Ultrahigh-temperature airflow total temperature probe based on Fabry-Perot structure and manufacturing method thereof

Abstract

The invention discloses a super-high-temperature airflow total temperature probe based on a Fabry-Perot structure and a manufacturing method thereof. The total temperature probe comprises a Fabry-Perot fixing frame, a single crystal wafer, a support and a supporting frame. The single crystal wafer is inserted into the Fabry-Perot fixing frame; the Fabry-Perot fixing frame is fixed in the support through a supporting frame. The bracket is a hollow T-shaped bracket; the interior of the support serves as an air flow channel. The manufacturing method comprises the following steps: 1) inserting a single crystal wafer into a Fabry-Perot fixing frame; (2) machining of a support and a supporting frame is completed through a cutting process; and (3) processing a light guide hole in the bracket. The transparent single crystal wafer is used as a Fabry-Perot temperature sensing element, a spatial light transmission mode is adopted, temperature sensing and transmission are separated, optical fiber structures are reduced, the overall structural strength is good, and the high temperature resistance is higher.

Description

Technical Field

[0001] The present invention relates to the technical field of flow field total temperature testing, and in particular to an ultra-high temperature airflow total temperature probe based on a Fabry-Perot structure and a manufacturing method thereof. Background Art

[0002] As an important power unit of aircraft, the efficient and stable operation of the engine is the basic guarantee for the safe operation of aircraft and the full play of its maneuverability. At the same time, combustion efficiency is one of the most important technical indicators of aircraft engines, which directly determines the unit thrust performance of the engine. With the gradual deepening of my country's independent research and development of aircraft engines, and the requirements of new generation aircraft for high maneuverability, high thrust and other performance of engines, higher requirements are put forward for temperature measurement in the combustion process of engines. At present, the temperature of the combustion chamber has reached 2000℃, and the turbine inlet and outlet temperature of the fourth-generation fighter engine has reached 1977K. There is an urgent need to develop high temperature resistant, high stability and miniaturized temperature sensors.

[0003] High temperature sensing methods include thermocouples, temperature indicating paint and fiber optic high temperature sensors. Temperature indicating paint is mainly used to test wall temperature. Precious metal thermocouples such as platinum and rhodium can achieve high temperature measurement of 1800℃, but they are easily oxidized in high temperature environment, have poor long-term stability and are susceptible to electromagnetic interference. With the development of single crystal fiber sensing technology, the field of high temperature measurement has ushered in new vitality. Single crystal fiber has a high melting point, small size and anti-electromagnetic interference. Using it to make high temperature temperature sensors has great potential in the field of aerospace measurement. At present, high temperature sensors have been made by sputtering high temperature resistant precious metal iridium or ceramic film on the end of sapphire fiber or other single crystal fiber to form a black body cavity, and the temperature measurement range can reach 2000℃. However, this sensor has a fatal problem: single crystal fiber and black body (metal / ceramic) are heterogeneous materials, and the difference in thermal expansion coefficient causes the sensor probe to crack at high temperature, which affects the life of the sensor. The second single crystal fiber high temperature sensing technology is to write fiber grating on single crystal fiber. Sapphire fiber grating is the most widely studied high temperature grating sensor. However, sapphire fiber does not have a conventional core-cladding structure and exhibits a highly multimode characteristic. Sapphire fiber Bragg grating is a typical multimode fiber Bragg grating. Its spectrum is very different from that of conventional single-mode gratings, which seriously affects high-precision spectrum peak finding and sensing characteristics. And because high-power femtosecond lasers are required to make gratings, the production system is complex, difficult to maintain, and costly, making it difficult to use for actual testing. The third single-crystal fiber high-temperature sensor technology is to make a Fabry-Perot structure on a single-crystal fiber, but the FP interferometer has a serious high-temperature debonding problem. In addition, the back end of the single-crystal fiber sensor needs to be connected to a single-mode fiber. How to connect to achieve mode field matching and improve coupling efficiency is also a major difficulty of single-crystal fiber sensors. Summary of the invention

[0004] The object of the present invention is to provide an ultra-high temperature airflow total temperature probe based on a Fabry-Perot structure, comprising a Fabry-Perot fixing frame, a single crystal, a bracket and a support frame.

[0005] The single crystal wafer is inserted into a Fabry-Perot holder.

[0006] The Fabry-Perot fixing frame is fixed inside the bracket through a supporting frame.

[0007] The bracket is a T-shaped bracket with a hollow interior, comprising a connected transverse bracket and a longitudinal bracket.

[0008] The interior of the bracket serves as an air flow channel.

[0009] An air inlet and an air outlet are respectively formed at two ends of the transverse bracket.

[0010] A light guide hole is formed at the bottom end of the longitudinal bracket.

