JPS59160007A - Stationary blade for gas turbine - Google Patents

Abstract

PURPOSE:To improve a gas turbine in its operating efficiency, by arranging such that while the head portion of blade and a blade body are respectively formed with a different material each other and a cooling air blow-off port is provided along the boundary surface thereof, the width of blade is made smaller at the boundary surface than at the head portion of blade. CONSTITUTION:A plurality of stationary blades 1 are arranged in an annular configuration and comprise a blade body 2 made of heat resistant alloy and the ceramics head portion 3 of blade provided at a forward edge for preventing the flow of main stream gas. These two elements 2, 3 are formed such that their boundary surface may be convexed at the blade body 2 side. On the other hand, the interior of blade body 2 is partitioned by a partition wall 6 for defining two hollow portions 4, 5 which communicate with a cooling air source. One hollow portion 4 communicates with a cooling air blow-off port 7 and furthermore with a cooling air blow-off passage 8 defined along the boundary surface of these two elements 2, 3. The hollow portion 4 is opened at opposite sides of stationary blade 1. The width l of the blade is made smaller by the size of notched portion 10 at the blade body 2 than the width L of blade at the blade head portion 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates primarily to stator blades used in high-temperature gas turbines and the like.

In recent years, gas turbines have tended to become hotter and hotter in order to improve the performance and output of the turbines. Therefore, a major technical issue is how to maintain the strength of turbine blades under such high temperature gas conditions. In order to solve these problems, a method of cooling the blades has been adopted, and in order to dam up the mainstream gas in the stator blades, the blade head, which is the hottest part, is separated from the blade body, and it is made of a material with high heat resistance. It is conceivable that the i section be supported by the wing body or other components of the wing. However, with stator blades of this configuration, gaps may occur in the head support due to differences in thermal expansion coefficients due to different members, and the blade head may be misaligned with the blade body due to manufacturing errors. If the head is even slightly misaligned with the wing body, causing the wing body side to protrude outward and forming a step, this step will cause the mainstream gas flowing on the wing surface to separate, reducing aerodynamic performance and reducing extension. In this case, a problem arises in that the performance of the gas turbine is deteriorated.

An object of the present invention is to solve the above-mentioned problems and to provide a blade structure that can be effectively used as a blade structure without causing separation of mainstream gas when the blade is constructed by combining different members. It is an object of the present invention to provide a stationary blade for a gas turbine that improves the performance of the gas turbine.

A stationary blade for a gas turbine according to the present invention that achieves the above object is composed of several heads and a blade body, which are made of separate members, and a blowout passage for cooling air is provided along the boundary surface thereof. The wing span on the wing body side is smaller than the wingspan on the wing head side.

Hereinafter, the present invention will be explained with reference to embodiments shown in the drawings.

FIG. 1'' shows a stator blade of a gas turbine according to an embodiment of the present invention. In this figure, 1 is a stator blade;
These plural pieces are arranged in a ring. High temperature gas is supplied to the left side of the stationary blade group arranged in this manner as shown by the arrow.

The stationary blade 1 is composed of a blade main body 2 made of a heat-resistant alloy and several heads 6 made of ceramic on the leading edge side for damming the mainstream gas. The boundary surface between the wing body 2 and the head 6 is convex on the wing body 2 side. The lines of cross section forming the interface of this convex surface may be curved lines or may be lines of force. Furthermore, the extension lines of the boundary surfaces extending to the wing sides on both sides are at acute angles α and α, respectively, with respect to the tangent to the wing sides.
'.

On the other hand, inside the blade body 2, a cooling air supply source (not shown) (a compressor driven by a turbine section of a gas turbine) is provided.
A partition wall 6 separates two hollow portions 4° 5 which communicate with each other.

One hollow part 4 communicates with cooling air blowing holes 7, 7,
Furthermore, a cooling air blowing passage 8 provided along the boundary surface between the blade body 2 and the several heads 6 through these blowing holes 7, 7.
, 8, and open on both sides of the wing.

At the boundary surface, as shown in FIG. 2, the wing span l on the wing body side is made smaller than the wing span on the head side by a distance of 100 minutes at the notch.

The cooling air supplied to the hollow portion 4 is blown out from the blow-off passages 8, 8 to the outside of the blade through the blow-off holes 7.7. The other hollow portion 5 opens at the trailing edge of the blade through a cooling air blowout hole 9. Therefore, the cooling air supplied to the hollow portion 5 convects the inside and is then blown out from the blow-off holes 9 toward the trailing edge of the blade.

