Method for replacing flame tube in field under engine whole machine state

Abstract

The present application belongs to the field of aero-engine maintenance technology, and provides a method for replacing a flame tube in an engine under an overall engine state, which is implemented when the engine is in an overall engine state under field conditions, and the turbine, turbine rear support and reverse thrust device are not disassembled. By sequentially disassembling the combustion chamber rear casing and the combustion chamber removable shell, the flame tube to be replaced in the inner channel is exposed. After the anti-falling pretreatment, the rear end fixing screw and the front end working nozzle are disassembled, the old flame tube is integrally pulled out along the engine axial direction, and the new flame tube is inserted into the predetermined position. When reassembling, the connection and sealing of each part are restored in the reverse order. The present application does not need to disassemble the engine in the factory, can complete the field replacement within 1 to 4 working days, significantly shortens the maintenance cycle, greatly reduces the maintenance cost, and effectively improves the supportability and rapid repair ability of the aero-engine in the field environment.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine maintenance technology and relates to a method for replacing the flame tube in the field while the engine is in its entirety. Background Technology

[0002] In the field of aero-engine maintenance and repair, ensuring the efficient and reliable operation of engines is one of the most crucial tasks. The combustion chamber mixes and burns compressed air and fuel, converting the chemical energy of the fuel into the kinetic energy of the high-temperature, high-pressure combustion gas, which drives the turbine to expand and perform work. As the core component of the combustion chamber, the flame tube is the main site of fuel combustion, and its structural integrity and thermal protection performance are directly related to the overall performance and operational safety of the engine.

[0003] The flame tubes within the combustion chamber (especially the sixth section) are prone to cracking and ablation due to high-temperature exhaust erosion and thermal fatigue. To ensure flight safety, the condition of the flame tubes must be inspected regularly during service. If the damage exceeds permissible limits, the engine must be shut down, and the entire engine removed from the aircraft and returned to the factory for repair. Figure 3 As shown, the order of disassembling the flame tube after returning to the factory is: thrust reverser 8 → turbine rear support 7 → low-pressure turbine 6 → high-pressure turbine 5 → combustion chamber rear casing 4.

[0004] In the prior art, Chinese patents CN222951051U (assembly tooling for combustion chamber components), CN221659126U (a gas turbine overhaul tooling), CN222986884U (a support device for the production and processing of combustion chamber shells), and CN221817821U (a welding tooling for engine flame tubes) all focus on the manufacturing or assembly process at the component level, and do not involve the disassembly and assembly method of the flame tube on the whole machine.

[0005] Other Chinese patents CN222244610U (a special tool for disassembling the combustion chamber of a heavy-duty gas turbine) and CN221111575U (a tool for assembling and tightening the combustion chamber) involve the disassembly and assembly of the combustion chamber, but their application scenarios are limited to the state of the combustion chamber after it has been disassembled from the engine, and they cannot be applied to the operation under the condition of whole machine installation.

[0006] Research revealed that existing technologies generally focus on preventative structural improvements or component-level repairs in factory environments, failing to address the issue of rapid replacement of the flame tube in both the engine's overall condition and field environments. Because the flame tube is located deep within the engine's internal combustion chamber, and suitable technical means and specialized equipment are lacking in field settings, the engine currently requires returning to the factory for disassembly down to the combustion chamber component level before the flame tube can be completely removed for replacement. This process is time-consuming, costly, and slow to respond, failing to meet users' urgent needs for high availability, rapid troubleshooting, and field maintainability. Summary of the Invention

[0007] To address the aforementioned technical issues and achieve safe and efficient replacement of the flame tube without disassembling the engine or returning it to the factory, thereby significantly shortening the maintenance cycle, reducing maintenance costs, and ensuring operational safety and engine internal cleanliness, this invention discloses a method for field replacement of the flame tube while the engine is in its entirety.

[0008] Specifically, the engine is in an outdoor environment, and the turbine, turbine rear support, and thrust reverser have not been disassembled; the method includes the following steps performed sequentially:

[0009] S1. Remove the combustion chamber rear casing; S2. Remove the removable outer casing of the combustion chamber located inside the rear casing of the combustion chamber to expose the flame tube to be replaced inside the inner duct; S3. After performing anti-detachment pretreatment on the flame tube to be replaced, remove the fixing screws connecting its rear end to the combustion chamber mounting base, and remove the working nozzle assembled at its front end.

