Dynamic total temperature probe based on double-film platinum resistor and measuring method

Abstract

The invention belongs to the technical field of dynamic temperature testing, and particularly relates to a dynamic total temperature probe based on double film platinum resistors, which comprises a probe head, a probe support rod, two film platinum resistors and two lead holes. The head of the probe is in a semi-spherical shape and directly faces a main stream to form a vertical section, the two thin-film platinum resistors are arranged on the section along the axis of the probe, leads of the thin-film platinum resistors are led out through lead holes located behind the thin-film platinum resistors, a four-wire system connection mode is adopted, and a cylindrical surface of a supporting rod of the probe and the vertical section are in a Vitdosski curve shape. The calibration and measurement data processing method provided by the invention greatly improves the measurement frequency response and the measurement precision of the probe, is suitable for measuring the transient temperature fields of the inlet, the outlet and the interstage of the turbomachinery, can quickly and accurately measure the transient temperature change of the turbomachinery under different working conditions, and provides a technical means for the transient temperature measurement of the turbomachinery.

Description

Technical Field

[0001] The present invention belongs to the technical field of dynamic temperature testing, and specifically relates to a dynamic total temperature probe and a measurement method based on a double-thin film platinum resistor, which is suitable for measuring the transient temperature field at the inlet, outlet and between stages of a turbine. The core of the method is to quickly and accurately measure and monitor the transient temperature changes at the inlet, outlet and between stages of the turbine under different working conditions. Background Art

[0002] Temperature is an important thermodynamic parameter in the working process of the impeller. At present, how to quickly and accurately measure the transient temperature field in the field of impeller testing has become an important scientific problem that needs to be solved urgently. The internal flow of the impeller is complex and changeable when it is working, especially when the inlet, outlet and interstage positions are facing complex and high-speed rotation. Due to the mutual interference between the rotor and stator blades and the narrow flow channel, the internal flow presents non-uniform and asymmetric characteristics, and there are radial and circumferential vortex mixing. It has strong three-dimensionality and strong non-steadyness, which makes it very difficult to quickly and accurately obtain the change of the temperature field of the inlet, outlet and interstage of the impeller over time. Therefore, in order to quickly and accurately obtain the transient temperature field of the inlet, outlet and interstage of the impeller, it is necessary to develop more targeted testing methods.

[0003] For contact measurement methods, armored platinum resistors are often used to accurately obtain the temperature of the flow field for durability, reliability and accuracy considerations. During the operation of the impeller, the temperature field at the inlet, outlet and stage has a strong transient change characteristic, and the temperature changes in these areas are frequent and rapid. Although the existing armored platinum resistor temperature sensor can meet the temperature measurement accuracy requirements under static or quasi-static conditions, its low-frequency response characteristics make it difficult to accurately capture these transient temperature changes, and thus cannot meet the precise testing requirements for the complex transient temperature field inside the impeller. For transient temperature fields, there are existing thermocouple temperature sensors and hot wire temperature probes. Although thermocouple temperature sensors have a faster thermal response time than armored platinum resistor temperature sensors, the fine-wire thermocouple temperature sensor with the highest frequency response cannot fully meet the testing requirements of the transient temperature field at the inlet, outlet and stage of the impeller under special working conditions, and compared with armored platinum resistor temperature sensors, the accuracy of thermocouples is lower. During long-term use, thermocouples may increase measurement errors due to material aging and thermoelectric effect drift, and are easily affected by environmental factors. Hot-wire temperature probes have extremely fast thermal response time and can quickly capture transient changes in temperature and flow. Hot-wire temperature probes are usually very small and have high spatial resolution, but they are usually made of very thin metal wires. The manufacturing and maintenance costs of hot-wire temperature probes are high, and they are prone to breakage and damage. Their durability is poor, which increases the test cost and unreliability.

[0004] For non-contact measurement methods, infrared temperature measurement and optical fiber temperature measurement are commonly used. Infrared temperature measurement requires an optical entrance, and the optical path is limited by the complex structure inside the impeller. In addition, the measurement distance and the field of view of the infrared sensor will affect the measurement accuracy and resolution. Too far a distance or too large a field of view will lead to increased measurement errors. Fiber optic temperature measurement is expensive, and the installation and wiring of the fiber optic temperature measurement system are complicated. In addition, the optical fiber is easily affected by mechanical stress, bending, and physical damage during the rotation of the impeller, which will affect the measurement accuracy.

