Combustion chamber outlet cooling structure

Abstract

The application discloses a combustion chamber outlet cooling structure, a small-bend-pipe starting section is inserted into an inner-ring-beak-ring, impact holes are formed in the inner-ring-beak-ring, part of the inner two-channel airflow is introduced into a combustion chamber outlet flow channel through the impact holes, and a wall-attached cooling air film covers the small-bend-pipe starting section. A plurality of sets of dispersion hole groups are formed in a small-bend-pipe middle section, part of the inner two-channel airflow is introduced into the combustion chamber outlet flow channel through the plurality of sets of dispersion hole groups, and a large cooling air film is formed at a large-curvature position of the small-bend-pipe middle section. A tongue-groove cooling structure and an air-film groove hole are arranged on a small-bend-pipe outlet section, part of the inner two-channel airflow is introduced into the impact tongue-groove cooling structure, and a cooling air film which flows along the wall of the small-bend-pipe outlet section is formed. The small-bend-pipe further comprises an annular upper-edge-plate supporting ring which is located behind the small-bend-pipe outlet section. The structure of the application can guarantee the release of thermal expansion stress under a hot state, so that the inner-ring wall of the flame tube is not deformed by thermal arching to cause other faults or safety accidents.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aero-engine, in particular, to a combustion chamber outlet cooling structure. BACKGROUND

[0002] Small and medium-sized gas turbine engines have the characteristics of high speed and high temperature rise. In order to avoid rotor dynamics problems, when selecting a combustion chamber, a backflow type combustion chamber is often considered. As a unique structure in the backflow combustion chamber, the small elbow pipe, together with the combustion chamber inner casing, forms the inner two passages of the combustion chamber, and together with the large elbow pipe and the inner ring of the flame tube, forms the high-temperature gas passage. The high-temperature gas turns 180° through the large and small elbow pipes and enters the gas turbine guide vane. The small elbow pipe works under extremely high temperature. With the development direction of future engine high temperature rise and high speed, the small elbow pipe structure innovation and cooling design are extremely important.

[0003] Currently, the small elbow pipe mainly includes two forms: double-wall structure and single-wall structure. The existing double-wall small elbow pipe often adopts impingement cooling form. The cooling gas after impingement flows out through the gap between the double walls to the gas turbine guide vane and cools the upper edge plate of the gas turbine guide vane. The single-wall small elbow pipe is often designed as a whole with the inner ring of the flame tube. The small elbow pipe starting gas film is formed through the impingement holes on the inner ring of the flame tube to protect the body. The gas film groove is added at the tail end of the small elbow pipe to strengthen the cooling of the small elbow pipe and cool the upper edge plate of the gas turbine guide vane.

[0004] The double-wall small elbow pipe of the prior art has many parts, high machining difficulty, high processing cost, and multiple welds. Due to the large temperature gradient at the small elbow pipe, the inner and outer walls of the small elbow pipe deform inconsistently, which is easy to produce weld cracks. Once deformed, the cooling effect of the guide vane is greatly reduced.

[0005] Due to the extremely high temperature at the outlet of the combustion chamber, the small elbow pipe bears a large thermal stress. The existing single-wall small elbow pipe, which is designed as a whole with the inner ring of the flame tube, has a small thermal stress release space, which may eventually cause the thin-walled inner ring of the flame tube to arch and deform. On the other hand, the middle section of the small elbow pipe lacks cooling gas, and the small elbow pipe directly bears the high-temperature gas, which has a high risk of cracking and falling off. SUMMARY

[0006] The present application provides a combustion chamber outlet cooling structure to solve the technical problem of the small thermal stress release space in the existing conventional structure, which may eventually cause the thin-walled inner ring of the flame tube to arch and deform.

[0007] The technical scheme adopted by the present application is as follows:

