JP2753234B2 - Ceramic stationary blade - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a low thermal stress structure of a ceramic sidewall, and in particular, to a static gas which is indispensable to a high combustion gas temperature necessary for high efficiency of a gas turbine stationary blade. Improve the heat resistance of the wing,
The present invention also relates to a structure suitable for improving the strength reliability of the ceramic wall. [Prior art] Conventionally, in a high-temperature gas turbine vane, a surface exposed directly to combustion gas is formed by a ceramic sidewall and a blade portion.
A ceramic / metal composite vane having a metal blade core structure as a strength member was provided therein. However, in this ceramic sidewall structure of the stationary blade, no consideration has been given to the low range of the thermal stress in the sidewall portion. Incidentally, as this type of apparatus, for example, Japanese Patent Application Laid-Open No. 61-8990
No. 6, JP-A-61-89908, and the like. [Problems to be Solved by the Invention] The above prior art does not take into account the local high surface heat transfer conditions of the ceramic sidewall,
There is a problem of destruction of ceramic sidewall due to large thermal stress due to uneven temperature distribution generated in high temperature combustion gas flow. SUMMARY OF THE INVENTION An object of the present invention is to provide a ceramic side wall of a ceramic stator vane which suppresses generation of a large thermal stress even in a high-temperature combustion gas flow brought to achieve high efficiency and has high strength and reliability. is there. [Means for Solving the Problems] The above object is achieved by providing a cutout at the front edge of the wing of the ceramic sidewall. [Action] The leading edge of the wing portion of the ceramic sidewall exposed to the high-temperature combustion gas flow is a portion where the heat transfer coefficient changes rapidly, and high thermal stress and high compressive stress are generated due to thermal deformation constraint due to ceramic rigidity. By providing a notch at the front edge of the wing portion of the ceramic sidewall, the thermal deformation constraint is released, so that thermal stress and compressive stress are reduced, and the strength reliability of the ceramic sidewall can be secured. Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a ceramic sidewall according to an example of the present invention. FIG. 2 shows a longitudinal sectional view of a ceramic stator vane to which the present invention is applied. FIG. 3 is a cross-sectional view of a conventional vane, and FIG.
A 'corresponds to a sectional view. FIG. 2 is a cross-sectional view showing a state in which a ceramic stator vane using the present invention is supported by a retainer ring 2 fixed to a casing of a gas turbine. Wing part 1 made of ceramic and ceramic side wall 3 fitted thereto
Is a support plate 5 formed by a metal blade core 4 penetrating through the inside of the wing portion 1.
Is held fastened through. The sidewall 3 is positioned by fitting with the groove of the wing portion 1, and has a structure in which a heat shield layer 6 also serving as a deformation buffer layer is provided between the ceramics and the metal component. . The side wall 3 and the wing 1 that are directly exposed to the combustion gas
Is held by When the stationary blade is exposed to the high-temperature combustion gas, the surface of the stationary blade constantly reaches the combustion gas temperature. Further, not only a mechanical load based on the pressure distribution of the wall surface acts on the surface of the stationary blade, but also an effect of a vibration load due to pulsation of the combustion gas is considered. On the other hand, since the stationary blade skin has the wing portion and the side wall made of ceramics having excellent heat resistance, it can sufficiently withstand high-temperature exposure. On the other hand, with respect to the mechanical load caused by the combustion gas, the metal blade core 4 shares the load via the heat shield layer 6, so that a large mechanical load does not act on the blade 1. Thus, only the thermal stress generated by exposure to the combustion gas is applied to the ceramic component. FIG. 3 is a schematic diagram of the structure of a conventional ceramic stator vane.
1500 ℃ of the ceramic sidewall forming this stationary blade