[0005] Therefore, in order to quickly and accurately obtain the transient temperature field at the inlet, outlet and between stages of the impeller, it is urgent to develop a dynamic total temperature probe that is fast, high-precision, resistant to airflow erosion, has little interference with the flow field, and can simultaneously measure the transient temperature field at the inlet, outlet and between stages of the impeller, so as to achieve accurate measurement of the dynamic temperature of the unsteady flow field and provide reliable measurement means and technical support for the high-performance design and optimization of impeller machinery. Summary of the invention

[0006] The present invention discloses a dynamic total temperature probe based on a double thin film platinum resistor, comprising a probe head, a probe support rod, two thin film platinum resistors, and two lead holes. The probe head is semi-spherical and forms a vertical section facing the mainstream. The two thin film platinum resistors are arranged along the probe axis on the section, and their leads are led out through the lead holes behind the thin film platinum resistors, using a four-wire connection method. The cylindrical surface of the probe support rod and the vertical section are in the shape of a Vidosinsky curve, and a circular pipe is opened inside the probe support rod along the axial direction.

[0007] In the calibration wind tunnel, a dynamic total temperature probe based on a double thin film platinum resistor is calibrated over a wide range. The calibration speed range is 0.1 Mach to 1.4 Mach, the deflection angle range is -80° to 80°, and the pitch angle range is -40° to 40°. During the wind tunnel test calibration, the temperature is measured simultaneously by using two thin film platinum resistors. The two thin film thermal resistors are provided with different constant currents by a signal generator. The two resistors have different initial temperatures, but have the same convective heat transfer surface heat transfer coefficient h. The ratio of the heat flux density of the two thin film platinum resistors under different working conditions can be obtained. The heat flux ratio is defined as C and satisfies the following equation:

[0008] q1=h(T t -T w1 )

[0009] q2=h(T t -T w2 )

[0010]

[0011] Where, q1, q2——heat flux density of thin film thermal resistor, unit W / m 2; Tw1, Tw2 - the temperature measured by the thin film thermal resistor, unit K; Tt - the total temperature of the calibration wind tunnel inflow, unit K. The ratio C of the heat flux density under different calibration conditions can be obtained by the above calibration method;

[0012] During the test measurement, when the incoming flow condition is known, the corresponding heat flux ratio C can be found from the calibration data. The total temperature T of the measured airflow can be calculated from the measured Tw1 and Tw2 data by the following formula: g :

[0013]

[0014] The present invention provides a dynamic total temperature probe based on a double-thin-film platinum resistor, and the technical problems to be solved are: first, the problem of insufficient accuracy of the existing dynamic temperature probe is solved; second, the problem that the existing dynamic temperature probe is limited by the low frequency response of the traditional dynamic temperature sensor is solved; third, the problem of durability of the existing dynamic temperature probe is solved.

[0015] The technical solution of the present invention is:

[0016] 1. A dynamic total temperature probe based on a double thin film platinum resistor, comprising a probe head (1), a probe support rod (2), an upper thin film platinum resistor (3), a lower thin film platinum resistor (4), and two lead holes (6) (7), characterized in that: the probe head (1) is semi-spherical, and the probe head (1) forms a vertical section facing the mainstream side; an upper lead hole (6) and a lower lead hole (7) are opened along the axis of the section, and the upper thin film platinum resistor (3) and the lower thin film platinum resistor (4) are installed respectively; the wires of the thin film platinum resistors are led out through the corresponding lead holes; the side surface of the probe support rod (2) is connected to the vertical section by a Vidosinski curve (5), and a circular pipe (8) is opened inside the probe support rod (2) along the axial direction.