[0008] The combustion chamber outlet cooling structure comprises an inner ring beak ring of a tail section of an inner ring of a flame tube, a single-wall small bend pipe and a gas turbine guide vane, an initial section of the small bend pipe at an air inlet end of the small bend pipe is inserted into the inner ring beak ring from an opening of the inner ring beak ring, impact holes are formed on the inner ring beak ring, part of the inner two-pass channel airflow is introduced into a combustion chamber outlet flow channel through the impact holes and a beak ring cavity of the inner ring beak ring, and a wall-attached cooling air film is formed on the combustion chamber outlet flow channel to cover the initial section of the small bend pipe; a plurality of sets of divergent holes are formed on a middle section of the small bend pipe at a middle part of the small bend pipe, the sets of divergent holes are sequentially and radially spaced, part of the inner two-pass channel airflow is introduced into the combustion chamber outlet flow channel through the sets of divergent holes, and a large cooling air film is formed at a large curvature of the middle section of the small bend pipe; a tongue groove cooling structure and an air film groove hole are arranged on an outlet section of the small bend pipe at an air outlet end of the small bend pipe, part of the inner two-pass channel airflow is introduced into the impact tongue groove cooling structure through the air film groove hole, a cooling air film is formed along a profile of the outlet section of the small bend pipe to flow on a wall, and the outlet section of the small bend pipe and an upper edge plate of the gas turbine guide vane are cooled; the small bend pipe further comprises an upper edge plate supporting ring which is annular and located behind the outlet section of the small bend pipe, and the gas turbine guide vane is arranged at the air outlet end of the small bend pipe and located in the upper edge plate supporting ring.

[0009] Further, a plurality of impact holes are sequentially and spaced on a circumference of the inner ring beak ring; the plurality of impact holes have the same diameter and are sequentially and sparsely spaced along the circumference; or the plurality of impact holes have different diameters and are sequentially and uniformly spaced along the circumference.

[0010] Further, the initial section of the small bend pipe and a cavity bottom of the beak ring cavity have an axial gap δ, 0.5mm≤δ≤3.5mm; an inner ring surface of the initial section of the small bend pipe and an inner ring surface of the beak ring cavity have a radial gap θ, 0.07mm≤θ≤0.15mm; an outer ring surface of the initial section of the small bend pipe and an outer ring surface of the beak ring cavity have a radial gap D; a gap L between the cavity bottom of the beak ring cavity and an end surface of an outer ring of the inner ring beak ring is axial, and D / L=0.1-0.2, and an included angle α between a center line of the impact hole and the outer ring surface of the beak ring cavity is related to D / L, the larger D / L is, the larger the included angle α is to 90°, and the smaller D / L is, the smaller the included angle α is to more than 0°.

[0011] Further, each set of divergent holes comprises a plurality of divergent holes which are sequentially and spaced along a circumference, and the plurality of divergent holes of adjacent two sets of divergent holes are sequentially and spaced along the circumference; the tangential angle of the divergent holes of the sets of divergent holes except the innermost set is 80°-100°, and the punching angle is 20°-30°; the tangential angle of the divergent holes of the innermost set of divergent holes is more than 0°-15°, and the punching angle is less than 30°.

[0012] Further, the inner concave extension of the small-bend outlet section forms a circumferential gas film groove, and a tongue ring and a tail ring located on both sides of the gas film groove and in a ring shape; the gas film groove and the tongue ring form a tongue-groove cooling structure; a gas film groove hole is opened on the tail ring and communicates with the gas film groove to introduce part of the inner two-channel airflow into the tongue ring to form a cooling gas film flowing along the profile of the small-bend outlet section.

[0013] Further, the number of gas film groove holes is multiple, and the multiple gas film groove holes are uniformly spaced in the circumferential direction; the height of the gas film groove is 1mm-2mm.

[0014] Further, the inner ring of the small-bend starting section is provided with a chamfer; and the gas side profile of the small-bend is also sprayed with a thermal barrier coating.

[0015] Further, the gas turbine guide vane includes guide vane blades arranged in the circumferential direction in sequence, and the guide vane blade includes a blade body and an upper edge plate, and the upper edge plate is arranged in the circumferential direction in sequence and spaced apart from the upper edge plate support ring; the upper edge plate support ring is provided with support ring holes penetrating through and arranged in the circumferential direction in sequence, so as to introduce part of the inner two-channel airflow into the blade body through the support ring holes and the upper edge plate; the combustion chamber outlet cooling structure further includes a large-bend pipe arranged outside the small-bend pipe, and the large-bend pipe flange edge of the large-bend pipe is provided with flange edge holes penetrating through and arranged in the circumferential direction in sequence, so as to introduce the airflow outside the large-bend pipe into the gas turbine guide vane and the blade body through the flange edge holes.

[0016] Further, the combustion chamber outlet cooling structure further includes a positioning pin, which is inserted into the upper edge plate after being interference-fitted through the upper edge plate support ring, so as to position the small-bend pipe; the support ring holes and the flange edge holes are uniformly spaced in the circumferential direction in sequence, and the number of the support ring holes and the flange edge holes is proportional to the number of the guide vane blades.

