A temperature and convection heat transfer coefficient integrated sensor and its testing method

Abstract

This application discloses an integrated temperature and convective heat transfer coefficient sensor and its testing method, relating to the fields of aviation technology and thermal physics technology. The sensor includes a substrate, a primary heating platinum film, a secondary heating platinum film, leads, wires, 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 the primary heating platinum film, the secondary heating platinum film, leads, wires, and a conductive paste. The metal platinum thin film resistor structure is a cylindrical structure. The primary heating platinum film and the secondary heating platinum film are located on the upper and lower bottom surfaces of the metal platinum thin film resistor structure, respectively. The leads are arranged in vertical holes in the substrate, with one end of the leads connected to the primary heating platinum film or the secondary heating platinum film and the other end connected to the wires. The conductive paste is used to fill the vertical holes in the substrate. The device based on this application can achieve accurate measurement of multiple parameters.

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 testing method thereof. Background Art

[0002] In recent years, aircraft engines have been gradually developing towards high flow ratios, high thrust-to-weight ratios, and high turbine inlet temperatures. Taking turbine inlet temperature as an example, the typical value for currently in-service fourth-generation aircraft engines is 1977K, and the typical value for future fifth-generation aircraft engines will be no less than 2250K. Because the melting points of materials used in current turbine components are lower than these typical values, ensuring the overall safety and performance of the aircraft engine requires comprehensive thermal design and thermal protection. Furthermore, with the continuous development of aircraft engines, the rate of increase in turbine inlet temperature is significantly higher than the melting point of new materials, placing higher demands on thermal protection technology for aircraft engine hot-end components. As an essential core parameter in the thermal design of aircraft engine hot-end components, accurate measurement of the convective heat transfer coefficient is crucial to component performance and service life. However, the harsh operating environment of aircraft engine hot-end components, represented by the turbine disk, often involves high temperatures, high speeds, and high heat fluxes, making accurate measurement of the surface convective heat transfer coefficient extremely difficult.

[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 and heat transfer between fluid and solid cannot be separated from this parameter. Currently, there are two more mainstream methods for measuring the convective heat transfer coefficient. One is to use thermocouples 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, thereby obtaining 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. Small temperature measurement errors 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, particularly in traditional construction and machining industries, for measuring convective heat transfer coefficients and correcting for heat loss. However, due to its low maximum operating temperature and the need for on-site calibration, it is difficult to measure the convective heat transfer coefficient on the surfaces of aircraft engine hot-end components. Consequently, a sensor capable of accurately measuring the convective heat transfer coefficient on aircraft engine hot-end components is lacking. 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 convective heat transfer coefficient sensor, comprising:

[0007] Substrate, main heating platinum film, auxiliary heating platinum film, lead, 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, 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.

[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 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 aforementioned integrated temperature and convective heat transfer coefficient sensor, comprising:

[0014] 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.

[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, the temperature T of the main heating platinum film is determined. f .

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

[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 law of cooling, 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 heat conduction 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 an integrated temperature and convective heat transfer coefficient sensor and its testing method. The sensor includes a substrate, a primary heating platinum film, a secondary heating platinum film, leads, wires, 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 the primary heating platinum film, the secondary heating platinum film, leads, wires, and a conductive paste. The metal platinum thin film resistor structure is cylindrical. The primary heating platinum film and the secondary heating platinum film are located on the upper and lower bottom surfaces of the metal platinum thin film resistor structure, respectively. The leads are disposed in vertical holes in the substrate, with one end of the leads connected to the primary heating platinum film or the secondary heating platinum film and the other end connected to the wires. The conductive paste is used to fill the vertical holes in the substrate. The device based on the present application can achieve accurate temperature measurement and real-time monitoring of the convective 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 following briefly introduces the drawings required for use in the embodiments. 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 creative work.

[0037] Figure 1 This is a schematic diagram of the structure of an integrated temperature and convective 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 this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

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

[0041] Example 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 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, 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.

[0045] In this embodiment, the cylindrical test probe of the integrated temperature and convective heat transfer coefficient sensor has an overall diameter of no more than 4 mm and a height of no more than 3 mm.

[0046] Among them, such as Figure 1 As shown, the test probe substrate is the carrier for the deposition of the metal platinum thin film resistor structure. This embodiment uses a ceramic material as the substrate material. Alumina ceramic can be used as the substrate material because it can withstand high temperatures exceeding 850°C, has good insulation and acid and alkali resistance, and has a thermal expansion coefficient close to that of platinum metal.

