Convection heat flow calibration device and calibration method

Abstract

The invention discloses a convective heat flow calibration device and method, the device comprises an air compressor air source, a regulating valve, an electric heater, a stable section and a test section which are connected in sequence, and pure air flow generated by the air compressor air source is heated by the electric heater, then enters the stable section to be rectified, and then enters the test section to be accelerated; the test section comprises a spray pipe, a reference flat plate, a calibration flat plate, a shielding radiation source and a film thermocouple, the reference flat plate and the calibration flat plate are completely consistent in boundary dimension and symmetrically located on the two sides of a nozzle of the spray pipe, the shielding radiation source is located in the center of the interior of the spray pipe, and the film thermocouple is plated on the surface of the shielding radiation source; two film platinum resistors are symmetrically plated on the center of the reference flat plate to serve as reference platinum resistors, a calibrated heat flow meter is installed in the center of the calibration flat plate, and film platinum resistors are plated on the periphery of the calibrated heat flow meter. The device can provide a uniform and stable heat flow field which can be continuously adjusted within a certain working condition range, and can be used for calibrating or verifying a convection heat flow meter.

Description

Technical Field

[0001] The invention belongs to the technical field of airflow temperature measurement, and in particular relates to a convection heat flux calibration device and a calibration method. Background Art

[0002] During high Mach number flight and reentry, aerospace vehicles are accompanied by strong aerodynamic effects, forming an extremely high temperature boundary layer on the surface of the vehicle. The fluid in the boundary layer and the vehicle surface transfer high temperature heat to the vehicle in the form of strong convective heat exchange, forming an extreme high temperature thermal environment, which brings severe tests to the safety and reliability of the vehicle and increases the difficulty of vehicle design and development. Convective heat flux density (abbreviated as convective heat flux) is one of the most critical parameters in aerodynamic thermal parameters. When the aerospace plane reenters, the convective heat flux on the fuselage flaps, elevators, etc. can reach 30W / cm2 or even higher. As an important technical basis for aerodynamic thermal theory research, thermal protection safety design, engineering test verification and other research, the convective heat flux density calibration technology is of great significance to the development of aerospace technology.

[0003] At present, there is no research on convective heat flux calibration in China, and no convective heat flux measurement standard device has been established. There is also a lack of corresponding calibration methods. The heat flux meter can only realize the measurement and calibration of radiation heat flux. When calibrating the heat flux meter, the radiation heat flux calibration method is also used, resulting in the calibration results not being able to truly reflect the metrological characteristics of the heat flux meter. Therefore, it is urgent to establish a convective heat flux measurement standard device and study the convective heat flux calibration method. Summary of the invention

[0004] The object of the present invention is to provide a convective heat flux calibration device and calibration method, which can provide a uniform and stable heat flow field that can be continuously adjusted within a certain range of working conditions and can be used for the calibration or verification of a convective heat flux meter.

[0005] In order to achieve the above-mentioned object, one aspect of the present invention provides a convection heat flow calibration device, comprising an air compressor source, a regulating valve, an electric heater, a stable section, and a test section connected in sequence, wherein the pure air flow generated by the air compressor source is heated by the electric heater and enters the stable section for rectification, and then enters the test section for acceleration, and the Mach number is adjusted by the regulating valve;

[0006] The test section includes a nozzle, a fast response displacement mechanism, a reference plate, a calibration plate, a shielded radiation source and a thin film thermocouple. The reference plate and the calibration plate have completely identical dimensions and are mounted on the fast response displacement mechanism and symmetrically located on both sides of the nozzle of the nozzle. The center heights of the reference plate and the calibration plate are consistent with the center height of the nozzle, and the horizontal distance from the nozzle is 1 to 2D, where D is the diameter of the calibration plate. The shielded radiation source is located at the center of the nozzle, and the thin film thermocouple is plated on the surface of the shielded radiation source. The fast response displacement mechanism is used to achieve rapid position replacement of the reference plate and the calibration plate.

[0007] Two thin-film platinum resistors are symmetrically plated around the center of the reference plate as reference platinum resistors. The sensing part of each reference platinum resistor is the same size as the sensing part of the calibrated heat flux meter. The calibrated heat flux meter is installed in the center of the calibration plate. Thin-film platinum resistors are plated around the calibrated heat flux meter to calculate the surface temperature of the calibrated heat flux meter.

[0008] Preferably, the reference plate is made of the same material as the sensing part of the calibrated heat flow meter, and the calibration plate is made of a material with low thermal conductivity and large specific heat capacity.