[0017] Further, the radial end face of the outlet end of the upper edge plate support ring is concave to form a mounting ring groove, and the inner ring located on the inner side is sequentially opened to form a boss in the circumferential direction; the combustion chamber outlet cooling structure further includes a special-shaped sealing ring clamped in the mounting ring groove, which is used to seal the radial gap between the outlet end of the upper edge plate support ring and the outlet side of the upper edge plate.

[0018] The present application has the following beneficial effects:

[0019] In the combustion chamber outlet cooling structure, the maximum temperature of the inner ring wall of the flame tube is about 1000 DEG C under the maximum thermal state, and the local average stress is more than 200 MPa, the inner ring of the flame tube is a large-diameter thin-walled part, and the stress resistance level is limited, so in the cooling structure, the starting section of the small elbow pipe at the gas inlet end of the small elbow pipe is directly inserted into the beak ring cavity of the inner ring beak ring, and is not designed integrally with the inner ring beak ring, that is, the small elbow pipe and the inner ring of the flame tube are designed in a split body, which is not only beneficial to assembly, but also can ensure the release of the expansion stress under the hot state, so that the flame tube inner ring wall is not deformed by the hot arching to cause other faults or safety accidents, and the technical problem of the existing structure that the heat stress release space is small, and the thin wall of the flame tube inner ring may finally arch and deform is solved, the cooling structure in the application is used as the upper edge plate support ring of the upper edge plate support plate of the gas turbine guide vane, and the small elbow pipe is an integral part, which is formed by machining of the integral forging part, thereby reducing the number of parts and the assembly difficulty of the gas turbine guide vane, in the cooling structure, a tongue groove cooling structure is further added at the outlet of the small elbow pipe, compared with the ordinary divergent cooling, the cooling gas film at the outlet of the tongue groove cooling structure has a long covering distance along the flow direction and a large thickness, which can effectively reduce the gas temperature near the wall of the outlet section of the small elbow pipe, and further reduce the thermal load of the upper edge plate of the gas turbine guide vane, and the cooling structure has passed the combustion chamber component test, the whole machine bench test and the field test flight, and has good effect.

[0020] In addition to the objects, features, and advantages described above, the present application has other objects, features, and advantages. The present application will be further described below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, illustrate preferred embodiments of the application, and assist in the explanation of the application. In the drawings:

[0022] Figure 1 is a front structure schematic view of the combustion chamber outlet cooling structure of the preferred embodiment of the present application;

[0023] Figure 2 is Figure 1 is a schematic view of the support ring hole / flange hole in the application;

[0024] Figure 3 is Figure 1 is a schematic view of the structure in which the boss is formed on the inner side of the mounting ring groove in the application;

[0025] Figure 4 is Figure 1 is a schematic view of the structure in which the boss is formed on the inner side of the mounting ring groove in the application;

[0026] Figure 5 isFigure 1 Schematic diagram of the divergent hole on the small bend pipe;

[0027] Figure 6 is Figure 1 Schematic diagram of the impact hole on the inner ring beak ring Figure 1 ;

[0028] Figure 7 is Figure 1 Schematic diagram of the impact hole on the inner ring beak ring Figure 2 ;

[0029] Figure 8 is Figure 1 Schematic diagram of the overlap size between the initial section of the small bend pipe and the inner ring beak ring

[0030] Figure 9 is Figure 1 Schematic diagram of the arrangement of the divergent hole on the middle section of the small bend pipe

[0031] Figure 10 is Figure 9 Schematic diagram of the angle of the divergent hole on the middle section of the small bend pipe

[0032] Legend:

[0033] 10, small bend pipe; 101, thermal barrier coating; 102, divergent hole; 103, gas film groove hole; 104, tongue ring; 105, pin hole; 106, upper edge plate support ring; 107, boss; 108, support ring hole; 20, inner ring beak ring; 201, impact hole; 30, large bend pipe; 301, flange edge hole; 40, gas turbine guide vane; 401, upper edge plate; 402, blade body; 50, large bend pipe outside airflow; 70, combustion chamber outlet flow channel; 80, positioning pin; 90, special seal ring. DETAILED DESCRIPTION

[0034] The embodiments of the present application are described in detail below with reference to the accompanying drawings, but the present application can be implemented in various different ways as defined and covered below.

