阅读说明：本技术 基于超声原理的蓝宝石光纤测温装置 (Sapphire optical fiber temperature measuring device based on ultrasonic principle ) 是由 王高 张猛 魏艳龙 吕建刚 周汉昌 王仲杰 李盘文 李铁林 于 2019-10-15 设计创作，主要内容包括：本发明公开基于超声原理的蓝宝石光纤测温装置,包括蓝宝石光纤超声传感器、超声脉冲检测器、电脑数据采集系统构成,蓝宝石光纤超声传感器与超声脉冲检测器的激励端连接,蓝宝石光纤超声传感器包括蓝宝石光纤传播杆,蓝宝石光纤传播杆的敏感区上间隔设有至少一个径向凹槽,蓝宝石光纤传播杆的敏感区用于温度测量,超声脉冲检测器的数据端与电脑数据采集系统连接。本案运用超声脉冲测温技术通过测量超声波在敏感材料中的延时数据得到声速来推算温度值,即选取从凹槽以及端面处反射回来的信号波形,通过计算波形之间的延时数据就可以获得在此温度下的声速值,得到不同温度值下的延时数据图,从而获得超声传播速度随温度的变化曲线。(The invention discloses a sapphire optical fiber temperature measuring device based on an ultrasonic principle, which comprises a sapphire optical fiber ultrasonic sensor, an ultrasonic pulse detector and a computer data acquisition system, wherein the sapphire optical fiber ultrasonic sensor is connected with an excitation end of the ultrasonic pulse detector, the sapphire optical fiber ultrasonic sensor comprises a sapphire optical fiber transmission rod, at least one radial groove is arranged on a sensitive area of the sapphire optical fiber transmission rod at intervals, the sensitive area of the sapphire optical fiber transmission rod is used for measuring temperature, and a data end of the ultrasonic pulse detector is connected with the computer data acquisition system. The temperature value is calculated by measuring the delay data of ultrasonic waves in the sensitive material by using an ultrasonic pulse temperature measurement technology to obtain the sound velocity, namely, the signal waveforms reflected from the grooves and the end faces are selected, the sound velocity value at the temperature can be obtained by calculating the delay data among the waveforms, and delay data graphs at different temperature values are obtained, so that the change curve of the ultrasonic propagation velocity along with the temperature is obtained.)

1. Sapphire optic fibre temperature measuring device based on supersound principle, its characterized in that: the ultrasonic temperature measurement device comprises a sapphire optical fiber ultrasonic sensor, an ultrasonic pulse detector and a computer data acquisition system, wherein the sapphire optical fiber ultrasonic sensor is connected with an excitation end of the ultrasonic pulse detector, the sapphire optical fiber ultrasonic sensor comprises a sapphire optical fiber propagation rod, at least one radial groove is formed in a sensitive area of the sapphire optical fiber propagation rod at intervals, the sensitive area of the sapphire optical fiber propagation rod is used for temperature measurement, and a data end of the ultrasonic pulse detector is connected with the computer data acquisition system.

2. The sapphire optical fiber temperature measuring device based on the ultrasonic principle as claimed in claim 1, wherein: the electric signal of the ultrasonic pulse detector is converted into an ultrasonic signal through the transducer, the ultrasonic signal is transmitted into the sapphire optical fiber transmission rod from the excitation end to be transmitted, the ultrasonic signal is reflected back to the excitation end at the groove and the end face, and then the ultrasonic signal is converted into the electric signal which is transmitted into the computer data acquisition system through the data end to be analyzed by subsequent signals.

3. The sapphire optical fiber temperature measuring device based on the ultrasonic principle as claimed in claim 2, wherein: the signal analysis is that the computer data acquisition system calculates the sound velocity value by calculating the delay data between the echo signal generated at the radial groove and the end surface reflection signal of the sapphire optical fiber transmission rod at different temperatures, and calculates to obtain the delay data graph at different temperature values, thereby obtaining the change curve of the velocity along with the temperature.

4. The sapphire optical fiber temperature measuring device based on the ultrasonic principle as claimed in claim 1, wherein: the radial grooves are more than two and form a multi-distribution temperature measuring point.

5. The sapphire optical fiber temperature measuring device based on the ultrasonic principle as claimed in claim 1, wherein: the distance between the radial groove position of the temperature measurement sensitive area and the end face of the sapphire optical fiber transmission rod is called as a reflection interval, and when the length of the reflection interval is selected, the following relational expression is satisfied:

in the formula: Δ L — reflection spacing; t is t₁-ultrasonic pulse excitation time; v (T) -the ultrasonic wave velocity; Δ t — time difference.