FIG. 4 shows an example of the results of thermal stress analysis when exposed to a high-temperature combustion gas flow. FIG. 4 shows an iso-stress diagram of stress in the y-axis direction of the ceramic sidewall. FIG. 5 shows a schematic view of the sidewall. In the groove 11, a high stress is generated at a position corresponding to the leading edge 12, and its value is about 600 MPa as a tensile stress. At the same time, an extremely high compressive stress is generated at the outer peripheral edge of the sidewall close to the high stress generating position, and this value reaches about 2000 MPa. It is said that ceramics is inherently high strength against compression.However, the existence of tensile stress in the vicinity of this part causes the deformation situation to suddenly change in the vicinity of this part, causing a large deformation constraint. That means. Accordingly, it is effective to release the deformation constraint in the low thermal stress region of the sidewall. Therefore, it is possible to reduce the thermal stress by providing a cut or a partial division in a portion of the sidewall that is under large deformation constraint. The cause of the thermal stress is mainly due to the heat transfer conditions of the surface exposed to the combustion gas. FIG. 6 shows an example obtained by analyzing this situation. The following table shows the data. Tip; sidewall Inlet total temperature; 1553K (1280 ° C) Inlet total pressure; 15ata As is clear from these results, the portion where the heat transfer coefficient changes abruptly is near-or-, as shown in Fig. 4. In addition, high compressive stress is generated together with high thermal stress. From the above results, it is effective to reduce the high thermal stress by providing a discontinuous portion in the structure at the portion where the heat transfer coefficient changes suddenly. FIG. 1 shows an embodiment that realizes this concept. Notch 13 in leading edge 12 for effective area
Is provided. Thereby, since the restraint of the thermal deformation is basically released, the thermal stress in the vicinity of the portion is reduced, and the strength reliability of the ceramic sidewall can be secured.
This effect can also be achieved by another embodiment shown in FIG. That is, even if the notch 14 is provided instead of the notch 13, the effect of reducing the thermal stress can be obtained. FIG. 8 shows another embodiment. The same effect can be obtained by providing a slot row 15 instead of the notch 13 or the cut 14. In short, what is necessary is just to provide something which can make thermal deformation free in the leading edge portion 12 where the thermal condition changes rapidly. [Effects of the Invention] According to the present invention, by releasing the deformation constraint caused by the temperature difference, only a relatively small thermal stress is generated in the ceramics member in the high-temperature combustion gas flow, and the strength reliability is reduced. It can provide high ceramic stator vanes. In addition, a high temperature of 1300 ° C. or more can be achieved, and the amount of cooling air can be reduced, so that high efficiency can be expected.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a ceramic sidewall according to one embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a stationary blade to which the sidewall as in the present invention can be applied, FIG. FIG. 4 is a cross-sectional view of a conventional stationary vane, FIG. 4 is an analysis diagram of thermal stress generated in a sidewall, FIG. 5 is a perspective view of a general ceramic sidewall, and FIG. 6 is an example of the present invention. FIGS. 7 and 8 are perspective views of a sidewall showing another embodiment of the present invention, respectively. 1 ... wing part, 2 ... retainer ring, 3 ... ceramic sidewall, 4 ... metal core, 5 ... support plate, 6 ...
Heat shielding layer, 7 Supporting, 8 Cooling holes, 9
Air inflow holes, 11 ... grooves, 12 ... front edge, 13 ... notches, 14 ... notches, 15 ... slots.

Continuation of front page    (72) Inventor Minoru Hisamatsu               2-6-1 Nagasaka, Yokosuka City, Kanagawa Prefecture               The Central Research Institute of Electric Power Industry Yokosuka Research Institute (72) Inventor Takashi Machida               502 Kandate-cho, Tsuchiura-shi, Ibaraki Pref.               Hitachi Machinery Laboratory (72) Inventor Hiroshi Miyata               502 Kandate-cho, Tsuchiura-shi, Ibaraki Pref.               Hitachi Machinery Laboratory (72) Inventor Shiro Iijima               4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Co., Ltd.               Hitachi Research Laboratory, Hitachi Research Laboratory                (56) References JP-A-61-89909 (JP, A)

Claims (1)

(57) [Claims] A ceramic blade having a hollow portion, a metal blade core having a heat shield layer on a surface inserted into the hollow portion of the ceramic blade, and a ceramic sidewall fitted to both widthwise end surfaces of the ceramic blade. A ceramic sidewall having a metal sidewall support plate disposed on the side of the ceramic sidewall opposite to the ceramic blade portion side via the heat shield layer, wherein a leading edge of the blade portion of the ceramic sidewall is provided. A ceramic stationary blade characterized by having a notch in the section.