JPH03207916A - Cooling structure of gas turbine combustion device - Google Patents

Abstract

PURPOSE:To maintain a film cooling performance without an increase in pressure loss by a method wherein a structural member is provided with an air path which connects the air side to the combustion gas side and also a bypass which directly connects the air side to the combustion gas side, and a lip having an eave-like shape is provided to close the upstream side of the combustion gas. CONSTITUTION:Cooling air 103 flows from a groove 3 on the air side 101 into an air path 2 inside a structural member 11, then into a groove 4 on the combustion gas side 102 while cooling a combustion device, is transformed into a film cooling air 105 by an eave-like lip 5 and flows out. Bypass cooling air 104 flowing from the air side into a bypass 6 is transformed into a film cooling air 107 by an eave-like lip 9 and flows out, so that it joints with the cooling air 105 and smoothly covers the surface on the combustion gas side. A shortfall in the flow rate of the cooling air 105 is supplied from the bypass 6 so that a specified cooling performance is achieved. Thereby, the cooling performance can be maintained without an increase in pressure loss.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas turbine combustor, and particularly to a cooling structure suitable for a high-temperature gas turbine combustor with a high combustor exit gas temperature.

[Conventional technology]

Conventionally, the cooling method for a combustor consisting of an inner cylinder and a transition cylinder is as follows:
Film cooling, in which cooling air is flowed in a film along the combustor on the combustion gas side, has often been used to prevent the structural materials of the high-temperature combustion gas combustor from being directly exposed. Air supplied to the combustor flows on the opposite side from the combustion gas, and the combustor is also cooled by forced convection of this air. However, in recent years, in order to increase the thermal efficiency of gas turbines, higher temperatures and pressures have been promoted, and higher combustor cooling performance is required. It is no longer possible to obtain sufficient cooling performance with a simple combination. Therefore, in order to further improve cooling performance, we installed an air passage through which cooling air flows in the structural material of the combustor, strengthening forced convection cooling, and guiding the air to the combustion gas side, allowing it to flow along the combustor. A cooling structure was devised that could also be used for film cooling, by flowing the film in the form of a film. Regarding this type of cooling structure, please refer to the 25th section.
Collected lectures from the annual conference on aerodynamic engines (1985) No. 34
Pages 37 to 37.

Its structure is shown in FIG.

An air flow path 2 is provided inside the structural member 1 forming the combustor, and this flow path 2 is provided with grooves 3 and 4 provided on the air 101 side and the combustion gas 102 side to allow air in the combustor to flow through the air flow path 2. The 101 side and the combustion gas 102 side are connected. Also,
A rib-like lip 5 extends on the combustion gas 102 side so that a film-like film cooling air 105 flows smoothly along the combustor. The cooling air 103 flows into the air passage 3 inside the structural member 1 from the groove 3 on the air 101 side, and flows through the air passage 2 toward the groove 4 on the combustion gas 102 side while cooling the combustor. In the groove 4 on the side of the combustion gas 102, the direction is reversed and the gas expands to the full extent of the groove 4, and flows out as a uniform film-like flow 105 along the combustor due to the rib-like lip 5, and the combustion gas in the combustor is Cover the surface on the gas 102 side. The combustor is cooled by forced convection of the air 101 supplied into the combustor, forced convection of the cooling air 103 flowing through the air passage 2 provided inside the structural material 1 forming the combustor, and further by forced convection of the cooling air 103 on the combustion gas 102 side. A film of cooling air is distributed along the combustor.
This is done by film cooling with 05 flowing. Film cooling not only removes heat from the surface on the combustion gas 102 side, but also has the role of protecting the combustor surface from being directly exposed to the high-temperature combustion gas 102.

By adopting such a cooling structure for the gas turbine combustor, the cooling of the combustor, which was previously performed by film cooling and forced convection of air supplied into the combustor, is now performed inside the structural material that forms the combustor. Forced convection cooling of the cooling air flowing through the provided air flow path is added, and the heat transfer area subjected to forced convection cooling is significantly increased, resulting in high cooling performance.

