Temperature and convective heat transfer coefficient integrated sensor and testing method thereof

Abstract

The invention discloses a temperature and convective heat transfer coefficient integrated sensor and a testing method thereof, and relates to the technical field of aviation technology and thermophysics, the sensor comprises a substrate, a main heating platinum film, an auxiliary heating platinum film, a lead, a wire and conductive slurry; the substrate is used for bearing the metal platinum thin-film resistor structure; the metal platinum thin-film resistor structure is composed of a main heating platinum film, an auxiliary heating platinum film, a lead, a wire and conductive slurry. The metal platinum film resistor structure is a cylindrical structure; the main heating platinum film and the auxiliary heating platinum film are respectively positioned on the upper bottom surface and the lower bottom surface of the metal platinum film resistor structure; the lead is arranged in the vertical hole of the substrate, one end of the lead is connected with the main heating platinum film or the auxiliary heating platinum film, and the other end is connected with the wire; the conductive paste is used to fill the vertical hole of the substrate. Based on the device, accurate measurement of multiple parameters can be realized.

Description

Technical Field

[0001] The present application relates to the fields of aviation technology and thermal physics technology, and in particular to a temperature and convection heat transfer coefficient integrated sensor and a test method thereof. Background Art

[0002] In recent years, aircraft engines are gradually developing in the direction of high flow ratio, high thrust-to-weight ratio, and high turbine inlet temperature. Taking the turbine inlet temperature as an example, in the fourth-generation aircraft engines currently in service, its typical value is 1977K, and the typical value of the future fifth-generation aircraft engines is even not less than 2250K. Since the melting point of the materials used in the current turbine components is lower than the typical temperature value, in order to ensure the overall safety performance of the aircraft engine, it is necessary to carry out thermal design and thermal protection of the entire engine. At the same time, with the continuous development of aircraft engines, the rate of increase of the turbine inlet temperature is significantly higher than the rate of increase of the melting point of new materials, which puts forward higher requirements on the thermal protection technology of the hot end components of aircraft engines. As one of the indispensable core parameters for the thermal design of the hot end components of aircraft engines, the accurate measurement of the convective heat transfer coefficient is related to the working performance and service life of the components. However, since the working environment of the hot end components of aircraft engines represented by turbine disks is mostly a harsh environment of high temperature, high speed, and large heat flow, it makes it extremely difficult to accurately measure the surface convective heat transfer coefficient.

[0003] The convective heat transfer coefficient is an important thermodynamic parameter that describes the intensity of heat exchange between fluid and solid when the fluid flows over the solid surface. Any research involving flow heat transfer between fluid and solid cannot be separated from this parameter. At present, there are two mainstream methods for measuring the convective heat transfer coefficient. One is to use a thermocouple to measure the temperature values ​​at multiple measuring points on the surface to be measured, obtain the temperature distribution of the surface to be measured, and then obtain the temperature distribution and surface heat flux density value inside the test piece to be measured by solving the heat conduction differential equation, so as to obtain the convective heat transfer coefficient of the surface to be measured. However, the convective heat transfer coefficient of the surface to be measured obtained by this method is completely dependent on the multi-point temperature measurement on the surface of the test piece to be measured. The small temperature measurement error will be amplified in the process of solving the problem through the heat conduction differential equation, making the final convective heat transfer coefficient measurement error much greater than the design value. Another method is to use a heat flux meter to measure the heat flux density on the surface of the test piece to be measured, and substitute it into the corresponding solution formula to obtain the convective heat transfer coefficient of the surface to be measured. This method is widely used, and is commonly used in the measurement of convective heat transfer coefficient and heat loss correction in traditional construction and mechanical processing industries. However, due to its common problems such as low maximum operating temperature and the need for on-site calibration, it is difficult to meet the requirements of the convective heat transfer coefficient measurement on the surface of the hot end components of aircraft engines. Therefore, there is a lack of a sensor that can accurately measure the convective heat transfer coefficient on the surface of the hot end components of aircraft engines. Summary of the invention

[0004] The purpose of this application is to provide an integrated temperature and convective heat transfer coefficient sensor and a testing method thereof, which can realize accurate measurement of multiple parameters.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] In a first aspect, the present application provides an integrated temperature and convection heat transfer coefficient sensor, comprising:

[0007] Substrate, main heating platinum film, auxiliary heating platinum film, lead wire, wire and conductive paste.

