A calibration system for ultra-high temperature sensors

Abstract

A calibration system for an ultra-high temperature sensor, with an operating temperature of 20°C to 2800°C, is characterized in that the calibration system comprises: a sealed cavity, an environmental control unit, a graphite heat spreader, a heat source unit, a temperature measuring unit and a main control unit, the sealed cavity is provided with a laser transmission lens for allowing external laser to be injected, the graphite heat spreader and the temperature measuring unit are arranged in the sealed cavity, the graphite heat spreader is arranged within the irradiation range of the laser transmission lens, the temperature measuring unit is used to detect the graphite heat spreader, the heat source unit is arranged outside the sealed cavity, the heat source unit heats the graphite heat spreader in the sealed cavity by emitting laser through the laser transmission lens, and the environmental control unit, the heat source unit and the temperature measuring unit are all electrically connected to the main control unit.

Description

Technical Field

[0001] The invention belongs to the technical field of temperature sensor testing and measurement, and in particular relates to an ultra-high temperature sensor calibration system. Background Art

[0002] Faster flight speed, higher strike accuracy, greater destructive power, and stronger comprehensive performance are the eternal goals of weapon development. In the process of pursuing these goals, it is inevitable to encounter some new problems that have not been encountered before or some problems that can be avoided in the initial research.

[0003] The technical problem of temperature parameter testing in ultra-high temperature environment is a typical example. For example, parameters such as temperature in various engine test runs need to be obtained in real time, and the closer to the original position, the better. However, the temperature of the engine combustion chamber exceeds 1600°C, and there are harsh environments such as high oxidation, particle deposition and airflow scouring. Therefore, the existing technology cannot achieve long-term in-situ testing. In addition, the reentry of advanced missile rockets, the shape of the penetrating warhead, and the load design tasks all require the acquisition of multiple dynamic parameters in ultra-high temperature environments and confined space conditions. In fact, all military powers have realized and begun to address this major basic problem that restricts the development of weapons and equipment.

[0004] Temperature and other parameter tests in ultra-high temperature environments provide various basic data (temperature, etc.) for performance optimization design and health status monitoring of various advanced engines. For example, the temperature distribution change law inside the base and the heat transfer law along the wall thickness direction obtained in the hot test of the solid engine can be used as a basis to more accurately optimize the insulation structure of the combustion chamber, reduce the mass of the insulation structure, and increase the mass ratio. Obtaining the law of pressure change inside the engine can verify the ballistic design parameters of the engine and optimize the pressure-bearing parts structure. The optimization of the shape and load of the high-speed flying body and the design of the penetrating warhead are all based on dynamic parameters such as temperature obtained during the flight. The above tests all require long-term exposure (>30min) to an ultra-high temperature environment above 1000℃ and are completed in situ in a confined space.

[0005] Ultra-high temperature testing is a prerequisite for optimizing the design of the thermal insulation structure of the solid rocket engine combustion chamber. The thermal protection structure of the combustion chamber is designed according to the thermal conductivity, specific heat capacity, and oxyacetylene ablation rate test parameters of the thermal insulation layer material based on the thermal insulation layer exposure time, flow field, and temperature field analysis and calculation results of the solid rocket engine. At present, the design and working reliability of the thermal insulation layer can only be evaluated by relying on the empirical judgment of the static ablation state of the thermal insulation layer after the hot test cooling down, resulting in the ablation layer thickness can only be redundantly designed to ensure system reliability, reducing the mass ratio and seriously affecting the engine performance.

[0006] In nuclear reactor experiments, engine operation, advanced missile rocket reentry, ammunition explosion, and penetrating warhead shape design, long-term ultra-high temperature testing problems are inevitable. For example, in various engine test runs, it is necessary to obtain temperature parameters in situ for a long time to provide basic data for performance optimization design and health status monitoring for various advanced engines, but the temperature of the engine combustion chamber exceeds 1600°C. Advanced missile rocket reentry, penetrating warhead shape design, and payload design tasks all require obtaining high-precision temperature parameters under ultra-high temperature environments and confined space conditions. Therefore, ultra-high temperature calibration is of great significance for effective temperature measurement and ensuring industrial design production and scientific experiments. Since the 1970s, in response to the needs of industrial control processes, foreign temperature measurement and control technology has developed rapidly under the impetus of computer and microelectronics technology. The temperature measurement and control systems produced by Germany, Japan, the United States, Sweden, etc. are technologically advanced and widely used in various fields. In 1980, the dry body calibration system was born in AMETEK (USA). The calibration system divides the heating part into two parts, upper and lower, so that the heat loss of the calibrated system can be compensated. Compared with Japan, the United States, Germany and other countries, the level of temperature measurement and control systems in domestic temperature calibration systems is still very backward, only at the level of the above countries in the mid-1980s. However, for ultra-high temperature calibration exceeding 1600℃, there is no high-precision, large-range solution at home and abroad.

