Annular combustor of gas turbine engine

An annular combustor of a gas turbine engine comprising a front burner device located in the inlet section of the combustor and a flame tube, featuring a longitudinal split coinciding with that of the engine. The flame tube is formed by two concentric, outer and inner, shells with curvilinear surfaces. Each one of the shells is split longitudinally into sections, the places of the split being sealed with sealing members. In addition, the combustor is provided with at least two ring-shaped longitudinally-split load-bearing members for each one of the shells. The ring-shaped load-bearing member located in the zone of the combustor inlet section is capable of longitudinal and radial movements while the load-bearing member located in the zone of the combustor outlet section is capable of only radial movement. Each one of the shell sections is coupled with a respective ring-shaped load-bearing member, such that the middle portion of the section is rigidly attached to the ring-shaped member while the ends of said section are connected to the ring-shaped member with the provision for movement in the circumferential direction.

The present invention relates to gas turbine engines and, more 
particularly, it relates to annular combustors. 
This invention can be used most advantageously in stationary gas turbine 
engines. 
BACKGROUND OF THE INVENTION 
At present, gas turbine engines employ annular combustors built-in between 
the compressor and turbine. In so doing, the combustor has usually no 
longitudinal split and the gas turbine engine is assembled by way of 
successive assembly of stator parts while mounting the vanes 
simultaneously or assembling the turbine rotors, and disassembled in an 
inverse sequence. This results in an increased consumption of labor during 
manufacture and, especially, during the servicing of the engine, inasmuch 
as access to the engine elements for inspection and repair is rather 
difficult. 
Therefore, the designers' efforts are aimed at developing annular 
combustors having a longitudinal split in the plane of the split of other 
engine components. In this respect one of, main difficulties are offered 
by the flame tube of the combustor which is, affected by high 
temperatures, and whose design should satisfy the requirement of enhanced 
stiffness while ensuring the freedom of thermal expansion of its 
components inasmuch as the failure to meet this requirement results in the 
loss of shape by the flame tube, emergence of thermal stresses and, as a 
consequence, the warping of the flame tube components and the formation in 
the latter of cracks causing the failure of both the combustor and the 
entire engine. 
Attempts at developing annular combustors with compensation for thermal 
expansion of individual components resulted in the combustor according to 
British Pat. No. 799,605. 
This prior art annular combustor comprises a burner device located in the 
combustor inlet section and a flame tube formed by two concentric, outer 
and inner, shells. 
The outer shell is split into sections in the longitudinal direction. Each 
section has, along the line of split, alternating projections and 
recesses, meshing with each other upon the assembly of the shell to form a 
movable joint serving to partly compensate for thermal deformation of the 
combustor in the circumferential direction. In a large-size combustor, 
however, the outer shell lacks stiffness, which is characteristic of 
combustors of stationary gas turbine engines. This affects the reliability 
of operation of the combustor and of the entire gas turbine engine. 
Also known in the art is another annular combustor for a gas turbine 
engine, whose design helps facilitate the assembly and maintenance of the 
engine due to a longitudinal split of the combustor whose plane coincides 
with that of the engine split (cf., Trudy Uralskogo turbomotornogo zavoda 
"Opyt sozdaniya turbin i dizelei"--Proceedings of Uralskii Turbine Engine 
Works on the "Turbines and Diesels. Design and Manufacturing Experience," 
No. 2, 1972, pp. 88-94). 
Said latter prior art annular combustor includes a front burner device 
secured in the inlet section of the combustor and a flame tube formed by 
two concentric, outer and inner, shells with curvilinear surfaces. Each 
one of the shells is split into sections in the longitudinal direction, 
the places of split being sealed with sealing members in the form of two 
plates. The first one of said plates, a flat plate, is attached to one 
section with its one end and, with its other end, rests freely on another 
section. The other one of said plates is attached with its one end to the 
section on which the first plate rests freely and, with its other end, 
envelops the latter to form therewith and with the section a sliding 
mortise joint. For joining the sections of the outer and inner shells in 
the combustor inlet portion, provision is made of a load-bearing 
arrangement in the form of a massive frame having a longitudinal split and 
including several massive rings, at least one of which embraces the 
sections of the outer shell while at least one other ring embraces the 
sections of the inner shell. The rings are rigidly interconnected with 
ribs of which two, arranged at a longitudinal horizontal plane in each 
half of the frame split, form the split flange while part of the other 
ribs are used for fixing the frame in the engine casing. 
For joining the sections of the outer and inner shells in the combustor 
outlet section provision is made of single load-bearing rings likewise 
fixed on the engine casing. In this manner, the load-bearing arrangement 
in the form of a circular frame and the load-bearing rings are rigidly 
secured on the engine casing to form an integral rigid system. 
