High-frequency-response high-temperature heat flux sensor for flight test

Abstract

The invention relates to a high-frequency-response high-temperature heat flux sensor for a flight test, which is characterized in that the type of a thermocouple is selected according to the maximum value of the surface temperature of an aircraft in the flight process, a heat transfer element is of a cylindrical structure, the end part is polished and ground, and two mounting through holes are symmetrically formed in the same distance from the center line of the cylindrical structure; positive and negative electrodes of the thermocouple are processed into wires with corresponding diameters and are fixed in the two mounting through holes of the heat transfer element, and one ends of the two electrodes are flush with the end surface of the heat transfer element; the end face of the heat transfer element provided with the thermocouple is sequentially plated with a copper film and a silicon dioxide film in a magnetron sputtering mode, and the high-frequency response characteristic of the heat flow sensor is achieved. The coated heat transfer element is fixed in the high-temperature alloy packaging shell, the tail parts of the positive electrode and the negative electrode of the thermocouple are welded with the compensating leads with the same polarity, and a cavity in the tail part of the high-temperature alloy packaging shell is filled with high-temperature glue. The sensor has the advantages of being small in size, resistant to temperature and high in frequency response.

Description

Technical Field

[0001] The invention belongs to the technical field of aerodynamics and relates to a high-frequency response and high-temperature heat flow sensor for flight tests. Background Art

[0002] Flight testing is a crucial tool for hypersonic aerodynamic research and the most realistic verification method. Heat flux density data from flight tests serves as the only experimental reference for validating and refining hypersonic aerodynamic heating calculation methods and establishing correlation mechanisms for flow field parameters in wind tunnel equipment. Therefore, flight test heat flux measurement technology has long been a key focus of technological development in the aerospace sector, particularly in the hypersonic field. The rapid development of commercial test platforms in recent years has effectively addressed development cycle and cost challenges, further lowering the industry's entry threshold. The number of domestic flight tests has increased significantly in recent years, and universities and research institutes have conducted relevant flight test research, leading to a period of rapid development in the industry. As a key test item in hypersonic flight testing, heat flux measurement has generated significant demand for highly reliable, long-range, and long-duration heat flux sensors, creating a promising market. However, currently used heat flux measurement sensors, such as Gordon gauges and Plug-type calorimeters, suffer from large size, low frequency response, and low temperature resistance, making them inadequate for the needs of aircraft innovation and development. Consequently, effective and mature heat flux measurement methods are still lacking. Summary of the Invention

[0003] The technical problem solved by the present invention is: to overcome the shortcomings of the existing technology and propose a high-frequency response and high-temperature heat flux sensor for flight tests, so as to solve the problem of high temporal and spatial resolution measurement of the heat flux density on the surface of the aircraft in hypersonic flight tests, and to have significant technical advantages in the stage of rapid increase in heat flux.

[0004] The solution to the technical problem of the present invention is: a high-frequency response and high-temperature heat flow sensor for flight testing, comprising a thermocouple, a silicon dioxide film, a copper film, a heat transfer element, a high-temperature alloy packaging shell and a compensation wire;

[0005] The type of thermocouple is selected based on the maximum surface temperature of the aircraft during flight. The heat transfer element is a cylindrical structure with polished ends. Two mounting holes are symmetrically machined at the same distance from the centerline of the cylindrical structure. The positive and negative electrodes of the thermocouple are processed into wires of corresponding diameters and fixed in the two mounting holes of the heat transfer element, with one end of each electrode flush with the end face of the heat transfer element. The end face of the heat transfer element where the thermocouple is mounted is coated with copper film and then silicon dioxide film by magnetron sputtering, achieving the high-frequency response characteristics of the heat flow sensor while enhancing the sensor's erosion resistance.

[0006] The coated heat transfer element is fixed in a high-temperature alloy packaging shell, the tails of the positive and negative electrodes of the thermocouple are welded to compensation wires of the same polarity, and the tail cavity of the high-temperature alloy packaging shell is sealed with glue.

[0007] Furthermore, the thermocouple type is selected based on the maximum surface temperature of the aircraft during flight, as follows:

[0008] Based on the flight trajectory of the flight test, commercial fluid calculation software is used to calculate the temperature change of the aircraft surface during the flight, and the maximum temperature T of the aircraft surface during the flight is obtained. max , after considering the safety margin of 1.2 times, determine the thermocouple type of the heat flow sensor: when 1.2T max When the temperature is less than 1300℃, a K-type thermocouple made of nickel-chromium-nickel-silicon is used. max When the temperature is greater than 1300℃, a B-type thermocouple made of platinum-rhodium 30-platinum-rhodium 6 is used.