[0010] S4. The flame tube to be replaced is pulled out of the combustion chamber along the engine axis as a whole, and the new flame tube is inserted into the predetermined installation position along the same path.

[0011] The flame tube to be replaced is located at least partially in the engine inner duct corresponding to the area inside the combustion chamber diffuser casing, and the flame tube has cracks or ablation.

[0012] Furthermore, in step S3, the anti-detachment pretreatment includes: using metal fuses to sequentially connect and lock the flame tube to be replaced with two flame tubes adjacent to it in the circumferential direction, so as to prevent the flame tube to be replaced from falling off due to gravity or vibration during disassembly.

[0013] Furthermore, in steps S1 to S4, during the disassembly of the flame tube to be replaced, a polyethylene film is used to temporarily seal the combustion chamber opening, and the compressor outlet and turbine guide inlet connected to the flame tube to be replaced are also temporarily sealed.

[0014] Furthermore, in step S3, a special disassembly and assembly tool is used to operate the fasteners in space-constrained locations; The special disassembly and assembly tool includes a tool body with a first square hole and a second square hole at both ends and a handle in the middle. Both the first square hole and the second square hole are used to disassemble and assemble the fixing screw, and the central axes of the first square hole and the second square hole form a 30° angle to accommodate different angles of the fixing screw. The handle has avoidance grooves extending along the engine axis on both sides to avoid interference from adjacent flame tubes or support structures during operation.

[0015] Furthermore, the specialized disassembly and assembly tool is used to disassemble and assemble the circumferentially distributed fixing screws at the rear end of the flame tube.

[0016] Furthermore, after the new flame tube is inserted into the predetermined installation position along the same path, the following reassembly steps are performed in the reverse order of disassembly: S5. Reinstall the working nozzle and tighten its connecting screws; S6. The combustion chamber can be installed by removing the outer shell and sealing its joints; S7. Reinstall the combustion chamber rear casing and connect it to the engine outer casing using circumferential bolts.

[0017] The method of this invention solves the problems of long cycles and high costs caused by the need to return the engine to the factory for repair after thermal damage to the flame tube or gas duct in the prior art. Traditional factory repair requires the engine to be completely disassembled from the aircraft and broken down to the combustion chamber component level. The entire repair cycle is usually no less than one month and involves high transportation, disassembly and assembly, and factory-level labor costs.

[0018] Using the method described in this invention, the flame tube replacement can be completed directly while the engine is in the field condition and in its entirety, without the need for returning it to the factory or disassembling critical components such as the turbine, turbine rear support, and thrust reverser. The entire maintenance process can be completed by a small number of technicians within 1 to 4 working days, significantly reducing downtime and greatly improving equipment availability.

[0019] Meanwhile, by eliminating engine disassembly, transportation, and factory-level overhaul processes, maintenance costs are significantly reduced. This method transforms flame tube replacement from "factory-level repair" to "field-level rapid maintenance," effectively meeting the technical requirements of modern aero engines for high supportability, high maintainability, and rapid fault response capabilities. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is the process for disassembling the flame tube in the field while the engine is in its complete state, as described in this embodiment of the invention. Figure 2 This is the process for installing the flame tube in the field when the engine is in its complete state, as described in this embodiment of the invention. Figure 3 This is a schematic diagram showing the disassembly of the flame tube after the engine is returned to the factory. Figure 4A schematic diagram of the decomposition of the flame tube under the overall engine condition in the field. Figure 5 This is a schematic diagram of the engine combustion chamber components; Among them, 4 is the rear casing of the combustion chamber; 5 is the high-pressure turbine; 6 is the low-pressure turbine; 7 is the rear support of the turbine; 8 is the thrust reverser; and 9 is the removable outer shell of the combustion chamber. Detailed Implementation

[0022] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0023] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features of the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] This invention discloses a method for replacing the flame tube in the field while the engine is in its entirety. This method enables flame tube replacement under field operating conditions without returning to the factory, optimizing flame tube maintenance for this type of engine from the base level to the field level, shortening the engine maintenance cycle, and reducing maintenance costs. Specifically, the engine remains installed on the aircraft, and the high-pressure turbine 5, low-pressure turbine 6, turbine rear support 7, and thrust reverser 8 are not disassembled. Figure 1 As shown, the method includes the following steps performed sequentially: S1, such as Figure 4 As shown, the combustion chamber rear casing 4 will be disassembled.