[Problem to be solved by the invention]

The above conventional technology does not take into consideration the pressure loss that occurs when cooling air flows through the air flow path provided inside the structural material forming the combustor. Considering this, (1) film cooling Decrease in performance (2) Increase in pressure loss in the combustor and the resulting decrease in gas turbine efficiency (3) Increase in combustor weight and material costs due to increase in the thickness of the structural materials forming the combustor, and forced convection cooling performance There was a problem that led to either a decline in This is due to the mechanism of forced convection cooling and film cooling, and will be explained below.

Forced convection cooling using air supplied into the combustor has a heat transfer coefficient that is not affected by the cooling structure, so the thinner the structural material is, the more it is possible to move the inside of the structural material from the combustion gas side to the air side. The temperature difference that occurs when heat is transferred becomes smaller, improving cooling performance.

When the flow is turbulent, the heat transfer coefficient α of the cooling air flowing through the air flow path provided inside the structural material is 0 of the flow velocity U of the cooling air.
．． It is proportional to the 8th power and inversely proportional to the 0.2 power of the representative length Q.

uO·δ Regarding the heat transfer area related to the amount of heat removed by forced convection cooling, to simplify the discussion, we will explain the case where the cross-sectional shape of the air flow path is the same shape and the case where it is square. However, the length of the air flow path shall be equal to the length of the air flow path. When the cross-sectional shape is circular, the ratio of the air flow path interval p to the air flow path diameter d is p / d
Assuming that is constant, the heat transfer area A is L d A=-πdQ=πLQ p p with respect to the circumferential length L of the combustor, and the heat transfer area is constant regardless of the diameter d of the flow path. In addition, even when the cross-sectional shape is square, if the ratio p / d of the interval p of the air flow path and the length a of one side of the air flow path is constant, the circumference L of the combustor
The heat transfer area A is L a A = − 4 a Q = 4 L Qp
p, and the heat transfer area is constant regardless of the length a of one side of the flow path. For this reason, in forced convection cooling using cooling air flowing through the air flow path, the pressure loss in the combustor is increased and the flow velocity of the cooling air is increased, or the flow path is forced to flow so that the typical length of the flow path becomes small within the range of turbulent flow. Cooling performance can be improved by reducing the dimensions of the passage (for example, the diameter d of the passage for a circular passage, and the length a of one side of the passage for a square passage).

The most important role of film cooling is to create a uniform flow of film-like film cooling air along the combustor, and by covering the combustor surface on the combustion gas side with low-temperature film cooling air, high-temperature combustion is prevented. This is to protect the combustor surface from direct exposure to gas. Its performance is greatly influenced by the ratio of the mass flow rate of the combustion gas (= (density) x (flow rate)) and the mass flow rate of the film cooling air. Since the flow of combustion gas is not affected by the cooling structure, the performance of film cooling is determined by the mass flow rate of film cooling air, or in other words, the film cooling air flow rate. The higher the flow rate of film cooling air, the better its performance. Therefore, in order to obtain high film cooling performance, it is necessary to increase the pressure loss and increase the flow rate of cooling air flowing through the air passages provided inside the structural material. Alternatively, the cross-sectional area of the air flow path will be increased. As a method to increase the cross-sectional area of the air flow path, we will explain the case where the cross-sectional shape is circular and square again. At this time, if the heat transfer area of the forced convection cooling of the cooling air flowing through the air flow path changes, it is difficult to compare the cooling performance of the combustor as a whole, so p/d or p/a is kept constant. The cross-sectional area B of the air flow path with respect to the circumferential length L of the combustor is p P in the case of a circular cross section, and p P in the case of a square cross section, L d B = 1● a'' = L−● a p p, and p/d. or , In order to increase the cross-sectional area of the flow path while keeping p/a constant, the diameter d of the flow path must be increased for a circular flow path, and the length a of one side of the flow path must be increased for a square flow path. As can be seen from the above explanation, the performance of forced convection cooling depends on the thickness of the structural materials forming the combustor,
Alternatively, it is better to reduce the size of the air flow path provided inside the film, and the contradictory results that it is better to increase the size of the internal air flow path in order to improve the film cooling performance, You have to sacrifice one or the other. As a method that satisfies both types of cooling performance, there is a method of increasing the pressure loss and increasing the flow velocity of the cooling air flowing through the air flow path. However, in general, the pressure loss generated in a gas turbine combustor is 3 to 5% of the compressor discharge pressure.
However, if the pressure loss generated in the combustor increases, the thermal efficiency of the entire gas turbine will decrease, so it must be kept as small as possible, and this method also has its problems.

