A dual-channel operating condition switching temperature probe dynamic response calibration device and method

Abstract

This invention provides a dual-channel operating condition switching type temperature probe dynamic response calibration device and method. The device includes an experimental section, a jet pipe, a temperature probe to be calibrated, a solenoid valve, a pressure relief valve, a hot air blower, and a cover plate. The first airflow channel formed by the experimental section provides a uniform and stable airflow calibration environment. The jet pipe serves as the second airflow channel, and the jet generates a step thermal excitation on the temperature probe to be calibrated. The airflow temperature of the experimental section, the airflow temperature of the hot air blower, and the switching of the solenoid valve are controlled. The step thermal excitation form is selected as either a positive step or a negative step. By normalizing the dynamic response curve and taking the natural logarithm of the residual function, the dynamic response parameters are accurately identified by the slope and intercept of the straight line. This invention can provide a high-speed airflow environment, fast thermal excitation speed, clear and controllable thermal excitation input, and high accuracy in identifying dynamic response parameters. It is suitable for dynamic calibration of temperature probes used for temperature measurement in turbomachinery flow fields.

Description

Technical Field

[0001] This invention belongs to the field of dynamic characteristic calibration technology of temperature probes, specifically involving a dual-channel operating condition switching type temperature probe dynamic response calibration device and method, which is suitable for dynamic response calibration of temperature probes used for turbomachinery flow field testing. It features fast thermal excitation speed, clear and controllable thermal excitation input, and provides reliable technical support for dynamic temperature measurement of turbomachinery flow fields. Background Technology

[0002] The measurement of airflow temperature in an unstable state over time is called dynamic temperature measurement. The airflow temperature measurement during the start-up and acceleration process of turbomachinery falls into this category. Due to the thermal inertia of the temperature probe, the temperature value at the measuring end of the temperature probe deviates from the airflow temperature in magnitude, which is the dynamic response error of the temperature probe. To determine the magnitude of this error, a time constant is used to represent the response speed of the temperature probe. The time constant is generally determined experimentally, and it is not only related to the structure, size and material of the temperature probe, but also affected by the airflow conditions. In order to obtain an accurate temperature probe time constant, the dynamic temperature calibration device is required to have precise thermal excitation and calibration conditions that match the actual use environment.

[0003] Existing dynamic temperature calibration methods mostly employ drop-in dynamic temperature calibration devices. By constructing two environments with different temperatures, the temperature probe is made to quickly break through the environmental boundary, thereby generating a step thermal excitation. However, most calibration devices currently in use use isothermal liquids as the isothermal environment, which is significantly different from the environment experienced by impeller machinery in aerodynamic flow fields. The airflow in the actual environment usually has high temperature, large flow velocity fluctuations, and complex unsteady characteristics. Traditional isothermal liquid calibration devices cannot truly simulate this high-temperature, high-speed, and dynamically changing airflow environment.

[0004] Laser heating, as another commonly used dynamic calibration method, can provide rapid pulsed radiative thermal excitation with high precision in controlling the timing and intensity of the thermal excitation. However, the thermal excitation generated by laser heating is mainly radiative heat transfer, which deviates from the heat transfer mechanism mainly based on convection heat transfer in turbomachinery testing. It cannot fully simulate the thermal response of the temperature probe in unsteady airflow. In addition, in order to reduce the velocity error when measuring high-speed airflow, temperature probes often adopt a stagnation shield design, which prevents the laser from accurately irradiating the temperature sensing element of the temperature probe. This limits the popularity and operability of this method in dynamic calibration of temperature probes.