[0009] Preferably, an insulating layer is first plated on the surface of the reference plate, and then two thin-film platinum resistors are plated symmetrically as reference platinum resistors, with the distance between the two reference platinum resistors not exceeding 1 mm. Finally, a high-emissivity coating is coated on the surface of the reference plate to ensure that the surface emissivity is close to 1.

[0010] Preferably, the surface of the shielded radiation source is successively plated with an insulating layer and a thin-film thermocouple, and then coated with a high-emissivity coating to ensure that the surface emissivity is close to 1.

[0011] Preferably, the reference plate is made of constantan, and the calibration plate is made of aerogel ceramics.

[0012] Preferably, a single action time of the fast response displacement mechanism does not exceed 50 ms.

[0013] Preferably, the test section further comprises a support rod, and the shielding radiation source is fixed at the inner center position of the nozzle via the support rod.

[0014] Preferably, the test section further comprises a calibrated heat flux meter mounting seat, and the calibrated heat flux meter is mounted at the center of the calibration plate through the calibrated heat flux meter mounting seat.

[0015] Another aspect of the present invention provides a convective heat flux calibration method, which uses the above-mentioned convective heat flux calibration device to perform convective heat flux calibration, comprising:

[0016] The reference plate and the plate to be calibrated are subjected to transient thermal shock of the airflow respectively through a fast response displacement mechanism, the total heat flux is calculated according to the temperature history of the reference platinum resistor on the reference plate, the shielded radiation source is used to radiate heat to the reference plate and the radiation heat flux is calculated, the convective heat flux of the reference plate is obtained by subtracting the radiation heat flux from the total heat flux, the convective heat transfer coefficient and the adiabatic wall temperature are calculated according to the values ​​of the convective heat flux and the radiation heat flux of the reference plate at different times, and the values ​​are assigned to the calibration plate, and the convective heat flux is calculated according to the calculated convective heat transfer coefficient and the adiabatic wall temperature and the measured surface temperature of the calibration plate as the standard value of the convective heat flux of the calibration plate;

[0017] Measure the surface temperature of the shielded radiation source and the calibration plate, calculate the radiation heat flux of the calibration plate, subtract the ratio of the radiation heat flux of the calibration plate to the radiation heat flux sensitivity coefficient from the output voltage of the calibrated heat flux meter, and obtain the voltage corresponding to the convective heat flux. Divide the standard value of the convective heat flux by the voltage to obtain the convective heat flux sensitivity coefficient.

[0018] The convective heat flux calibration device and calibration method according to the above aspects of the present invention can provide a uniform and stable heat flow field that can be continuously adjusted within a certain range of working conditions, and can be used for calibration or verification of a convective heat flux meter. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0020] Figure 1 is a schematic diagram of the overall structure of a convective heat flux calibration device according to an embodiment of the present invention;

[0021] Figure 2 It is a schematic diagram of the rear section structure of a test section of an embodiment of the present invention;

[0022] Figure 3 It is a schematic diagram of the front section structure of a test section of an embodiment of the present invention;

[0023] Figure 4 4 is a flow chart of a convective heat flux calibration method according to an embodiment of the present invention.

[0024] Among them, 1-air compressor gas source, 2-regulating valve, 3-electric heater, 4 stable section, 5-test section, 6-thin film platinum resistor, 7-calibration plate, 8-mounting seat of calibrated heat flow meter, 9-fast response displacement mechanism, 10-reference platinum resistor, 11-reference plate, 12-nozzle, 13-shielded radiation source, 14 thin film thermocouple, 15-support rod. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. 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.

[0026] One embodiment of the present invention provides a convection heat flux calibration device, such as Figure 1 As shown, the convective heat flux calibration device of the embodiment of the present invention comprises an air compressor gas source 1, a regulating valve 2, an electric heater 3, a stable section 4, and a test section 5, and each section is connected in sequence. The air compressor gas source 1 generates a pure air flow, which is heated by the electric heater 3 and enters the stable section 4 for rectification, and then enters the nozzle section of the test section 5 for acceleration, and the Mach number is adjusted by the regulating valve 2. The high-temperature airflow sweeps the reference plate and the calibration plate at the test section 5 respectively to realize the convective heat flux calibration.

[0027] like Figure 2 and Figure 3 As shown, the test section 5 includes a thin film platinum resistor 6, a calibration plate 7, a mounting base 8 for the calibrated heat flux meter, a fast response displacement mechanism 9, a reference platinum resistor 10, a reference plate 11, a nozzle 12, a shielded radiation source 13, a thin film thermocouple 14, and a support rod 15.