Technical Field

The invention relates to the field of liquid high-temperature measurement, in particular to a sapphire optical fiber temperature measuring device based on an ultrasonic principle.

Background

With the continuous innovation of the technology in the manufacturing industry, many liquid high-temperature environments need to be subjected to temperature accurate testing. For example, the temperature test of molten aluminum, molten iron and molten steel in the metallurgical industry, the plasma temperature measurement in the electromagnetic field environment and the like, especially the aluminum alloy smelting technology has more and more prominent position in the manufacturing industry, and the quality of aluminum castings is directly influenced by the temperature of the molten aluminum. Therefore, temperature monitoring at different locations of the smelting process over a long period of time is required. Because the aluminum liquid has high-temperature corrosivity, the aluminum liquid can react with most metals. At present, the commonly used method for measuring the temperature of molten aluminum is provided with a k-shaped armored thermocouple and a portable handheld infrared thermometer.

(1) Intermittent temperature measurement is carried out by a k-type armored thermocouple: the thermal electrode and the insulating material are placed in a protected metal tube to be pressed. During measurement, the front end is immersed in the aluminum liquid for temperature measurement reading. Although the method is relatively simple, the protected metal pipe is easily damaged due to the characteristics of strong corrosion of high-temperature aluminum liquid, easy slag accumulation and the like, so that the measurement result is inaccurate, secondary pollution of the aluminum liquid can be caused, and the quality of the produced product cannot be ensured.

(2) Handheld portable infrared aluminium liquid thermoscope: the system comprises an amplifying system, a display system, a circuit system, an optical system and the like. The temperature of an object is determined primarily by receiving infrared radiation energy emitted outwardly from the object and converting it into a corresponding electrical signal. The method adopts non-contact measurement and is simple, but the measurement error is large, and the temperature value of the internal aluminum liquid cannot be accurately obtained.

The armored thermocouple can only carry out transient internal temperature point type measurement, and a plurality of test points need to be distributed for temperature distribution. The handheld infrared thermometer mainly collects the heat radiation energy on the surface of the aluminum liquid by using an infrared temperature measurement technology, cannot test the internal temperature, and has larger errors in the measurement results of the two. Meanwhile, the temperature of the aluminum liquid is monitored in real time, and the high-temperature strong corrosivity of the aluminum liquid must be considered. Because the aluminum liquid can react with almost all metals and oxides thereof.

Therefore, there is an urgent need to design a novel temperature sensor with high measurement accuracy and without causing secondary pollution to the aluminum liquid, and the temperature distribution gradient inside the aluminum liquid can be accurately measured, so as to obtain an aluminum alloy material with higher quality and performance through casting.

Disclosure of Invention

The invention aims to provide a sapphire optical fiber temperature measuring device based on an ultrasonic principle, which can accurately measure the temperature in liquid metal and cannot cause secondary pollution to the liquid metal.

In order to achieve the purpose, the technical scheme of the invention is as follows:

sapphire optic fibre temperature measuring device based on supersound principle, including sapphire optic fibre ultrasonic sensor, ultrasonic pulse detector, computer data acquisition system constitute, sapphire optic fibre ultrasonic sensor is connected with ultrasonic pulse detector's excitation end, sapphire optic fibre ultrasonic sensor includes sapphire optic fibre propagation pole, the interval is equipped with at least one radial recess on the sensitive district of sapphire optic fibre propagation pole, the sensitive district of sapphire optic fibre propagation pole is used for temperature measurement, the data end and the computer data acquisition system of ultrasonic pulse detector are connected.

Furthermore, the electric signal of the ultrasonic pulse detector is converted into an ultrasonic signal through the transducer, the ultrasonic signal is transmitted into the sapphire optical fiber transmission rod from the excitation end to be transmitted, the ultrasonic signal is reflected back to the excitation end at the groove and the end face, and then the ultrasonic signal is converted into an electric signal which is transmitted into a computer data acquisition system through the data end to be analyzed by subsequent signals.

Further, the signal analysis is that the computer data acquisition system calculates the sound velocity value by calculating the delay data between the echo signal generated at the radial groove and the end surface reflection signal of the sapphire optical fiber transmission rod at different temperatures, and calculates to obtain delay data graphs at different temperature values, thereby obtaining the change curve of the velocity along with the temperature.

Furthermore, more than two radial grooves form a multi-distribution temperature measuring point.