[0005] Given that the above two methods each have their advantages and disadvantages, and their calibration results cannot fully represent the characteristics of the temperature probe in the flow field test of turbomachinery, there is an urgent need for a temperature probe response calibration device and method that integrates high environmental matching degree, rapid thermal excitation, clear and controllable thermal excitation input, so as to realize dynamic response calibration of temperature probe and provide reliable technical support for enhancing the understanding of turbomachinery flow field and high-performance design. Summary of the Invention

[0006] This invention is a dual-channel operating condition switching temperature probe dynamic response calibration device, including an experimental section, a jet tube, a temperature probe to be calibrated, a solenoid valve, a pressure relief valve, a hot air blower, and a cover plate. The first airflow channel formed by the experimental section can simulate different airflow calibration environments from low temperature to high temperature and from low speed to high speed. The jet tube serves as the second airflow channel, and its outlet jet generates a step thermal excitation on the temperature probe to be calibrated. The outlet of the jet tube and the sensing part of the temperature probe to be calibrated are arranged in the core area of ​​the experimental section. By controlling the airflow temperature of the experimental section, the airflow temperature of the hot air blower, and the switching of the solenoid valve, positive and negative step thermal excitations can be generated on the temperature probe to be calibrated. By normalizing the response curve and taking the natural logarithm of the response residual, the dynamic response parameters are accurately identified by the slope and intercept of the straight line.

[0007] This invention provides a dual-channel operating condition switching temperature probe dynamic response calibration device. The technical problems it addresses are: First, the low matching degree between the existing temperature probe dynamic response calibration device's environment and the actual operating environment of the temperature probe. Second, the unclear thermal excitation start time and thermal excitation temperature change amplitude in existing temperature probe dynamic response calibration devices. Third, the difficulty in providing multi-condition thermal excitation input in existing temperature probe dynamic response calibration devices. Fourth, the large identification deviation of the dynamic characteristics of the calibrated temperature probe.

[0008] The technical solution of this invention is:

[0009] 1. A dual-channel operating condition switching type temperature probe dynamic response calibration device is composed of an experimental section (1), a jet pipe (2), a temperature probe to be calibrated (3), a solenoid valve (4), a pressure relief valve (5), a hot air blower (6), and a cover plate (7). The experimental section (1) is the first airflow channel that provides a stable and uniform flow field. The jet pipe (2) is the second airflow channel that generates a step thermal excitation to the temperature probe to be calibrated (3). The outlet of the jet pipe (2) and the sensing part of the temperature probe to be calibrated (3) are both located in the core area of ​​the experimental section (1). The jet at the outlet of the jet pipe (2) can completely cover the sensing part of the temperature probe to be calibrated (3). The solenoid valve (4), the pressure relief valve (5), and the hot air blower (6) are connected in sequence to form a jet air source.

[0010] 2. The experimental section (1) can provide a stable, uniform and adjustable airflow. The total temperature of the incoming flow in the experimental section (1) is adjustable from 20℃ to 1200℃, the Mach number of the incoming flow is adjustable from 0.1 to 2.0, and the total pressure of the incoming flow is adjustable from 0.2MPa to 2MPa, ensuring that the experimental section (1) can simulate different airflow conditions from low temperature to high temperature and from low speed to high speed. The experimental section (1) has 2 to 6 experimental windows on its wall. The experimental windows are tightly fitted by the cover plate (7) to ensure the airtightness of the experimental section (1).

[0011] 3. The inner diameter of the jet tube (2) is 10 mm to 40 mm and the wall thickness is 1 mm to 5 mm. The outlet of the jet tube (2) is located in the core area of ​​the experimental section (1). The distance between the outlet of the jet tube (2) and the sensing part of the calibrated temperature probe (3) is 1 mm to 8 mm.

[0012] 4. The temperature probe (3) to be calibrated has a diameter of 4 mm to 12 mm and a length of 200 mm to 500 mm. The sensing part of the temperature probe (3) to be calibrated is installed in the core area of ​​the experimental section (1) through the cover plate (7), and the sensing part of the temperature probe (3) to be calibrated is located in the jet coverage area of ​​the jet tube (2).

[0013] 5. The inner diameter of the solenoid valve (4) is 20 mm to 200 mm, and the opening and closing time is 0.5 ms to 5 ms. Its airflow inlet is connected to the pressure relief valve (5), and its airflow outlet is connected to the jet pipe (2). The solenoid valve (4) can be set to normally open or normally closed. When the solenoid valve (4) is normally open, the airflow can continuously flow out from the jet pipe (2). When the solenoid valve (4) is normally closed, the airflow in the jet pipe (2) will be blocked until the solenoid valve (4) is opened, and the airflow can enter the jet pipe (2).