[0009] Furthermore, the parameter settings for calculating the temperature change of the aircraft surface during flight include:

[0010] In the turbulent flight section, the SA model is used as the turbulence model, and the structured grid is used as the calculation grid. The height of the first layer of grid is not greater than 0.05 mm, and the grid growth rate is not greater than 1.2.

[0011] Furthermore, the heat transfer element is processed by silicon nitride, the thermal conductivity of which differs from that of the high-temperature alloy packaging shell by no more than 30%.

[0012] Furthermore, the size parameters of the heat transfer element are set as follows: diameter 5mm-10mm, length 10mm-30mm, and two mounting holes are symmetrically processed at a distance of 2-5mm from the center line of the heat transfer element.

[0013] Furthermore, the copper film has a thickness of 10 to 20 μm, and the silicon dioxide film has a thickness of 15 to 30 μm.

[0014] Furthermore, the outer shape of the high-temperature alloy packaging shell is formed by integrating a cylindrical portion and an external hexagonal structure. The cylindrical portion is processed with an external thread to facilitate sensor installation. A stepped hole is processed on the inner diameter of the external hexagonal structure. The large hole diameter of the stepped hole matches the diameter of the heat transfer element, and the small hole diameter of the stepped hole is 1 to 2 mm smaller than the large hole diameter.

[0015] Furthermore, the material of the high-temperature alloy packaging shell is processed using GH3030.

[0016] Furthermore, the compensation wire is braided with a single strand of glass fiber and covered with a stainless steel shielding mesh.

[0017] Furthermore, the heat flux sensor uses an unsteady-state heat transfer control equation to calculate the wall heat flux density.

[0018] The beneficial effects of the present invention compared with the prior art are:

[0019] (1) The present invention proposes a high-frequency response and high-temperature heat flux sensor for flight testing. The sensor is mainly composed of a thermocouple, a high-temperature alloy packaging shell, a silicon nitride heat transfer element, a compensation wire, a copper film, and a silicon dioxide film. The end of the heat transfer element is plated with a copper film by magnetron sputtering, and a silicon dioxide non-metallic film is plated on the copper film. The thickness of the plated copper film and the non-metallic film are both verified to have an optimal range through a large number of flight tests. The temperature sensing node is made by coating, which greatly reduces the time constant of the node and realizes the high-frequency response measurement of the heat flux. At the same time, the erosion resistance and durability of the sensor are enhanced by adding the silicon dioxide non-metallic film. The sensor has the advantages of small size, temperature resistance and high frequency response, and has significant technical advantages in the stage of rapid acceleration of the aircraft and the sharp increase of heat flux.

[0020] (2) The present invention calculates the temperature change of the aircraft surface during flight and determines the type of thermocouple used in the heat flux sensor based on the maximum temperature calculated during the flight of the aircraft. This ensures that the aircraft surface temperature does not exceed the maximum range of the sensor during the test, thereby achieving full-trajectory heat flux measurement.

[0021] (3) The present invention ensures that the sensor is easy to manufacture, compact in size, strong and durable by designing the structural dimensions of the heat transfer element. The present invention further achieves thermal matching between the heat transfer element and the high-temperature alloy packaging shell by selecting and matching the material, structural shape and size of the step hole of the heat transfer element. The heat transfer process of the heat transfer element in the test satisfies the one-dimensional heat transfer law, simplifies the heat flow calculation process, and improves the heat flow measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic structural diagram of a high-frequency response and high-temperature heat flow sensor used in flight tests according to the present invention;

[0023] Figure 2 It is a partial schematic diagram of the heat transfer element of the present invention;

[0024] Figure 3 A partial schematic diagram of a high-temperature alloy packaging shell of the present invention;

[0025] Description of reference numerals:

[0026] 1. Silicon dioxide film, 2. Copper film, 3. Thermocouple positive electrode, 4. Heat transfer element, 5. High-temperature alloy packaging shell, 6. Compensating wire, 7. Thermocouple negative electrode. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings and examples.