Further, the distance between the radial groove position of the temperature measurement sensitive area and the end face of the sapphire optical fiber propagation rod is called as a reflection interval, and when the length of the reflection interval is selected, the following relational expression is satisfied:

in the formula: Δ L — reflection spacing; t is t₁-ultrasonic pulse excitation time; v (T) -the ultrasonic wave velocity; Δ t — time difference.

The temperature value is calculated by measuring the delay data of ultrasonic waves in the sensitive material by using an ultrasonic pulse temperature measurement technology to obtain the sound velocity, namely, the signal waveforms reflected from the grooves and the end faces are selected, the sound velocity value at the temperature can be obtained by calculating the delay data among the waveforms, and delay data graphs at different temperature values are obtained, so that the change curve of the ultrasonic propagation velocity along with the temperature is obtained.

Drawings

FIG. 1 is a graph of incident waves versus reflected and transmitted waves in accordance with the present invention;

FIG. 2 is a schematic view of a sapphire fiber waveguide of the present invention;

FIG. 3 is a schematic view of acoustic wave propagation of a sapphire optical fiber multi-distribution ultrasonic sensor of the present invention;

FIG. 4 is a sapphire optical fiber temperature measuring device based on the ultrasonic principle of the present invention;

FIG. 5 is a static calibration temperature measurement system of a molten aluminum laboratory of the sapphire optical fiber temperature measurement device based on the ultrasonic principle;

FIG. 6 is a waveform diagram of time-delay data from normal temperature to 1600 ℃ of the sapphire optical fiber temperature measuring device based on the ultrasonic principle;

FIG. 7 is a graph showing the relationship between the delay data and the temperature of the first groove and the second groove of the sapphire optical fiber propagation rod of the present invention;

FIG. 8 is a graph showing the relationship between the temperature and the sound velocity of the first and second grooves of the sapphire optical fiber propagation rod of the present invention;

FIG. 9 is a time-dependent temperature profile measured during a process in which the sapphire optical fiber temperature sensor of the present invention is inserted into molten aluminum.

Detailed Description

The invention is further described with reference to the following drawings and specific embodiments.

The ultrasonic temperature measurement technology obtains temperature information by testing the propagation speed of ultrasonic in liquid, and the ultrasonic sensor material has good thermal conductivity and sound transmission property and can quickly reach thermal balance with temperature measurement liquid. The material is called temperature-sensing material, and usually some metal wires, metal rods, single crystal material, etc. are selected. According to the scheme, a sapphire optical fiber which is drawn by an alumina single crystal is selected as a sensitive material by combining the high-temperature corrosion characteristic of molten aluminum.

As shown in fig. 4, the invention designs a sapphire optical fiber temperature measuring device based on the ultrasonic principle according to the ultrasonic temperature measuring principle, which comprises a sapphire optical fiber ultrasonic sensor 1, an ultrasonic pulse detector 2 and a computer data acquisition system 3, wherein the sapphire optical fiber ultrasonic sensor 1 is connected with an excitation end 21 of the ultrasonic pulse detector 2, the sapphire optical fiber ultrasonic sensor 1 comprises a sapphire optical fiber propagation rod 11, at least one radial groove 12 is arranged on a sensitive area of the sapphire optical fiber propagation rod 11 at intervals, the sensitive area of the sapphire optical fiber propagation rod 11 is used for temperature measurement, and a data end 22 of the ultrasonic pulse detector 2 is connected with the computer data acquisition system 3.

The working principle of the scheme is that as shown in fig. 1 and 4, an electric signal of the ultrasonic pulse detector 2 is converted into an acoustic signal through a transducer (not shown), the acoustic signal is transmitted into the sapphire optical fiber transmission rod 11 from the excitation end 21 to be transmitted, and is reflected back to the excitation end 21 at the groove 12 and the end face 13, and then the acoustic signal is converted into an electric signal which is transmitted into the computer data acquisition system 3 through the data end 22 to be analyzed by subsequent signals; the signal analysis is that the computer data acquisition system 3 calculates the sound velocity value by calculating the delay data between the echo signal generated at the radial groove 12 and the reflected signal of the end surface 13 of the sapphire optical fiber transmission rod 11 at different temperatures, and calculates the delay data graph at different temperature values, thereby obtaining the change curve of the velocity along with the temperature.