[0014] 6. When the solenoid valve (4) is in the normally open state, if the total temperature of the incoming flow in the experimental section (1) is greater than the jet temperature of the jet pipe (2), the solenoid valve (4) is suddenly closed, and the calibrated temperature probe (3) is subjected to a positive step thermal excitation. If the total temperature of the incoming flow in the experimental section (1) is less than the jet temperature of the jet pipe (2), the solenoid valve (4) is suddenly closed, and the calibrated temperature probe (3) is subjected to a negative step thermal excitation.

[0015] 7. When the solenoid valve (4) is in the normally closed state, if the total temperature of the incoming flow in the experimental section (1) is greater than the jet temperature of the jet tube (2), the solenoid valve (4) is suddenly opened, and the calibrated temperature probe (3) is subjected to negative step thermal excitation. If the total temperature of the incoming flow in the experimental section (1) is less than the jet temperature of the jet tube (2), the solenoid valve (4) is suddenly opened, and the calibrated temperature probe (3) is subjected to positive step thermal excitation.

[0016] 8. The pressure relief valve (5) has an inner diameter of 20 mm to 200 mm. Its airflow inlet is connected to the hot air blower (6), and its airflow outlet is connected to the solenoid valve (4). The pressure relief valve (5) has an automatic adjustment function. When the solenoid valve (4) is closed, the pressure relief valve (5) automatically releases gas according to the pipeline pressure to keep the gas source system of the jet pipe (2) stable.

[0017] 9. The inner diameter of the air outlet pipe of the hot air blower (6) is 20 mm to 200 mm, the output air temperature range is 20℃ to 1500℃, the output air total pressure range is 0.5MPa to 5MPa, and the hot air blower (6) maintains a continuous output air state during dynamic calibration.

[0018] 10. The present invention proposes a dual-channel operating condition switching temperature probe dynamic response calibration method based on a dual-channel operating condition switching temperature probe dynamic response calibration device. After completing the above device installation preparation, the signal output terminal of the temperature probe (3) to be calibrated and the signal input terminal of the solenoid valve (4) are connected to the signal acquisition system, and time synchronization sampling is adopted so that the two sets of signals are in the same time domain. The airflow parameters of the experimental section (1), the on / off state of the solenoid valve (4) and the output airflow parameters of the hot air blower (6) are set, and the total pressure of the output airflow of the hot air blower (6) is ensured to be greater than the total pressure of the airflow of the experimental section (1), so that a jet is formed at the outlet of the jet pipe (2).

[0019] 11. The moment when the solenoid valve (4) receives the opening or closing control signal is taken as the start time of the step thermal excitation. Steady-state temperature before thermal excitation Steady-state temperature after thermal excitation The temperature boundary condition, which serves as the step thermal excitation input for the calibrated temperature probe (3), is denoted as the output temperature response of the calibrated temperature probe (3) under step thermal excitation. .

[0020] 12. Normalized step response: Define the normalized residual function: If the temperature probe being calibrated is an nth-order thermal inertial system, its normalized residual function can be expressed as a superposition of multiple exponentially decaying components: ,in For the first The dynamic time constant corresponding to each dynamic decay component For the corresponding weighting coefficients, Let be the dynamic response order of the calibrated temperature probe (3), and satisfy: .

[0021] 13. In high-order thermal inertial systems, the residual function is mainly controlled by the slowest decaying component, that is: Take its natural logarithm: Thus, the parameters of the slowest dynamically decaying component are obtained: , That is, the time constant is obtained from the slope of the line, and the weight corresponding to the time constant is obtained from the intercept of the line.

[0022] 14. Further subtract the attenuation component from the original normalized residual function to obtain a new residual function to be identified: By repeating the above process of taking the natural logarithm and subtraction, the time constants and weights corresponding to all orders of thermal inertia can be obtained.

[0023] This invention provides a dual-channel operating condition switching type temperature probe dynamic response calibration device and method, which has the following beneficial effects:

[0024] Beneficial effect 1: The dual-channel operating condition switching temperature probe dynamic response calibration device and method designed in this invention can simulate the high temperature and high-speed airflow conditions experienced by the temperature probe in the actual use environment, ensuring that the dynamic response calibration environment is highly matched with the actual use environment of the temperature probe, thereby improving the accuracy and reliability of the dynamic calibration of the temperature probe.