[0007] Because lasers have the characteristics of high thermal efficiency, good uniformity, high conversion efficiency and fast light output rate, they can achieve non-contact heating and are ideal radiation heating heat sources. Applying them in the field of temperature sensor calibration will greatly improve the temperature and efficiency of temperature sensor calibration. Summary of the invention

[0008] In order to effectively solve the above problems, an object of the present invention is to provide an ultra-high temperature sensor calibration system.

[0009] The technical solution of the present invention is as follows:

[0010] A calibration system for an ultra-high temperature sensor, with an operating temperature of 20°C to 2800°C, is characterized in that the calibration system comprises: a sealed cavity, an environmental control unit, a graphite heat spreader, a heat source unit, a temperature measuring unit and a main control unit, the sealed cavity is provided with a laser transmission lens for allowing external laser to be injected, the graphite heat spreader and the temperature measuring unit are arranged in the sealed cavity, the graphite heat spreader is arranged within the irradiation range of the laser transmission lens, the temperature measuring unit is used to detect the graphite heat spreader, the heat source unit is arranged outside the sealed cavity, the heat source unit heats the graphite heat spreader in the sealed cavity by emitting laser through the laser transmission lens, and the environmental control unit, the heat source unit and the temperature measuring unit are all electrically connected to the main control unit.

[0011] Optionally, a sensor placement hole and a temperature measurement hole are provided on the graphite heat soaking block, and the sensor placement hole and the temperature measurement hole are symmetrically arranged.

[0012] Optionally, a sensor for calibration is placed in the sensor placement hole, and a ratio of the depth to the diameter of the temperature measuring hole is greater than 6.

[0013] Optionally, the environment control unit comprises: a vacuum pumping device and an inert gas filling device, and both the vacuum pumping device and the inert gas filling device are connected to the sealed cavity.

[0014] Optionally, the sealed cavity has a containing space therein, and the sealed cavity provides a sealed environment for internal components.

[0015] Optionally, the ultra-high temperature sensor calibration system further includes a cooling unit, which is connected to the heat source unit and is used to cool the heat source unit.

[0016] Optionally, the ultra-high temperature sensor calibration system further includes a power supply, which is electrically connected to the heat source unit, the temperature measurement unit, the cooling unit and the main control unit of the environment control unit for power supply.

[0017] The beneficial effects of the present invention are that the ultra-high temperature temperature sensor calibration system of the present invention can operate at a maximum temperature of 2800°C, the holes on the graphite heat-saturating block are processed to reach a specific size of the blackbody cavity, the emissivity is approximately about 1, the measured temperature is accurate, and the calibration of equipment such as ultrasonic temperature sensors, thermocouples, and infrared thermometers can be realized. The main control unit adjusts the high-power laser through the temperature data of the radiation thermometer to make the temperature field constant. The adjustment method is simple and easy, and has the characteristics of fast heating, stable temperature field, low energy consumption, etc., and has high application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the present invention;

[0019] Figure 2 It is a schematic diagram of the cross-sectional structure of the graphite heat equalizing block of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] like Figure 1As shown, a calibration system for an ultra-high temperature sensor has an operating temperature of 20°C to 2800°C. The calibration system comprises: a sealed cavity 1, an environmental control unit 2, a graphite heat-saturating block 3, a heat source unit 4, a temperature measuring unit 5 and a main control unit 6. The sealed cavity 1 is provided with a laser transmission lens 11 for allowing external laser to be injected. The graphite heat-saturating block 3 and the temperature measuring unit 5 are arranged in the sealed cavity 1. The graphite heat-saturating block 3 is arranged within the irradiation range of the laser transmission lens 11. The temperature measuring unit 5 is used to detect the graphite heat-saturating block 3. The heat source unit 4 is arranged outside the sealed cavity 1. The heat source unit 4 heats the graphite heat-saturating block 3 in the sealed cavity 1 by emitting laser through the laser transmission lens 11. The environmental control unit 2, the heat source unit 4 and the temperature measuring unit 5 are all electrically connected to the main control unit 6.

