A capacitive blade tip clearance sensor with cooling channel and cooling channel design method

Abstract

The invention discloses a capacitive blade tip clearance sensor with a cooling flow channel and a cooling flow channel design method. The sensor comprises a sensor probe, a cable and a mounting seat. The sensor probe comprises a sensor core, an outer metal layer, an insulating layer and a tail top ring. A mounting flange is arranged on the mounting seat, and the mounting seat is fixed on the casing wall of an aircraft engine through the mounting flange. A through hole is arranged in the middle of the mounting seat, and an outer metal layer is arranged on the inner wall of the through hole. An annular closed cavity is formed between the outer metal layer and the inner wall. Inlet flow channels and outlet flow channels are symmetrically arranged on the mounting seats on both sides of the annular closed cavity, respectively. The air inlet of the inlet flow channel is connected to an air inlet pipe, and the air outlet of the outlet flow channel is connected to an air outlet pipe. An insulating layer is arranged in the outer metal layer, and the sensor core is installed in the insulating layer. A tail top ring fixed to the outer metal layer is arranged at the tail of the insulating layer, and the middle of the tail top ring is connected to the metal outer shielding layer of the cable, and the core of the cable is connected to the sensor core.

Description

Technical Field

[0001] The invention relates to the field of blade tip clearance measurement, and in particular to a capacitive blade tip clearance sensor with an internal cooling channel and a cooling channel design method. Background Art

[0002] The tiny distance between the top of the rotor blade of an aircraft engine and the inner wall of the casing is called the tip clearance, which is one of the important parameters affecting the mechanical performance of the engine. Reducing the tip clearance can reduce fuel consumption and significantly improve operating efficiency, but too small a tip clearance value will cause friction between the blade and the casing, seriously endangering the safety of engine operation. Therefore, the tip clearance measurement technology is of great significance to improving the performance of aircraft engines and ensuring safe operation.

[0003] At present, mature methods for measuring blade tip clearance include discharge probe method, laser triangulation method, fiber bundle method, eddy current method, capacitance method and microwave method. Among them, capacitance method is suitable for harsh environments such as high temperature and high pressure, has fast response speed and good reliability, and is widely used in engineering tests of blade tip clearance. However, the performance requirements of modern aircraft engines such as high thrust-to-weight ratio and high efficiency have led to a gradual increase in turbine inlet temperature, and the working environment of blade tip clearance sensors has become increasingly harsh, reaching the limit that the sensor design materials can withstand.

[0004] In response to the extremely high temperature working environment, the foreign TYCO company has developed a capacitive sensor with cooling grooves. The cooling gas introduced from the outside enters the casing through the cooling grooves on the surface of the sensor, effectively reducing the ambient temperature near the end face of the sensor. The sensor is designed to withstand a temperature of 1400°C and can meet the tip clearance measurement requirements of most aircraft engines. However, this method directly introduces external cooling gas into the casing, destroying the original working environment inside the aircraft engine. At the same time, the internal pressure of the turbine can reach more than 3MPa, and the cooling grooves on the surface of the sensor increase the risk of high-temperature and high-pressure gas entering the cold end components of the engine. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of insufficient temperature resistance of sensor materials in the prior art, the cooling structure of the sensor introducing external cooling gas into the interior of the casing, destroying the original working environment inside the aircraft engine, and increasing the risk of high-temperature, high-pressure fuel gas entering the cold end components of the engine, and to provide a capacitive tip clearance sensor with an internal cooling flow channel suitable for extremely high-temperature working environments and capable of isolating the cooling gas from the external fuel gas environment, and a cooling flow channel design method.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A capacitive blade tip clearance sensor with a cooling flow channel is installed on the casing wall of an aircraft engine. Rotating blades are installed in the casing. The capacitive blade tip clearance sensor includes a sensor probe, a cable and a mounting seat. The sensor probe includes a sensor core, an outer metal layer, an insulating layer, and a tail top ring. A mounting flange is provided on the mounting seat. The mounting seat is fixed to the casing wall of the aircraft engine through the mounting flange. A through hole is provided in the middle of the mounting seat. The outer metal layer is provided on the inner wall of the through hole. The outer metal layer An annular closed cavity is formed between the layer and the inner wall; an inlet flow channel and an outlet flow channel are symmetrically arranged on the mounting seats on both sides of the annular closed cavity, the inlet hole of the inlet flow channel is connected to the inlet pipe, and the outlet hole of the outlet flow channel is connected to the outlet pipe, an insulating layer is arranged in the outer metal layer, the sensor core pole is installed in the insulating layer, a tail top ring fixed to the outer metal layer is arranged at the tail of the insulating layer, the middle part of the tail top ring is connected to the metal outer shielding layer of the cable, and the core pole of the cable is connected to the sensor core pole.