[0025] S2, such as Figure 5 As shown, the removable outer casing 9 of the combustion chamber, located inside the rear casing of the combustion chamber, is removed to expose the flame tube to be replaced within the internal duct. The flame tube to be replaced is at least partially located in the region within the engine internal duct corresponding to the combustion chamber diffuser casing, and the flame tube exhibits cracks or ablation.

[0026] S3. After performing anti-detachment pretreatment on the flame tube to be replaced, remove the fixing screws connecting its rear end to the combustion chamber mounting base, and remove the working nozzle assembled at its front end.

[0027] In practice, the pre-treatment to prevent detachment includes: using metal fuses to sequentially connect the flame tube to be replaced with two adjacent flame tubes in the circumferential direction and lock them in place, so as to prevent the flame tube to be replaced from falling off due to gravity or vibration during disassembly.

[0028] Since the fixing screws connecting the rear end of the flame tube to the combustion chamber mounting base, the connecting screws of the working nozzle mounted at its front end, and other fasteners are all located in a space-constrained area, a special disassembly and assembly tool needs to be designed for their disassembly and assembly. In an embodiment where no drawings are shown, the special disassembly and assembly tool includes a tool body with a first square hole and a second square hole at both ends, and a handle in the middle.

[0029] Both the first and second square holes are used for installing and removing the fixing screws, and the central axes of the first and second square holes form a 30° angle to accommodate different angles of the fixing screws. The handle has clearance grooves extending along the engine axis on both sides to avoid interference from adjacent flame tubes or support structures during operation. In practice, by providing two asymmetrical square holes and clearance grooves on the tool body, the problem of removing and installing fixing screws in confined spaces can be solved.

[0030] S4. The flame tube to be replaced is pulled out of the combustion chamber along the engine axis as a whole, and the new flame tube is inserted into the predetermined installation position along the same path.

[0031] In one embodiment, during steps S1 to S4, when disassembling the flame tube to be replaced, a polyethylene film is used to temporarily seal the combustion chamber opening, and the compressor outlet and turbine guide inlet connected to the flame tube to be replaced are also temporarily sealed to prevent foreign objects from entering the engine core flow channel and to ensure the cleanliness of the core engine.

[0032] In another embodiment, such as Figure 2 As shown, after the new flame tube is inserted into the predetermined installation position along the same path, the following reassembly steps are performed in the reverse order of disassembly: S5. Reinstall the working nozzle and tighten its connecting screws; S6. Install the removable outer casing 9 for the combustion chamber and seal its seams; S7. Reinstall the combustion chamber rear casing 4 and connect the combustion chamber rear casing to the engine core casing using circumferential bolts.

[0033] This invention takes the combustion chamber of a certain type of aircraft engine as an example, which includes multiple circumferentially distributed flame tubes. The sixth section of each flame tube is a high-risk area for cracking and ablation due to the erosion caused by high-temperature exhaust gases, requiring periodic replacement of the flame tube. The disassembly and assembly process of the flame tubes is as follows: First, disassemble the flame tube in the field (in its complete state): Technicians approached the engine tail section on the aircraft tarmac (outdoors), first removing the circumferential connecting bolts of the combustion chamber rear casing and then removing the rear casing. Subsequently, they removed the inner combustion chamber removable outer shell, exposing the flame tube to be replaced.

[0034] To prevent the flame tube from accidentally falling off, a stainless steel fuse can be used to connect the flame tube to be replaced to its two adjacent flame tubes on the left and right in sequence, and then tie a knot at the end to lock it in place.

[0035] Using a specialized disassembly and assembly tool: Insert the first or second square hole on the tool body into the three fixing screws at the rear end of the flame tube, and loosen them by applying force with the handle; due to space constraints, a conventional wrench cannot be used, but the clearance grooves on both sides of the tool handle can avoid adjacent structures. The included angle α between the central axes of the two square holes is 30° to accommodate different installation angles.

[0036] Subsequently, the entire flame tube is extracted along the engine axis, and a new flame tube is inserted into the predetermined position along the same path. The new flame tube is then reassembled in the reverse order of disassembly.