[0008] The substrate is used to support a metal platinum thin film resistor structure; the metal platinum thin film resistor structure is composed of a main heating platinum film, an auxiliary heating platinum film, leads, wires and conductive paste; the metal platinum thin film resistor structure is a cylindrical structure; the main heating platinum film and the auxiliary heating platinum film are respectively located on the upper bottom surface and the lower bottom surface of the metal platinum thin film resistor structure; the lead is arranged in a vertical hole of the substrate, one end of the lead is connected to the main heating platinum film or the auxiliary heating platinum film, and the other end is connected to the wire; the conductive paste is used to fill the vertical hole of the substrate.

[0009] Optionally, the main heating platinum film uses a noble metal platinum thin film resistor as the main heating platinum film material, and the thickness of the noble metal platinum thin film is 1 μm.

[0010] Optionally, the main heating platinum film and the auxiliary heating platinum film both adopt two circles of symmetrical semicircular shapes that are axially symmetrical to each other.

[0011] Optionally, the material used for the substrate is alumina ceramics.

[0012] Optionally, the material of the lead wire is platinum-rhodium alloy or pure platinum.

[0013] In a second aspect, the present application provides a temperature testing method based on the temperature and convection heat transfer coefficient integrated sensor, comprising:

[0014] The secondary heating platinum film in the integrated sensor of temperature and convection heat transfer coefficient is kept in an unpowered state, and a small current is passed through the main heating platinum film.

[0015] Measure the current value I of the circuit where the main heating platinum film is located and the voltage value U across the main heating platinum film.

[0016] The resistance value R of the main heating platinum film is calculated based on the current value I and the voltage value U.

[0017] According to the TR curve of the main heating platinum film, determine the temperature T of the main heating platinum film f .

[0018] In a third aspect, the present application provides a method for testing a convective heat transfer coefficient based on the temperature and convective heat transfer coefficient integrated sensor, comprising:

[0019] Based on two regulated DC power supplies, voltage is applied to the main and auxiliary heating platinum film resistors respectively.

[0020] After reaching a steady state, the voltage U1 across the main heating platinum film resistor, the current I1 passing through the main heating platinum film resistor, the voltage U2 across the auxiliary heating platinum film resistor, and the current I2 passing through the auxiliary heating platinum film resistor are determined.

[0021] According to the voltage U1 across the main heating platinum film resistor and the current I1 passing through the main heating platinum film resistor, the heating power P1, the resistance R1 and the temperature T1 of the main heating film are calculated.

[0022] According to the voltage U2 across the auxiliary heating platinum film resistor and the current I2 passing through the auxiliary heating platinum film resistor, the heating power P2 of the auxiliary heating film, the resistance R2 and the temperature T2 of the auxiliary heating film are calculated.

[0023] According to the temperature T1 of the main heating film and the temperature T2 of the auxiliary heating film, the heat flow Q from the main heating film to the bottom surface is calculated. down .

[0024] According to the heating power P1 of the main heating film and the heat flow Q from the main heating film to the bottom surface down , calculate the convective heat transfer heat Q from the main heating film to the fluid direction effect .

[0025] Based on Newton's cooling law, the temperature T of the measuring point is measured when the auxiliary heating platinum film is not energized and the main heating platinum film is energized with a small current. f , calculate the convection heat transfer coefficient h; the measuring point temperature T f It is determined based on the TR curve of the main heating platinum film by measuring the current value I of the circuit where the main heating platinum film is located and the voltage value U across the main heating platinum film.

[0026] Optionally, the heat conduction heat flow Q down The calculation formula is:

[0027] Q down =f(T1,T2).