The purpose of the present invention is to achieve forced convection cooling by air supplied into the combustor without increasing pressure loss in the combustor, and cooling that flows through air passages provided inside the structural material forming the combustor. An object of the present invention is to provide a cooling structure for a gas turbine combustor that can maximize the performance of forced convection cooling using air and also ensure the performance of film cooling.

[Means to solve the problem]

The purpose of the above is to create a gap between the lip and the combustor structural material, which is specially provided on the combustion gas side of the combustor to flow a uniform, smooth film-like film cooling air along the combustor, and a gap between the combustor structural material. This is achieved by providing a bypass passage that directly communicates with the air side of the air.

[Effect]

A new lip is installed separately from the lip that allows air to flow from the air flow path inside the structural material into the combustor, and a bypass flow path is created that directly communicates the gap between this lip and the structural material and the air side of the combustor. By providing this, it is possible to always procure the amount of film cooling air necessary to ensure film cooling performance without increasing pressure loss in the combustor.

For this reason, the size and shape of the air flow path provided inside the structural material that forms the combustor is designed to improve the forced convection cooling performance of the cooling air flowing through it, apart from the film cooling performance. It becomes possible to decide. That is, in order to improve the cooling performance due to forced convection of air supplied into the combustor and forced convection of cooling air flowing through air channels provided inside the structural material, the plate thickness of the structural material or The dimensions of the air flow path are reduced, and the air is made to flow along the inner surface of the inner cylinder for film cooling. In order to ensure the performance of film cooling, the insufficient amount of air is passed directly from the air side of the combustor through a bypass flow path and from another lip along the inner surface of the combustor, without increasing pressure loss.
This means that film cooling performance can be ensured while maintaining high forced convection cooling performance. Furthermore, since the thickness of the structural material can be reduced, the weight and material cost of the combustor can also be reduced.

〔Example〕

An embodiment of the present invention will be explained below with reference to FIG. An air flow path 2 is provided inside the structural member 1 forming the combustor, and this flow path 2 is connected to the air 101 side and the combustion gas 10 side.
The air 101 of the combustor is
It connects the side and the combustion gas 102 side. Further, on the combustion gas 102 side, a rib-like lip 5 extends so that a film-like film cooling air 105 flows smoothly along the combustor. Furthermore, the structural material 1 has a combustion gas 102 side and an air 1 side.
A bypass flow path 6 is provided that directly communicates with the combustion gas 102 side, and a rib-like lip 9 extends on the combustion gas 102 side so that a film-like film cooling air 107 flows smoothly along the combustor. ing. The cooling air 103 flows from the groove 3 on the air 101 side into the air passage 2 provided inside the structural member 1, and the combustion gas 1 flows through the air passage 2 while cooling the combustor.
It flows toward the groove 4 on the 02 side. Groove 4 on the combustion gas 102 side
Then, while reversing its direction, it spreads to the full extent of the groove 4, and then flows out as a uniform film-like film cooling air 105 along the combustor by the rib-like lip 5.

On the other hand, bypass air 104 flowing from the air 101 side of the combustor through the bypass flow path 6 is formed into a uniform film-like film cooling air 107 along the combustor by the rib-like lip 9.
The air flows out, and when combined with the film cooling air 105, smoothly covers the surface of the combustor on the combustion gas 102 side. The plate thickness of the structural material 1 and the shape and dimensions of the air passage 2 are such that the forced convection cooling by the air 101 supplied into the combustor and the forced convection cooling by the cooling air 103 flowing through the air passage 2 have high performance. The dimensions are small so that In addition, in order to ensure that the film cooling satisfies a predetermined performance, the insufficient flow rate of the film cooling air 105 that has passed through the air flow path 2 is supplied through the bypass flow path 6, and a lip 9 provided upstream of the lip 5 is used. Film cooling air from 10
7, a uniform and smooth film of cooling air can be formed along the combustor on the combustion gas 102 side of the combustor, without increasing the pressure loss of the combustor.
This ensures the necessary film cooling performance. With this cooling structure, it is possible to manufacture the combustor using a thin structural material, and the weight of the combustor and its material cost can be reduced. In addition, when adjusting the cooling performance according to the heat load, not only the plate thickness of the structural material 1 and the spacing, shape, and dimensions of the air flow path 2, but also the cross-sectional area of the bypass flow path 6 and the flow rate of the bypass air 104 are changed. Control is also possible by changing . Naturally, the spacing between the air channels 2 and the spacing between the bypass channels 6 may be different, and should be determined taking into consideration material strength and the like.