[0037] Throughout the disassembly and reassembly of the flame tube, the combustion chamber opening needs to be covered with polyethylene film, and auxiliary sealing of parts such as the compressor outlet should be carried out according to the actual site conditions.

[0038] Verification has shown that the method of this invention can be completed within 1–4 working days with the cooperation of 2–3 technicians, meeting the needs of rapid field repair.

[0039] The embodiments of the present invention achieve the following technical effects: The method of this invention solves the problems of long cycles and high costs caused by the need to return the engine to the factory for repair after thermal damage to the flame tube or gas duct in the prior art. Traditional factory repair requires the engine to be completely disassembled from the aircraft and broken down to the combustion chamber component level. The entire repair cycle is usually no less than one month and involves high transportation, disassembly and assembly, and factory-level labor costs.

[0040] Using the method described in this invention, the flame tube replacement can be completed directly in the field while the engine is in its complete state, without the need to return it to the factory or disassemble critical components such as the turbine, turbine rear support, and thrust reverser. The entire maintenance process can be completed by a small number of technicians within 1 to 4 working days, significantly reducing downtime and greatly improving equipment availability.

[0041] Meanwhile, by eliminating engine disassembly, transportation, and factory-level overhaul processes, maintenance costs are significantly reduced. This method transforms flame tube replacement from "factory-level repair" to "field-level rapid maintenance," effectively meeting the technical requirements of modern aero engines for high supportability, high maintainability, and rapid fault response capabilities.

[0042] Obviously, those skilled in the art should understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Various modifications and variations of the embodiments of the present invention are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for replacing the flame tube in the field while the engine is in its entirety, characterized in that, The engine is in an outdoor environment, and the turbine, turbine rear support, and thrust reverser have not been disassembled; the method includes the following steps performed in sequence: S1. Remove the rear casing of the combustion chamber; S2. Remove the removable outer casing of the combustion chamber located inside the rear casing of the combustion chamber to expose the flame tube to be replaced inside the inner duct; S3. After performing anti-detachment pretreatment on the flame tube to be replaced, remove the fixing screws connecting its rear end to the combustion chamber mounting base and remove the working nozzle assembled at its front end. S4. Pull the flame tube to be replaced out of the combustion chamber along the engine axis as a whole, and insert the new flame tube into the predetermined installation position along the same path; The flame tube to be replaced is located at least partially in the engine inner duct corresponding to the area inside the combustion chamber diffuser casing, and the flame tube has cracks or ablation.

2. The method for replacing the flame tube in the field while the engine is in its complete state, as described in claim 1, is characterized in that... The anti-fall-off pretreatment includes: using metal fuses to sequentially connect the flame tube to be replaced with the two flame tubes adjacent to it in the circumferential direction and then locking them in place.

3. The method for replacing the flame tube in the field while the engine is in its complete state, as described in claim 1, is characterized in that... During the disassembly of the flame tube to be replaced, a polyethylene film is used to temporarily seal the combustion chamber opening, and the compressor outlet and turbine guide inlet connected to the flame tube to be replaced are also sealed.

4. The method for replacing the flame tube in the field while the engine is in its complete state, as described in claim 1, is characterized in that... Specialized disassembly and assembly tools are used to operate fasteners in space-constrained locations; The special disassembly and assembly tool includes a tool body, with a first square hole and a second square hole at both ends and a handle in the middle; both the first square hole and the second square hole are used to disassemble and assemble the fixing screw, and the central axis of the first square hole and the second square hole form a 30° angle; the handle has clearance grooves extending along the engine axis on both sides.

5. The method for replacing the flame tube in the field while the engine is in its complete state, as described in claim 4, is characterized in that... The special disassembly and assembly tool is used to disassemble and assemble the fixing screws distributed circumferentially at the rear end of the flame tube.

6. The method for replacing the flame tube in the field while the engine is in its complete state, as described in claim 1, is characterized in that... After the new flame tube is inserted into the predetermined installation position along the same path, perform the following reassembly steps in the reverse order of disassembly: S5. Reinstall the working nozzle and tighten its connecting screws; S6. The combustion chamber can be installed by removing the outer shell and sealing its joints; S7. Reinstall the combustion chamber rear casing and connect it to the engine outer casing using circumferential bolts.

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