generated is 200 MPa, which indicates that the thermal stress is about 1.5 times the centrifugal stress.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a turbine blade capable of reducing unsteady thermal stress generated during operation.

[0007]

In order to achieve the above object, in the present invention, in a turbine blade made of fiber-reinforced ceramics, reinforcing fibers are oriented in the blade thickness direction or the turbine rotation direction. Further, it is preferable to set the orientation amount of the reinforcing fibers in the blade thickness direction or the turbine rotation direction to 50 to 100% of the orientation amount in the turbine radial direction.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a turbine rotor blade to which the present invention is applied. In the figure, reference numeral 10 is a disk, and 11 is a moving blade attached to a groove formed on the outer periphery of the disk 10 by fitting a platform on the base end side. This moving blade 11 is F
It is made of RC. The reinforcing fibers 13 embedded in the matrix portion 12 are oriented not only in the turbine radial direction (Z direction) but also in the blade thickness direction. Here, the blade thickness direction is
A direction that is substantially perpendicular to the outer peripheral surface of the blade, that is, a normal direction. The amount of orientation of the reinforcing fibers 13 in the blade thickness direction is set to 50 to 100% of the amount of orientation in the turbine radial direction (Z direction).

In the turbine rotor blade having the above structure, the reinforcing fibers 13 are oriented not only in the turbine radial direction (Z direction) but also in the blade thickness direction. Therefore, the blade thickness direction closest to the blade outer surface is obtained. Since the heat transfer coefficient of the heat flow path to the heat transfer path is relatively high and the heat can be easily transferred in this direction, the temperature distribution in the non-steady state is relaxed and the heat stress is significantly reduced.

FIG. 2 shows the thermal stress analysis results of the turbine rotor blade when the reinforcing fibers are oriented in the blade thickness direction and the turbine radial direction by 20% of the total weight. In this analysis, it can be seen that the generated thermal stress is about 120 MPa, and the generated thermal stress is reduced to about 60 to 70% of the thermal stress generated in the conventional fiber orientation (the one already described in FIG. 8). .

FIG. 3 shows that the total Vf value (the ratio of the reinforcing fiber weight to the total weight) is 40%, the blade thickness direction,
It is a comparison of the maximum thermal stresses generated when the fiber orientation amount in the chord length direction is changed. From this figure, it is understood that when the fiber ratio in the blade thickness direction is increased, the amount of decrease in the generated thermal stress is large. However, in the case of turbine blades, centrifugal stress is applied in addition to thermal stress. In this case, if the fiber orientation ratio in the blade thickness direction is simply increased, the Vf value of the FRC has an upper limit in the manufacturing method, so that V in the centrifugal stress direction is increased.
The f value decreases, and the strength in the radial direction of the turbine decreases.
This phenomenon results in a decrease in the margin against fracture stress, and therefore, in the case of turbine blades, fiber orientation that balances anti-centrifugal stress and anti-thermal stress is required.

FIG. 4 shows the ratio of the principal stress to the breaking stress in each fiber orientation state when the total Vf value is 40% and the fiber orientation amount in the blade thickness direction, the chord length direction, etc. is changed. . The principal stress is a value obtained by adding centrifugal stress to thermal stress, and when the principal stress / breaking stress is 1 or more, the blade breaks. From this figure, for 100 fiber orientations in the radial direction of the turbine, 5
It can be seen that the reinforcing fibers of about 0 to 100 oriented in the blade thickness direction have a large margin for the breaking stress.

This analysis was conducted in the blade thickness direction and the blade chord length direction. However, when the fiber orientation is the turbine rotation direction (X direction) and the turbine axis direction (Y direction), 5
It is known that orientation in the turbine rotation direction (X direction) corresponding to the blade thickness is effective in reducing thermal stress, as shown in Fig. 4, and the orientation amount in this direction is also the turbine radial direction (Z direction). About 50 to 100% of the orientation amount has the highest effect of reducing thermal stress. 5 shows another embodiment of the present invention, in which the reinforcing fibers 13 embedded in the matrix portion 12 include the turbine radial direction (Z direction) and the turbine rotation direction ( It is also oriented in the X direction).

In the embodiment of the invention described above, the turbine moving blade is described as an example, but it goes without saying that the present invention is not limited to this and can be applied to a turbine stationary blade. Yes.

[0015]

According to the invention of claim 1, since the reinforcing fibers are oriented not only in the turbine radial direction but also in the blade thickness direction, the heat flow in the blade thickness direction closest to the blade outer surface is obtained. The heat transfer coefficient of the passage becomes relatively high, and the temperature distribution during non-steady state is relaxed. As a result, it becomes possible to significantly reduce the unsteady thermal stress.

According to the invention described in claim 2, since the turbine rotating direction corresponds approximately to the blade thickness, it is possible to greatly reduce the unsteady thermal stress as in the invention described in claim 1. .

According to the third aspect of the invention, the orientation amount of the reinforcing fibers in the blade thickness direction or the turbine rotation direction is set to 50 to 100% of the orientation amount in the turbine radial direction. As a result, the balance between the anti-centrifugal stress and the anti-heat stress becomes good, and it is possible to obtain a turbine blade that is more excellent in strength.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a diagram showing a thermal stress analysis result of a turbine rotor blade.

FIG. 3 is a diagram showing a difference in generated thermal stress depending on fiber orientation.

FIG. 4 is a diagram showing a ratio of principal stress to breaking stress of fiber orientation in the case of total Vf of 40%.

FIG. 5 is a plan view showing another embodiment of the present invention.

FIG. 6 is a view showing an example of orientation of reinforcing fibers in a conventional FRC turbine blade.

FIG. 7 is a diagram showing another example of orientation of reinforcing fibers in a conventional FRC turbine blade.

FIG. 8 is a diagram showing a difference in thermal stress generated due to fiber orientation in a conventional turbine rotor blade.

[Explanation of symbols]

 10 Disc 11 Turbine Blade 12 Matrix 13 Fiber for Reinforcement

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Maie 229 Togaya, Mizuho-cho, Nishitama-gun, Tokyo Ishi Kawashima Harima Heavy Industries Ltd. Mizuho Plant Co., Ltd.

Claims (3)

[Claims] 1. A turbine blade made of fiber-reinforced ceramics, characterized in that the reinforcing fibers (13) are also oriented in the blade thickness direction. 2. A turbine blade made of fiber-reinforced ceramics, characterized in that the reinforcing fibers (13) are also oriented in the turbine rotation direction (X). 3. The turbine blade according to claim 1 or 2, wherein an amount of orientation of the reinforcing fibers in a thickness direction of the blade or a direction of rotation of the turbine is 50 to 100 which is an amount of orientation in a turbine radial direction (Z). Turbine blades characterized by being set to%.