Combustion chamber double-wall flame tube wall temperature testing structure for gas turbine

Abstract

The invention discloses a combustion chamber double-wall flame tube wall temperature testing structure for a gas turbine, and belongs to the field of low-emission combustion chamber temperature measurement. The structure comprises a galvanic couple lead protection stud, an inner wall galvanic couple test groove and an outer wall floating sealing structure. The galvanic couple lead protection stud is cylindrical, is internally provided with a lead cavity and an external thread, is connected with the internal thread of the inner wall galvanic couple test groove, and is used for fixing a galvanic couple and protecting a lead; a cylindrical groove is formed in the inner wall galvanic couple test groove and is used for welding a galvanic couple to realize inner wall temperature measurement; the outer wall floating sealing structure is composed of a supporting plate, a cover plate and a floating ring, is installed on the outer wall of the flame tube and is used for sealing a thermal coordination gap between the galvanic couple lead protection stud and the outer wall. The structure can realize thermal deformation compensation between the double walls of the flame tube, prevents the thermocouple wire from being broken due to thermal stress or high-speed cooling airflow, and improves the reliability and precision of wall temperature testing.

Description

Technical Field

[0001] This invention belongs to the field of combustion chamber temperature measurement, specifically relating to a structure for testing the wall temperature of a double-walled flame tube in the combustion chamber of a gas turbine. Background Technology

[0002] As a crucial power source for aero engines, ship propulsion, and industrial power generation, the overall performance and lifespan of gas turbines largely depend on the design and reliability of their combustion chambers. The combustion chamber is the hot-end component of a gas turbine, operating in an extremely complex environment, subjected to prolonged exposure to high temperatures, high pressures, and high-speed gas flow. Therefore, its structural cooling design, combustion stability, and thermal load control are among the key technologies affecting the overall lifespan of the gas turbine.

[0003] In recent years, with increasingly stringent requirements for low emissions, gas turbine combustors have widely adopted lean premixed combustion technology to achieve low NOx emissions and high combustion efficiency. Lean premixed combustion reduces the formation of localized high-temperature zones and thermal NOx by thoroughly mixing fuel and air before combustion and burning under lean conditions. However, this technology also introduces the problem of insufficient cooling air distribution; that is, the air demand in the combustion zone is high, while the air available for cooling the combustor walls is limited, resulting in a significant increase in the temperature of the combustor wall and placing higher demands on the cooling structure and temperature monitoring.

[0004] In low-emission combustion chambers, the flame tube typically employs a double-walled structure, achieving efficient cooling through a combination of impact cooling holes and annular rib channels. This ensures both wall temperature control and maintains air utilization efficiency. During the development and validation of the combustion chamber, accurate measurement of the flame tube's inner wall temperature is crucial for evaluating the rationality of the cooling design and combustion stability. Currently, the common approach is to lay thermocouples on the inner wall surface and extract the temperature signal from the outer wall. However, this traditional structure has several problems: First, the significant temperature gradient and thermal expansion difference between the inner and outer walls during operation leads to inconsistent axial thermal deformation between the two walls, often causing the thermocouple leads to breakage due to stress concentration, resulting in temperature measurement failure. Second, the high-speed impact cooling airflow within the double-walled interlayer exposes the thermocouple wires directly to the airflow, making them prone to violent shaking or wear, resulting in large temperature signal fluctuations and poor stability. Third, the thermocouples, welded to the outer wall surface, are susceptible to the cooling effect of the interlayer airflow, causing the measured temperature to deviate from the actual engine temperature and reducing test accuracy.

[0005] Furthermore, to seal the lead holes on the outer wall, existing technologies typically only use mechanical clamping or high-temperature adhesive to seal the small holes. This approach struggles to balance sealing performance and thermal compensation, and is prone to failure during high-temperature cycling. These issues lead to frequent occurrences of thermocouple wire breakage, signal drift, and measuring point failure during combustion chamber component thermal testing. This not only affects the accuracy of test data but also increases maintenance and retesting costs, hindering the reliability of combustion chamber cooling structure optimization and lifespan assessment.

[0006] Therefore, how to achieve high-precision measurement of the true temperature of the inner wall in a double-walled flame tube, while taking into account thermal deformation compensation and airflow sealing, preventing damage to the thermocouple wire and improving signal stability, has become an urgent problem to be solved in the field of gas turbine combustion chamber design and testing technology. Summary of the Invention

[0007] The purpose of this invention is to solve the problems of poor reliability, low temperature measurement accuracy, and easy damage to thermocouple wires caused by thermal deformation and cooling airflow in the existing double-walled flame tube temperature test.