[0025] Second beneficial effect: The dual-channel operating condition switching temperature probe dynamic response calibration device and method designed in this invention, by recording the on / off signals received by the solenoid valve and referencing the high-precision measurement of the steady-state temperature before and after thermal excitation by the temperature probe, ensures that the start time and amplitude of thermal excitation are clear, providing an accurate input signal for the dynamic response calibration of the temperature probe.

[0026] Thirdly, the dual-channel operating condition switching temperature probe dynamic response calibration device and method designed in this invention can provide a wide range of thermal excitation inputs by adjusting the airflow temperature of the experimental section and the hot air blower, thus meeting the needs of dynamic response calibration of temperature probes under different operating conditions.

[0027] Beneficial Effect 4: The dual-channel operating condition switching temperature probe dynamic response calibration device and method designed in this invention takes the moment when the solenoid valve receives the control signal as the start time of the step thermal excitation. By normalizing the response curve and taking the natural logarithm of the residual function, the dynamic response parameters are determined by the slope and intercept of the straight line, thereby improving the accuracy of dynamic characteristic identification. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a dual-channel operating condition switching temperature probe dynamic response calibration device in an embodiment of the present invention.

[0029] Figure 2 This is a schematic diagram of the installation of the calibrated temperature probe in an embodiment of the present invention.

[0030] Figure 3 yes Figure 2 Sectional view along direction A.

[0031] Figure 4 This is a schematic diagram of a jet tube.

[0032] Among them: 1-experimental section, 2-jet tube, 3-calibrated temperature probe, 4-solenoid valve, 5-pressure relief valve, 6-hot air blower, 7-cover plate. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more explicit definition of the scope of protection of the present invention.

[0034] Example 1:

[0035] like Figures 1-4 The device shown is a dual-channel operating condition switching type temperature probe dynamic response calibration device, including an experimental section (1), a jet tube (2), a temperature probe to be calibrated (3), a solenoid valve (4), a pressure relief valve (5), a hot air blower (6), and a cover plate (7).

[0036] The experimental section (1) is part of the subsonic wind tunnel system. The subsonic wind tunnel has a shrinkage ratio of 16. The inner diameter of the experimental section (1) is 150 mm and the axial length is 300 mm. The total temperature of the airflow in the experimental section (1) is 100℃, the Mach number is 0.2, and the total pressure of the incoming flow is 0.5 MPa. The experimental section (1) is equipped with two experimental windows, each 130 mm long and 80 mm wide.

[0037] The jet tube (2) has an inner diameter of 20 mm and a wall thickness of 2 mm. The outlet of the jet tube (2) is located in the core area of ​​the experimental section (1). The distance between the outlet of the jet tube (2) and the sensing part of the calibrated temperature probe (3) is 5 mm.

[0038] The calibrated temperature probe (3) is a K-type bare thermocouple probe with a diameter of 8 mm and a length of 400 mm. The calibrated temperature probe (3) is installed in the experimental section (1) through the cover plate (7). The sensing part is located in the core area of ​​the experimental section (1), and the sensing part of the calibrated temperature probe (3) is located in the jet coverage area of ​​the jet tube (2).

[0039] The solenoid valve (4) has an inner diameter of 50 mm and a response time of 4 milliseconds. Its airflow inlet is connected to the pressure relief valve (5), and its airflow outlet is connected to the jet pipe (2). The solenoid valve (4) is set to the normally open state, and the airflow can continuously flow out from the jet pipe (2).

[0040] The pressure relief valve (5) has an inner diameter of 50 mm. Its air inlet is connected to the hot air blower (6), and its air outlet is connected to the solenoid valve (4). The pressure relief valve (5) has an automatic adjustment function. When the solenoid valve (4) is closed, the pressure relief valve (5) automatically releases gas according to the pipeline pressure to keep the gas source system of the jet pipe (2) stable.

[0041] The hot air blower (6) has an air outlet pipe with an inner diameter of 50 mm, an output air temperature of 200℃, and a total air pressure of 0.8 MPa. During dynamic calibration, the hot air blower (6) maintains a continuous output air state.