[0017] 2. Probe head (1) The diameter d of the cylinder has a value range of 2 mm ≤ d ≤ 10 mm. The curved rotating body can be formed by rotating an arc line, a Vidosinski curve or a conic curve. The curved design helps the airflow to smoothly bypass the probe head, avoid turbulence and eddy currents, and effectively reduce the impact of the probe on the flow field, thereby improving the measurement accuracy and ensuring the accuracy of the measurement.

[0018] 3. The probe head (1) is made of insulating thermal insulation material to reduce the thermal conductivity error during measurement and improve the measurement accuracy and frequency response of the probe.

[0019] 4. The probe head (1) is a cylindrical body that forms a vertical section facing the mainstream side; the thickness of the section is y, and the value range of y is 1 mm ≤ y ≤ 5 mm; the height of the section along the axis is z, and the value range of z is 10 mm ≤ z ≤ 15 mm. The section can better stop the airflow and improve the measurement accuracy. The section provides a plane for the installation of the thin film platinum resistor, making the fixing and lead-in more convenient and reliable.

[0020] 5. An upper lead hole (6) and a lower lead hole (7) are provided on the vertical section along the axis. The two lead holes are equal in size. The diameter of the lead holes is b, and the value range of b is 0.2 mm ≤ y ≤ 1 mm. The center distance is x, and the value range of x is 0.5 mm ≤ y ≤ 1.5 mm.

[0021] 6. The upper thin-film platinum resistor (3) and the lower thin-film platinum resistor (4) are respectively installed in the upper lead hole (6) and the lower lead hole (7). The upper thin-film platinum resistor (3) and the lower thin-film platinum resistor (4) are made of the same material and size. The upper thin-film platinum resistor (3) and the lower thin-film platinum resistor (4) are both miniature four-wire thin-film platinum resistors with a length of 1 mm to 3 mm, a width of 0.5 mm to 1.5 mm, and a thickness of 0.05 mm to 0.2 mm. The four-wire measurement can effectively eliminate the influence of the lead resistance on the measurement result, improve the measurement accuracy, and ensure the stability and accuracy of the data.

[0022] 7. The side surface of the probe support rod (2) and the vertical section are connected by a Vidosinski curve (5) to reduce the interference of the airflow on the probe surface, so that the measuring flow field fluid can bypass the probe more smoothly. This uniform fluid flow allows heat to be transferred more evenly, thereby reducing the risk of local overheating, reducing the interference of the probe on the measuring flow field, and improving the measurement accuracy.

[0023] 8. A circular pipe (8) is opened inside the probe support rod (2) along the axial direction. The diameter of the circular pipe is a, and the value range of a is 1 mm≤a≤8 mm. The thin film platinum resistance wire passes through the lead hole and is connected to the external collection equipment through the circular pipe (8).

[0024] The present invention provides a dynamic total temperature probe based on a double-thin-film platinum resistor, which has the following beneficial effects:

[0025] Beneficial effect 1: The present invention can effectively improve the measurement accuracy after being calibrated in a standard wind tunnel. Through a precise calibration process, the response of the thin film platinum resistor at different temperature points is ensured to be accurate and reliable, and during measurement, only the incoming flow parameters need to be obtained without understanding the physical properties of the measured medium.

[0026] Beneficial effect two: The present invention is based on the design of a double thin film platinum resistor. The two thin film platinum resistors compensate each other during temperature measurement. The temperature analysis transfer function coefficient is obtained through calibration experiments, and the temperature measurement transfer function of the double thin film platinum resistor dynamic total temperature probe is constructed. The total airflow temperature of the measured flow field is reconstructed, which can greatly improve the frequency response of the dynamic total temperature probe.

[0027] Beneficial effect three: The probe design of the present invention has a self-positioning function, and the vertical section of the probe head is used as a positioning reference, making the installation of the probe simpler and faster. There is no need to rotate the probe during measurement, which reduces the error that may be caused by improper operation. It has a wide range of applications and is suitable for accurate measurement of non-periodic flow fields.

[0028] Beneficial effect 4: The sensing part of the thin film platinum resistor of the present invention is located on the vertical section of the probe, which is not affected by the structure of the probe itself and can directly sense the temperature change of the incoming flow. The thin film platinum resistor can respond to the pulsation information of the flow field in the first time, ensuring the authenticity of the data and the high precision of the measurement, especially showing extremely high response efficiency in the measurement of dynamic temperature fields.