[0011] Furthermore, when the ultra-high temperature airflow total temperature probe is working, the airflow enters the airflow channel and stagnates when encountering the single wafer, and the heat is transferred to the single wafer.

[0012] The external light source is collimated and enters the interior of the bracket through the light guide hole.

[0013] The single crystal reflects the incident external light source, forms an interference light path in space, and transmits out through the light guide hole.

[0014] Furthermore, it also includes a water cooling channel for cooling.

[0015] The water cooling channel is arranged inside the bracket.

[0016] Furthermore, the single crystal wafer is a high temperature resistant transparent single crystal wafer.

[0017] Furthermore, the thickness of the single crystal wafer is ≤0.8 mm.

[0018] The method for manufacturing an ultra-high temperature airflow total temperature probe based on a Fabry-Perot structure comprises the following steps:

[0019] 1) Insert the single crystal into the Fabry-Perot holder.

[0020] 2) Use cutting technology to complete the processing of brackets and support frames.

[0021] 3) The two parts of the bracket are connected by threads to ensure the overall structural strength.

[0022] Furthermore, the steps of completing the processing of the bracket and the support frame by using the cutting process include:

[0023] 2.1) Use metal cutting method to complete the rough processing of brackets and support frames.

[0024] 2.2) Use laser cutting to complete the finishing of the bracket and support frame.

[0025] The technical effect of the present invention is undoubted, and the beneficial effects of the present invention are as follows:

[0026] 1) Use a high temperature resistant transparent single crystal as the Fabry-Perot cavity, separate it from the transmission light system, and improve the upper temperature limit of the sensor;

[0027] 2) High-intensity collimated light is transmitted in free space, reducing the fiber structure, the overall structural strength is good, and there is no need to add more protective devices;

[0028] 3) The overall structure of the probe adopts water cooling cycle to ensure that the entire device does not deform during measurement.

[0029] In summary, the present invention proposes an ultra-high temperature airflow total temperature sensor based on the Fabry-Perot principle, with a single crystal chip as a temperature sensing element, and the temperature sensing element and the optical transmission system are separated. The single crystal chip is clamped on the bracket by a mechanical structure, and the signal is transmitted by spatial light. There is no problem of bonding and fixing between the temperature sensing element and the light transmission optical fiber, and there is no need for single crystal optical fiber mode field matching. A water cooling channel is opened on the probe bracket to greatly improve the temperature resistance of the bracket. In theory, the melting point of the single crystal optical fiber is the upper limit of the temperature measurement of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a total temperature probe structure;

[0031] Figure 2 It is the Fabry-Perot interference principle;

[0032] Figure 3 is the Fabry-Perot spectroscopy signal;

[0033] Figure 4 Schematic diagram of the optical path inside the probe;

[0034] Figure 5 It is a method for measuring the total temperature inside an aircraft engine;

[0035] Figure 1 In the figure, there are a Fabry-Perot fixing frame 1, a single crystal 2, a bracket 3, a water cooling channel 4, a light guide hole 5, an air flow channel 6, and a support frame 7. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with the embodiments, but it should not be understood that the above subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to the common technical knowledge and customary means in the art, which should all be included in the protection scope of the present invention.

[0037] Embodiment 1:

[0038] See also Figures 1 to 5 , an ultra-high temperature airflow total temperature probe based on a Fabry-Perot structure, comprising a Fabry-Perot fixing frame 1, a single crystal 2, a bracket 3, and a support frame 7.

[0039] The single crystal 2 is inserted into the Fabry-Perot fixing frame 1 .

[0040] The Fabry-Perot fixing frame 1 is fixed inside the bracket 3 via a supporting frame 7 .

[0041] The bracket 3 is a T-shaped bracket with a hollow interior, including a connected transverse bracket and a longitudinal bracket.

[0042] The interior of the bracket 3 serves as an air flow channel 6 .

[0043] An air inlet and an air outlet are respectively formed at two ends of the transverse bracket.

[0044] The bottom end of the longitudinal support is provided with a light guide hole 5. The light guide hole 5 allows incident light to enter, and at the same time receives interference signals and performs demodulation.

[0045] Embodiment 2:

[0046] An ultra-high temperature airflow total temperature probe based on a Fabry-Perot structure, the technical content of which is the same as that of Example 1. Furthermore, when the ultra-high temperature airflow total temperature probe is working, the airflow enters the airflow channel 6 and stagnates when encountering a single wafer 2, and heat is transferred to the single wafer 2.

[0047] The external collimated light enters the interior of the bracket 3 through the light guide hole.

[0048] The single crystal 2 reflects the incident light source to form an interference light path in space, and the interference light is transmitted outward through the light guide hole.

[0049] Embodiment 3:

[0050] An ultra-high temperature airflow total temperature probe based on a Fabry-Perot structure, the technical content of which is the same as any one of Examples 1-2, and further includes a water cooling channel 4 for cooling.