[0008] The objective of this invention is achieved through the following technical solution: A double-walled combustion chamber flame tube temperature testing structure for a gas turbine includes: a thermocouple lead protection stud, an inner wall thermocouple testing groove, and an outer wall floating sealing structure. The thermocouple lead protection stud is cylindrical, with a thermocouple lead cavity inside and external threads on the outside; The inner wall of the thermocouple test slot is cylindrical, and its inner side is provided with an internal thread that mates with the thermocouple lead protection stud. The thermocouple is welded to the bottom of the test slot and led out through the thermocouple lead protection stud. The floating sealing structure on the outer wall is installed on the outer wall of the flame tube to seal the thermal coordination gap between the protective stud of the galvanic lead and the outer wall, so as to realize thermal deformation compensation and sealing of the inner and outer walls of the flame tube. Preferably, the diameter of the thermocouple lead cavity of the thermocouple lead protection stud is no greater than 1.8 mm, in order to reduce the impact of cooling airflow on the thermocouple wire and stabilize the temperature measurement signal.

[0009] Preferably, the galvanic lead protection stud and the inner wall galvanic test groove are connected by threads to form a clamping and fixing structure to enhance the structural stability under thermal cycling conditions.

[0010] Preferably, the outer wall floating sealing structure includes a support plate, a cover plate, and a floating ring, which are arranged coaxially. The support plate is welded and fixed to the outer wall of the flame tube, and a groove is formed inside. The floating ring is set in the groove and can slide axially. The cover plate is welded to the support plate to restrict the floating ring from falling out.

[0011] Preferably, the groove is a cylindrical groove.

[0012] Preferably, the gap between the floating ring and the protective stud of the thermocouple lead is no greater than 0.2 mm, thereby achieving thermal compensation degree of freedom while maintaining sealing.

[0013] Preferably, the bottom of the inner wall thermocouple test groove is a cylindrical groove, and the thermocouple solder joint is located on the inner surface of the metal at the bottom of the groove, which is used to measure the actual body temperature of the inner wall.

[0014] Preferably, the floating ring of the outer wall floating sealing structure is made of a high-temperature resistant alloy, and its surface is treated with a wear-resistant coating to extend the sealing life and maintain sliding stability.

[0015] Preferably, the galvanic lead protection stud and the inner wall galvanic test groove are sealed with metal threads, and the thread surface is coated with a high-temperature resistant sealant to prevent leakage of combustion gas or cooling gas.

[0016] Preferably, the floating sealing structure can slide freely within the range of axial thermal deformation caused by the temperature difference between the inner and outer walls of the flame tube (0.1-0.3 mm) to achieve thermal compensation of the inner and outer walls and maintain the integrity of the seal.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention proposes a double-walled combustion chamber flame tube temperature testing structure for gas turbines. Through the coordinated design of the thermocouple lead protection stud, the inner wall thermocouple testing slot, and the outer wall floating sealing structure, it achieves high-reliability and high-precision temperature testing under complex environments of high temperature, high-speed airflow, and thermal deformation. The key technical concept lies in using thermal compensation and sealing coordination of the mechanical structure to maintain stable contact and signal transmission path between the temperature sensing element and the tested wall surface under the combined effects of thermal stress and aerodynamic disturbances. This structure not only improves temperature measurement accuracy but also significantly extends the lifespan and data consistency of the thermocouple during combustion tests.

[0018] In principle, the inner wall thermocouple test groove adopts a cylindrical groove structure, with the thermocouple solder joints located directly on the inner metal surface of the groove bottom, maintaining close thermal contact with the flame tube substrate. Compared to the traditional method of soldering the thermocouple to the exposed wall surface, this design reduces the interference of the interlayer cooling airflow on the measuring point, making the temperature measured by the thermocouple closer to the actual temperature of the wall. The thermocouple is led out through a threaded thermocouple lead protection stud. The inner cavity of the stud forms a stable lead channel, effectively isolating the high-speed cooling airflow and avoiding the risk of signal noise or breakage of the thermocouple wire due to aerodynamic vibration. At the same time, the threaded compression connection improves the overall mechanical strength, enabling the temperature measuring device to maintain stable positioning under thermal cycling and aerodynamic impact, ensuring the continuity of the temperature measurement signal.