[0029] Beneficial effect 5: The probe head adopts a compact "I"-shaped structure design with small size and vertical arrangement of double thin-film platinum resistors, which greatly improves the spatial resolution of the probe. The head profile is designed with curve optimization to allow the airflow to pass through, reducing the interference of boundary layer separation on the measurement. It is particularly suitable for high-precision measurement of the inlet, outlet and stage of the impeller, and shows excellent performance in complex aerodynamic environments.

[0030] Beneficial effect 6: The side of the probe support adopts the Vidosinsky curve design, which optimizes the aerodynamic performance and makes the fluid flow more smoothly.

[0031] The probe is smoothly bypassed, significantly reducing the impact and interference of the airflow on the probe. By reducing the generation of fluid turbulence and eddy currents, the phenomenon of local overheating on the probe surface is reduced, ensuring the uniformity of the temperature measurement process. At the same time, the thermal conductivity of the probe support rod is effectively reduced, and the influence of the probe material itself on heat conduction is reduced, thereby avoiding possible temperature deviations during the measurement process. This design not only improves the dynamic response speed of the probe, but also significantly improves the measurement accuracy and stability, so that good measurement performance can be maintained even in complex fluid environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of a dynamic total temperature probe based on a double-thin film platinum resistor in an embodiment of the present invention.

[0033] Figure 2 yes Figure 1 A-section view.

[0034] Figure 3 yes Figure 1 Side view of.

[0035] Figure 4 yes Figure 1 Top view of the .

[0036] Figure 5 yes Figure 4 B-direction cross-sectional view.

[0037] Wherein: 1-probe head, 2-probe support rod, 3-upper thin film thermal resistor, 4-lower thin film thermal resistor, 5-Vidosinsky curve, 6-upper lead hole, 7-lower lead hole, 8-circular pipe. DETAILED DESCRIPTION

[0038] The present invention is described in detail below in conjunction with the accompanying drawings and specific implementation examples so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0039] like Figures 1 to 5 The present invention shows a dynamic total temperature probe based on a double thin film platinum resistor, which is composed of a probe head (1), a probe support rod (2), an upper thin film platinum resistor (3), a lower thin film platinum resistor (4), and two lead holes (6) (7), and is characterized in that: the probe head (1) is semi-spherical, and the probe head (1) is directly opposite to the mainstream side to form a vertical section; an upper lead hole (6) and a lower lead hole (7) are opened along the axis on the section, and the upper thin film platinum resistor (3) and the lower thin film platinum resistor (4) are installed respectively; the wires of the thin film platinum resistors are led out through the corresponding lead holes; the side surface of the probe support rod (2) is connected to the vertical section by a Vidosinski curve (5), and a circular pipe (8) is opened inside the probe support rod (2) along the axial direction.

[0040] The diameter of the cylindrical body of the probe head (1) is 10 mm, and the curved rotating body is formed by rotating along a circular arc curve. The curved design helps the airflow to smoothly bypass the probe head, avoiding turbulence and eddy currents, and can effectively reduce the impact of the probe on the flow field, improve measurement accuracy, and ensure measurement accuracy.

[0041] The cylindrical body of the probe head (1) forms a vertical section facing the mainstream side; the thickness of the section is 2 mm; the height of the section along the axis is 10 mm. The section can better stop the airflow and improve the measurement accuracy. The section provides a plane for the installation of the thin film platinum resistor, making the fixing and wiring more convenient and reliable.

[0042] The probe head (1) is made of insulating heat-insulating material, which reduces the thermal conductivity error during measurement and improves the measurement accuracy and frequency response of the probe.

[0043] An upper lead hole (6) and a lower lead hole (7) are provided on the vertical section along the axis. The two lead holes are of equal size, and the diameter of the lead holes is 0.5 mm. The center distance is 0.7 mm.