[0028] Among them, f() represents the mapping relationship between the thermal conduction heat flux and the upper and lower surface temperatures.

[0029] Optionally, the convection heat transfer heat Q effect The calculation formula is:

[0030] Q effect =P1-Q down .

[0031] Optionally, the calculation formula of the convective heat transfer coefficient h is:

[0032]

[0033] Among them, m(U1 / I1) represents the resistance-temperature characteristic function of the main heating platinum film, n(U2 / I2) represents the resistance-temperature characteristic function of the auxiliary heating platinum film, and A is the area of ​​the main / auxiliary heating platinum film.

[0034] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0035] The present application provides a temperature and convection heat transfer coefficient integrated sensor and a test method thereof, wherein the sensor comprises a substrate, a main heating platinum film, a secondary heating platinum film, a lead, a wire and a conductive paste; wherein the substrate is used to carry a metal platinum thin film resistor structure; the metal platinum thin film resistor structure is composed of a main heating platinum film, a secondary heating platinum film, a lead, a wire and a conductive paste; the metal platinum thin film resistor structure is a cylindrical structure; the main heating platinum film and the secondary heating platinum film are respectively located on the upper bottom surface and the lower bottom surface of the metal platinum thin film resistor structure; the lead is arranged in a vertical hole of the substrate, one end of the lead is connected to the main heating platinum film or the secondary heating platinum film, and the other end is connected to the wire; the conductive paste is used to fill the vertical hole of the substrate. The device based on the present application can realize accurate temperature measurement and real-time monitoring of the convection heat transfer coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 A schematic diagram of the structure of an integrated temperature and convection heat transfer coefficient sensor provided in one embodiment of the present application.

[0038] Figure 2 A schematic diagram of a ceramic surface after coating provided in one embodiment of the present application. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0040] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0041] Embodiment 1

[0042] like Figure 1 As shown, this embodiment provides an integrated temperature and convection heat transfer coefficient sensor, including:

[0043] Substrate, main heating platinum film, auxiliary heating platinum film, lead wire, wire and conductive paste.

[0044] The substrate is used to support a metal platinum thin film resistor structure; the metal platinum thin film resistor structure is composed of a main heating platinum film, an auxiliary heating platinum film, leads, wires and conductive paste; the metal platinum thin film resistor structure is a cylindrical structure; the main heating platinum film and the auxiliary heating platinum film are respectively located on the upper bottom surface and the lower bottom surface of the metal platinum thin film resistor structure; the lead is arranged in a vertical hole of the substrate, one end of the lead is connected to the main heating platinum film or the auxiliary heating platinum film, and the other end is connected to the wire; the conductive paste is used to fill the vertical hole of the substrate.

[0045] In this embodiment, the overall size of the cylindrical test probe of the temperature and convection heat transfer coefficient integrated sensor is no more than 4 mm in diameter and no more than 3 mm in height.

[0046] Among them, Figure 1 As shown, the substrate of the test probe is a carrier for the deposition of the metal platinum thin film resistor structure. In this embodiment, a ceramic material is used as the substrate material. Alumina ceramics that can withstand high temperature environments above 850°C, have good insulation and acid and alkali resistance, and have a thermal expansion coefficient that is relatively close to that of platinum metal can be used as the substrate material.

[0047] The precious metal platinum thin film resistor is used as the main heating film material, which also serves as a heating element and a temperature sensing element. The convective heat transfer coefficient value of the measuring point is calculated based on the platinum resistor heating power and resistance value in steady state. The thickness of the metal platinum film is 1μm.

[0048] Since the temperature of the heating surface is significantly higher than that of other positions, there is considerable heat loss from the bottom and sides due to thermal conduction. Therefore, this embodiment reduces the heat loss from the bottom and sides by adding an auxiliary heating film, that is, a layer of metal platinum film is also coated on the lower surface of the ceramic cylinder to reduce the proportion of heat loss from the main heating film on the upper surface and improve the test accuracy of the convective heat transfer coefficient of the integrated sensor.

