JPS6189903A - Thermal impact structure for ceramic stationary blade - Google Patents

Abstract

PURPOSE:To reduce thermal stresses by deviding a wing section of a ceramic stattionary blade chordwise into more than two segments. CONSTITUTION:A wing section of a ceramic stationary blade is devided chordwise into more than two segments: a leading edge section 11 and a trailing edge section 12. This enables each of the segments to deform freely in expansion or contraction allowing thermal stresses to be reduced.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a ceramic stator blade for a high-temperature gas turbine;
In particular, it relates to a stator blade structure with excellent thermal shock resistance.

[Background of the invention]

Conventional gas turbine stationary blades are made of heat-resistant superalloys, and active air cooling is carried out, but in the current range where heat-resistant superalloys are used, the temperature of the alloy must be kept at around 800C. is required for its heat resistance9, and as a result, the combustion gas temperature at the turbine inlet is said to be limited to about 1300C at most.

However, in order to further improve the efficiency of a gas turbine, it is essential to increase the temperature of the combustion gas, and it is said that in order to achieve this, it is essential to make the parts directly exposed to the high-temperature gas flow ceramic. However, it is also known that ceramics, which have excellent heat resistance, are significantly inferior in thermal shock strength compared to metal materials. Therefore, it is shown that sufficient thermal shock resistance reliability cannot be ensured under the usage conditions of a gas turbine by simply converting the conventional stator vane structure made of a metal material into a ceramic material.

[Purpose of the invention]

The purpose of the present invention is to create a ceramic stator vane for an industrial gas turbine, which takes advantage of the excellent heat resistance inherent in ceramics and suppresses the thermal shock stress generated under the same operating conditions, in order to compensate for the inherent low thermal shock resistance. Our goal is to provide the following.

[Summary of the invention]

In order to improve the efficiency of gas turbines, it is also very effective not to release cooling air into the high-temperature combustion gas flow. Therefore, in consideration of the heat resistance of the ceramic itself, we omitted the extensive cooling of the ceramic portion that constitutes the stationary blade and is directly exposed to high-temperature gas. Next, we focused on the flaw in the brittleness of ceramics itself, that is, the allowable elongation before breaking. It has a structure that allows it to expand and contract freely.

Such a structure does not allow for the realization of a fine-grained cooling structure that corresponds to the temperature distribution on the surface of the stator blade, which was conventionally adopted with metal stator blades, and by making the stator blades ceramic. This is the first time this has become possible.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 10.

FIG. 1 shows the overall configuration including one embodiment of the present invention. The invention relates in particular to the wing 1, which consists of several segments that are joined together by means of a mating connection, and includes ceramic side plates 4 and 5, side walls 2.3. The side worms are fixedly supported by a member 6 which penetrates the inside of the wing section and firmly fastens the side worms together. Detailed embodiments of the wing section 1 are shown in FIGS. 2 to 10. 2 to 4 are each characterized in that the wing section is divided into one segment at the leading edge of the wing section in the longitudinal direction. Gas turbine stationary blades undergo rapid temperature changes when starting or stopping. In particular, ceramics generally have poor thermal conductivity properties, resulting in a large temperature difference between the leading edge and the remaining region, but in these embodiments, each segment 11 and 12 can freely expand and contract, and each The segments are not restrained from deforming each other.

FIG. 5 shows another embodiment aiming at a different effect, in which the combustion gas temperature at the inlet of the gas turbine stator blade exhibits a trapezoidal temperature distribution in the gas turbine radial direction (corresponding to the longitudinal direction of the stator blade). This example focuses on the fact that the vane is high at the center of the vane and low at the sidewall side, that is, at the tip of the vane, and the stator vane is divided into three parts in the longitudinal direction: a central segment 22, and upper and lower segments 21 and 23. In this case, it is desirable to determine the dimensions of each segment so that the temperature within each segment is as uniform as possible according to the given design specifications for the gas turbine inlet temperature distribution. Figure 6 is a combination of the embodiments shown in Figures 2 and 5 with different aims, and aims to create a stator blade that can withstand the trapezoidal distribution of turbine inlet temperature and rapid fluctuations in combustion gas temperature. That's what I was aiming for.

FIGS. 7 and 8 show examples in which the same effect is aimed at for the temperature difference between the back side and the vent side of the stationary blade.

FIG. 9 shows an example of the fitting structure of each segment in the case of the embodiment shown in FIG. 5. The upper segment 21 is provided with a convex portion 41 having an R cross-sectional shape, and to match this, the central segment 22 is provided with four portions 42 on the upper surface and a convex portion 43 on the lower surface in the figure. Further lower segment 23
Similarly, a concave portion 44 is provided on the upper surface, and a convex portion 41
are fitted into the recesses 42, and the protrusions 43 are fitted into the recesses 44, respectively, and the entire wing section is formed by each segment.

FIG. 10 further shows the detailed structure of one segment of FIG. 6 in the same way as FIG. 9. Although this example shows the center segment in Fig. 6, the concave and convex parts shown in Fig. M9 are not necessary for fitting segments 51 and 52, and in this case, there is no need for the concave and convex portions shown in Fig. M9. The mating structure provides fixed support for each segment.

〔Effect of the invention〕

According to the present invention, each part of the stator blade is divided into segments, and the right segment is configured to have as uniform a temperature as possible, so each segment can freely expand and contract. Therefore, the thermal stress in each segment is significantly reduced, and the thermal stress generated in the entire stationary blade is therefore suppressed to a low level, resulting in the effect that strength reliability can be significantly improved. Further, in case of damage caused by exposure to the combustion gas flow, only the corresponding segment can be partially replaced. On the other hand, since the load conditions differ depending on the segment, side effects such as the ability to save maintenance costs as a whole are also expected, such as by replacing segments sequentially when they reach the end of their design life.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the entire stator vane, Figs. 2 to 8 are perspective views of the Okonobe showing different embodiments, and Figs. 9 to 10 show different embodiments. FIG. 3 is a perspective view of the constituent parts of the wing section. 11... Segment of the leading edge of the butt, 12... Trailing edge of the wing 'ij g Continued from Page 1 of the Registrar 5 Inventor: Miya 1) Hiroshi 50, Kandate-cho, Tsuchiura City■ Inventor: Iijima History Department 3-1 Saiwaimachi, Hitachi City

Claims (1)

[Scope of Claims] 1. Upper and lower sidewalls forming a flow path for guiding high-temperature combustion gas to rotary rotor blades that perform work; In a gas turbine ceramic stator vane consisting of a vane section arranged to allow gas flow to flow into a rotating rotor blade at a constant angle, the leading edge and the trailing edge of the vane section are arranged in the chord direction of the vane section. Along 2
A ceramic stator vane with a thermal shock-resistant structure characterized by being separated into more than one individual piece.