FIG. 3 shows an example of a structure in which an inflow hole 7 and an outflow hole 8 are opened to communicate the air passage 2 inside the structural member 1 with the air 101 side and the combustion gas 102 side. cooling air 1
03 flows into the air passage 2 through the two inflow holes 7, flows through the air passage 2 while cooling the combustor, flows out from the outflow hole 8 into the gap between the structural material 1 and the lip 5, and becomes the lip. 5, the cooling air flows out along the combustor as a uniform film cooling air 105. On the other hand, the bypass air 104 that has flowed in through the bypass air hole 6 flows out through the lip 9 as a uniform film cooling air 107 along the combustor. The cooling action and effect are the same as those explained in FIG. By changing this cross-sectional area, the flow rate of the cooling air 103 can be adjusted, and the cooling performance can be controlled more easily. Note that similar actions and effects can be obtained when the number of inflow holes 7 is one or more, and the air flow inside the air flow path 2 is made unidirectional.

FIG. 4 shows an example in which the cooling air 103 flowing through the air flow path 2 inside the structural material 1 directly flows out to the combustion gas 102 side from the outlet hole 8 which is inclined with respect to the structural material 1. There is no 5. The cooling air 103 that has flowed into the air flow path 2 from the inflow hole 7 flows through the air flow path 2 while cooling the combustor, and flows out from the outflow hole 8 toward the combustion gas 102 side. The outflowing air cannot form a uniform film, but together with the film cooling air 107 from the upstream lip 9, it forms a substantially uniform film of film cooling air.

The cooling action and effect are the same as those explained in FIG. 3, but the absence of the lip 5 makes manufacturing easier. In addition, the plate thickness can be made almost constant, which improves the strength.

FIG. 5 shows the air 10 in the air flow path 2 provided inside the structural material 1.
This is an embodiment in which a plurality of inflow holes 7 and a plurality of outflow holes 8 are provided which communicate with the combustion gas 102 side and the combustion gas 102 side, and there is no lip 5 for forming a film-like film cooling air with outflow air. Cooling air 103 flows into the air passage 2 through the plurality of inflow holes 7, cools the combustor while flowing in opposite directions depending on the location, and flows into the combustion gas 102 through the plurality of outflow holes 8.
It flows out to the side. The outflowing air is combined with the uniform film-like film cooling air 107 from the bypass air hole 6 flowing from the upstream rib 9 to form a substantially uniform film-like film cooling air. The effects of cooling are the same as explained in Figure 4. FIG. 6 shows that the air passages 2 provided inside the structural member 1 are connected vertically and horizontally, and the air passages 2 are communicated with the air 101 side and the combustion gas 102 side through the inlet hole 7 and the outlet hole 8. This is an example. The action and effect of cooling are the same as those shown in Fig. 4. Note that similar actions and effects can be obtained when the bypass air hole 6 is provided between adjacent air flow paths 2.

FIG. 7 shows an example of the embodiment shown in FIG. 3 in which the structural material 1 having the air flow path 2 inside is arranged so that there is no step in the direction of flow of combustion gas.

FIG. 8 shows an example of the embodiment shown in FIG. 4 in which the structural member 1 having an air passage 2 inside is arranged so that there is no step in the flow direction of the combustion gas.