[0028] like Figure 1As shown, the present invention proposes a high-frequency response and high-temperature heat flow sensor for flight testing, comprising a thermocouple, a silicon dioxide film 1, a copper film 2, a heat transfer element 4, a high-temperature alloy packaging shell 5, and a compensation wire 6;

[0029] The type of thermocouple is selected based on the maximum surface temperature of the aircraft during flight. Heat transfer element 4 is a cylindrical structure with polished ends. Two symmetrical mounting holes are machined at equal distances from the centerline of the cylindrical structure. The positive and negative electrodes 3 and 7 of the thermocouple are machined into wires of corresponding diameters and fixed within the two mounting holes of heat transfer element 4, with one end of each electrode flush with the end face of heat transfer element 4. The end face of heat transfer element 4, where the thermocouple is mounted, is coated with a copper film 2 and then a silicon dioxide film 1 via magnetron sputtering, achieving the high-frequency response characteristics of the heat flow sensor while enhancing the sensor's erosion resistance.

[0030] The coated heat transfer element 4 is fixed in the high-temperature alloy packaging shell 5. The tail ends of the positive and negative electrodes of the thermocouple are welded to the compensation wires 6 of the same polarity. The tail cavity of the high-temperature alloy packaging shell 5 is sealed with high-temperature glue.

[0031] The thermocouple type is selected based on the maximum temperature of the aircraft surface during flight, as follows:

[0032] Based on the flight trajectory of the flight test, commercial fluid calculation software is used to calculate the temperature change of the aircraft surface during the flight, and the maximum temperature T of the aircraft surface during the flight is obtained. max , after considering the safety margin of 1.2 times, determine the thermocouple type of the heat flow sensor: when 1.2T max When the temperature is less than 1300℃, a K-type thermocouple made of nickel-chromium-nickel-silicon is used. max When the temperature is greater than 1300℃, a B-type thermocouple made of platinum-rhodium 30-platinum-rhodium 6 is used.

[0033] Leveraging silicon nitride's high-temperature resistance, insulation, and high thermal conductivity, the heat transfer element 4 is fabricated from high-purity silicon nitride. The thermal conductivity of the silicon nitride used in the heat transfer element 4 is within 30% of that of the high-temperature alloy housing 5. The dimensions of the heat transfer element 4 are set as follows: diameter 5mm to 10mm, length 10mm to 30mm, and two mounting holes symmetrically positioned 2 to 5mm from the centerline of the heat transfer element 4. This ensures high-performance insulation between the two electrodes at high temperatures, while also simplifying sensor fabrication and miniaturizing the sensor. By selecting silicon nitride with high thermal conductivity, thermal matching between the heat transfer element 4 and the high-temperature alloy housing 5 is achieved, minimizing the impact of lateral heat transfer on heat flow measurement.

[0034] When coating the end face of the heat transfer element 4, a copper film 2 is first plated onto the end face using a copper target. When the film thickness reaches 10-20 μm, the copper film plating is stopped. Then, a non-metallic film is added to the copper film 2 using a silicon dioxide target. When the film thickness reaches 15-30 μm, the silicon dioxide film 1 is stopped. This significantly reduces the time constant of the node, enabling high-frequency response measurement of heat flow. At the same time, the addition of the silicon dioxide film 1 enhances the sensor's erosion resistance and durability. Figure 2 shown.

[0035] like Figure 1 、 Figure 3 As shown, the high-temperature alloy package shell 5 is formed by integrating a cylindrical and external hexagonal structure. The material of the high-temperature alloy package shell 5 is GH3030. The cylindrical portion of the high-temperature alloy package shell 5 is processed with external threads to facilitate sensor installation. The internal diameter of the external hexagonal structure of the high-temperature alloy package shell 5 is processed with a stepped hole. The large hole diameter of the stepped hole matches the diameter of the heat transfer element 4, and the small hole diameter of the stepped hole is 1 to 2 mm smaller than the large hole diameter, thereby effectively fixing the heat transfer element 4 and reducing the amount of heat transferred to the bottom of the heat transfer element 4.

[0036] The compensation wire 6 is braided with a single strand of glass fiber and covered with a stainless steel shielding mesh.

[0037] During the flight test, the output signal E of the heat flux sensor is obtained through a data acquisition device with an ADC resolution of no less than 24 bits. According to the requirements of the national standard for thermocouples, Part 1: Graduation table (GB / T16839.1-1997), the change of temperature T over time is calculated.