[0047] A precious metal platinum thin film resistor is used as the primary heating film material, serving as both a heating element and a temperature sensing element. The convective heat transfer coefficient at the measurement point is calculated based on the platinum resistor's heating power and resistance value at 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 heat conduction. Therefore, this embodiment reduces the heat loss from the bottom and sides by adding a secondary 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 adopts a lead-base integrated structure design. The lead is buried in the vertical hole of the ceramic part through sintering and other processes. One end is directly connected to the thin film at the pin through the coating process to achieve a high-strength and reliable connection, completing the input and output of electrical signals between the film and the lead; the other end is at the corner of the inner hole 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℃), the lead material of the thin film platinum resistor is selected to be 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 to connect to the pure platinum lead to improve 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 while maintaining the uniformity of the temperature distribution of the main and auxiliary heating films. For the main and auxiliary heating platinum films, two circles of symmetrical semicircular lines are used. The coating thickness is designed to be 0.5μm, the coating width is 0.1mm, the adjacent spacing is 0.05mm, and the total length is 69.3mm. The ceramic surface after coating is as follows Figure 2 shown.

[0052] Example 2

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

[0054] Step 201: 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 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] Example 3

[0059] This embodiment provides a method for testing the convective heat transfer coefficient based on the aforementioned integrated temperature and convective heat transfer coefficient 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, resistance R1 and 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 based on the temperature T1 of the main heating film and the temperature T2 of the auxiliary heating film. down .

[0065] Step 306: Based on 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 .

[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 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.

[0067] The convective heat transfer coefficient measurement of the novel integrated temperature and convective heat transfer coefficient sensor disclosed in this embodiment is primarily based on Newton's cooling equation. During the test, two regulated DC power supplies simultaneously applied voltage to the primary and secondary platinum film resistors. After the system reached a steady state, the voltage across the primary resistor (U1) and the current through it (I1) were read, as were the voltage across the secondary resistor (U2) and the current through it (I2).

[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 at this time 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 flow Q of the main heating platinum film to the bottom surface can be calculated. down for:

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

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

[0083]

[0084] Where Q is the heat flux, λ is the thermal conductivity, and dt / dx is the temperature gradient in the direction of heat conduction. The negative sign indicates that the direction of heat transfer is opposite to the direction of temperature increase. Fourier's law of heat conduction shows that the heat flux is related to the temperature gradient and thermal conductivity, with the temperature gradient being 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] Wherein, 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 effectively addresses the problem of measuring the temperature and convective heat transfer coefficient of convective heat transfer surfaces, particularly complex surfaces, in complex environments (e.g., inside aircraft engine turbine blades). This method eliminates the need for tedious temperature field or heat flow measurements, enabling integrated testing of temperature and convective heat transfer coefficients.

[0094] The technical features of the above embodiments can 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 document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may 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 integrated temperature and convection heat transfer coefficient sensor comprises: a substrate, a main heating platinum film, a secondary heating platinum film, a lead, a wire and a conductive paste; The main heating platinum film adopts precious metal platinum thin film resistor as the main heating platinum film material; the main heating platinum film and the auxiliary heating platinum film are both in the shape of two symmetrical semicircles that are axially symmetrical to each other; the material selected for the substrate is alumina ceramic; 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, 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.

2. The integrated temperature and convection heat transfer coefficient sensor according to claim 1, characterized in that: The thickness of the noble metal platinum film is 1 μm.

3. 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.

4. A temperature testing method based on a temperature and convection heat transfer coefficient integrated sensor according to any one of claims 1 to 3, 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; Calculate the resistance R of the main heating platinum film based on the current value I and the voltage value U; According to the TR curve of the main heating platinum film, the temperature T of the main heating platinum film is determined. f .

5. A method for testing the convective heat transfer coefficient based on the temperature and convective heat transfer coefficient integrated sensor according to any one of claims 1 to 3, 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 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; Calculate the heating power P1, resistance R1 and 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; Calculate the heating power P2, resistance R2 and 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; 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 law of cooling, 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; 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 heat conduction flux and the upper and lower surface temperatures; The convection heat transfer heat Q effect The calculation formula is: Q effect =P1-Q down ; 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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