[0019] To address the issue of thermal expansion mismatch between the double-walled structure, a thermally coordinated gap is established between the outer wall and the protective studs of the thermocouple leads, and a floating sealing structure is employed on the outer wall to achieve a balance between sealing and compensation. The floating ring in the floating sealing structure can slide freely within the groove formed by the cover plate and the support plate, thereby absorbing the relative displacement caused by the temperature difference between the inner and outer walls. When the combustion chamber operating temperature rises, the inner wall expands more due to heat than the outer wall; this floating mechanism releases stress, preventing the thermocouple wire from breaking under tension at the fixed point. This "floating compensation" mechanism achieves flexible absorption of thermal stress mechanically, enabling the device to maintain its integrity and sealing performance over long-term under thermal cycling conditions.

[0020] Furthermore, the sealing ring of the floating sealing structure on the outer wall, through a precise gap design (no more than 0.2 mm), ensures that the cooling gas inside the interlayer does not leak while allowing for slight slippage. This maintains the cooling efficiency of the combustion chamber while preventing high-temperature airflow from eroding the thermocouple wire. The overall structure forms multiple layers of protection: the thermocouple test groove ensures accurate temperature measurement contact, the protective stud guarantees mechanical strength and airflow isolation, and the floating sealing structure achieves thermal deformation compensation and sealing durability. These three elements constitute a stable temperature measurement system integrating thermo-mechanical-fluid properties.

[0021] By coupling the above-mentioned technical mechanisms, this invention effectively solves the problems of thermocouple wire breakage, signal fluctuation, and large temperature measurement errors in traditional temperature measurement methods. Experimental results show that this structure can reduce temperature measurement errors by approximately 10%–15% and thermocouple wire failure rate by more than 25%, achieving high-precision and high-reliability temperature measurement under complex operating conditions. It provides reliable technical support for the optimized design and life assessment of combustion chamber cooling structures, and has significant engineering application value and promising prospects for widespread adoption. Attached Figure Description

[0022] Figure 1 This is a cross-sectional view of the existing technology combustion chamber double-walled flame tube wall temperature testing structure; Figure 2 yes Figure 1 Detailed view of the wall temperature test structure in the image; Figure 3 This is a cross-sectional view of a combustion chamber double-walled flame tube wall temperature testing structure according to the present invention; Figure 4 This is a three-dimensional cross-sectional view of a combustion chamber double-walled flame tube wall temperature testing structure according to the present invention; Figure 5 yes Figure 3 A magnified view of a portion of the wall temperature testing structure; Figure 6 yes Figure 4 A three-dimensional magnified view of the wall temperature testing structure.

[0023] Among them: 11. Combustion chamber, 101. Double-walled flame tube, 102. Flame tube outer wall, 103. Flame tube inner wall, 104. Inner and outer wall connecting ring, 105. Wall temperature testing structure, 106. Flame tube interlayer, 107. Impact cooling hole, 108. Cooling ring rib, 109. Coupling wire, 110. Outer wall small hole, 111. Nozzle cyclone assembly, 112. Coupling lead protection stud, 113. Inner wall coupling test groove, 114. Outer wall floating sealing structure, 115. Lead cavity, 116. Support plate, 117. Cover plate, 118. Floating ring, 119. Columnar groove. Detailed Implementation

[0024] The technical solution will be further described below with reference to the accompanying drawings and specific embodiments to help understand the content of the present invention.

[0025] This invention provides a double-walled combustion chamber flame tube temperature testing structure for gas turbines. The specific testing structure consists of a thermocouple lead protection stud, an inner wall thermocouple testing slot, and an outer wall floating sealing structure. It can achieve high-precision measurement of the inner wall temperature of the flame tube under high-temperature combustion environment and significantly improve the reliability and stability of the temperature measurement system.

[0026] The thermocouple lead protection stud is cylindrical with a central thermocouple lead cavity and an external threaded structure. This stud connects and is secured to the thermocouple test groove on the inner wall of the flame tube via the threads. This protects the thermocouple wire passing through the double-walled interlayer from the scouring and vibration interference of the high-speed cooling airflow, thus ensuring the stability of the thermocouple signal and the accuracy of temperature measurement. The thermocouple lead cavity accommodates and leads out the thermocouple wire, effectively protecting it as it passes through the interlayer and preventing signal fluctuations or mechanical damage caused by airflow disturbances.

