JPS6213571B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a ceramic gas turbine combustor, and is applicable to various gas turbine engines for automobiles, aircraft, industrial use, etc.

As a conventional general ceramic gas turbine combustor, there is one shown in FIG. 1, for example. This combustor 1 is integrally molded from a ceramic material such as SiC or Si ₃ N ₄ , and its side wall has a large number of circular dilution air holes 3 that expand as they move away from the fuel injection valve 2, and a swirler 4. It is fixed to the combustor outer cylinder 7 via mounting bolts 5 and 6.

However, in such a conventional device, when the combustor 1 is exposed to high temperature and placed under conditions of complicated temperature distribution during engine ignition using the ignition spark plug 8 or during other operations, Excessive stress concentration occurs around the air holes 3 due to thermal strain, and the stress exceeds the material strength, causing cracks, resulting in damage to the combustor 1 and further problems leading to engine stoppage.

Therefore, as shown in FIG. 2, for example, by providing a slit 9 that communicates from the inner wall of the air hole 3 to the outer end surface of the combustor 1 or other air holes 3, stress concentration due to thermal strain can be dispersed, absorbed, and alleviated. Some ideas have been proposed.

However, since such a combustor 1 is integrally molded, it is structurally difficult to provide slits 9 for all air holes 3, and a sufficient effect cannot be expected. The formation must also be performed by machining after the combustor 1 is molded or sintered, and therefore machining requires means such as electrical discharge machining or diamond grinding, which has the disadvantage of increasing machining costs.

This invention was made in view of these conventional problems, and consists of a combustor made up of a plurality of segments formed into rings in the radial direction at each dilution air hole. It is an object of the present invention to solve the above-mentioned problems by interposing a plurality of anti-rotation brackets for forming slits.

The present invention will be explained below based on the drawings.

3 and 4 are diagrams showing a first embodiment of the present invention.

First, to explain the configuration, this combustor 1 has ceramic cylindrical segments 11a to 11d made of Si ₃ N ₄ , SiC, etc., which are formed into rings in the radial direction from the center of each air hole 3a, 3b, and 3c. ,
It is comprised of a ceramic slit-forming detent bracket (connector) 12 interposed between each of the segments 11a to 11d.

The dome segment 11a to which the fuel injection valve 2 is attached is connected to the mounting bolts 5, 6 through the swirler 4.
It is fixed to the outer cylinder 7 by. On the other hand, the final stage segment 11d and the ceramic scroll 13 downstream thereof are connected in the axial direction by a cylindrical coupling fitting 17 with a leaf spring 16 that is detachably engaged with annular protrusions 14 and 15 formed on the respective outer walls. connected. Furthermore, since a portion of the scroll 13 is fixed to a portion of the engine (not shown), movement of each of the segments 11a to 11d in the axial direction is restricted.

Each segment 11a to 11d facing each other in the axial direction
A plurality of rectangular notch grooves (bracket receiving grooves) 18, 19 are formed at equal intervals in the circumferential direction on opposite sides in the radial direction on the end faces of the brackets.
A bracket 12 made of a bent plate having a substantially Z-shaped cross section is inserted and fitted in between the two in substantially close contact with each other. As a result, the segments 11a to 11d are connected in the axial direction, and their rotation in the radial direction is restricted, so that the shapes of the air holes 3a to 3c are maintained correctly, and the slits 9 are formed along the circumferential direction. Ru.

A plurality of air holes 3a to 3c are usually provided for each of the slits 9, so that each air hole 3a to 3c is connected to another air hole 3 on the same circumference.
It communicates with a to 3c through a slit 9, and has an open structure that prevents stress concentration during engine operation.

In addition, the central column shaft portion 1 of the bracket 12
By appropriately setting the wall thickness in the axial direction of the slit 2a, a slit 9 of a predetermined width can be obtained.
As shown by the chain line (imaginary line) in the figure, if the tip (open end) of the insertion groove 18 or 19 is notched in the axial direction and the bracket column shaft portion 12a is fitted into the notch 20, Since the width of the slit 9 can be made zero, it is possible to avoid the possibility that the width of the slit 9 is too wide and adversely affects the combustion performance.

Next, the action will be explained.

As explained above, each of the segments 11a to 11d constituting the combustor 1 is separately molded into ring shapes at the air holes 3a to 3c and sintered by a reaction sintering method, an atmospheric pressure sintering method, etc. It is processed by binding,
Since the brackets 12 are interposed between the segments 11a to 11d and the slits 9 are formed and held while being connected and assembled, as a result, all the air holes 3
In addition to being promising for a to 3c, it can be molded by a slip cast method, isostatic press method, injection molding method, etc. without requiring machining, resulting in a significant reduction in processing costs.

Therefore, since each air hole 3a to 3c has an open structure, stress concentration due to thermal strain is difficult to occur, and even if stress is applied, it can be easily deformed through the slit 9, so the stress is relaxed and excessive stress is avoided. Breakage and cracks due to concentration are less likely to occur, and as a result, durability can be improved.

Furthermore, generally speaking, the larger ceramic parts are, the more likely they are to crack, create cavities, and other defects during molding, burn-off of molding aids, or final sintering, making it difficult to manufacture high-strength parts. Since each of the segments 11a to 11d is manufactured separately as described above, it is smaller than an integrally formed combustor, and therefore has the advantage of being able to manufacture a combustor with good strength and no internal defects.