[0049] The lead wire adopts the lead wire-base integrated structure design. The lead wire is buried in the vertical hole of the ceramic part through sintering and other processes. One end is directly connected to the film at the pin through the coating process to achieve high-strength and reliable connection, completing the input and output of electrical signals between the film and the lead wire; the other end is at the inner corner of the vertical hole, and is subsequently connected to the external circuit through a wire, thereby realizing the reliable lead-out of the overall test signal of the integrated sensor. Considering the operating temperature of this embodiment (not less than 850°C), the lead wire material of the thin film platinum resistor is selected as platinum-rhodium alloy or pure platinum, with a diameter of 0.25mm.

[0050] Pure nickel wire with low resistivity and good resistance-temperature characteristics is used as the conductor connected to the pure platinum lead to improve the test accuracy. Conductive silver paste is used as the grouting material in the side hole to achieve high-strength, low-resistance connection between the pure platinum lead and the pure nickel wire. After the conductive silver paste is cured, the side groove is covered with high-temperature resistant inorganic insulating glue for further reinforcement.

[0051] In order to further improve the test accuracy of the integrated sensor, it is necessary to appropriately amplify the test signal of the test probe and maintain the uniformity of the temperature distribution of the main and auxiliary heating films. The main and auxiliary heating platinum films are both symmetrical semicircular lines with two circles of axial symmetry. The coating thickness is designed to be 0.5μm, the coating width is 0.1mm, the adjacent interval is 0.05mm, and the total length is 69.3mm. The ceramic surface after coating is as follows Figure 2 shown.

[0052] Embodiment 2

[0053] This embodiment provides a temperature testing method based on the temperature and convection heat transfer coefficient integrated sensor, including:

[0054] Step 201: Keep the secondary heating platinum film in the integrated sensor for temperature and convection heat transfer coefficient unpowered, and pass a small current through the primary heating platinum film.

[0055] Step 202: Measure the current value I of the circuit where the main heating platinum film is located and the voltage value U across the main heating platinum film.

[0056] Step 203: Calculate the resistance value R of the main heating platinum film according to the current value I and the voltage value U.

[0057] Step 204: Determine the temperature T of the main heating platinum film according to the TR curve of the main heating platinum film f .

[0058] Embodiment 3

[0059] This embodiment provides a method for testing the convective heat transfer coefficient based on the temperature and convective heat transfer coefficient integrated sensor, including:

[0060] Step 301: Based on two regulated DC power supplies, voltages are applied to the primary and secondary heating platinum film resistors respectively.

[0061] Step 302: After reaching a steady state, determine the voltage U1 across the main heating platinum film resistor, the current I1 passing through the main heating platinum film resistor, the voltage U2 across the auxiliary heating platinum film resistor, and the current I2 passing through the auxiliary heating platinum film resistor.

[0062] Step 303: Calculate the heating power P1, the resistance R1 and the temperature T1 of the main heating film according to the voltage U1 across the main heating platinum film resistor and the current I1 passing through the main heating platinum film resistor.

[0063] Step 304: Calculate the heating power P2, the resistance R2 and the temperature T2 of the secondary heating film according to the voltage U2 across the secondary heating platinum film resistor and the current I2 passing through the secondary heating platinum film resistor.

[0064] Step 305: Calculate the heat flow Q from the main heating film to the bottom surface according to the temperature T1 of the main heating film and the temperature T2 of the auxiliary heating film. down .

[0065] Step 306: According to the heating power P1 of the main heating film and the heat flow Q of the main heating film to the bottom surface down , calculate the convective heat transfer heat Q from the main heating film to the fluid direction effect .

[0066] Step 307: Based on Newton's cooling law, the temperature T of the measuring point is measured when the auxiliary heating platinum film is not powered and the main heating platinum film is powered by a small current. f , calculate the convection heat transfer coefficient h; the measuring point temperature T f It is determined based on the TR curve of the main heating platinum film by measuring the current value I of the circuit where the main heating platinum film is located and the voltage value U across the main heating platinum film.