[0042] At this time, the solenoid valve (4) remains open. The total temperature of the airflow in the experimental section (1) is less than the jet temperature of the jet pipe (2). The solenoid valve (5) is suddenly closed. The calibrated temperature probe (3) is subjected to negative step thermal excitation. The airflow generated by the hot air blower (6) is discharged through the pressure relief valve (5) and does not affect the operation of the hot air blower (6).

[0043] The moment when the solenoid valve (4) receives the closing control signal is taken as the start time of the step thermal excitation. Steady-state temperature before thermal excitation Steady-state temperature after thermal excitation The temperature boundary condition, which serves as the step thermal excitation input for the calibrated temperature probe (3), is denoted as the output temperature response of the calibrated temperature probe (3) under step thermal excitation. .

[0044] Construct the normalized residual function: The K-type bare thermocouple probe is considered as a first-order temperature probe, and its normalized residual function can be expressed as: Taking its natural logarithm, we get the straight line: The time constant and corresponding weight of the calibrated temperature probe can be obtained by using the slope and intercept of the straight line.

[0045] Example 2:

[0046] Compared with Example 1, this embodiment is identical in all devices and system parameters except that the temperature probe being calibrated is a Pt100 armored platinum resistance probe.

[0047] Using the initial moment of thermal excitation as the zero point of time, construct the normalized residual function: The Pt100 platinum resistance temperature probe is considered a second-order temperature probe, and its normalized residual function is expressed as the superposition of two exponential decay components: ,in: , For fast dynamic time constant, For slow dynamic time constant, These are the corresponding weighting coefficients.

[0048] Because the fast decay component decreases very quickly, the residual function is mainly dominated by the slow decay component. Taking the natural logarithm of the residual function yields: The dynamic response parameters are obtained from the slope and intercept of the straight line: , .

[0049] Subsequently, the slow decay component is subtracted from the original normalized residual function to obtain the corrected residual function: Taking the natural logarithm of the corrected residual function, the dynamic response parameters are obtained from the slope and intercept of the line: , .