FIG. 9 shows the embodiment shown in FIG. 3, in which the structural material having the air flow path 2 inside is constructed so that there is no step in the flow direction of the combustion gas, and the structure is arranged on the upstream side of the combustion gas 102 from the outflow hole 8. This is an example in which the corresponding air flow path 2 is eliminated and the processing of the air flow path 2 in the previous process of forming the structural member 1 is reduced.

FIG. 10 shows an example in which the rib 5 is eliminated from the embodiment shown in FIG. 9, and the air flow 105 from the outlet hole 8 is ejected without running along the combustor wall surface. The air flow 105 together with the uniform film cooling air 107 from the bypass air holes 6 flowing from the upstream lip 9 forms a substantially uniform film cooling air flow.

In Fig. 11, the structural member 1 is constructed so that there is no step in the direction of flow of combustion gas, and the air passages 2 inside the structure are arranged in the middle of adjacent air passages 2 without providing a partition in the middle in the direction of flow of combustion gas. This is an example in which a bypass air hole 6 is provided.

In FIG. 12, the structural member 1 is arranged so that there is no step in the combustion gas flow direction 102, and the air passages 2 provided inside the structural member 1 are connected vertically and horizontally. This is an example in which a bypass air hole 6 is provided. [Effects of the Invention] According to the present invention, the insufficient amount of film cooling air flow rate necessary to ensure film cooling performance can be caused to flow directly into the gap between the structural material and the specially provided lip through the bypass flow path. This makes it possible to maintain high performance of forced convection cooling by the air supplied into the combustor and forced convection cooling by the cooling air flowing through the air passages provided inside the structural material forming the combustor. The thickness of the structural material and the dimensions of the air passages can be reduced, and the required flow rate of the film cooling air can be increased by extending the required flow rate along the combustor to the combustion gas side of the combustor by means of a flared lip. Since the flow smoothly covers the combustor surface in a uniform film, it is possible to maintain the required film cooling performance without increasing pressure loss in the combustor and maintaining high forced convection cooling performance. become. Furthermore, since the plate thickness of the structural material can be made thinner, the weight of the combustor and the cost of materials can be reduced. Furthermore, the cooling performance can be adjusted according to the heat load by changing not only the plate thickness of the structural material and the spacing, shape, and dimensions of the air flow passages, but also the cross-sectional area of the bypass flow passages.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a cooling structure for a gas turbine combustor showing an embodiment of the present invention, FIG. 2 is a perspective view of a conventional gas turbine combustor cooling structure, and FIGS. 3 and 4 are in accordance with the present invention. FIGS. 5 and 6 are a perspective view of a cooling structure for a gas turbine combustor showing a modification of the present invention, and FIGS. Figure 8,
9 and 10 are perspective views of a cooling structure for a gas turbine combustor showing a modification of the present invention, and FIGS. 11 and 12 are
The figures are a sectional view and a plan view of a cooling structure for a gas turbine combustor showing a modification of the present invention. 1... Structural material, 2... Air flow path, 5... Lip,
6... Bypass flow path, 8... Outlet hole, 9... Lip, 101... Air 5102... Combustion gas, 103
...Cooling air, 104...Bypass air, 105.
...Film cooling air, 107...Film cooling air. Fig. 1 WJ2 Fig./02 Fig. 5 (CL) Fig. 6/θ2 Fig. 7 Fig. 8 Fig. 9 Mouth/υ/ Fig. 10 Fig. 11 Fig. 12

Claims (1)

[Claims] 1. In a gas turbine combustor, an air flow path communicating between the air side and the combustion gas side of the combustor is provided inside a structural member forming the combustor, and further, the combustor A bypass passage that directly communicates the air side and the combustion gas side of the combustor is provided in the structural member, and the bypass passage communicates with the combustion gas side of the combustor through a gap between the structural member and the lip. A gas turbine combustor cooling structure characterized in that the lip is provided in a rib shape to close an upstream side of combustion gas from the structural member. 2. In claim 1, an air passage provided inside the structural material forming the combustor for communicating the air side and the combustion gas side of the combustor is provided through a gap between the structural material and the lip. A gas turbine combustor cooling structure provided so as to be closed on the upstream side of the combustion gas from the structural member so as to communicate with the combustion gas side of the combustor.