[0035] Reference Figure 1The preferred embodiment of the present application provides a combustion chamber outlet cooling structure, which comprises an inner ring bird mouth ring 20 of a tail section of an inner ring of a flame tube, a single-wall small bend pipe 10, and a gas turbine guide vane 40. A small bend pipe starting section at an air inlet end of the small bend pipe 10 is inserted into the inner ring bird mouth ring 20 through an opening of the inner ring bird mouth ring 20. Impact holes 201 are formed on the inner ring bird mouth ring 20, and are used to introduce part of the inner two-pass channel airflow into a combustion chamber outlet flow channel 70 through the impact holes 201 and a bird mouth ring cavity of the inner ring bird mouth ring 20, so as to form a wall-attached cooling air film covering the small bend pipe starting section in the combustion chamber outlet flow channel 70. A plurality of sets of radial direction-divergent holes are formed on a small bend pipe middle section at a middle part of the small bend pipe 10, and are used to introduce part of the inner two-pass channel airflow into the combustion chamber outlet flow channel 70 through the sets of radial direction-divergent holes, so as to form a large cooling air film at a large curvature position of the small bend pipe middle section. A tongue groove cooling structure and an air film groove hole 103 are arranged on a small bend pipe outlet section at an air outlet end of the small bend pipe 10, and are used to introduce part of the inner two-pass channel airflow into the impact tongue groove cooling structure through the air film groove hole 103, so as to form a cooling air film flowing along a profile of the small bend pipe outlet section, thereby cooling the small bend pipe outlet section and an upper edge plate 401 of the gas turbine guide vane 40. The small bend pipe 10 further comprises an upper edge plate supporting ring 106 arranged at a rear of the small bend pipe outlet section and in a ring shape, and the gas turbine guide vane 40 is arranged at the air outlet end of the small bend pipe 10 and is located in the upper edge plate supporting ring 106.

[0036] During operation of the combustion chamber outlet cooling structure, the temperature of the gas discharged from the combustion chamber into the combustion chamber outlet flow channel 70 is high, and the small bend pipe 10 needs to withstand high-temperature erosion, and is prone to failure such as ablation. Therefore, in the cooling scheme of the present application, first, impact holes 201 are formed on the inner ring bird mouth ring 20 at an outlet end of the inner ring of the flame tube, and part of the inner two-pass channel airflow from the inner two-pass channel is introduced into a bird mouth ring cavity in the inner ring bird mouth ring 20 through the impact holes 201. The part of the airflow enters the combustion chamber outlet flow channel 70 from the bird mouth ring cavity, and forms a good wall-attached cooling air film covering the small bend pipe starting section. Second, a plurality of sets of radial direction-divergent holes are formed on the small bend pipe middle section, and part of the inner two-pass channel airflow enters the combustion chamber outlet flow channel 70 through the sets of radial direction-divergent holes, thereby forming a large cooling air film at a large curvature position of the small bend pipe middle section, and cooling the small bend pipe middle section and further cooling the metal matrix of the small bend pipe 10. Finally, a tongue groove cooling structure and an air film groove hole 103 are arranged on the small bend pipe outlet section, and part of the inner two-pass channel airflow is introduced into the impact tongue groove cooling structure through the air film groove hole 103, so that the inner two-pass channel airflow forms a cooling air film flowing along a downstream profile of the small bend pipe outlet section, thereby cooling the small bend pipe outlet section and the upper edge plate 401 of the gas turbine guide vane 40.

[0037] In the combustion chamber outlet cooling structure, it is calculated that the maximum thermal state of the inner ring wall of the flame tube is up to about 1000 DEG C, and the local average stress is more than 200 MPa, the inner ring of the flame tube is a large-diameter thin-walled part, and the stress resistance level is limited, so in the cooling structure, the small-bend-pipe starting section at the gas inlet end of the small-bend-pipe 10 is directly inserted into the beak ring cavity of the inner ring beak ring 20, and is not designed in an integrated manner with the inner ring beak ring 20, that is, the small-bend-pipe 10 and the inner ring of the flame tube are designed in a split manner in the application, which not only facilitates assembly, but also ensures the release of thermal expansion stress under thermal state, so that the flame tube inner ring wall is not deformed by thermal arching to cause other faults or safety accidents, and the technical problem of the existing structure that the thermal stress release space is small, and the thin-walled inner ring of the flame tube may finally arch and deform is solved; in the cooling structure, the upper edge plate support ring 106 of the upper edge plate support plate of the gas turbine guide vane 40 is an integral part with the small-bend-pipe 10, and is formed by machining of an integral forging part, thereby reducing the number of parts and the assembly difficulty of the gas turbine guide vane 40; in the cooling structure, a tongue and groove cooling structure is additionally arranged at the outlet of the small-bend-pipe, compared with the ordinary divergent cooling, the cooling gas film at the outlet of the tongue and groove cooling structure has a long coverage distance along the flow direction and a large thickness, which can effectively reduce the gas temperature near the wall of the outlet section of the small-bend-pipe to a certain extent, and further reduce the thermal load of the upper edge plate 401 of the gas turbine guide vane 40; the cooling structure has been tested by the combustion chamber component test, the whole machine bench test and the field flight test, and has good effect.