Upon the combustor operation, especially, under unsteady conditions, a 
considerable temperature difference is observed between the circular frame 
and shell sections, which results in the emergence of temperature 
expansions of the sections relative to each other and to the frame. Each 
section is secured in the rings having an annular groove by means of a 
bracket. Due to the rigid attachment of the frame and single load-bearing 
rings to the engine casing, the annular groove and brackets, 
simultaneously serve to compensate for temperature expansion in the 
radial, circumferential and longitudinal directions. Therefore, this 
attachment is rather complicated and practically fails to accomplish a 
reliable operation of the combustor due to the absence of necessary 
expansion gaps, which results in the emergence of thermal stresses causing 
the warping of the combustor, for example, in the inlet section thereof, 
and the loss of shape. 
SUMMARY OF THE INVENTION 
It is the object of the present invention to develop an annular combustor 
of a gas turbine engine, wherein provision is made for such a connection 
of the sections of the flame tube shells with load-bearing members as to 
preclude the emergence of stresses in the sections of the outer and inner 
shells of the combustor flame tube caused by thermal deformation while 
maintaining the enhanced stiffness of the flame tube. 
In accordance with this object and other objects, the present invention 
resides in that in an annular combustor of a gas turbine engine, having a 
front burner device located in the inlet section of the combustor 
featuring a longitudinal split coinciding with that of the engine and a 
flame tube formed by two concentric, outer and inner, shells with 
curvilinear surfaces, each one of said shells being split longitudinally 
into sections while the places of the split are sealed with sealing 
members. Also, this is provided at least two ring-shaped 
longitudinally-split load-bearing members for each one of the shells. One 
of said load-bearing members is located in the zone of the combustor inlet 
section with a possibility of longitudinal and radial movement while the 
other one of said load-bearing members is located in the zone of the 
combustor outlet section with a possibility of radial movement, and each 
one of the shell sections is coupled with a respective ring-shaped 
load-bearing member, such that the middle portion of the section is 
rigidly attached to the ring-shaped member while the ends of said section 
are connected to the ring-shaped member with the provision for movement in 
the circumferential direction. 
During the engine operation, there takes place in the combustor non-uniform 
heating of the outer and inner shells, ring-shaped load-bearing members 
and the engine casing. The maximum temperature is observed on the outer 
and inner shells of the flame tube while the highest temperature 
difference occurs between the outer and inner shells and the ring-shaped 
load-bearing members. 
In order to eliminate the difference in radial temperature expansions 
between the outer and inner shells of the combustor flame tube and the 
ring-shaped load-bearing members, the shells are made split, consisting of 
separate sections provided with an appropriate gap therebetween, with said 
gap being sealed with sealing members which do not prevent the relative 
expansion of the sections upon heating. Nevertheless, this is insufficient 
for a reliable combustor operation inasmuch as a series of rather complex 
relative movements are to be further compensated for upon temperature 
expansion between the sections of the outer and inner shells, ring-shaped 
load-bearing members and the engine casing, called upon to rule out the 
possibility of stresses emerging in the sections of the flame tube shells 
as a result of thermal deformations and, at the same time, maintain the 
geometric shape of the shells under working conditions. 
In the combustor according to the present invention, simple means are 
employed to provide for the compensation of the relative movement upon 
temperature expansion such as, first, in the circumferential direction 
between the shell sections due to attaching the sections of the outer and 
inner shells to the respective ring-shaped load-bearing members in such a 
manner that the middle portion of the section is rigidly attached to the 
ring-shaped load-bearing member while the section ends are connected to 
the ring-shaped member with provision for movement in the circumferential 
direction and, at the same time, restrained in the radial direction and, 
second, in the longitudinal and radial directions between the ring-shaped 
load-bearing members and the engine casing due to the provision of at 
least two ring-shaped load-bearing members for each one of the shells. One 
of said load-bearing members is located in the zone of the combustor inlet 
section with a possibility of longitudinal and radial movement, while the 
other one of said load-bearing members is located in the zone of the 
combustor outlet section with a possibility of radial movement permitting 
of fully compensating for the temperature expansion difference between the 
shell sections, ring-shaped load-bearing members and the engine casing. 
The afore-described means serve to preclude the emergence of stresses 
caused by thermal deformation and increase the stiffness of the structure, 
thereby considerably improving the reliability of operation of an annular 
combustor having a longitudinal split, as well as of the overall operation 
of the gas turbine engine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to FIG. 1 of the accompanying drawings, an annular combustor 
1 is mounted in a casing 2 of a gas turbine engine and is located between 
a diffusor 3 of the compressor and a housing 4 of a gas turbine stator 5. 
The combustor 1 is made with a longitudinal split coinciding with that of 
the engine and has a front burner device 6 with gas supply connections 7 
mounted in the inlet section of the combustor 1, and a flame tube 8. The 
latter tube is formed by two concentric, outer 9 and inner 10, shells with 
curvilinear surfaces, namely, cylindrical surface conjugated with a 
conical one receding in section in the direction of the gas flow and 
conjugated with a cylindrical one. Each one of the shells 9 and 10 is 
split in the longitudinal direction into sections 11 and 12 (FIG. 2), 
respectively. The places of split are closed throughout the entire length 
with sealing members in the form of corrugated springs 13 (FIG. 3), with 
one end of each spring 13 being fixed on one of the sections 11, while the 
other end of said spring rests against the adjacent section 11 offering no 
obstruction to relative thermal expansions of said sections in the 
circumferential direction. The sealing members on the inner shell 10 are 
analogous with those described above. 