In addition, since the coupling fitting 17 with the leaf spring 16 that biases each segment 11a to 11d and the bracket 12 in the axial direction is used, it is possible to appropriately suppress the occurrence of vibration, and the segments 11a to 1 due to thermal stress can be appropriately suppressed.
A buffering effect against deformation of the bracket 1d and the bracket 12 can also be obtained. Furthermore, since the bracket 12 is molded separately, the bracket 1 may have different dimensions such as wall thickness.
By preparing the slit 2 in advance, there is an advantage that fine adjustment of the width of the slit 9 can be easily performed during maintenance work or the like.

5 and 6 are diagrams showing a second embodiment of the present invention.

In this embodiment, the bracket 12 is fitted into a notch groove (in this case, the notch groove 18) provided at the end of one of the segments, and is integrally molded with the end of the other segment. ′. That is, a rectangular cutout groove 18 is provided at one end of the opposing cylindrical ceramic segments 11a to 11d, and a tongue-like protrusion 12' matching the shape of the groove 18 is provided at the other end.
The combustor 1 is constructed by inserting and fitting the protrusion 12' into the groove 18. At this time, protrusion 1
The width of the slit 9 can be arbitrarily selected by appropriately changing the axial length of the groove 2' or the axial length of the groove 18.

This embodiment has the advantage that the number of parts can be reduced compared to the first embodiment, and dynamic stability can be improved.

FIG. 7 is a diagram showing a third embodiment of the present invention.

In this embodiment, only the most upstream dome segment 11a to which the fuel injection valve 2 is attached is molded from metal, and the other segments 11b to 11d are molded from ceramic. This dome segment 11a has a primary air hole 3 at its downstream end.
A cylindrical coupling fitting 2 with a plate spring 22 fixed to the outer circumferential wall by welding.
It has 3. One end of the coupling fitting 23 is removably engaged with an annular protrusion 24 provided on the outer peripheral wall of the adjacent ceramic segment 11b, thereby connecting the dome segment 11a and the downstream segment 1.
1b are connected in the axial direction, and a slit 9 of a predetermined width is formed.

Incidentally, during engine operation, the dome portion 11a of the combustor 1 is subjected to a maximum thermal stress that is much higher than that of the downstream segments 11b to 11d, and it is often difficult to withstand it with the strength of the ceramic material. Further, if the dome portion 11a is made of ceramic, there is a risk that the dome portion 11a will not be able to withstand the mechanical stress caused by the tightening force of the mounting bolt 5 for fixing it to the outer cylinder 7, and will be damaged. However, in this embodiment, only the dome segment 11a is made of metal, so it can withstand the large thermal stress generated in the dome segment 11a, and is not damaged by the mechanical stress caused by the mounting bolts 5, improving durability. can.

Note that the temperature to which the dome portion 11a is exposed is considerably lower than that of the downstream portions 11b to 11d. For example, even when the temperature at the turbine inlet is 1350°C, the dome portion 1
In 1a, the air temperature at the heat exchanger outlet is 900 to 950
Since the temperature is slightly higher than ℃, the dome part 1
There is no problem even if only 1a is made of metal. Since its configuration is substantially the same as that of the first or second embodiment, a description thereof will be omitted.

As explained above, the present invention has a structure in which a combustor is formed by segments formed into ring shapes in the radial direction at each air hole, and connecting brackets interposed between the segments. As a result, thermal stress concentration can be sufficiently alleviated, durability can be improved, and processing costs can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a general conventional device, Fig. 2a is a longitudinal sectional view of the main part of a conventional device with a slit,
2b is a side view of FIG. 2a, FIG. 3 is a longitudinal sectional view of the first embodiment of the present invention, FIG. 4 is a bottom view of the main part as seen from the direction of arrow A in FIG. 5 is a vertical sectional view of the main part of the second embodiment of the present invention, FIG. 6 is a bottom view of the main part seen from the direction of arrow B in FIG. 5, and FIG. 7 is a main part of the third embodiment of the invention. FIG. 1... Combustor, 2... Injection valve, 3... Air hole,
9...Slit, 11a-11d...Segment, 12...Bracket, 13...Scroll,
16, 22...Plate spring, 17, 23...Joining metal fittings, 18, 19...Notch groove.

Claims (1)

[Claims] 1. In a gas turbine combustor constructed using ceramic, there are segments that are molded separately in the radial direction at the air holes provided in the side wall, and segments that are interposed between these divided segments to separate each other. A gas turbine combustor assembled from connecting brackets. 2. The gas turbine combustor according to claim 1, wherein a plurality of air holes are provided on the same circumference, and the air holes on the same circumference communicate with each other via slits. 3. The bracket according to claim 1 or 2, wherein the bracket is a freely attachable insertion member that fits substantially tightly into notch grooves provided on opposite sides in the radial direction at the ends of the opposing segments. Gas turbine combustor. 4. Claim 1, wherein the bracket is a protrusion integrally formed on the end of the other segment so as to fit substantially tightly into the notch groove provided at the end of the other segment. The gas turbine combustor according to item 2. 5. The gas turbine combustor according to any one of claims 1 to 4, wherein the dome segment to which the fuel injection valve is attached is made of metal.