[0038] Optionally, as shown in Figure 1 , Figures 6-7 , a plurality of impact holes 201 are arranged on the circumference of the inner ring beak ring 20 in sequence and at intervals. The plurality of impact holes 201 have the same diameter and are arranged in sequence and at intervals in the circumferential direction, as shown in Figure 7 ; or the plurality of impact holes 201 have different diameters and are arranged in sequence and at uniform intervals in the circumferential direction, as shown in Figure 6 . In actual design, a plurality of heads are arranged on the circumference of the combustion chamber, the wall temperature of the small-bend-pipe at the head of the flame tube is obviously higher than that at other positions between the heads, and accordingly, in this optional scheme, the impact holes 201 on the inner ring of the flame tube are arranged in the manner of dense and sparse intervals, as shown in Figure 7 , or in the manner of large and small intervals, as shown in Figure 6 , and the small-bend-pipe 10 opposite to the head of the flame tube can be arranged with impact holes 201 having a larger diameter or arranged compactly, or vice versa, to better meet the cooling demand.

[0039] Optionally, as shown in Figure 1 and Figure 8As shown in the drawings, the small-bend pipe starting section and the cavity bottom of the bird-mouth ring cavity have an axial gap δ, 0.5mm≤δ≤3.5mm; in actual design, δ should meet the size chain calculation requirements, and ensure that the small-bend pipe 10 and the inner ring of the flame tube do not interfere with each other in cold and hot states, release the expansion stress in the hot state, and ensure that the inner ring wall surface of the flame tube is not deformed by thermal arching to cause other faults or safety accidents.

[0040] Optionally, as shown in the drawings, Figure 1 and Figure 8 the inner ring surface of the small-bend pipe starting section and the inner ring surface of the bird-mouth ring cavity have a radial gap θ, 0.07mm≤θ≤0.15mm; in this optional scheme, the small gap θ between the inner ring surface of the small-bend pipe starting section and the inner ring surface of the bird-mouth ring cavity meets the assembly requirements and can ensure that the flame tube does not leak in the hot state.

[0041] Optionally, as shown in the drawings, Figure 1 and Figure 8 the outer ring surface of the small-bend pipe starting section and the outer ring surface of the bird-mouth ring cavity have a radial gap D, the gap L between the cavity bottom of the bird-mouth ring cavity and the end surface of the outer ring of the bird-mouth ring 20 is axial, and D / L=0.1-0.2, and the included angle α between the center line of the impact hole 201 and the outer ring surface of the bird-mouth ring cavity is related to D / L, the larger D / L is, the larger the included angle α is to 90°, and the smaller D / L is, the smaller the included angle α is to more than 0°.

[0042] Optionally, as shown in the drawings, Figure 1 , Figures 9-10 each circle of the divergent hole group includes a plurality of divergent holes 102 arranged in sequence and spaced apart in the circumferential direction, and the plurality of divergent holes 102 of adjacent two circles of the divergent hole group are arranged in a one-to-one staggered manner in the circumferential direction, that is, the positions of adjacent two circles in the circumferential direction are staggered, forming a long rhombus arrangement. The tangential angle of the divergent hole 102 of the remaining circle of the divergent hole group except the innermost circle is 80°-100°, and the punching angle is 20°-30°. In the conventional way, the small-bend pipe adopts a conventional gas film+divergent cooling structure, and due to the convex surface of the special large-curvature profile structure, it is extremely difficult for the cooling gas film to adhere to the surface. In the cooling structure of the present application, the divergent holes 102 of the remaining circle of the divergent hole group except the innermost circle all adopt a large-angle (tangential angle 80°-100°) compound angle (each divergent hole 102 has a tangential angle and a punching angle) to greatly improve the gas film adhesion effect. The tangential angle of the divergent hole 102 of the divergent hole group of the innermost circle is greater than 0°-15°, and the punching angle is less than 30°.