[0028] The calibration plate 7 and the reference plate 11 have the same dimensions, such as a diameter of 100 mm and a thickness of 10 mm. They are mounted on the fast response displacement mechanism 9 and are symmetrically located on both sides of the nozzle of the nozzle 12. The center distance is, for example, 200 mm, and the center height of the plate is consistent with the center height of the nozzle. The horizontal distance between the plate and the nozzle outlet is (1-2)D, where D is the diameter of the calibration plate 7. In one embodiment, the horizontal distance between the plate and the nozzle outlet is 100 mm. The shielding radiation source 13 is located at the center of the nozzle 12, and the thin film thermocouple 14 is plated on the surface of the shielding radiation source 13. The fast response displacement mechanism 7 is used to realize the rapid position replacement of the two plates, and the single action time does not exceed 50 ms, for example, 50 ms.

[0029] The reference plate 11 is made of the same material as the sensing part of the calibrated heat flux meter, and the calibration plate 7 is made of a material with low thermal conductivity and large specific heat capacity, including but not limited to aerogel ceramics, fused quartz, etc. In one embodiment, the reference plate 11 is made of constantan, and the calibration plate 7 is made of aerogel ceramics. The surface of the reference plate 11 is first plated with an insulating layer, and then two thin-film platinum resistors are plated symmetrically as reference platinum resistors 10. The sensing part size of each reference platinum resistor 10 is, for example, 3 mm, which is the same as the sensing part of the calibrated heat flux meter. The distance between the two reference platinum resistors 10 does not exceed 1 mm, for example, 1 mm. Finally, the surface of the reference plate 11 is coated with a high-emissivity coating, such as high-temperature black paint 1200 coating, to ensure that the surface emissivity is close to 1. The calibrated heat flux meter is installed in the center of the calibration plate 7 through the calibrated heat flux meter mounting seat 8. The calibrated heat flux meter is plated with thin-film platinum resistors 6 around it to calculate the surface temperature of the calibrated heat flux meter.

[0030] In one embodiment, the shielding radiation source 13 is made of 310S stainless steel, with a diameter of 120 mm and a thickness of 4 mm. The surface of the shielding radiation source 13 is plated with an insulating layer and a thin film thermocouple 14 in sequence, and then coated with a high emissivity coating to ensure that the surface emissivity is close to 1. The shielding radiation source 13 is fixed to the center of the nozzle 12 by a support rod 15, for example, 200 mm away from the nozzle outlet.

[0031] The embodiment of the present invention further provides a convective heat flux calibration method, which uses the convective heat flux calibration device of the embodiment of the present invention to perform convective heat flux calibration. The convective heat flux calibration method of the embodiment of the present invention uses a double-plate transient method for calibration, such as Figure 4 As shown, including:

[0032] The reference plate 11 and the calibration plate 7 are subjected to transient heat shock of the airflow respectively by the fast response displacement mechanism 9, and the total heat flow is calculated according to the temperature history of the reference platinum resistor 10 on the reference plate 11. The shielded radiation source 13 is used to radiate heat to the reference plate 11 and calculate the radiation heat flow. The convective heat flow of the reference plate 11 is obtained by subtracting the radiation heat flow from the total heat flow. The convective heat transfer coefficient and the adiabatic wall temperature are calculated according to the values ​​of the convective heat flow and the radiation heat flow of the reference plate 11 at different times, and the values ​​are assigned to the calibration plate 7. The convective heat flow is then calculated according to the calculated convective heat transfer coefficient and the adiabatic wall temperature and the measured surface temperature of the calibration plate 7, which is the standard value of the convective heat flow of the calibration plate 7. The surface temperatures of the shielded radiation source 13 and the calibration plate 7 are measured to calculate the radiation heat flow of the calibration plate 7. The output voltage of the calibrated heat flow meter is subtracted from the ratio of the radiation heat flow of the calibration plate 7 to the radiation heat flow sensitivity coefficient (the voltage corresponding to the radiation heat flow) to obtain the voltage corresponding to the convective heat flow. The standard value of the convective heat flow is divided by the voltage to obtain the convective heat flow sensitivity coefficient.

[0033] The convective heat flux calibration device and calibration method of the embodiments of the present invention have the following beneficial effects: they can provide a uniform and stable heat flow field that can be continuously adjusted within a certain range of working conditions, and can be used for the calibration or verification of convective heat flux meters, filling the gap in my country's convective heat flux parameter transmission system, solving the problem that convective heat flux meters cannot be calibrated and data cannot be effectively traced in the fields of aerospace vehicle development, and preliminarily establish a convective heat flux parameter transmission system to achieve effective traceability of convective heat flux parameters.