For a better operation of the spring 13 as a sealing member, provision is 
made of plates 14 (FIG. 4) attached to the outer section 11 on which the 
end of the spring 13 rests freely, said plates resting against the 
corrugations of the spring 13 and spaced from each other over the length 
of the section. 
The sections 11 of the outer shell 9 and sections 12 of the inner shell 10 
are secured each on at least two ring-shaped load-bearing members 15, 16 
(FIG. 1) and 17, 18, respectively. 
The sections 11 are attached to the ring-shaped load-bearing members 15, 16 
(FIG. 3) in such a manner that the sections 11 in the zone of the 
ring-shaped load-bearing members 15, 16 are rigidly attached by their 
middle portions to said load-bearing members with the aid of angles 19 and 
rods 20 while the ends of the sections are made fast with the aid of 
angles 21 (FIGS. 5, 6) having oval-shaped holes 22 (FIG. 5) in which rods 
23 are receivable mounted in the ring-shaped load-bearing member 16. 
As seen from FIGS. 2, 3, 4, 5, the sections 11 are capable of moving in the 
circumferential direction relative to the ring-shaped load-bearing members 
15, 16 (FIG. 3) upon temperature expansion. 
The attachment of the sections 12 of the inner shell 10 to the ring-shaped 
load-bearing members 17, 18 is analogous to that described above with 
respect to the sections 11. 
The arrangement of the ring-shaped load-bearing members 15, 16, 17, 18 
(FIG. 1) will become clear upon considering the ring-shaped load-bearing 
member 15 (FIG. 3), the rest being analogous. The ring-shaped load-bearing 
member 15 consists of two halves 24 and 25 rigidly interconnected over the 
split by means of, say, angles 26, each of which is attached to each one 
of the halves 24 and 25. The angles are coupled with each other by means 
of bolts 27 to provide for rigid separable joint of both halves. 
The ring-shaped load-bearing members 16, 18 (FIG. 1) located in the zone of 
the outlet section of the combustor 1 are free to move radially relative 
to the housing 4 of the gas turbine stator 5. This free radial movement, 
for example, in the case of the ring-shaped load-bearing member 16, is 
provided through the use of means including a bracket 28 (FIG. 7) secured 
with its one end on the housing 4 and provided on its other end with a pin 
receivable in a groove in a boss 29 whose finger 30 is in turn receivable 
in a radial hole 31 of the ring-shaped load-bearing member 16. The bracket 
28 is coupled with the boss 29 by means of a finger 32 fixed with a 
lockpin. The ring-shaped load-bearing member 16 is free to move radially 
with the aid of a shoulder 33 (FIG. 8) made on the member 18 and 
receivable in an annular groove 34 in the housing 4 to lock the 
ring-shaped load-bearing member 18 in the longitudinal direction and to 
provide freedom for its thermal expansion in the radial direction relative 
to the housing 4. Thermal protection of the housing 4 is provided by 
shields 35 attached to the sections 12. 
The ring-shaped load-bearing member 15 (FIG. 1) located in the zone of the 
inlet section of the combustor 1 is capable of longitudinal and radial 
movement relative to the casing 2. To this end, in the plane of the split 
of the member 15, there are secured cleats 37 (FIG. 9) located in a socket 
38 of the flange of the longitudinal split of the casing 2 with a radial 
gap 39 (FIG. 10) and a longitudinal gap 40. 
The ring-shaped load-bearing member 17 (FIG. 1) located in the zone of the 
inlet section of the combustor 1 is capable of longitudinal and radial 
movement relative to the diffusor 3. To this end, in the plane of the 
split of the member 17 (FIG. 11), there are secured cleats 41 located in a 
socket 42 of the flange of the longitudinal split of the diffusor 3 with a 
radial gap 43 (FIG. 10) and a longitudinal gap 44. 
With a view to increasing the stiffness and strength of the split of the 
inner shell 10, the latter is reinforced with additional half-rings 45 and 
46 (FIGS. 1, 10) connected with said shell in the same way as the 
ring-shaped load-bearing members 17 and 18. In order to facilitate the 
disassembly of the combustor 1, the half-rings 45 and 46 are not secured 
to each other rigidly but only rest against each other in the plane of the 
split and are locked radially with respect to each other by means of, say, 
a key joint. 
In order to reduce the temperature of the diffusor 3, shields 47 are 
attached to the ring-shaped load-bearing members 17 and 18 and additional 
half-rings 45 and 46 are disposed between the diffusor 3 and the inner 
shell 10 (FIG. 10). 
Although the present invention has been described in some detail by way of 
illustration and example for purposes of clarity of understanding, it 
will, of course, be understood that various changes and modifications may 
be made in the form, details, and arrangements of the parts without 
departing from the scope of the invention as set forth in the following 
claims.