[0008] Furthermore, a mounting seat located on the inner wall side of the casing is provided with a boss protruding toward the center of the through hole, and a flange is provided on the outer metal layer located on the outer wall side of the casing, the boss is connected to the outer wall of the outer metal layer, and the flange of the outer metal layer is connected to the inner wall of the mounting seat to form the annular closed cavity.

[0009] Furthermore, a truncated cone with an enlarged diameter is provided on one side of the sensor core close to the rotating blades to lock the insulating layer and prevent the insulating layer from falling off and entering the interior of the casing to cause danger.

[0010] Furthermore, the insulating layer is made of ceramic material with a purity greater than 95%, and the insulating layer is connected to the sensor core electrode and the outer metal layer through mechanical cooperation.

[0011] Furthermore, the outer metal layer is used to shield signal interference and protect the insulation layer.

[0012] Furthermore, the tail top ring plays the role of pressing the insulating layer, fixing the cable and protecting the welding point between the sensor core and the cable core. The tail top ring is fixed to the outer metal layer and the metal outer shielding layer of the cable by welding.

[0013] Furthermore, the cable is a coaxial cable or a triaxial cable.

[0014] Furthermore, the annular closed cavity serves as a flow channel for cooling gas. The cooling gas is discharged after rotating one circle in the annular closed cavity, and the heat on the outer metal layer of the tip clearance sensor is removed by convection heat exchange. The mounting base is connected to the outer metal layer by welding, which ensures the sealing of the cooling gas flow channel and prevents the cooling gas from leaking out. Bends are provided inside the inlet and outlet flow channels, and the outlet of the inlet flow channel points to the wall of the outer metal layer, so that the cooling gas entering the annular closed cavity from the inlet flow channel impacts the cooling sensor probe, thereby improving the heat exchange efficiency of the cooling gas.

[0015] Furthermore, the air inlet pipe and the air outlet pipe are made of stainless steel metal pipes or stainless steel metal hoses, which are connected to the mounting seat by welding, and the inner diameters of the air inlet pipe and the air outlet pipe are consistent with the sizes of the inlet flow channel and the outlet flow channel.

[0016] The present invention also provides a design method for a cooling flow channel, based on the above-mentioned capacitive blade tip clearance sensor with a cooling flow channel, the cooling flow channel includes an inlet flow channel and an outlet flow channel, including:

[0017] S1. Determine the dimensions of the mounting base;

[0018] Set r1 as the outer diameter of the outer metal layer, r2 as the outer diameter of the flange of the outer metal layer; the outer diameter of the mounting flange R2> the outer diameter of the mounting seat R1; the length of the mounting seat h≤ the thickness of the casing L;

[0019] The boss thickness b has a minimum value bmin:

[0020] ;

[0021] Among them, P in P is the cooling gas pressure in the annular closed cavity; out is the working environment pressure of the blade tip clearance sensor; k1 is the safety margin, k1>1; [τ] is the allowable shear stress of the mounting seat material, and the corresponding [τ] value can be obtained by consulting the material manual;

[0022] Assume that the diameters of the inlet and outlet holes are both a, a <R1-r2;

[0023] Bends are provided in both the inlet and outlet channels to allow the gas to directly impact the outer metal layer, thereby improving the heat exchange efficiency of the sensor probe; the angle α of the bend is:

[0024] ;