[0043] In this optional scheme, as shown in the drawings, Figures 9-10 three rows of divergent holes 102 are arranged on the arc surface of the middle section of the small-bend pipe, 210×φ0.5 small holes are arranged in each row, and the positions of adjacent two rows are staggered in the circumferential direction, forming a long rhombus arrangement, as shown in the drawings, Figure 5As shown. The first two rows are tangentially perforated. The tangential angle of the first row of holes is 80° to 90°, preferably 86°, and the tangential angle of the second row of holes is 90° to 100°, preferably 92°. The perforations face the same direction, i.e., towards the direction of the rotating airflow. The perforation angle of the first two rows of holes is 20° to 30°, preferably 25°. Thus, through the design of the larger tangential angle of the diverging holes 102 and the composite angle of the two directions, a large air film cooling can be formed at the large curvature of the middle section of the small bend tube 10 by the airflow of the two inner channels, thereby better protecting the metal substrate of the small bend tube 10. The third row of diverging holes is perforated at 0° to 15° along the airflow direction (excluding the tangential angle of 0°), and the perforation angle should preferably be less than 30° to ensure the formation of a more closely attached wall airflow to protect the metal substrate of the small bend tube 10.

[0044] Optionally, such as Figure 1 As shown, the concave extension of the outlet section of the small bend forms a circumferential air film groove, and an annular tongue ring 104 and a tail ring are located on both sides of the air film groove. The air film groove and the tongue ring 104 form a tongue groove cooling structure. The air film groove hole 103 is opened on the tail ring and communicates with the air film groove, so as to introduce part of the airflow from the two inner channels into the tongue ring 104 to impact the tongue ring 104, thereby forming a cooling air film that flows along the wall of the outlet section of the small bend.

[0045] In this optional solution, such as Figure 1 As shown, there are multiple film cooling slots 103, and these slots are evenly spaced circumferentially. The height of the film cooling slots is 1mm to 2mm; preferably, the height is 1.5mm. During operation, the airflow passes through the film cooling slots 103 and impacts the tongue ring 104, causing it to form a cooling film flowing along the downstream profile of the small bend outlet section, thereby cooling the gas turbine guide vane and further reducing the blade tip temperature.

[0046] Preferably, such as Figure 8 As shown, the inner ring of the starting section of the small bend has a chamfer, which facilitates guiding the small bend 10 during assembly. Figure 1 As shown, the gas-side profile of the small bend 10 is also coated with a thermal barrier coating 101 to improve its heat resistance.

[0047] Optionally, such as Figure 1As shown, the gas turbine guide vane 40 includes guide vanes arranged in sequence along the circumference, the guide vanes including a blade body 402 and an upper edge plate 401, and the upper edge plate 401 is arranged in the upper edge plate support ring 106. The upper edge plate support ring 106 is provided with a support ring hole 108 arranged in sequence along the circumference and penetrating through, so as to introduce part of the inner two-channel airflow into the blade body 402 through the support ring hole 108 and the upper edge plate 401. The combustion chamber outlet cooling structure further includes a large elbow pipe 30 arranged outside the small elbow pipe 10, and the large elbow pipe 30 is provided with a flange edge hole 301 arranged in sequence along the circumference and penetrating through on the flange edge of the large elbow pipe 30, so as to introduce the airflow 50 outside the large elbow pipe into the gas turbine guide vane 40 and the blade body 402 through the flange edge hole 301.

[0048] The cooling structure of the present application further includes the support ring hole 108 provided on the upper edge plate support ring 106, and the support ring hole 108 is used to introduce part of the inner two-channel airflow into the blade body 402 of the gas turbine guide vane 40 through the support ring hole 108. After the airflow enters the inside of the blade body 402, the blade body 402 is cooled by the airflow flowing through the holes on both sides, thereby reducing the probability of ablation and cracks caused by high-temperature gas erosion on the blade body 402. Further, the cooling structure further includes the flange edge hole 301 provided on the flange edge of the large elbow pipe 30, and the airflow 50 outside the large elbow pipe enters the turbine through the flange edge hole 301, part of which flows into the main flow channel after cooling the blade body 402, and the other part enters other parts for sealing cooling. Therefore, in the cooling structure of the present application, the inner two-channel airflow and the airflow 50 outside the large elbow pipe are introduced to cool the small elbow pipe 10 and the gas turbine guide vane 40 through the combined action of the impact hole 201, the divergent hole 102, the gas film groove hole 103, the tongue ring 104, the support ring hole 108, and the flange edge hole 301. Both have good cooling effect and are not easy to cause ablation and cracks due to high-temperature gas erosion.