[0027] The inner wall of the flame tube is equipped with a thermocouple test slot. The test slot is cylindrical in shape, with an internal cylindrical groove for welding thermocouple measuring points. The thermocouple wires are led out through the lead cavity of the thermocouple lead protection stud, achieving stable transmission of the temperature signal from the inner wall. The inner side of the thermocouple test slot has internal threads that mate with the external threads of the thermocouple lead protection stud, achieving a reliable mechanical connection and gas-tight seal. This ensures accurate positioning and good contact of the thermocouple measuring points, thereby improving the accuracy and consistency of temperature acquisition.

[0028] The outer wall of the flame tube is equipped with a floating sealing structure. This structure is cylindrical and is welded or installed on the outer wall of the flame tube to seal the thermal compatibility gap between the thermocouple lead protection stud and the outer wall. This gap absorbs and compensates for the difference in axial thermal deformation between the inner and outer walls of the flame tube under high-temperature conditions, preventing the thermocouple wire from breaking or failing due to uncoordinated thermal expansion, thereby significantly improving the long-term reliability of the temperature measurement system. The floating sealing structure not only maintains the thermal compensation space but also ensures the overall sealing of the double-wall structure, preventing cooling gas leakage that could affect combustion stability.

[0029] In a preferred embodiment, the diameter of the lead cavity of the thermocouple lead protection stud is no greater than 1.8 mm to ensure the passage of the lead while improving mechanical strength and impact resistance. The gap between the outer wall floating sealing structure and the thermocouple lead protection stud is controlled within a range of no more than 0.2 mm to ensure sealing performance and meet thermal compensation requirements. Through the above structural design, the present invention can effectively prevent damage and signal interference caused by the high-speed cooling airflow in the double-wall interlayer to the thermocouple wire, maintain stable contact between the thermocouple measuring point and the inner wall of the flame tube, and achieve high-precision and high-reliability measurement of the temperature of the combustion chamber wall.

[0030] like Figure 1 As shown, the existing gas turbine combustion chamber 11 has a double-walled flame tube 101 structure, wherein the double-walled flame tube 101 has a conical-cylindrical combination shape. The double-walled flame tube 101 includes an outer wall 102, an inner wall 103, and a connecting ring 104 between the inner and outer walls. The outer wall 102, the inner wall 103, and the connecting ring 104 are coaxially distributed. The outer wall 102 and the inner wall 103 are conical-cylindrical combination shapes and are welded to the connecting ring 104, which is cylindrical. The nozzle swirler assembly 111 is coaxially distributed with the double-walled flame tube 101. Fuel is ejected through the nozzle swirler assembly 111 and mixes with air in the double-walled flame tube 101 for combustion, generating high-temperature gas to do work. The outer wall 102 and the inner wall 103 form the flame tube. The interlayer 106 has an impact cooling hole 107 on the conical section of the outer wall 102 of the flame tube and a cooling ring rib 108 on the cylindrical section of the inner wall 103 of the flame tube. Cooling air enters the interlayer 106 of the flame tube through the impact cooling hole 107 on the outer wall 102 of the flame tube and then participates in combustion through the cooling ring rib 108 on the inner wall 103 of the flame tube. This forms a typical double-walled flame tube with a combination of impact and ring rib cooling, which can reduce the amount of cooling air, achieve lean premixed combustion, and reduce the emission of pollutants such as NOx. The existing double-walled flame tube 101 inner wall 103 thermocouple temperature measurement method involves directly welding the thermocouple wire 109 to the measuring point on the inner wall 103 of the flame tube, and opening a small hole 110 on the outer wall at the corresponding position on the outer wall 102 of the flame tube. The thermocouple wire 109 is led out through the small hole 110 to complete the measurement of the temperature of the inner wall 103 of the flame tube.

[0031] Figure 2 yes Figure 1 A detailed view (partial enlarged view) of the wall temperature testing structure. The thermocouple wire 109 is directly welded to the inner wall 103 of the double-layer flame tube to measure the wall temperature. The wire is led out through the small hole 110 on the outer wall of the outer wall 102 of the flame tube to complete the measurement of the temperature of the inner wall 103 of the flame tube.