[0038]

[0039] Where d is the polynomial coefficient, which can be obtained from the national standard GB / T 16839.1-1997, and n1 is the number of polynomials.

[0040] Then the wall heat flux density q is calculated using the unsteady heat transfer control equation:

[0041]

[0042] Wherein, τ is the test measurement time, ρ is the density of silicon nitride, c is the specific heat capacity of silicon nitride, k is the thermal conductivity of silicon nitride, and n2 is the number of collected data points.

[0043] Example 1

[0044] like Figure 1 The high-frequency response and high-temperature heat flow sensor proposed in this embodiment includes a thermocouple, a silicon dioxide film 1, a copper film 2, a heat transfer element 4, a high-temperature alloy packaging shell 5 and a compensation wire 6;

[0045] First, based on the flight trajectory of the predetermined flight test, the commercial fluid calculation software Fluent (a well-known fluid calculation software) is used to adopt the RANS method to calculate the temperature changes on the aircraft surface during the flight. The calculation parameters are set as follows: in the turbulent flight section, the turbulence model uses the SA model, the calculation grid uses a structured grid, the first layer of grid height is not greater than 0.05mm, and the grid growth rate is not greater than 1.2.

[0046] The maximum surface temperature T of the aircraft during the flight is obtained by calculation max , after considering the safety margin of 1.2 times, determine the thermocouple type of the heat flux density sensor: when 1.2T max When the temperature is less than 1300℃, a K-type thermocouple made of nickel-chromium-nickel-silicon is used. max When the temperature is greater than 1300℃, a B-type thermocouple made of platinum-rhodium 30-platinum-rhodium 6 is used.

[0047] Taking advantage of the high temperature resistance and insulation properties of silicon nitride, high purity silicon nitride is used to process the heat transfer element 4. The heat transfer element 4 is a cylinder with a diameter of 8mm and a length of 15mm. Two diameters are symmetrically processed at a distance of 2.75mm from the center line of the cylinder. Mounting through holes.

[0048] The positive and negative electrodes of the thermocouple are processed into diameters The wires are fixed to the two mounting holes of the silicon nitride heat transfer element 4 using HASUNCAST732 high-temperature adhesive. One end of the two electrodes must be flush with the end surface of the heat transfer element 4.

[0049] The ends of the heat transfer element 4 were polished and cleaned with alcohol. The polished end faces of the heat transfer element 4 were then coated using a JCP500 high-vacuum multi-target magnetron sputtering coating machine from Beijing Techno Technology Co., Ltd. Copper and silicon dioxide targets were installed in the coating machine. First, a copper film 2 was applied to the end faces using the copper target. When the film thickness reached 20 μm, the metal film coating was stopped. Then, a silicon dioxide film 1 was added to the metallic copper film using the silicon dioxide target. When the film thickness reached 15 to 30 μm, the non-metallic film coating was stopped.

[0050] The high temperature alloy package shell 5 is made of GH3030 and the inner diameter of the outer hexagonal structure is a step hole, and the large hole diameter is The diameter of the small hole is The outer diameter of the cylindrical part is processed with M12 thread structure to facilitate sensor installation.

[0051] The coated heat transfer element 4 is secured to the high-temperature alloy housing 5 using HASUNCAST 732 high-temperature adhesive. The positive and negative ends of the thermocouple are welded to compensating wires 6 of the same polarity. The compensating wires 6 are braided from single-strand glass fiber and covered with a stainless steel shield. The tail chamber of the high-temperature alloy housing 5 is potted with HASUNCAST 732 high-temperature adhesive.

[0052] During the flight test, the output signal E of the heat flux sensor is obtained through a data acquisition device with an ADC resolution of no less than 24 bits. According to the requirements of the national standard for thermocouples, Part 1: Graduation table (GB / T16839.1-1997), the change of temperature T over time is calculated.

[0053]

[0054] Where d is the polynomial coefficient, which can be obtained from the national standard GB / T 16839.1-1997, and n1 is the number of polynomials.

[0055] Then the wall heat flux density q is calculated using the unsteady heat transfer control equation:

[0056]

[0057] Wherein, τ is the test measurement time, ρ is the density of silicon nitride, c is the specific heat capacity of silicon nitride, k is the thermal conductivity of silicon nitride, and n2 is the number of collected data points.