[0049] Optionally, as shown in Figure 1 and Figure 3 , the combustion chamber outlet cooling structure further includes a positioning pin 80, which is inserted into the upper edge plate 401 after being interference-fitted through the upper edge plate support ring 106, so as to position the small elbow pipe 10. In this optional scheme, the small elbow pipe 10 and the upper edge plate support ring 106 are designed as an integral piece, and the upper edge plate support ring 106 is provided with a pin hole 105 along the circumference. The small elbow pipe 10 and the gas turbine guide vane 40 can be fixed by using the positioning pin 80, that is, the small elbow pipe 10 is positioned, and the small elbow pipe 10 and the gas turbine guide vane 40 are connected together by skillfully using the positioning pin 80. Compared with other connection methods, this method has the advantages of simple structure, fewer parts, economy and reliability, simple and reliable assembly, and convenient disassembly, which improves the level of modular design.

[0050] Optionally, as shown in Figure 1 and Figure 2As shown, the support ring holes 108 and the flange edge holes 301 are uniformly spaced along the circumference, and the number of the support ring holes 108 and the flange edge holes 301 is proportional to the number of the guide vane, that is, the support ring holes 108 and the flange edge holes 301 are uniformly arranged corresponding to the guide vane, and the internal two-channel airflow is used to cool the inside of the gas turbine guide vane, thereby improving the cooling effect of the guide vane.

[0051] Preferably, as shown in Figure 1 and Figure 4 As shown, the radial end face of the outlet end of the upper edge plate support ring 106 is concave to form a mounting ring groove, and the inner ring on the inner side of the mounting ring groove is sequentially opened in the circumferential direction to form a boss 107. The combustion chamber outlet cooling structure further comprises a special-shaped sealing ring 90 clamped in the mounting ring groove, and the special-shaped sealing ring 90 is used to seal the radial gap between the outlet end of the upper edge plate support ring 106 and the outlet side of the upper edge plate 401. In the preferred embodiment, the circumferential opening on the inner ring on the inner side of the mounting ring groove facilitates the removal of the special-shaped sealing ring 90 from the mounting ring groove and the installation of the special-shaped sealing ring 90, and the operation is simple.

[0052] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A combustion chamber outlet cooling structure, comprising an inner shroud bird beak ring (20) of a shroud tail section of a flame tube, a single-wall small bend tube (10) and a gas turbine guide vane (40), characterized in that, a small bend tube initial section at an air inlet end of the small bend tube (10) is inserted into the inner shroud bird beak ring (20) through an opening of the inner shroud bird beak ring (20), the inner shroud bird beak ring (20) is provided with impact holes (201), and part of the inner two-pass channel airflow is introduced into a combustion chamber outlet flow passage (70) through the impact holes (201) and a bird beak ring cavity of the inner shroud bird beak ring (20), so as to form a wall-attached cooling air film covering the small bend tube initial section in the combustion chamber outlet flow passage (70) ; a plurality of sets of divergent holes are arranged on a small bend tube middle section of the small bend tube (10), and the sets of divergent holes are arranged along a radial direction in turn, so as to introduce part of the inner two-pass channel airflow into the combustion chamber outlet flow passage (70) through the sets of divergent holes, so as to form a large cooling air film at a large curvature of the small bend tube middle section; a tongue slot cooling structure and an air film slot hole (103) are arranged on a small bend tube outlet section of the small bend tube (10), so as to introduce part of the inner two-pass channel airflow into the impact tongue slot cooling structure through the air film slot hole (103), so as to form a cooling air film flowing along a profile of the small bend tube outlet section and attaching to a wall, so as to cool the small bend tube outlet section and an upper edge plate (401) of the gas turbine guide vane (40) ; the small bend tube (10) further comprises an upper edge plate support ring (106) arranged behind the small bend tube outlet section and in a ring shape, and the gas turbine guide vane (40) is arranged at an air outlet end of the small bend tube (10) and located in the upper edge plate support ring (106) ; a radial end surface of an outlet end of the upper edge plate support ring (106) is concave, an installation ring groove is formed in the radial end surface, an inner ring of the installation ring groove is opened in a circumferential direction in turn to form a boss (107), and the combustion chamber outlet cooling structure further comprises a special-shaped sealing ring (90) clamped in the installation ring groove, the special-shaped sealing ring (90) is used for sealing a radial gap between the outlet end of the upper edge plate support ring (106) and an outlet side of the upper edge plate (401). 2.The combustion chamber outlet cooling structure according to claim 1, characterized in that, a plurality of impact holes (201) are arranged on a circumferential direction of the inner shroud bird beak ring (20) in turn and in a spaced manner; the plurality of impact holes (201) are of the same diameter and arranged in a spaced manner in turn along the circumferential direction; or the plurality of impact holes (201) are of different diameters and arranged in a uniformly spaced manner along the circumferential direction. 3.The combustion chamber outlet cooling structure according to claim 1, characterized in that, a gap δ along an axial direction is arranged between a cavity bottom of the bird beak ring cavity and the small bend tube initial section, and 0.5mm≤δ≤3.5mm; a gap θ along a radial direction is arranged between an inner surface of the bird beak ring cavity and an inner surface of the small bend tube initial section, and 0.07mm≤θ≤0.15mm. The outer ring surface of the initial section of the small bend pipe and the outer ring surface of the beak ring cavity have a radial gap D, the gap L between the cavity bottom of the beak ring cavity and the end surface of the outer ring of the inner ring beak ring (20) is axial, and D / L=0.1-0.2, and the angle α between the center line of the impact hole (201) and the outer ring surface of the beak ring cavity is related to D / L, the larger D / L is, the larger the angle α is to 90°, the smaller D / L is, and the smaller the angle α is to more than 0°.