[0022] like Figure 1 As shown, the sealed cavity 1 has a containing space, and the sealed cavity 1 provides a sealed environment for the internal components. The sealed cavity 1 can withstand the heat radiation at a high temperature of 2800°C emitted by the graphite heat block 3 without gas leakage. The laser transmission lens 11 can achieve high-efficiency transmission of the laser, heat the graphite heat block 3, and achieve more than 90% energy transmission of the laser, and has the characteristics of high temperature resistance, and the transmittance does not decrease with the increase of temperature.

[0023] like Figure 1 As shown, the environmental control unit 2 includes: a vacuum pumping device 21 and an inert gas filling device 22. Both the vacuum pumping device 21 and the inert gas filling device 22 are connected to the sealed cavity 1. The environmental control unit 2 can control the environment of the sealed cavity 1 to realize the vacuum pumping and inert gas filling operations of the sealed cavity 1. The inert gas can maintain a positive pressure of 0.1 MPa.

[0024] like Figure 1 , 2 As shown, the graphite heat equalizing block 3 is provided with a sensor placement hole 31 and a temperature measuring hole 32, and the sensor placement hole 31 and the temperature measuring hole 32 are symmetrically arranged. A sensor for calibration is placed in the sensor placement hole 31, and the ratio of the depth to the diameter of the temperature measuring hole 32 is greater than 6. According to the black body cavity radiation principle, when the aspect ratio of the deep hole is greater than 5, the emissivity of the deep hole is about 1. The symmetrical arrangement of the sensor placement hole 31 and the temperature measuring hole 32 can ensure that the temperatures of the two holes are equal. Optionally, the bottom of the temperature measuring hole 32 is conical, and the cone top angle is 120°. The inner wall of the temperature measuring hole 32 is roughened to enhance the diffuse reflection of light.

[0025] like Figure 1As shown, the heat source unit 4 includes a high-power laser. The high-power laser has good uniformity in light power distribution and small output power fluctuation. At the same time, the laser spot size can change with the change of focal length and can completely cover the surface of the graphite heat equalizing block 3.

[0026] The ultra-high temperature sensor calibration system further includes a cooling unit 7 , which is connected to the heat source unit 4 and is used to cool the heat source unit 4 .

[0027] like Figure 1 As shown, the detection end of the temperature measuring unit 5 is facing the temperature measuring hole 32 on the graphite heat-saturating block 3 and detects the temperature measuring hole 32 . The temperature measuring unit 5 includes a radiation thermometer for feeding back temperature data of the temperature measuring hole 32 .

[0028] like Figure 1 As shown, the main control unit 6 can be an MCU or a single chip microcomputer, which has a temperature control program recorded inside and can control the heating rate of the graphite heat block 3.

[0029] The high-power laser, radiation thermometer and main control unit 6 can constitute a feedback control module. The radiation thermometer serves as a temperature monitoring device for the graphite heat block 3 and feeds back the real-time temperature to the main control unit 6. The main control unit 6 controls the output current of the laser power supply 8 to adjust the laser power and achieve stable control of the temperature of the heat block.

[0030] like Figure 1 As shown, the ultra-high temperature sensor calibration system also includes a power supply 8, which is electrically connected to the heat source unit 4, the temperature measurement unit 5, the cooling unit 7 and the main control unit 6 of the environment control unit 2 for supplying power to each component.

[0031] The principle of the present invention is to use a high-power laser as an excitation source to radiate and heat a graphite heat block. Assuming that the temperature of the graphite heat block is uniform at the beginning and equal to the ambient air temperature t0, its physical parameters ρ (density), c (specific heat capacity), λ (thermal conductivity, W / (m·K), a (thermal diffusivity, m 2 / s) are constants. According to the first law of thermodynamics and Fourier's law, the mathematical description of the change of the temperature field of the graphite heat block with time and space is as follows:

[0032]

[0033] In the formula, is the Laplace operator. In rectangular coordinates,

[0034] When the geometric dimensions and boundary conditions of the graphite heat block are known, the temperature distribution and constant heat flux density q of the graphite heat block at different times can be determined.w relationship.