[0058] The heat flux sensor of the present invention has the advantages of small size, temperature resistance and high frequency response, and has significant technical advantages during the stage of rapid acceleration of the aircraft when the heat flux increases sharply.

[0059] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the scope of protection of the technical solutions of the present invention.

[0060] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A high-frequency response and high-temperature heat flow sensor for flight testing, characterized in that: It comprises a thermocouple, a silicon dioxide film (1), a copper film (2), a heat transfer element (4), a high-temperature alloy packaging shell (5) and a compensation wire (6); The type of thermocouple is selected based on the maximum surface temperature of the aircraft during flight. The heat transfer element (4) is a cylindrical structure, the end portion of which is polished and ground, and two mounting holes are symmetrically processed at the same distance from the center line of the cylindrical structure. The positive and negative electrodes of the thermocouple are processed into wires of corresponding diameters and fixed in the two mounting holes of the heat transfer element (4), and one end of the two electrodes is flush with the end face of the heat transfer element (4); the end face of the heat transfer element (4) on which the thermocouple is installed is successively plated with a copper film (2) and a silicon dioxide film (1) by magnetron sputtering, so as to realize the high-frequency response characteristics of the heat flow sensor; The coated heat transfer element (4) is fixed in a high-temperature alloy packaging shell (5), the tails of the positive and negative electrodes of the thermocouple are welded to compensation wires (6) of the same polarity, and the tail cavity of the high-temperature alloy packaging shell (5) is sealed with glue.

2. The high-frequency response and high-temperature heat flow sensor for flight testing according to claim 1, characterized in that: The thermocouple type is selected based on the maximum temperature of the aircraft surface during flight, as follows: The temperature change of the aircraft surface during the flight is calculated based on the flight trajectory of the flight test, and the maximum temperature T of the aircraft surface during the flight is obtained. max , after considering the safety margin of 1.2 times, determine the thermocouple type of the heat flow sensor: when 1.2T max When the temperature is less than 1300℃, a K-type thermocouple made of nickel-chromium-nickel-silicon is used. max When the temperature is greater than 1300℃, a B-type thermocouple made of platinum-rhodium 30-platinum-rhodium 6 is used.

3. The high-frequency response and high-temperature heat flow sensor for flight testing according to claim 2, characterized in that: The parameter settings for calculating the temperature change of the aircraft surface during flight include: In the turbulent flight section, the SA model is used as the turbulence model, and the structured grid is used as the calculation grid. The height of the first layer of grid is not greater than 0.05 mm, and the grid growth rate is not greater than 1.

2.

4. The high-frequency response and high-temperature heat flow sensor for flight testing according to claim 1, characterized in that: The heat transfer element (4) is made of silicon nitride, the thermal conductivity of which differs from that of the high-temperature alloy packaging shell (5) by no more than 30%.

5. The high-frequency response and high-temperature heat flow sensor for flight testing according to claim 1, characterized in that: The size parameters of the heat transfer element (4) are set as follows: diameter 5mm-10mm, length 10mm-30mm, and two mounting through holes are symmetrically processed at a distance of 2-5mm from the center line of the heat transfer element (4).

6. The high-frequency response and high-temperature heat flow sensor for flight testing according to claim 1, characterized in that: The copper film (2) has a thickness of 10 to 20 μm, and the silicon dioxide film (1) has a thickness of 15 to 30 μm.

7. The high-frequency response and high-temperature heat flow sensor for flight testing according to claim 5, characterized in that: The high-temperature alloy packaging shell (5) is formed by integrally processing a cylindrical portion and an external hexagonal structure. The cylindrical portion is processed with an external thread to facilitate sensor installation. The internal diameter of the external hexagonal structure is processed with a stepped hole. The large hole diameter of the stepped hole matches the diameter of the heat transfer element (4), and the small hole diameter of the stepped hole is 1 to 2 mm smaller than the large hole diameter.

8. The high-frequency response and high-temperature heat flow sensor for flight testing according to claim 1, characterized in that: The high-temperature alloy packaging shell (5) is made of GH3030.

9. The high-frequency response and high-temperature heat flow sensor for flight testing according to claim 1, characterized in that: The compensation conductor (6) is braided with a single strand of glass fiber and covered with a stainless steel shielding mesh.

10. The high-frequency response and high-temperature heat flow sensor for flight testing according to claim 1, characterized in that: The heat flux sensor calculates the wall heat flux density using an unsteady-state heat transfer control equation.

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