[0032] like Figure 3 and 4As shown, this invention provides a combustion chamber double-walled flame tube wall temperature testing structure 21. The double-walled flame tube 101 has a conical-cylindrical combined shape and includes an outer wall 102, an inner wall 103, and an inner-outer wall connecting ring 104. The outer wall 102, the inner wall 103, and the inner-outer wall connecting ring 104 are coaxially distributed. The outer wall 102 and the inner wall 103 are conical-cylindrical combined and welded to the inner-outer wall connecting ring 104, which is cylindrical. A nozzle swirler assembly 111 is coaxially distributed with the double-walled flame tube 101. Fuel is ejected through the nozzle swirler assembly 111 and mixes with air in the double-walled flame tube 101 for combustion, generating high-temperature combustion gas to perform work. The outer wall 102 and the inner wall 103 are coaxially distributed with the flame tube. The inner wall 103 forms a flame tube interlayer 106. The conical section of the outer wall 102 of the flame tube has impact cooling holes 107, and the cylindrical section of the inner wall 103 of the flame tube has cooling ring ribs 108. Cooling air enters the flame tube interlayer 106 through the impact cooling holes 107 on the outer wall 102 of the flame tube and passes through the cooling ring ribs 108 on the inner wall 103 of the flame tube, and finally participates in combustion, forming a typical double-walled flame tube with impact + ring rib combination cooling method, which can reduce the amount of cooling air, realize lean premixed combustion, and reduce the emission of pollutants such as NOx. The present invention proposes a wall temperature testing structure 105 for the inner wall 103 of the double-walled flame tube 101 to realize the measurement of the wall temperature of the inner wall 103 of the double-walled flame tube 101.

[0033] like Figure 5 and Figure 6As shown, the wall temperature testing structure 105 consists of a thermocouple lead protection stud 112, an inner wall thermocouple testing groove 113, and an outer wall floating sealing structure 114. The thermocouple lead protection stud 112, the inner wall thermocouple testing groove 113, and the outer wall floating sealing structure 114 are coaxially distributed. The inner wall of the flame tube 103 has an inner wall thermocouple testing groove 113 at the thermocouple measuring point location. The inner wall thermocouple testing groove 113 is cylindrical and has internal threads on its inner side. The thermocouple lead protection stud 112... 2 is cylindrical with external threads on the outside, connecting to the internal threads of the inner wall thermocouple test groove 113; the thermocouple lead protection stud 112 has a lead cavity 115 inside, and the thermocouple lead protection stud 112 and the lead cavity 115 are coaxially distributed; the outer wall floating sealing structure 114 is cylindrical and is welded to the outer wall 102 of the flame tube. The outer wall floating sealing structure 114 consists of a support plate 116, a cover plate 117 and a floating ring 118. 7. Coaxially distributed with the floating ring 118; the support plate 116 is cylindrical and welded to the outer wall 102 of the flame tube, and the support plate 116 has a cylindrical groove 119 inside; the floating ring 118 is cylindrical and set in the cylindrical groove 119, and the cover plate 117 is welded to the support plate 116. The floating ring 118 is axially fixed by the cover plate 117, and the end face can slide freely within a certain range to achieve thermal compensation of the inner and outer walls of the double-walled flame tube, while meeting the sealing requirements; to achieve A thermocouple wall temperature test is performed on the inner wall 103 of the flame tube. The thermocouple wire 109 is welded into the thermocouple test groove 113 on the inner wall. The thermocouple is led out through the lead cavity 115 in the thermocouple lead protection stud 112. The thermocouple lead protection stud 112 is connected to the thermocouple test groove 113 on the inner wall by threads and is pressed tightly. The floating sealing structure 114 on the outer wall seals the gap between the thermocouple test groove 113 on the inner wall and the outer wall 102 of the flame tube, thereby realizing thermocouple temperature measurement of the inner wall of the flame tube.

[0034] This invention provides a structure for testing the wall temperature of a double-walled combustion chamber flame tube in a gas turbine, which offers significant technical advantages and benefits compared to existing technologies. The invention incorporates a protective stud for the thermocouple lead, an inner wall thermocouple testing slot, and an outer wall floating sealing structure at the wall temperature measurement point of the double-walled flame tube. This enables axial thermal deformation compensation of the double-walled structure, preventing damage to the thermocouple wires due to asynchronous thermal deformation of the inner and outer walls. Simultaneously, the outer wall floating sealing structure creates a reliable seal between the outer wall and the thermocouple lead, thereby achieving accurate measurement of the flame tube's inner wall temperature while ensuring airtightness, thus improving the overall reliability of thermocouple temperature measurement.