4. The combustion chamber outlet cooling structure according to claim 1, wherein, Each circle of the divergent hole group comprises a plurality of divergent holes (102) arranged in sequence and spaced apart in the circumferential direction, and the plurality of divergent holes (102) of adjacent two circles of the divergent hole group are arranged in one-to-one staggered manner in the circumferential direction; The tangential angle of the divergent hole (102) of the divergent hole group of the remaining circles except the innermost circle is 80°-100°, and the punching angle is 20°-30°; The tangential angle of the divergent hole (102) of the divergent hole group of the innermost circle is greater than 0°-15°, and the punching angle is less than 30°.

5. The combustion chamber outlet cooling structure according to claim 1, wherein, The outlet section of the small bend pipe is concave to form a ring-shaped gas film groove, and a tongue ring (104) and a tail ring are arranged on both sides of the gas film groove; The gas film groove and the tongue ring (104) form a tongue groove cooling structure; The gas film groove hole (103) is arranged on the tail ring and communicates with the gas film groove, so as to introduce part of the inner two-channel airflow into the impact tongue ring (104), thereby forming a cooling gas film flowing along the surface of the outlet section of the small bend pipe.

6. The combustion chamber outlet cooling structure according to claim 5, wherein, The number of the gas film groove holes (103) is multiple, and the multiple gas film groove holes (103) are uniformly and spaced apart in the circumferential direction; The height of the gas film groove is 1mm-2mm.

7. The combustion chamber outlet cooling structure according to claim 1, wherein, The inner ring of the initial section of the small bend pipe is provided with a chamfer; The gas side surface of the small bend pipe (10) is further sprayed with a thermal barrier coating (101).

8. The combustion chamber outlet cooling structure according to claim 1, wherein, The gas turbine guide vane (40) comprises guide vanes arranged in sequence in the circumferential direction, and each guide vane comprises a vane body (402) and an upper edge plate (401), and the upper edge plate (401) is arranged in the circumferential direction and spaced apart from the upper edge plate support ring (106); The upper edge plate support ring (106) is provided with support ring holes (108) arranged in sequence and penetrating through in the circumferential direction, so as to introduce part of the inner two-channel airflow into the vane body (402) through the support ring holes (108) and the upper edge plate (401); The combustion chamber outlet cooling structure further comprises a large bend pipe (30) arranged outside the small bend pipe (10), and the large bend pipe (30) is provided with flange edge holes (301) arranged in sequence and penetrating through in the circumferential direction on the flange edge of the large bend pipe (30), so as to introduce the airflow (50) outside the large bend pipe into the gas turbine guide vane (40) and the vane body (402) through the flange edge holes (301).

9. The combustion chamber outlet cooling structure according to claim 8, wherein, The combustion chamber outlet cooling structure further comprises a positioning pin (80) which is inserted into the upper edge plate (401) through the upper edge plate supporting ring (106) after being interference fitted, so as to position the small elbow pipe (10); The supporting ring holes (108) and the flange edge holes (301) are respectively arranged in a uniform interval along the circumference, and the number of the supporting ring holes (108) and the flange edge holes (301) respectively has a proportional relationship with the number of the guide vane blades.

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