[0025] S2. Determine the cooling medium;

[0026] S3. Numerical simulation;

[0027] Use numerical simulation software to increase the volume flow of the cooling medium and compare the temperature changes on the end face and the center axis of the sensor probe; if in the simulation results, the temperature of the sensor probe end face is lower than the maximum use temperature of the corresponding material, and the core pole, cable and welding point temperature on the center axis of the tip clearance sensor are also lower than the corresponding maximum use temperature, then the corresponding volume flow is the ideal volume flow;

[0028] S4. High temperature experimental verification in laboratory environment

[0029] A high-temperature furnace is used as the heating source, and a high-temperature experimental verification platform for the sensor is built in a laboratory environment. A cooling medium with an ideal volume flow rate is introduced into the capacitive tip clearance sensor, and the furnace temperature of the high-temperature furnace is increased to the working environment temperature of the capacitive tip clearance sensor. The leakage capacitance and leakage resistance signals of the capacitive tip clearance sensor are monitored in real time. If during the experiment, the leakage capacitance and leakage resistance are both within the compensable range of the tip clearance measurement system, and there is no damage, deformation or oxidation on the appearance of the capacitive tip clearance sensor after cooling, and the gap waveform can be seen when the capacitive tip clearance sensor is installed on a rotating table, then the capacitive tip clearance sensor meets the working environment requirements of ≥1400℃.

[0030] S5. Finalization of capacitive tip clearance sensor with internal cooling channels.

[0031] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0032] 1. Improve high temperature resistance: The present invention overcomes the limitation that the capacitive tip clearance sensor in the prior art cannot work stably for a long time in an extremely high temperature environment by improving the sensor material and cooling structure, thereby ensuring the normal operation of the sensor under high temperature conditions and realizing real-time and accurate measurement of the tip clearance.

[0033] 2. Protect the original working environment of the aircraft engine: The present invention designs an internal cooling flow channel, and the cooling gas circulates in a closed manner in the flow channel without directly contacting the inside of the casing, thereby preventing external cooling gas from entering the engine casing, thereby maintaining the stability and safety of the internal working environment of the engine and preventing high-temperature, high-pressure fuel gas from entering the cold end components.

[0034] 3. Modular design and cost reduction: By adding a mounting base for the internal cooling channel to the existing capacitive tip clearance sensor, the cooling structure of the sensor achieves a modular design, meets the standardization requirements of components, facilitates the adaptation and modification of existing sensors, reduces production costs, and reduces user complexity.

[0035] 4. Flexible design to adapt to a variety of environments: The cooling medium and mounting size of the sensor can be flexibly adjusted according to user needs and usage environment. Cooling media such as nitrogen or inert gas can be used to improve the cooling effect, and the design can be flexibly adjusted according to the installation space and sensor operating temperature, so as to meet the tip clearance measurement needs in different harsh environments.

[0036] In summary, the present invention realizes reliable measurement performance of the sensor in a high temperature environment, while maintaining the environmental stability inside the engine. It has the advantages of modularity and flexible design, and meets the needs of various practical engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of the installation of a capacitive blade tip clearance sensor with a cooling channel according to the present invention is shown.

[0038] Figure 2 A schematic structural diagram of a capacitive blade tip clearance sensor with a cooling channel in the present invention is shown.

[0039] Figure 3 A half-section schematic diagram of the mounting base of the capacitive tip clearance sensor is shown.

[0040] Figure numerals: 1-capacitive tip clearance sensor, 101-sensor core, 102-insulating layer, 103-outer metal layer, 104-tail top ring, 105-cable, 106-mounting seat, 107-inlet air passage, 108-outlet air passage, 109-annular closed cavity, 110-mounting flange, 111-inlet pipe, 112-outlet pipe, 2-casing, 201-casing inner wall, 202-casing outer wall, 3-rotating blades. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0042] The capacitive blade tip clearance sensor 1 is based on the principle of a flat plate capacitor. The sensor probe is fixed to the wall of the casing 2 of the aircraft engine through a mounting flange 110, opposite to the top of the rotating blade 3. Figure 1 As shown, the sensor core 101 constitutes one electrode of the variable capacitor, the tip of the rotating blade 3 constitutes another electrode of the variable capacitor, and the capacitive tip clearance sensor measures the tip clearance by measuring the change in capacitance between the two electrodes of the flat plate capacitor. Ignoring the influence of the edge effect of the bipolar plate variable capacitor, the relationship between the measured capacitance and the tip clearance can be expressed as:

[0043] ;

[0044] Where C is the sensor capacitance, is the dielectric constant of the medium between the electrodes, S is the plate area, and d is the tip clearance value.

[0045] The capacitive blade tip clearance sensor 1 with internal cooling channel of the present invention has a structure as follows: Figure 2 As shown, the capacitive tip clearance sensor is based on a pseudo-triaxial structure, including a sensor probe, a cable 105 and a mounting seat 106 . The sensor probe mainly includes a sensor core 101 , an insulating layer 102 , an outer metal layer 103 , and a tail top ring 104 .

[0046] In this embodiment, the sensor core 101 is the main measuring component, and is made of high-temperature alloy material to meet the high-temperature resistance. The sensor core 101 is in the shape of a stepped shaft, and the end close to the rotating blade 3 has a larger diameter to obtain a larger measurement range and higher measurement sensitivity, and can lock the insulating layer 102 to prevent the insulating layer 102 from falling off and entering the casing 2 to cause danger; the other end has a smaller diameter and is connected to the core of the cable 105 by welding.

[0047] Furthermore, the insulating layer 102 is made of high-purity ceramic material to ensure that the insulating layer 102 still has good insulation properties under extremely high temperature conditions, so as to avoid the sensor core 101 and the outer metal layer 103 being connected to each other and causing the sensor to fail. The insulating layer 102 is connected to the sensor core 101 and the outer metal layer 103 through mechanical cooperation, and the tail top ring 104 presses the insulating layer 102 tightly.

[0048] Furthermore, the outer metal layer 103 plays the role of shielding signal interference and protecting the insulating layer 102, and is also made of high-temperature alloy material to meet the high-temperature resistance characteristics. The mounting seat 106 located on the inner wall 201 side of the casing is provided with a boss protruding toward the center of the through hole, and the outer metal layer 103 located on the outer wall 202 side of the casing is provided with a flange, the boss is connected to the outer wall of the outer metal layer 103, and the flange of the outer metal layer 103 is connected to the inner wall of the mounting seat 106 to form an annular closed cavity 109.

[0049] Furthermore, the tail top ring 104 plays the role of compressing the insulating layer 102, fixing the cable 105 and protecting the welding point between the sensor core 101 and the cable 105. The tail top ring 104 is fixed to the outer metal layer 103 and the metal outer shielding layer of the cable 105 by welding.

[0050] Furthermore, the cable 105 is a coaxial cable or a triaxial cable, and a high temperature resistant metal cable is selected to ensure good temperature resistance.

[0051] The mounting seat 106 with internal cooling flow channel is installed on the casing 2 through the mounting flange 110. The inner diameter size of the mounting seat 106 is designed with reference to the size of the outer metal layer 103 of the sensor. An annular closed cavity 109 is formed between the mounting seat 106 and the outer metal layer 103 as a flow channel for cooling gas. The cooling gas is discharged after rotating one circle in the annular closed cavity 109, and the heat on the outer metal layer 103 of the blade tip clearance sensor is removed by convection heat exchange. The mounting seat 106 and the outer metal layer 103 are connected by welding to ensure the sealing of the cooling gas flow channel and prevent the cooling gas from leaking out. An inlet flow channel 107 and an outlet flow channel 108 are opened inside the mounting seat 106. Bends are symmetrically arranged inside the two flow channels. The outlet of the inlet flow channel 107 points to the wall surface of the outer metal layer, so that the cooling gas entering the annular closed cavity 109 from the inlet flow channel 107 impacts the wall surface of the outer metal layer of the cooling sensor, thereby improving the heat exchange efficiency of the cooling gas.