[0035] Furthermore, the double-walled flame tube contains a high-speed impact cooling airflow. This invention effectively protects the thermocouple wires passing through the interlayer by incorporating protective studs for the thermocouple leads, stabilizing the temperature measurement signal, reducing signal disturbance, and significantly improving measurement accuracy. The design of the inner wall thermocouple test slot places the thermocouple measuring point on the inner wall of the flame tube, preventing direct exposure to the interlayer airflow and avoiding temperature measurement errors caused by flow field interference. Experimental results show that the thermocouple wall temperature testing structure proposed in this invention improves the temperature measurement accuracy by approximately 10%–15% compared to traditional structures. During high-temperature combustion tests, failure phenomena such as thermocouple wire breakage are significantly reduced, with the thermocouple wire failure rate decreasing by more than 25%, resulting in a substantial improvement in the reliability of the temperature measurement system.

[0036] The key innovation of this invention lies in the following: an inner wall thermocouple testing groove is provided on the inner wall of the flame tube, with thermocouple measuring points welded into the groove. The thermocouple wire is led out through a thermocouple lead protection stud, achieving mechanical and thermal protection for the thermocouple wire. The thermocouple lead protection stud and the inner wall thermocouple testing groove are connected by threads and pressed tightly together. Simultaneously, a thermal deformation gap is reserved between the stud and the outer wall of the flame tube to accommodate the thermal expansion and contraction differences of the double-walled structure during high-temperature operation. To ensure sealing performance, a floating sealing structure is provided on the outer wall to seal the thermal compensation gap, thereby preventing cooling gas leakage while ensuring thermal compensation function and achieving high-precision and high-reliability measurement of the inner wall temperature of the double-walled flame tube. This structure not only has good practicality and durability but is also suitable for wall temperature monitoring in high-temperature combustion environments such as gas turbines, further demonstrating its excellent innovation and engineering application value.

[0037] Existing technology CN113188155A discloses a combustion chamber wall temperature measurement structure. Its core solution involves creating a threaded hole in the combustion chamber casing or wall, through which a temperature measuring unit is inserted. The measuring unit consists of a sleeve and a thermocouple. The sleeve is a cylindrical structure closed at one end and open at the other, with the thermocouple placed inside. The probe extends from the open end and contacts the wall surface to achieve temperature measurement. The key technical aspects of this solution are enabling multi-point temperature measurement, convenient assembly and disassembly of the measuring unit, and reducing mutual interference between thermocouples. However, the structure of CN113188155A is only suitable for single-wall or ordinary combustion chamber walls. It does not address key issues such as the complex cooling airflow inside the double-walled flame tube interlayer, the difference in thermal deformation between the inner and outer walls, and sealing compensation. The threaded hole and sleeve are rigidly connected, failing to absorb the thermal expansion differences generated during high-temperature operation of the double walls. Furthermore, it does not provide a protective structure against the impact and vibration of the thermocouple wire caused by the high-speed cooling airflow in the interlayer. Therefore, stable and reliable temperature measurement is difficult to achieve in a double-walled environment.

[0038] In comparison, the combustion chamber double-walled flame tube temperature testing structure proposed in this invention is specifically designed to address the problems of large temperature difference, asynchronous thermal deformation, and strong cooling airflow disturbance existing in the inner and outer walls of the double-walled flame tube, exhibiting distinct technical features. This invention sets an inner wall thermocouple testing groove on the inner wall of the flame tube, welding the thermocouple measuring points into the groove. This ensures the thermocouple is tightly attached to the inner wall body and avoids direct exposure to the interlayer airflow, thereby improving the stability and accuracy of the measurement. The thermocouple wire is led out through a thermocouple lead protection stud. This stud is a cylindrical hollow structure with external threads, connecting to the internal threads of the inner wall thermocouple testing groove. This not only achieves a secure compression connection but also forms a through-type protective channel for the thermocouple wire, effectively preventing impact, vibration, or wear caused by the high-speed cooling gas in the interlayer on the thermocouple wire, fundamentally improving the reliability of the temperature measurement signal. In addition, the present invention reserves an axial thermal deformation compensation gap between the thermocouple lead protection stud and the outer wall of the flame tube to coordinate the thermal expansion difference of the double wall at high temperature, avoid the risk of thermocouple wire breakage or solder joint detachment due to asynchronous deformation of the inner and outer walls, thereby greatly enhancing the long-term stability of the temperature measurement system.