[0067] Among them, the measurement of the convective heat transfer coefficient of the new temperature and convective heat transfer coefficient integrated sensor disclosed in this embodiment is mainly based on Newton's cooling formula. During the test, two voltage-stabilized DC power supplies are used to apply voltage to the main and auxiliary heating platinum film resistors at the same time. After the overall steady state is reached, the voltage U1 across the main heating platinum film resistor, the current I1 passing through the main heating platinum film resistor, and the voltage U2 across the auxiliary heating platinum film resistor, and the current I2 passing through the main heating platinum film resistor are read.

[0068] At this time, the heating power P1 of the main heating platinum film is:

[0069] P1=U1×I1.

[0070] The resistance R1 of the main heating platinum film is:

[0071]

[0072] By querying the resistance-temperature curve of the thin film platinum resistor, the temperature T1 of the main heating platinum film can be obtained as:

[0073] T1=m(R1).

[0074] Where m() is the resistance-temperature characteristic function of the main heating platinum film.

[0075] Based on the same method, the heating power P2, resistance R2, and temperature T2 of the secondary heating platinum film can be obtained as follows:

[0076] P2=U2×I2.

[0077]

[0078] T2=n(R2).

[0079] Where n() is the resistance-temperature characteristic function of the secondary heating platinum film.

[0080] According to the obtained main and auxiliary heating film temperatures T1 and T2, the heat conduction heat flux Q of the main heating platinum film to the bottom surface can be calculated. down for:

[0081] Q down =f(T1,T2).

[0082] Among them, f() represents the mapping relationship between the heat conduction flow and the upper and lower surface temperatures. The theoretical basis is Fourier's law of heat conduction:

[0083]

[0084] In the formula, Q is the heat flow, λ is the thermal conductivity, dt / dx is the temperature gradient in the direction of heat conduction, and the negative sign indicates that the direction of heat transfer is opposite to the direction of temperature increase. According to Fourier's law of heat conduction, the heat flow is related to the temperature gradient and thermal conductivity, among which the temperature gradient is related to the temperature difference and the distance between the upper and lower surfaces.

[0085] In this embodiment, the temperature gradient is determined by the temperature difference (T1-T2) between the main heating platinum film and the auxiliary heating platinum film and the distance δ between the main heating platinum film and the auxiliary heating platinum film, and the thermal conductivity is the comprehensive thermal conductivity λ of the complex structure of the sensor.

[0086]

[0087] At this time, the convective heat transfer heat flow Q of the main heating platinum film to the fluid direction is effect for:

[0088] Q effect =P1-Qdown .

[0089] Based on Newton's law of cooling, the fluid reference temperature T f , the local convective heat transfer coefficient h can be obtained as:

[0090]

[0091] In the formula, m(U1 / I1) represents the resistance-temperature characteristic function of the main heating platinum film, n(U2 / I2) represents the resistance-temperature characteristic function of the auxiliary heating platinum film, and A is the area of ​​the main / auxiliary heating platinum film.

[0092] In summary, this application has the following technical effects:

[0093] This application can effectively solve the problem of measuring the temperature and convective heat transfer coefficient of convective heat transfer surfaces, especially complex surfaces, in complex environments (such as inside aircraft engine turbine blades). Through this method, the integrated test of temperature and convective heat transfer coefficient can be achieved without the need for cumbersome temperature field or heat flow measurements.

[0094] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0095] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A temperature and convection heat transfer coefficient integrated sensor, characterized in that: The test probe of the temperature and convection heat transfer coefficient integrated sensor comprises: a substrate, a main heating platinum film, a secondary heating platinum film, a lead, a wire and a conductive paste; The substrate is used to support a metal platinum thin film resistor structure; the metal platinum thin film resistor structure is composed of a main heating platinum film, an auxiliary heating platinum film, leads, wires and conductive paste; the metal platinum thin film resistor structure is a cylindrical structure; the main heating platinum film and the auxiliary heating platinum film are respectively located on the upper bottom surface and the lower bottom surface of the metal platinum thin film resistor structure; the lead is arranged in a vertical hole of the substrate, one end of the lead is connected to the main heating platinum film or the auxiliary heating platinum film, and the other end is connected to the wire; the conductive paste is used to fill the vertical hole of the substrate.