[0044] The upper thin-film platinum resistor (3) and the lower thin-film platinum resistor (4) are respectively installed in the upper lead hole (6) and the lower lead hole (7). The upper thin-film platinum resistor (3) and the lower thin-film platinum resistor (4) are made of the same material and have the same size. The upper thin-film platinum resistor (3) and the lower thin-film platinum resistor (4) are both miniature four-wire thin-film platinum resistors with a length of 1 mm, a width of 0.6 mm, and a thickness of 0.05 mm. The four-wire measurement can effectively eliminate the influence of the lead resistance on the measurement result, improve the measurement accuracy, and ensure the stability and accuracy of the data.

[0045] The side surface of the probe support rod (2) and the vertical section are connected by a Vidosinski curve (5), which reduces the interference of the airflow on the probe surface and allows the fluid in the measurement flow field to bypass the probe more smoothly. This uniform fluid flow allows heat to be transferred more evenly, thereby reducing the risk of local overheating, reducing the interference of the probe on the measurement flow field, and improving the measurement accuracy.

[0046] A circular pipe (8) is opened inside the probe support rod (2) along the axial direction. The diameter of the circular pipe is 8 mm. The thin-film platinum resistance wire passes through the lead hole and is connected to the external collection equipment through the circular pipe (8).

[0047] A dynamic total temperature probe based on a double thin film platinum resistor is calibrated over a wide range in a calibration wind tunnel. The calibration speed range is 0.1 Mach to 1.4 Mach, with an interval of 0.1 Mach, the deflection angle range is -80° to 80°, with an interval of 5°, and the pitch angle range is -40° to 40°, with an interval of 5°. During the wind tunnel test calibration, the temperature is measured simultaneously by using two thin film platinum resistors. The two thin film thermal resistors are provided with different constant currents by a signal generator. The two resistors have different initial temperatures, but have the same convective heat transfer surface heat transfer coefficient h. The ratio of the heat flux density of the two thin film platinum resistors under different working conditions can be obtained. The heat flux ratio is defined as C and satisfies the following equation:

[0048] q1=h(T t -T w1 )

[0049] q2=h(T t -T w2 )

[0050]

[0051] Where, q1, q2——heat flux density of thin film thermal resistor, unit W / m 2; Tw1, Tw2 - the temperature measured by the thin film thermal resistor, unit K; Tt - the total temperature of the calibration wind tunnel inflow, unit K. The ratio C of the heat flux density under different calibration conditions can be obtained by the above calibration method;

[0052] During the test measurement, when the incoming flow condition is known, the corresponding heat flux ratio C can be found from the calibration data. The total temperature T of the measured airflow can be calculated from the measured Tw1 and Tw2 data by the following formula: g :

[0053]

[0054] The present invention is based on a dynamic total temperature probe with double thin film platinum resistors. The temperature analytical transfer function coefficients are obtained through calibration experiments, the temperature measurement transfer function of the dynamic total temperature probe with double thin film platinum resistors is constructed, and the total airflow temperature of the measured flow field is reconstructed, which can greatly improve the frequency response and measurement accuracy of the dynamic total temperature probe.