[0039] To further ensure sealing performance and thermal compensation coordination, this invention incorporates a floating sealing structure on the outer wall of the flame tube. This structure, composed of a support plate, a cover plate, and a floating ring, is welded and fixed to the outer side of the outer wall. It seals the reserved thermal compensation gap while allowing the floating ring to slide axially within a certain range, achieving compatibility between sealing and thermal deformation compensation. This structure strikes a balance between sealing performance and thermal adaptability, ensuring that cooling gas does not leak and affect combustion efficiency, while also eliminating stress concentration problems caused by temperature differences. By precisely defining the inner cavity diameter (≤1.8mm) of the thermocouple lead protection stud and the floating sealing gap (≤0.2mm) on the outer wall, this invention also optimizes the coordination between airtightness and mechanical strength at the structural dimensions, ensuring the overall structure remains stable and manufacturable under high temperature, high pressure, and strong flow field environments.

[0040] CN113188155A uses a rigid insertion sleeve temperature measurement structure, which lacks thermal deformation compensation and interlayer protection design. In contrast, this invention achieves high-precision and high-reliability measurement of wall temperature in a double-walled flame tube through a systematic combination of an inner wall test groove, a thermocouple lead protection stud, a thermal compensation gap, and a floating sealing structure. It can resist interference from interlayer cooling airflow and absorb the stress effect caused by thermal expansion differences, significantly reducing thermocouple wire failure rate and improving temperature measurement accuracy.

[0041] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention.

Claims

1. A structure for testing the wall temperature of a double-walled combustion chamber flame tube in a gas turbine, characterized in that, include: The thermocouple lead protection stud, the inner wall thermocouple test groove and the outer wall floating sealing structure; The thermocouple lead protection stud is cylindrical, with a thermocouple lead cavity inside and external threads on the outside; The inner wall of the thermocouple test slot is cylindrical, and its inner side is provided with an internal thread that mates with the thermocouple lead protection stud. The thermocouple is welded to the bottom of the test slot and led out through the thermocouple lead protection stud. The floating sealing structure on the outer wall is installed on the outer wall of the flame tube to seal the thermal coordination gap between the protective stud of the galvanic lead and the outer wall, so as to realize thermal deformation compensation and sealing of the inner and outer walls of the flame tube.

2. The combustion chamber double-walled flame tube wall temperature testing structure according to claim 1, characterized in that, The diameter of the thermocouple lead cavity of the thermocouple lead protection stud is no greater than 1.8 mm.

3. The combustion chamber double-walled flame tube wall temperature testing structure according to claim 1, characterized in that, The protective stud for the galvanic leads and the inner wall galvanic test groove are connected by threads to form a clamping and fixing structure.

4. The combustion chamber double-walled flame tube wall temperature testing structure according to claim 1, characterized in that, The outer wall floating sealing structure includes a support plate, a cover plate, and a floating ring, which are arranged coaxially. The support plate is welded and fixed to the outer wall of the flame tube, forming a groove inside. The floating ring is placed in the groove, and the cover plate is welded to the support plate to restrict the floating ring from coming out.

5. The combustion chamber double-walled flame tube wall temperature testing structure according to claim 4, characterized in that, The gap between the floating ring and the protective stud of the thermocouple lead is no greater than 0.2 mm.

6. The combustion chamber double-walled flame tube wall temperature testing structure according to claim 4, characterized in that, The groove is a cylindrical groove.

7. The combustion chamber double-walled flame tube wall temperature testing structure according to claim 1, characterized in that, The bottom of the inner wall galvanometer test groove is a cylindrical groove, and the galvanometer welding point is located on the inner metal surface at the bottom of the groove.

8. The combustion chamber double-walled flame tube wall temperature testing structure according to claim 1, characterized in that, The floating ring of the outer wall floating sealing structure is made of high-temperature resistant alloy and its surface is treated with a wear-resistant coating.

9. The combustion chamber double-walled flame tube wall temperature testing structure according to claim 1, characterized in that, The protective stud for the galvanic leads and the galvanic test groove on the inner wall are sealed with metal threads, and the thread surface is coated with a high-temperature resistant sealant.

10. The combustion chamber double-walled flame tube wall temperature testing structure according to claim 1, characterized in that, The floating sealing structure can slide freely within the range of 0.1 to 0.3 mm within the axial thermal deformation caused by the temperature difference between the inner and outer walls of the flame tube.

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