[0051] The water cooling channel 4 is arranged inside the bracket 3 .

[0052] Embodiment 4:

[0053] An ultra-high temperature airflow total temperature probe based on a Fabry-Perot structure, the technical content of which is the same as any one of Examples 1-3, and further, the single crystal chip 2 is a high temperature resistant transparent single crystal chip.

[0054] Embodiment 5:

[0055] An ultra-high temperature airflow total temperature probe based on a Fabry-Perot structure, the technical content of which is the same as any one of Examples 1-4, and further, the thickness range of the single wafer is (0, 0.8 mm].

[0056] Embodiment 6:

[0057] A method for manufacturing an ultra-high temperature airflow total temperature probe based on a Fabry-Perot structure as described in any one of Embodiments 1-5 comprises the following steps:

[0058] 1) Insert the single crystal 2 into the Fabry-Perot holder 1.

[0059] 2) The bracket 3 and the support frame 7 are processed by cutting technology.

[0060] 3) Processing the light guide hole 5 on the bracket 3.

[0061] Embodiment 7:

[0062] A manufacturing method described in Example 6, the technical content is the same as that of Example 6, and further, the steps of completing the processing of the bracket 3 and the support frame 7 by cutting technology include:

[0063] 2.1) Use metal cutting method to complete the rough processing of bracket 3 and support frame 7.

[0064] 2.2) Use laser cutting to complete the fine processing of the bracket 3 and the support frame 7.

[0065] Embodiment 8:

[0066] A super-high temperature airflow total temperature probe based on a Fabry-Perot structure comprises a Fabry-Perot fixing frame (1), a single crystal chip (2), a bracket (3), a water cooling channel (4), a light guide hole (5), and a support frame (7).

[0067] The airflow enters the flow channel (6) and encounters the single crystal wafer, causing stagnation. The collimated light enters through the light guide hole, is freely transmitted in space, reaches the temperature sensing end of the single crystal wafer, is reflected by the single crystal wafer, forms an interference light path in space, and finally is transmitted out of the light guide hole. The support frame is used to support the Fabry-Perot fixed frame and maintain stability under the impact of high-speed airflow.

[0068] The entire Fabry-Perot structure is a transparent single crystal (1) with a certain thickness, which can withstand high temperatures and work stably in high-temperature and high-speed airflow;

[0069] The whole device adopts spatial light free light guidance method, the temperature sensing element is independent and no glue is required.

[0070] The overall bracket is made of metal with a higher melting point, and the water cooling system runs through the entire probe bracket, which can better ensure that the probe works stably in a high temperature environment.

[0071] The function of each component in the present invention is:

[0072] 1. The transparent single crystal is used as a Fabry-Perot structure for temperature sensing.

[0073] 2. High-speed and high-temperature airflow enters the flow channel and stops at the end of the temperature-sensitive single chip, thereby converting kinetic energy into internal energy and finally being discharged through the tail. The volume of the temperature-sensitive element in the entire flow channel is small, which does not affect the normal airflow and can achieve a good stopping effect.

[0074] 3. The fixed frame structure can ensure that the temperature measuring unit will not be damaged or moved when facing high-speed airflow, so as not to affect the temperature measurement accuracy.

[0075] 4. The light-guiding part is away from the high-temperature airflow, and the entire probe contains a circulating water-cooling channel, which can keep working in a high-temperature environment.

[0076] A method for manufacturing an ultra-high temperature airflow total temperature probe based on a Fabry-Perot structure, the steps comprising:

[0077] 1. Material preparation;

[0078] 2. Prepare the single crystal diaphragm and measure the specific values ​​of the diaphragm so that it can be stably inserted into the probe holder;

[0079] 3. Probe model processing. First, the probe outer model is processed by metal cutting and other methods, and the fixed frame structure is finely processed by laser cutting and other methods to ensure that it can accommodate the temperature sensing element.

[0080] Embodiment 9:

[0081] The working principle of the ultra-high temperature airflow total temperature probe based on the Fabry-Perot structure described in any one of Embodiments 1-8 is as follows:

[0082] When the high-speed airflow enters the internal flow channel of the probe and stops at the end of the Fabry-Perot single crystal, the kinetic energy of the air temperature is converted into internal energy, and the heat is transferred to the single crystal through heat conduction. The temperature measured at this time is the total temperature. The relationship between the static temperature and the total temperature is:

[0083]

[0084] The transparent single crystal is used as a Fabry-Perot structure, and the internal signal generation principle is based on the principle of multi-beam interference. The optical fiber FP sensor uses multi-beam interference between parallel optics to achieve sensing. The interference pattern is shown in Figure 3 As shown, the interference process is as follows.