According to the stationary blade described above, at the interface between the multiple heads and the blade body, the blade width on the wing body side is formed to be smaller than the wingspan of the multiple heads, so the multiple heads 6 are misaligned. Even if the blade main body 2 does not protrude into the mainstream gas passage to form a convex step, the mainstream gas will not separate. Here, a concave step is formed on the boundary surface due to the above configuration, but since the cooling air is blown out from this concave step, the separation phenomenon of the mainstream gas based on this step does not occur. do not have. Therefore, in a gas turbine equipped with this stationary blade, aerodynamic performance does not deteriorate due to separation of mainstream gas.

In the stator vane configured in the embodiment described above, the leading edge, which is the hottest part of the stator vane that holds back the mainstream gas, is formed by the head 6 made of ceramic, which has higher heat resistance than metal. Because of this, there is no need to provide cooling air blow-off holes or film cooling at this leading edge, unlike the front part of conventional stationary blades. On the other hand, the leading edge of the blade body 2 does not reach a high temperature, and its tip is shielded from the heat of the mainstream gas by the ceramic heads 3, and is heated by the blowout passage 8 provided at the interface between the two. Since the transmission is prevented, a large amount of cooling air is no longer required in the stationary blades of the conventional mechanism to cool the blade body 2 itself. As a result, the amount of cooling air mixed into the mainstream gas is reduced, suppressing the drop in average gas temperature, improving the efficiency of the gas turbine, and reducing the power required to drive the trench compressor. This will further improve efficiency. The bent blowout passage 8 does not open at the leading edge like in conventional vanes, but instead
Since the openings are made on the side of the blade, the dynamic pressure of the mainstream gas does not directly act on it, unlike in the case of conventional stationary blades.On the contrary, the speed of the mainstream gas increases and the pressure decreases. It is no longer necessary to take measures to lower the high-temperature gas pressure in consideration of the pressure difference with the high-temperature gas in order to enable the blowing of cooling air, so this also contributes to improving gas turbine efficiency. become. .

Furthermore, in the above embodiment, since the extension line of the blowout passage 8 is at an acute angle with respect to the tangent to the blade surface, even if the pressure of the cooling air becomes greater than the pressure of the mainstream gas, there is no possibility that it will be blown out forcefully. Even if this happens, a good film layer of cooling air will be formed on each 1 μm surface of the blade, and the cooling performance and aerodynamic performance will not be impaired.

In addition, in the stator blade of the above embodiment, since no cooling air blowing hole is provided at the leading edge that receives the dynamic pressure of the mainstream gas, the blade structure is designed to blow out the cooling air according to the pressure distribution of the mainstream gas. can be made simpler than conventional stator vanes that emit air from the front section.

Furthermore, because ceramic has inferior structural strength compared to metal, it was previously considered difficult to use it for the stationary blades of gas turbines. However, in the above embodiment, only the head 3 is made of ceramic, and The structure is such that the structural strength of the metal wing body 2 is maintained, and the aerodynamic force applied to the head 6 is also maintained by the wing body 2.
This makes it possible to use ceramics. Accordingly, it is possible to further improve gas turbine efficiency. Moreover, if the true head part 3 of the ceramic is made convex on the wing body 2 side as in the embodiment, even if the direction of the force of the mainstream gas acting on several heads B changes, this force will be transferred to the main body 2. It can be supported by If the true head 3 and the wing body 2 are a combination of concave and convex surfaces, even if the ceramic head is damaged for some reason, the joint surface with the wing body 2 will be convex. It is possible to maintain a certain level of aerodynamic performance, and it can be easily replaced.

As mentioned above, the stator blade of the gas turbine according to the present invention has the following features:
The true head and the wing body are constructed from separate members, and a cooling air blowout passage is provided along the boundary surface, and the blade width on the wing body side at the boundary surface is set to be equal to the width of the wing on the several head side. Since the blade is made smaller, even if the true head is misaligned with the blade body, there will be no step on the blade surface that will cause separation and reduction of mainstream gas, thereby preventing the performance of the gas turbine from deteriorating. Can be done.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a stationary blade of a gas turbine according to an embodiment of the present invention, and FIG. 2 is a sectional view of a main part of the blade of the same age. 1... Stationary blade, 2... Wing body, 3... True head, 4,
5...Hollow part, 7, 9...Blowout hole, 8...Blowout passage, 10...Notch part. Applicant Makoto Ishiita, Director General of the Agency of Industrial Science and Technology - Figure 1■ /

Claims (1)

[Claims] The wing head and the wing body are constructed from separate members, and a cooling air outlet passage is provided along the boundary surface, and the wing span on the wing body side at the boundary surface is set to the wing span on the wing head side. A gas turbine n-blade characterized by being smaller than.