2. The integrated temperature and convection heat transfer coefficient sensor according to claim 1, characterized in that: The main heating platinum film adopts a noble metal platinum thin film resistor as the main heating platinum film material, and the thickness of the noble metal platinum thin film is 1 μm.

3. The integrated temperature and convection heat transfer coefficient sensor according to claim 1, characterized in that: The main heating platinum film and the auxiliary heating platinum film are both in the shape of two circles of symmetrical semicircles that are axially symmetrical to each other.

4. The temperature and convection heat transfer coefficient integrated sensor according to claim 1, characterized in that: The material selected for the substrate is alumina ceramics.

5. The integrated temperature and convection heat transfer coefficient sensor according to claim 1, characterized in that: The material of the lead wire is platinum-rhodium alloy or pure platinum.

6. A temperature testing method based on a temperature and convection heat transfer coefficient integrated sensor according to any one of claims 1 to 5, characterized in that: include: The secondary heating platinum film in the integrated temperature and convection heat transfer coefficient sensor is kept in an unpowered state, and a small current is passed through the main heating platinum film; Measure the current value I of the circuit where the main heating platinum film is located and the voltage value U across the main heating platinum film; According to the current value I and the voltage value U, the resistance value R of the main heating platinum film is calculated; According to the TR curve of the main heating platinum film, determine the temperature T of the main heating platinum film f .

7. A method for testing convective heat transfer coefficient based on a temperature and convective heat transfer coefficient integrated sensor according to any one of claims 1 to 5, characterized in that: include: Based on two regulated DC power supplies, voltage is applied to the primary and secondary heating platinum film resistors respectively; After reaching a steady state, determine the voltage U1 across the main heating platinum film resistor, the current I1 through the main heating platinum film resistor, the voltage U2 across the auxiliary heating platinum film resistor, and the current I2 through the auxiliary heating platinum film resistor; According to the voltage U1 across the main heating platinum film resistor and the current I1 passing through the main heating platinum film resistor, the heating power P1, the resistance R1 and the temperature T1 of the main heating film are calculated; According to the voltage U2 across the secondary heating platinum film resistor and the current I2 passing through the secondary heating platinum film resistor, the heating power P2, the resistance R2 and the temperature T2 of the secondary heating film are calculated; According to the temperature T1 of the main heating film and the temperature T2 of the auxiliary heating film, the heat flow Q from the main heating film to the bottom surface is calculated. down ; According to the heating power P1 of the main heating film and the heat flow Q from the main heating film to the bottom surface down , calculate the convective heat transfer heat Q from the main heating film to the fluid direction effect ; Based on Newton's cooling law, the temperature T of the measuring point is measured when the auxiliary heating platinum film is not energized and the main heating platinum film is energized with a small current. f , calculate the convection heat transfer coefficient h; the measuring point temperature T f It is determined based on the TR curve of the main heating platinum film by measuring the current value I of the circuit where the main heating platinum film is located and the voltage value U across the main heating platinum film.

8. The method for testing the convective heat transfer coefficient according to claim 7, characterized in that: The thermal conduction heat flow Q down The calculation formula is: Q down =f(T1,T2); Among them, f() represents the mapping relationship between the thermal conduction heat flux and the upper and lower surface temperatures.

9. The method for testing the convective heat transfer coefficient according to claim 7, characterized in that: The convection heat transfer quantity Q effect The calculation formula is: Q effect =P1-Q down 。 10. The method for testing the convective heat transfer coefficient according to claim 7, characterized in that: The calculation formula of the convective heat transfer coefficient h is: Among them, m(U1 / I1) represents the resistance-temperature characteristic function of the main heating platinum film, n(U2 / I2) represents the resistance-temperature characteristic function of the auxiliary heating platinum film, and A is the area of ​​the main / auxiliary heating platinum film.

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