[0052] Furthermore, the air inlet hole of the inlet flow channel 107 is connected to the air inlet pipe 111, and the air outlet hole of the outlet flow channel 108 is connected to the air outlet pipe 112. The air inlet pipe 111 and the air outlet pipe 112 can be made of stainless steel metal pipes or stainless steel metal hoses, which are connected to the mounting seat by welding. The inner diameter of the air pipe is consistent with the aperture size of the inlet flow channel 107 and the outlet flow channel 108 of the mounting seat.

[0053] In summary, the mounting base 106 with internal cooling channels is the main cooling component of the sensor and has a significant impact on the cooling effect of the sensor. Therefore, the structural design of the mounting base 106 with internal cooling channels is very critical. Figure 3 As shown, the design method includes the following steps:

[0054] S1. Determine the dimensions of the mounting base 106;

[0055] In order to meet the requirements of component standardization and facilitate users to use existing sensors to achieve gap measurement in extreme high temperature environments, in this embodiment, r1 is used as the outer diameter of the outer metal layer, and r2 is the outer diameter of the flange of the outer metal layer.

[0056] Furthermore, the outer diameter R1 of the mounting seat 106 is usually related to the space of the mounting position and the opening size of the casing 2, and is specified by the user. The outer diameter R2 of the mounting flange is greater than R1, which is also related to the space of the mounting position and can be adjusted.

[0057] Furthermore, the length h of the mounting seat 106 is related to the thickness L of the casing 2. In order to avoid the danger caused by the blade tip clearance sensor protruding out of the casing, the mounting seat h≤L.

[0058] Furthermore, the mounting seat 106 is connected to the outer metal layer 103 by welding. The first welding point is the flange of the outer metal layer 103 and the inner wall of the mounting seat. The second welding point is the outer wall of the outer metal layer 103 and the boss of the mounting seat. After welding, an annular closed cavity 109 is formed between the mounting seat and the tip clearance sensor for the flow and heat dissipation of the cooling gas. In order to ensure that the high-pressure gas in the annular closed cavity 109 is strictly sealed, the boss of the mounting seat needs to overcome the huge shear force caused by the internal and external pressure difference. Therefore, the thickness b of the boss has a minimum value bmin:

[0059] ;

[0060] Among them, P in P is the cooling gas pressure in the closed cavity; out is the working environment pressure of the tip clearance sensor; k1 is the safety margin, k1>1; [τ] is the allowable shear stress of the mounting seat material, and the [τ] value can be obtained by consulting the relevant material manual.

[0061] Furthermore, an inlet air channel 107 and an outlet air channel 108 are opened at symmetrical positions in the mounting seat 106 to facilitate the connection of the inlet and outlet air pipes. Assuming that the diameters of the inlet air channel 107 and the outlet air channel 108 are both a, the value of a is as large as possible to allow more cooling gas to enter the annular closed cavity 109 and reduce the temperature of the sensor probe. However, due to the size limitation of the mounting seat 106, a <R1-r2。

[0062] Furthermore, bends are provided in both the inlet and outlet channels to allow the gas to directly impact the outer metal layer of the sensor probe, thereby improving the heat exchange efficiency of the sensor probe; the angle α of the bend is

[0063] ;

[0064] S2. Determine the cooling medium;

[0065] The cooling medium is selected based on a comprehensive consideration of multiple factors including user requirements, usage cost, working environment temperature of the tip clearance sensor, sensor size and material, etc.

[0066] Furthermore, for the tip clearance sensor that is easily oxidized at high temperatures, nitrogen or inert gas should be used as the cooling medium as much as possible to prevent the cooling medium from accelerating the oxidation of the sensor and reducing the service life of the sensor.

[0067] Furthermore, for use scenarios where the installation space is limited and the sensor size is small, or the sensor working environment temperature is too high, the cooling medium should try to use a gas or even a liquid with a higher specific heat capacity, so that the unit volume of cooling medium can absorb more heat.

[0068] Furthermore, the cooling medium should try to use the existing gas source near the working environment to avoid adding supporting equipment to reduce the impact on the overall system.