As shown in fig. 2, 3, and 4, the number of the radial grooves is two, which are the first groove 121 and the second groove 122, respectively, to form a multi-distributed temperature measurement point, an electrical signal of the ultrasonic pulse detector 2 is converted into an acoustic signal 41 by a transducer (not shown), the acoustic signal is transmitted from the excitation end 21 to the sapphire optical fiber propagation rod 11 for propagation, a second groove reflected wave 43 is generated at the second groove 122, a first groove reflected wave 42 is generated at the first groove 121, and an end surface reflected wave 44 is generated at the end surface 13, the first groove reflected wave 42, the second groove reflected wave 43, and the end surface reflected wave 44 are reflected back to the excitation end 21 by the sapphire optical fiber propagation rod 11, and the ultrasonic pulse detector 2 converts the acoustic signal into an electrical signal, and transmits the electrical signal to the computer data acquisition system 3 through the data end 22 for subsequent signal. The signal analysis is that the computer data acquisition system 3 calculates the sound velocity value by calculating the delay data between the echo signal groove two reflected wave 43 and the echo signal groove one reflected wave 42 generated by the groove two 122 and the groove one 121 and the echo signal end surface reflected wave 44 reflected by the end surface 13 of the sapphire optical fiber transmission rod 11 at different temperatures, and calculates the delay data graph at different temperature values, thereby obtaining the change curve of the speed of the multi-distribution temperature measurement points along with the temperature, and being more beneficial to the temperature measurement and analysis.

As shown in FIG. 3, the distance between the radial groove position of the temperature-measuring sensitive area and the end surface of the sapphire optical fiber propagation rod is called as the reflection interval, and the distance between the second groove 122 and the first groove 121 is called as the reflection interval DeltaL¹The distance between the first groove 121 and the end face 11 is called as a reflection interval DeltaL²The size of the reflection interval has an important influence on ultrasonic temperature measurement: the reflection pitch is selected to be too large, and the delay data between the waveforms reflected by the second groove 122 and the first groove 121 and the end face 11 is too large. Although beneficial for analysis, the length of the temperature sensing zone is increased due to the sapphire fiber ultrasonic sensorThe temperature is the average temperature of the lengths of the sensitive sections, and the longer temperature measuring section causes the reduction of temperature measuring precision, so that the identification of temperature gradient cannot be carried out; on the other hand, when the reflection distance is too small, the waveforms and secondary echoes reflected by the second groove 122, the first groove 121 and the end face 11 are superposed together, so that accurate identification cannot be performed, and great trouble is brought to analysis data. Therefore, in conjunction with the above description, when selecting the reflection pitch length, the following relationship should be satisfied:

in the formula: Δ L — reflection spacing; t is t₁-ultrasonic pulse excitation time; v (T) -the ultrasonic wave velocity; Δ t — time difference.

The sapphire optical fiber transmission rod is made of aluminum oxide (Al)₂O₃) The single crystal is formed by pulling, and has the characteristics of stable structure, high melting point (2053 ℃), good heat-conducting property and the like. Therefore, the temperature in the liquid metal is measured by adopting the sapphire optical fiber temperature measuring device based on the ultrasonic principle, the sapphire optical fiber temperature measuring device is firstly subjected to laboratory static calibration to obtain the sound velocity values of the sapphire optical fiber propagation rod with different temperatures from normal temperature to high temperature, and then the high-temperature molten liquid metal is measured in real time in actual occasions.

For example, the temperature in liquid metal is measured by a sapphire optical fiber temperature measuring device based on the ultrasonic principle₂O₃) The manufactured sapphire optical fiber transmission rod does not react with molten aluminum, and a designed sapphire optical fiber temperature sensor needs to be subjected to a static calibration experiment before measuring the temperature of the molten aluminum, so that the waveform amplitude, the time delay data, the structural performance stability and the like of the sensor are checked.

As shown in figures 2, 3, 4 and 5, experimental calibration data from normal temperature to 1600 ℃ is obtained by laboratory calibration, a 1600 ℃ high-temperature resistance furnace 5 is used for data calibration, double rows of silicon-molybdenum rods are used for heating in the furnace, a 100 x 100mm temperature zone is formed by heat insulation of high-temperature refractory bricks at the periphery, and the temperature is set to be kept for 5 minutes at an integral temperature point in the heating time process, so that the internal temperature zone can be approximately regarded as a constant temperature field. The sapphire optical fiber propagation rod 11 of the sapphire optical fiber temperature sensor 1 and a standard platinum rhodium thermocouple are placed in a constant temperature field, and data are collected and recorded once when the temperature of the thermocouple changes by 100 ℃. When the distance between the second groove 122 and the first groove 121 of the sapphire optical fiber propagation rod 11 and the end face is fixed, the influence of the thermal expansion of the optical fiber temperature sensor itself can be almost ignored, the waveforms reflected by the second groove 122 and the first groove 121 at different temperatures are collected, and the delay data between the second groove 122 and the first groove 121, and between the first groove 121 and the end face 13 have a certain relation with the temperature value at the current state. By calibrating the delay data, a delay data graph (shown in fig. 6) of normal temperature to 1600 ℃ (high temperature) is obtained, a relation curve (shown in fig. 7) of temperature and delay data is obtained by calculation, and a relation curve (shown in fig. 8) of temperature and sound velocity can be obtained by calculation according to the delay data at different temperatures in fig. 7 and according to v being 2 l/t.