[0035] During calibration, place the temperature sensor to be calibrated into the sensor placement hole of the graphite heat block, align the radiation thermometer with the temperature measurement hole of the graphite heat block, and irradiate the laser emitted by the high-power laser through the laser transmission mirror to the surface of the graphite heat block to make it reach a high temperature. After a period of heating, the graphite heat block reaches a constant temperature state. The graphite heat block contains a temperature measurement hole and a sensor placement hole. The temperature measurement hole is a simulated black body. According to the black body cavity radiation principle, when the depth-to-diameter ratio is greater than 5, the emissivity of the deep hole is about 1. The radiation thermometer measures the temperature of the simulated black body to achieve static calibration and calibration of the temperature monitoring in the sealed cavity and the ultra-high temperature temperature sensor. At the same time, the main control unit adjusts the power of the laser according to the temperature of the radiation thermometer to reach the set temperature. The vacuum or inert environment in the sealed cavity is achieved by the vacuum pumping device and the inert gas filling device.

[0036] The beneficial effects of the present invention are that the ultra-high temperature temperature sensor calibration system of the present invention can operate at a maximum temperature of 2800°C, the holes on the graphite heat-saturating block are processed to reach a specific size of the blackbody cavity, the emissivity is approximately about 1, the measured temperature is accurate, and the calibration of equipment such as ultrasonic temperature sensors, thermocouples, and infrared thermometers can be realized. The main control unit adjusts the high-power laser through the temperature data of the radiation thermometer to make the temperature field constant. The adjustment method is simple and easy, and has the characteristics of fast heating, stable temperature field, low energy consumption, etc., and has high application value.

Claims

1. An ultra-high temperature sensor calibration system, operating temperature 20 ℃ ~ 2800 ℃, characterized in that: The calibration system comprises: a sealed chamber (1), an environmental control unit (2), a graphite heat-saturating block (3), a heat source unit (4), a temperature measuring unit (5) and a main control unit (6); the sealed chamber (1) is provided with a laser transmission lens (11) for allowing external laser to be injected; the graphite heat-saturating block (3) and the temperature measuring unit (5) are arranged in the sealed chamber (1); the graphite heat-saturating block (3) is arranged within the irradiation range of the laser transmission lens (11); the temperature measuring unit (5) is used to detect the graphite heat-saturating block (3); the heat source unit (4) is arranged outside the sealed chamber (1); the heat source unit (4) heats the graphite heat-saturating block (3) in the sealed chamber (1) by emitting laser through the laser transmission lens (11); the environmental control unit (2), the heat source unit (4) and the temperature measuring unit (5) are all electrically connected to the main control unit (6); The graphite heat-saturating block (3) is provided with a sensor placement hole (31) and a temperature measurement hole (32), and the sensor placement hole (31) and the temperature measurement hole (32) are symmetrically arranged; A sensor for calibration is placed in the sensor placement hole (31), and a ratio of the depth to the diameter of the temperature measuring hole (32) is greater than 6; The environmental control unit (2) comprises: a vacuum pumping device (21) and an inert gas filling device (22); the vacuum pumping device (21) and the inert gas filling device (22) are both connected to the sealed chamber (1).

2. The ultra-high temperature sensor calibration system according to claim 1, characterized in that: The sealed cavity (1) has a containing space therein, and the sealed cavity (1) provides a sealed environment for internal components.

3. The ultra-high temperature sensor calibration system according to claim 1, characterized in that: The ultra-high temperature sensor calibration system further comprises a cooling unit (7), wherein the cooling unit (7) is connected to the heat source unit (4) and is used to cool the heat source unit (4).

4. The ultra-high temperature sensor calibration system according to claim 3, characterized in that: The ultra-high temperature sensor calibration system further comprises a power supply (8), wherein the power supply (8) is respectively electrically connected to the environment control unit (2), the heat source unit (4), the temperature measurement unit (5), the cooling unit (7) and the main control unit (6) for power supply.

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