[0069] S3. Numerical simulation;

[0070] Use numerical simulation software to increase the volume flow of the cooling medium and compare the temperature changes on the sensor probe end face and the central axis. If in the simulation results, the sensor probe end face temperature is lower than the maximum use temperature of the corresponding material, and the sensor core 101, cable 105 and solder joint temperature on the sensor central axis are also lower than the corresponding maximum use temperature, then the volume flow is the ideal volume flow.

[0071] S4. High temperature experimental verification in laboratory environment;

[0072] A capacitive blade tip clearance sensor with an internal cooling channel is manufactured, and a high-temperature furnace is used as a heating source to build a sensor high-temperature experimental verification platform in a laboratory environment. A cooling medium with an ideal volume flow rate is introduced into the capacitive blade tip clearance sensor, and the furnace temperature is raised to the sensor working environment temperature. The leakage capacitance and leakage resistance signals of the capacitive blade tip clearance sensor are monitored in real time. If the leakage capacitance and leakage resistance are both within the compensable range of the blade tip clearance measurement system during the experiment, and there is no obvious damage, deformation, or oxidation on the appearance of the capacitive blade tip clearance sensor after cooling, and an obvious gap waveform can be seen when the capacitive blade tip clearance sensor is installed on a rotating table, then the capacitive blade tip clearance sensor with an internal cooling channel can meet the requirements of an extremely high-temperature working environment.

[0073] S5. Finalization of capacitive tip clearance sensor with internal cooling channel;

[0074] After high-temperature experimental verification in a laboratory environment, the capacitive tip clearance sensor with internal cooling flow channel was finalized and can be experimentally verified in an actual engineering environment.

[0075] The present invention is not limited to the embodiments described above. The above description of the specific embodiments is intended to describe and illustrate the technical solution of the present invention. The above specific embodiments are merely illustrative and not restrictive. Without departing from the scope of the present invention and the scope of protection of the claims, a person of ordinary skill in the art can also make many forms of specific changes under the guidance of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A capacitive blade tip clearance sensor with a cooling channel is installed on the casing wall of an aircraft engine, and a rotating blade is installed in the casing. It is characterized in that The capacitive tip clearance sensor comprises a sensor probe, a cable and a mounting seat. The sensor probe comprises a sensor core, an outer metal layer, an insulating layer and a tail top ring. A mounting flange is arranged on the mounting seat. The mounting seat is fixed to the casing wall of the aircraft engine through the mounting flange. A through hole is arranged in the middle of the mounting seat. The outer metal layer is arranged on the inner wall of the through hole. An annular closed cavity is formed between the outer metal layer and the inner wall. Inlet and outlet airflow channels are symmetrically arranged on the mounting seats on both sides of the annular closed cavity. The air inlet hole of the inlet airflow channel is connected to an air inlet pipe. The air outlet of the air outlet passage is connected with an air outlet pipe, an insulating layer is arranged inside the outer metal layer, the sensor core is installed in the insulating layer, a tail portion of the insulating layer is provided with a tail top ring fixed to the outer metal layer, the middle portion of the tail top ring is connected to the metal outer shielding layer of the cable, and the core of the cable is connected to the sensor core; a mounting seat located on the inner wall side of the casing is provided with a boss protruding toward the center direction of the through hole, a flange is provided on the outer metal layer located on the outer wall side of the casing, the boss is connected to the outer wall of the outer metal layer, and the flange of the outer metal layer is connected to the inner wall of the mounting seat to form the annular closed cavity; The tail top ring plays the role of pressing the insulating layer, fixing the cable and protecting the welding points between the sensor core and the cable core. The tail top ring is fixed to the outer metal layer and the metal outer shielding layer of the cable by welding.

2. A capacitive tip clearance sensor with a cooling channel according to claim 1, It is characterized in that A truncated cone with an enlarged diameter is provided on one side of the sensor core close to the rotating blades to lock the insulating layer and prevent the insulating layer from falling off and entering the interior of the casing to cause danger.