[0034] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A convection heat flux calibration device, characterized in that: It includes an air compressor source, a regulating valve, an electric heater, a stable section, and a test section connected in sequence. The pure air flow generated by the air compressor source is heated by the electric heater and then enters the stable section for rectification, and then enters the test section for acceleration, and the Mach number is adjusted through the regulating valve. The test section includes a nozzle, a fast response displacement mechanism, a reference plate, a calibration plate, a shielded radiation source and a thin film thermocouple. The reference plate and the calibration plate have completely identical dimensions and are mounted on the fast response displacement mechanism and symmetrically located on both sides of the nozzle of the nozzle. The center heights of the reference plate and the calibration plate are consistent with the center height of the nozzle, and the horizontal distance from the nozzle is 1 to 2D, where D is the diameter of the calibration plate. The shielded radiation source is located at the center of the nozzle, and the thin film thermocouple is plated on the surface of the shielded radiation source. The fast response displacement mechanism is used to achieve rapid position replacement of the reference plate and the calibration plate. Two thin-film platinum resistors are symmetrically plated around the center of the reference plate as reference platinum resistors. The sensing part of each reference platinum resistor is the same size as the sensing part of the calibrated heat flux meter. The calibrated heat flux meter is installed in the center of the calibration plate. Thin-film platinum resistors are plated around the calibrated heat flux meter to calculate the surface temperature of the calibrated heat flux meter.

2. The convection heat flux calibration device according to claim 1, characterized in that: The reference plate is made of the same material as the sensing part of the calibrated heat flow meter, and the calibration plate is made of a material with low thermal conductivity and large specific heat capacity.

3. The convection heat flux calibration device according to claim 1 or 2, characterized in that: An insulating layer is first plated on the surface of the reference plate, and then two thin-film platinum resistors are plated symmetrically as reference platinum resistors. The distance between the two reference platinum resistors does not exceed 1 mm. Finally, a high-emissivity coating is coated on the surface of the reference plate to ensure that the surface emissivity is close to 1.

4. The convection heat flux calibration device according to claim 1 or 2, characterized in that: The surface of the shielded radiation source is plated with an insulating layer and a thin-film thermocouple in sequence, and then coated with a high-emissivity coating to ensure that the surface emissivity is close to 1.

5. The convection heat flux calibration device according to claim 1 or 2, characterized in that: The reference plate is made of constantan and the calibration plate is made of aerogel ceramic.

6. The convection heat flux calibration device according to claim 1 or 2, characterized in that: The single action time of the fast response displacement mechanism does not exceed 50ms.

7. The convection heat flux calibration device according to claim 1 or 2, characterized in that: The test section also includes a support rod, and the shielding radiation source is fixed at the inner center position of the nozzle through the support rod.

8. The convection heat flux calibration device according to claim 1 or 2, characterized in that: The test section also includes a calibrated heat flux meter mounting seat, through which the calibrated heat flux meter is mounted at the center of the calibration plate.

9. A convection heat flux calibration method, characterized in that: The convective heat flux calibration device according to any one of claims 1 to 8 is used to perform convective heat flux calibration, comprising: The reference plate and the plate to be calibrated are subjected to transient thermal shock of the airflow respectively through a fast response displacement mechanism, the total heat flux is calculated according to the temperature history of the reference platinum resistor on the reference plate, the shielded radiation source is used to radiate heat to the reference plate and the radiation heat flux is calculated, the convective heat flux of the reference plate is obtained by subtracting the radiation heat flux from the total heat flux, the convective heat transfer coefficient and the adiabatic wall temperature are calculated according to the values ​​of the convective heat flux and the radiation heat flux of the reference plate at different times, and the values ​​are assigned to the calibration plate, and the convective heat flux is calculated according to the calculated convective heat transfer coefficient and the adiabatic wall temperature and the measured surface temperature of the calibration plate as the standard value of the convective heat flux of the calibration plate; Measure the surface temperature of the shielded radiation source and the calibration plate, calculate the radiation heat flux of the calibration plate, subtract the ratio of the radiation heat flux of the calibration plate to the radiation heat flux sensitivity coefficient from the output voltage of the calibrated heat flux meter, and obtain the voltage corresponding to the convective heat flux. Divide the standard value of the convective heat flux by the voltage to obtain the convective heat flux sensitivity coefficient.

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