[0085] Set the reflectivity of the two reflective surfaces to R1 and R2, the Fabry-Perot spacing to l, the refractive index to n, the temperature to T, and the temperature change to ΔT

[0086] The reflected light intensity I is shown as follows

[0087]

[0088] The refractive index of the material changes with temperature and expands when the temperature rises. At this time, the thermo-optic coefficient CTE and the thermal expansion coefficient α are introduced, and the formula is expressed as

[0089] CET=dn / dT

[0090] α=Δl / (l*ΔT)

[0091] When the external temperature changes, the refractive index and cavity length of the Fabry-Perot cavity change. The change in external temperature can be obtained through the reflection spectrum, and the spectrum moves. The specific spectrum image is as follows: Figure 3 shown.

[0092] At this time, the spectral signal is expressed as

[0093]

[0094] Finally, the interference signal is demodulated, and different spectra are analyzed by demodulation means to further solve the total temperature.

[0095] The optical path diagram is as follows Figure 4 As shown, the collimated incident light is incident on the lower surface of the single wafer through the light guide hole, part of the light is reflected by the lower surface of the single wafer, and the other part of the light enters the single wafer and is reflected at the upper surface of the single wafer. The two beams of reflected light converge in the free space below the single wafer and interfere with each other. The interference light is transmitted to the light guide hole and received by an external light detector.

[0096] Embodiment 10:

[0097] See also Figure 5 The temperature measurement system using the ultra-high temperature airflow total temperature probe described in any one of Examples 1-9 includes: an ultra-high temperature airflow total temperature probe, a light source, a spectrometer, and a PC.

[0098] The working process of the temperature measurement system is as follows:

[0099] First, install the Fabry-Perot total temperature probe on the probe mounting device so that the air inlet of the probe faces the direction of the high-speed airflow. The collimated light source emits light to the Fabry-Perot end, and the interference light signal is generated through the Fabry-Perot structure. The reflected signal is received by the optical fiber through the light guide hole, and then input into the spectrometer for reading through the circulator, and finally demodulated by the PC.

Claims

1. An ultra-high temperature airflow total temperature probe based on a Fabry-Perot structure, characterized in that: It comprises a Fabry-Perot fixing frame (1), a single crystal (2), a bracket (3), and a support frame (7); The single crystal (2) is inserted into a Fabry-Perot fixing frame (1). The Fabry-Perot fixing frame (1) is fixed inside the bracket (3) via a supporting frame (7); The bracket (3) is a T-shaped bracket with a hollow interior, comprising a connected transverse bracket and a longitudinal bracket. The interior of the bracket (3) serves as an air flow channel (6); The two ends of the transverse bracket are respectively provided with an air inlet and an air outlet; A light guide hole (5) is provided at the bottom end of the longitudinal bracket; A lens is arranged inside the longitudinal support.

2. The ultra-high temperature airflow total temperature probe based on the Fabry-Perot structure according to claim 1, characterized in that: When the ultra-high temperature airflow total temperature probe is working, the airflow enters the airflow channel (6) and is stagnant when encountering the single wafer (2), and the heat is transferred to the single wafer (2); The external light source is collimated and enters the interior of the bracket (3) through the light guide hole; The single crystal (2) reflects the incident external light source, forms an interference light path in space, and transmits it through the light guide hole; The lens converges the free-space light and transmits it outward through the light-guiding hole.

3. The ultra-high temperature airflow total temperature probe based on the Fabry-Perot structure according to claim 1, characterized in that: The focal point of the lens is located in the light guide hole (5).

4. The ultra-high temperature airflow total temperature probe based on the Fabry-Perot structure according to claim 1, characterized in that: It also includes a water cooling channel (4) for cooling; The water cooling channel (4) is arranged inside the bracket (3).

5. The ultra-high temperature airflow total temperature probe based on the Fabry-Perot structure according to claim 1, characterized in that: The single crystal wafer (2) is a transparent single crystal wafer.

6. The ultra-high temperature airflow total temperature probe based on the Fabry-Perot structure according to claim 1, characterized in that: The thickness of the single crystal sheet (2) is ≤0.8 mm.

7. The method for manufacturing the ultra-high temperature airflow total temperature probe based on the Fabry-Perot structure according to any one of claims 1 to 5, characterized in that: The following steps are involved: 1) inserting the single crystal (2) into the Fabry-Perot holder (1); 2) using a cutting process to complete the processing of the bracket (3) and the support frame (7); 3) Calibrate the position of the light guide hole and place the lens so that the focus of the lens is located in the light guide hole, so that the position of the light guide hole can accurately receive the interference light path.

8. The method according to claim 7, characterized in that: The steps of completing the processing of the bracket (3) and the support frame (7) by using a cutting process include: 2.1) Rough processing of the bracket (3) and the support frame (7) is completed by metal cutting; 2.2) Using laser cutting to complete the fine processing of the bracket (3) and the support frame (7).

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