3. A capacitive tip clearance sensor with a cooling channel according to claim 1, It is characterized in that The insulating layer is made of ceramic material with a purity greater than 95%, and the insulating layer is connected to the sensor core electrode and the outer metal layer through mechanical matching.

4. A capacitive tip clearance sensor with a cooling channel according to claim 1, It is characterized in that The outer metal layer is used to shield signal interference and protect the insulation layer.

5. A capacitive tip clearance sensor with a cooling channel according to claim 1, It is characterized in that The cable used is coaxial cable.

6. A capacitive tip clearance sensor with a cooling channel according to claim 1, It is characterized in that The annular closed cavity serves as a flow channel for the cooling gas. The cooling gas is discharged after rotating one circle in the annular closed cavity, and the heat on the outer metal layer of the tip clearance sensor is removed by convection heat exchange. The mounting seat is connected to the outer metal layer by welding, which ensures the sealing of the cooling gas flow channel and prevents the cooling gas from leaking out. Bends are arranged inside the inlet and outlet flow channels, and the outlet of the inlet flow channel points to the wall of the outer metal layer, so that the cooling gas entering the annular closed cavity from the inlet flow channel impacts the cooling sensor probe, thereby improving the heat exchange efficiency of the cooling gas.

7. A capacitive tip clearance sensor with a cooling channel according to claim 1, It is characterized in that The air inlet pipe and the air outlet pipe are made of stainless steel metal pipes, which are connected to the mounting seat by welding. The inner diameters of the air inlet pipe and the air outlet pipe are consistent with the sizes of the inlet flow channel and the outlet flow channel.

8. A method for designing a cooling channel, based on the capacitive tip clearance sensor with a cooling channel according to any one of claims 1 to 7, wherein the cooling channel comprises an inlet channel and an outlet channel, It is characterized in that S1. Determine the dimensions of the mounting base; Setting r 1 is the outer diameter of the outer metal layer, r 2 The outer diameter of the flange of the outer metal layer; the outer diameter of the mounting flange R2> the outer diameter of the mounting seat R1; the length of the mounting seat h≤ the thickness of the casing L; The boss thickness b has a minimum value bmin: Among them, P in P is the cooling gas pressure in the annular closed cavity; out is the working environment pressure of the blade tip clearance sensor; k 1 is the safety margin, k 1 >1; [τ] is the allowable shear stress of the mounting seat material. The corresponding [τ] value can be obtained by consulting the material manual; Assume that the diameters of the inlet and outlet holes are both a, a <R1-r 2 ; Bends are provided in both the inlet and outlet channels to allow the gas to directly impact the outer metal layer, thereby improving the heat exchange efficiency of the sensor probe; the angle α of the bend is: S2. Determine the cooling medium; S3. Numerical simulation; Use numerical simulation software to increase the volume flow of the cooling medium and compare the temperature changes on the end face and the center axis of the sensor probe; if in the simulation results, the temperature of the sensor probe end face is lower than the maximum use temperature of the corresponding material, and the core pole, cable and welding point temperature on the center axis of the tip clearance sensor are also lower than the corresponding maximum use temperature, then the corresponding volume flow is the ideal volume flow; S4. High temperature experimental verification in laboratory environment; A high-temperature furnace is used as a heating source to build a high-temperature sensor experimental verification platform in a laboratory environment; a cooling medium with an ideal volume flow rate is introduced into the capacitive blade tip clearance sensor, the furnace temperature of the high-temperature furnace is increased to the working environment temperature of the capacitive blade tip clearance sensor, and the leakage capacitance and leakage resistance signals of the capacitive blade tip clearance sensor are monitored in real time. If the leakage capacitance and leakage resistance are both within the compensable range of the blade tip clearance measurement system during the experiment, and the capacitive blade tip clearance sensor has no damage, deformation or oxidation after cooling, and the gap waveform can be seen when the capacitive blade tip clearance sensor is installed on a rotating table, then the capacitive blade tip clearance sensor meets the working environment requirements of ≥1400℃; S5. Finalize the capacitive tip clearance sensor with internal cooling channel.

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