As shown in fig. 8, when the calibration is performed by using a high temperature resistance furnace, it is considered that the internal temperature field is uniform and constant, i.e. the temperature data of the first groove and the second groove obtained by the sapphire optical fiber temperature sensor in the temperature zone of 100 × 100 × 100mm are the same, and the curves of temperature and sound velocity should substantially coincide. Therefore, a relation graph of the temperature and the sound velocity obtained through a static calibration experiment is basically consistent with theoretical calculation data, and meanwhile, the feasibility of measuring the temperature of the sapphire optical fiber temperature sensor is verified.

And finally, measuring the temperature of the molten aluminum in real time by using a calibrated sapphire optical fiber temperature sensor, and analyzing the result.

In the actual temperature measurement process, a sapphire optical fiber propagation rod of a sapphire optical fiber temperature sensor needs to be inserted into molten aluminum for measurement, the lowest temperature of aluminum in a molten state is about 640 ℃, the highest upper limit temperature of an aluminum alloy resistance furnace adopted in the scheme can reach 740 ℃, and the temperature change process is not large. And carrying out temperature tests in two processes in the actual temperature measurement process. The first process is as follows: the sapphire optical fiber propagation rod is inserted into the aluminum liquid in the lowest melting state to reach thermal balance, and data are continuously collected to obtain a time response speed curve of the sapphire optical fiber temperature sensor; in addition, a plurality of single-point test temperature values under the state are also carried out; and a second process: the temperature value is set to the upper limit threshold value through the control cabinet, the heating process of the molten aluminum liquid is continuously collected, the temperature is raised in a furnace wall-air-dry pot heat exchange mode in the process, the heating process is slow, long-time continuous data collection is needed to obtain a temperature rise curve of the temperature along with the time, and multiple single-point temperature measurement is carried out on the aluminum liquid in the state of the highest temperature value.

After the aluminum liquid temperature is measured according to the first temperature measuring process, the data result is analyzed to obtain a temperature change curve along with time as shown in fig. 9, and the temperature change curve along with time as shown in fig. 9 can be obtained. In addition, it can be also found from the temperature rising curve of fig. 9 that the sapphire optical fiber temperature sensor reaches a thermal equilibrium state 43.8s after the molten metal aluminum liquid is inserted.

As the molten aluminum is subjected to heat transfer in a heat exchange mode, the data tested according to the test in FIG. 9 shows that the temperature gradient difference exists between the two sensitive sections of the first groove and the second groove in the longitudinal direction of the molten aluminum. The first groove is closer to the bottom of the dry pot, and the measured temperature value is higher after heat balance is carried out; the second groove is closer to the liquid level of the aluminum liquid, and the temperature is relatively lower, which indicates that the temperature distribution in the aluminum liquid is uneven in the heat exchange heating process.

After the first process is finished, the second process is carried out, and the temperature of the molten aluminum in the dry pot continuously rises along with the time by adjusting the rated temperature value of the control cabinet. After about 15min, the temperature reached 734 ℃ (740 ℃ peak upper control cabinet temperature, and continued increase would damage the control cabinet due to excessive power). And after the sapphire optical fiber transmission rod is measured in molten aluminum for a long time, the waveform amplitude is not changed, and no corrosion trace is found on the surface of the optical fiber in the temperature measurement sensitive area. Therefore, the sapphire optical fiber temperature sensor based on the ultrasonic temperature measurement principle can be used as a new method for measuring the temperature of molten aluminum.

The sapphire optical fiber temperature sensor that the present case designed according to supersound temperature measurement principle not only can use in aluminium liquid temperature measurement, moreover, because sapphire optical fiber itself has characteristics such as high melting point (2053 ℃), high temperature anti-oxidant, anti-electromagnetic interference, can be used for more occasions to carry out temperature test research. For example, the temperature test of molten iron and molten steel in the metallurgical industry, the plasma temperature measurement in the electromagnetic field environment and the like have wider research value and significance in the future.

The above are merely specific examples of the present invention, and do not limit the scope of the present invention. All equivalent changes made according to the design idea of the present application fall within the protection scope of the present application.