Claims

1. A dynamic total temperature probe based on a double thin film platinum resistor, comprising a probe head (1), a probe support rod (2), an upper thin film platinum resistor (3), a lower thin film platinum resistor (4), and two lead holes (6) (7), characterized in that: The probe head (1) is semi-spherical, and the probe head (1) forms a vertical section facing the mainstream side; an upper lead hole (6) and a lower lead hole (7) are opened on the section along the axis, and an upper thin film platinum resistor (3) and a lower thin film platinum resistor (4) are installed respectively; the wires of the thin film platinum resistor are led out through the corresponding lead holes; the side surface of the probe support rod (2) and the vertical section are connected by a Vidosinski curve (5), and a circular pipe (8) is opened inside the probe support rod (2) along the axial direction; The diameter d of the cylinder of the probe head (1) is in the range of 2 mm ≤ d ≤ 10 mm. The curved rotating body can be formed by rotating a circular arc, a Vidosinsky curve or a conic curve. The curved design helps the airflow to smoothly bypass the probe head, avoids turbulence and eddy currents, and can effectively reduce the influence of the probe on the flow field, improve the measurement accuracy, and ensure the accuracy of the measurement. The cylinder of the probe head (1) forms a vertical section facing the mainstream side; the thickness of the section is y, and the value range of y is 1 mm ≤ y ≤ 5 mm; the height of the section along the axis is z, and the value range of z is 10 mm ≤ z ≤ 15 mm. The section can better stop the airflow and improve the measurement accuracy. The section provides a plane for the installation of the thin film platinum resistor, making the fixing and lead-in more convenient and reliable. The probe head (1) is made of insulating heat-insulating material to reduce the thermal conductivity error during measurement and improve the measurement accuracy and frequency response of the probe; An upper lead hole (6) and a lower lead hole (7) are formed on the vertical section along the axis. The two lead holes are equal in size. The lead hole diameter is b, and the value range of b is 0.2 mm ≤ y ≤ 1 mm. The center distance is x, and the value range of x is 0.5 mm ≤ y ≤ 1.5 mm. The upper thin-film platinum resistor (3) and the lower thin-film platinum resistor (4) are respectively installed in the upper lead hole (6) and the lower lead hole (7). The upper thin-film platinum resistor (3) and the lower thin-film platinum resistor (4) are made of the same material and have the same size. The upper thin-film platinum resistor (3) and the lower thin-film platinum resistor (4) are both miniature four-wire thin-film platinum resistors with a length of 0.5 mm to 3 mm, a width of 0.1 mm to 1.5 mm, and a thickness of 0.01 mm to 0.2 mm. The four-wire measurement can effectively eliminate the influence of the lead resistance on the measurement result, improve the measurement accuracy, and ensure the stability and accuracy of the data. The side surface of the probe support rod (2) and the vertical section are connected by a Vidosinski curve (5), which reduces the interference of the airflow on the probe surface and allows the fluid in the measurement flow field to bypass the probe more smoothly. This uniform fluid flow allows heat to be transferred more evenly, thereby reducing the risk of local overheating, reducing the interference of the probe on the measurement flow field, and improving the measurement accuracy. A circular pipe (8) is opened inside the probe support rod (2) along the axial direction, the diameter of the circular pipe is a, and the value range of a is 1 mm≤a≤8 mm. The thin film platinum resistance wire passes through the lead hole and is connected to the external collection equipment through the circular pipe (8); The present invention proposes a data processing method based on a dynamic total temperature probe based on a double thin film platinum resistor. A dynamic total temperature probe based on a double thin film platinum resistor is calibrated over a wide range in a calibration wind tunnel. The calibration speed range is 0.1 Mach to 1.4 Mach, the deflection angle range is -80° to 80°, and the pitch angle range is -40° to 40°. During the wind tunnel test calibration, two thin film platinum resistors are used to measure the temperature simultaneously. The two thin film thermal resistors are provided with different constant currents by a signal generator. The two resistors have different initial temperatures but have the same convective heat transfer surface heat transfer coefficient h. The ratio of the heat flux densities of the two thin film platinum resistors under different working conditions can be obtained. The ratio of the heat flux densities is defined as C and satisfies the following equation: q1=h(T t -T w1 ) q2=h(T t -T w2 ) Where, q1, q2——heat flux density of thin film thermal resistor, unit W / m 2 ; Tw1, Tw2 - the temperature measured by the thin film thermal resistor, unit K; Tt - the total temperature of the calibration wind tunnel inflow, unit K. The ratio C of the heat flux density under different calibration conditions can be obtained by the above calibration method; During the test measurement, when the incoming flow condition is known, the corresponding heat flux ratio C can be found from the calibration data. The total temperature T of the measured airflow can be calculated from the measured Tw1 and Tw2 data by the following formula: g : The present invention is based on a dynamic total temperature probe with double thin film platinum resistors. The temperature analysis transfer function coefficient is obtained through calibration experiments, the temperature measurement transfer function of the dynamic total temperature probe with double thin film platinum resistors is constructed, and the total airflow temperature of the measured flow field is reconstructed. The frequency response and measurement accuracy of the dynamic total temperature probe can be greatly improved. During measurement, only the incoming flow parameters need to be obtained, and there is no need to understand the physical properties of the measured medium.

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