[0050] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the essential spirit of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A kind of double-channel operating mode switching temperature probe dynamic response calibration device, including experimental section (1), fluidic tube (2), the temperature probe (3) to be calibrated, electromagnetic valve (4), pressure relief valve (5), hot air blower (6), cover plate (7), it is characterized in that: The experimental section (1) is the first airflow channel that provides a stable and uniform flow field. The jet pipe (2) is the second airflow channel that generates a step thermal excitation to the calibrated temperature probe (3). The outlet of the jet pipe (2) and the sensing part of the calibrated temperature probe (3) are both located in the core area of ​​the experimental section (1). The jet at the outlet of the jet pipe (2) can completely cover the sensing part of the calibrated temperature probe (3). The solenoid valve (4), the pressure relief valve (5), and the hot air blower (6) are connected in sequence to form the jet air source. The experimental section (1) can provide a stable, uniform and adjustable airflow. The total temperature of the incoming flow in the experimental section (1) can be adjusted from 20℃ to 1200℃, the Mach number of the incoming flow can be adjusted from 0.1 to 2.0, and the total pressure of the incoming flow can be adjusted from 0.2MPa to 2MPa, ensuring that the experimental section (1) can simulate different airflow conditions from low temperature to high temperature and from low speed to high speed. The experimental section (1) has 2 to 6 experimental windows on its wall. The experimental windows are tightly fitted by the cover plate (7) to ensure the airtightness of the experimental section (1). The jet tube (2) has an inner diameter of 10 mm to 40 mm and a wall thickness of 1 mm to 5 mm. The outlet of the jet tube (2) is located in the core area of ​​the experimental section (1). The distance between the outlet of the jet tube (2) and the sensing part of the calibrated temperature probe (3) is 1 mm to 8 mm. The calibrated temperature probe (3) has a diameter of 4 mm to 12 mm and a length of 200 mm to 500 mm. The sensing part of the calibrated temperature probe (3) is installed in the core area of ​​the experimental section (1) through the cover plate (7), and the sensing part of the calibrated temperature probe (3) is located in the jet coverage area of ​​the jet tube (2). The solenoid valve (4) has an inner diameter of 20 mm to 200 mm and an opening and closing time of 0.1 ms to 5 ms. Its airflow inlet is connected to the pressure relief valve (5) and its airflow outlet is connected to the jet pipe (2). The solenoid valve (4) can be set to normally open or normally closed. When the solenoid valve (4) is normally open, the airflow can continuously flow out from the jet pipe (2). When the solenoid valve (4) is normally closed, the airflow in the jet pipe (2) will be blocked until the solenoid valve (4) is opened, and the airflow can enter the jet pipe (2). When the solenoid valve (4) is in the normally open state, if the total temperature of the incoming flow in the experimental section (1) is greater than the jet temperature of the jet pipe (2), the solenoid valve (4) is suddenly closed, and the calibrated temperature probe (3) is subjected to a positive step thermal excitation. If the total temperature of the incoming flow in the experimental section (1) is less than the jet temperature of the jet pipe (2), the solenoid valve (4) is suddenly closed, and the calibrated temperature probe (3) is subjected to a negative step thermal excitation. When the solenoid valve (4) is in the normally closed state, if the total temperature of the incoming flow in the experimental section (1) is greater than the jet temperature of the jet tube (2), the solenoid valve (4) is suddenly opened, and the calibrated temperature probe (3) is subjected to negative step thermal excitation. If the total temperature of the incoming flow in the experimental section (1) is less than the jet temperature of the jet tube (2), the solenoid valve (4) is suddenly opened, and the calibrated temperature probe (3) is subjected to positive step thermal excitation. The pressure relief valve (5) has an inner diameter of 20 mm to 200 mm. Its airflow inlet is connected to the hot air blower (6), and its airflow outlet is connected to the solenoid valve (4). The pressure relief valve (5) has an automatic adjustment function. When the solenoid valve (4) is closed, the pressure relief valve (5) automatically releases gas according to the pipeline pressure to keep the gas source system of the jet pipe (2) stable. The hot air blower (6) has an air outlet pipe with an inner diameter of 20 mm to 200 mm, an output air temperature range of 20℃ to 1500℃, and an output air total pressure range of 0.5MPa to 5MPa. During dynamic calibration, the hot air blower (6) maintains a continuous output air state.

2. According to claim 1, a dual-channel working condition switching temperature probe dynamic response calibration device is proposed. After completing the above device installation preparation, the signal output terminal of the temperature probe (3) to be calibrated and the signal input terminal of the solenoid valve (4) are connected to the signal acquisition system, and time synchronization sampling is adopted so that the two sets of signals are in the same time domain. The airflow parameters of the experimental section (1), the on / off state of the solenoid valve (4) and the output airflow parameters of the hot air blower (6) are set, and the total pressure of the output airflow of the hot air blower (6) is ensured to be greater than the total pressure of the airflow of the experimental section (1), so that a jet is formed at the outlet of the jet pipe (2). The time at which the electromagnetic valve (4) receives the opening or closing control signal is taken as the starting time of the step thermal excitation The steady-state temperature before the action of thermal excitation The steady-state temperature after the action of thermal excitation As the temperature boundary condition of the calibrated temperature probe (3) step thermal excitation input, the output temperature response of the calibrated temperature probe (3) under the action of step thermal excitation is recorded as ; Normalized step response: Define the normalized residual function: If the temperature probe being calibrated is an nth-order thermal inertial system, its normalized residual function can be expressed as a superposition of multiple exponentially decaying components: ,in For the first The dynamic time constant corresponding to each dynamic decay component For the corresponding weighting coefficients, Let be the dynamic response order of the calibrated temperature probe (3), and satisfy: ; In high-order thermal inertial systems, the residual function is mainly controlled by the slowest decaying component, i.e.: Take its natural logarithm: Thus, the parameters of the slowest dynamically decaying component are obtained: , That is, the time constant is obtained from the slope of the line, and the weight corresponding to the time constant is obtained from the intercept of the line; Further subtracting the attenuation component from the original normalized residual function yields a new residual function to be identified: By repeating the above process of taking the natural logarithm and subtraction, the time constants and weights corresponding to all orders of thermal inertia can be obtained.

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