A thin-film platinum resistance dynamic total temperature probe for measuring transonic flow fields

Abstract

The application belongs to the technical field of dynamic temperature test, and particularly relates to a thin-film platinum resistance dynamic total temperature probe for measuring transonic flow field, which comprises a probe head, a probe support rod, a thin-film platinum resistance, a lead hole and a circular pipeline. The probe head is a wedge-top double-arc prism structure, a thin-film platinum resistance temperature sensor is arranged at a sharp split, the thin-film platinum resistance lead is led out through the lead hole and the circular pipeline and connected with an external acquisition device, the windward surface of the probe head comprises a wedge-top inclined surface, a left side surface and a right side surface during measurement, and the leeward surface is a cylindrical surface. The calibration and measurement data processing method provided by the application greatly improves the measurement frequency response and measurement accuracy of the probe, is suitable for measuring the transient temperature field of the inlet, outlet and inter-stage transonic flow field of a turbomachine, can quickly capture the transient temperature change information of the turbomachine under different working conditions, and provides an efficient and accurate measurement method for the transonic unsteady flow field parameters of the turbomachine experiment.

Description

Technical Field

[0001] This invention belongs to the field of dynamic temperature testing technology and relates to a dynamic temperature measurement device for transonic unsteady flow fields. Specifically, it relates to a thin-film platinum resistance dynamic total temperature probe for measuring transonic flow fields, which is suitable for testing transonic three-dimensional dynamic flow fields at the inlet, outlet, and interstage of turbomachinery. Background Technology

[0002] Temperature is a crucial thermodynamic parameter during turbomachinery operation. Currently, the rapid and accurate measurement of transient temperature fields in turbomachinery testing remains a critical scientific challenge. During high-speed operation, the core flow field of a turbomachinery is often in a transonic flow state. In this transonic flow field, shock waves cause rapid changes in pressure and temperature. Due to complex flow phenomena such as rotor-stator interference and vortex mixing, the transonic flow at the inlet, outlet, and interstages of turbomachinery exhibits three-dimensionality, non-uniformity, asymmetry, and strong unsteadiness, making the testing of its internal flow field extremely difficult. Measuring the temperature of high-frequency pulsating flow fields, in particular, has always been a key and challenging area requiring breakthroughs. Currently, mature testing methods exist for pressure changes in transonic flow fields. Therefore, to enhance the understanding of transonic flow fields in turbomachinery and master the temperature information of the three-dimensional dynamic transonic flow fields at the inlet, outlet, and interstages, it is essential to develop measurement methods for the dynamic temperature of transonic flow fields.

[0003] Currently, small inertial thermocouples and swath-type hot wires are commonly used to test the dynamic temperature of flow fields. However, existing small inertial thermocouple dynamic temperature sensors have low frequency response; even using the fine-wire thermocouple temperature sensor with the highest frequency response still cannot meet the requirements for measuring the three-dimensional dynamic flow field at the inlet, outlet, and interstage of transonic flow fields in turbomachinery. Furthermore, small inertial thermocouples are easily affected by environmental factors and suffer from material aging and thermoelectric effect drift after prolonged use. Swath-type hot wire temperature probes have extremely fast thermal response times, enabling them to quickly capture transient changes in flow field pressure and temperature. However, swallow-type hot wire temperature probes are typically made of very fine metal wires, resulting in high manufacturing and maintenance costs, and they are prone to breakage and damage, increasing testing costs and unreliability.

[0004] Therefore, to rapidly and accurately obtain the three-dimensional dynamic flow field temperature information of the inlet, outlet, and interstage transonic flow fields of turbomachinery, there is an urgent need to develop a dynamic total temperature probe that is fast, resistant to airflow erosion, durable, has minimal interference with the flow field, and can measure the three-dimensional transient temperature field of the inlet, outlet, and interstage transonic flow fields of turbomachinery. This probe will enable accurate measurement of the dynamic temperature of unsteady flow fields, providing a reliable measurement method and technical support for enhancing the understanding of the inlet, outlet, and interstage transonic flow fields of turbomachinery and for high-performance design of turbomachinery. Summary of the Invention

[0005] This invention belongs to the field of dynamic temperature testing technology, specifically relating to a thin-film platinum resistance dynamic total temperature probe for measuring transonic flow fields. The probe includes a probe head, a probe support, a thin-film platinum resistance thermometer, a lead hole, and a circular tube. The probe head has a wedge-shaped double-arc prism structure, with a thin-film platinum resistance temperature sensor mounted at the wedge. The thin-film platinum resistance thermometer wires are led out through the lead hole and the circular tube to connect to an external data acquisition device. During measurement, the windward side of the probe head includes the wedge-shaped slope, the left side, and the right side, while the leeward side is a cylindrical surface.

[0006] A wide-range calibration was performed in a wind tunnel for a thin-film platinum resistance thermometer (PTT) dynamic total temperature probe used to measure transonic flow fields. The calibration speed range was Mach 0.8 to Mach 2, the deflection angle range was -60° to 60°, and the pitch angle range was -30° to 30°. During the wind tunnel calibration, temperature measurements were performed simultaneously using two thin-film PTTs. The two PTTs were supplied with different constant currents by a signal generator. The two PTTs had different initial temperatures but the same convective heat transfer surface heat transfer coefficient h. The ratio of the heat flux densities of the two PTTs under different operating conditions was obtained. The ratio of the heat flux densities was defined as B and satisfied the following equation:

[0007] q1=h(T t -T w1 )

[0008] q2=h(T t -T w2 )

[0009]

[0010] In the formula, q1 and q2 represent the heat flux density of the thin-film platinum resistance thermometer, in W / m³. 2 Tw1, Tw2 — Temperature measured by thin-film platinum resistance thermometer, in K; Tt — Total incoming flow temperature of the calibration wind tunnel, in K. The ratio B of heat flux density under different calibration conditions can be obtained through the above calibration method.

[0011] During the test measurement, under known incoming flow conditions, the corresponding heat flux density ratio B can be obtained from the calibration data. Using the measured Tw1 and Tw2 data, the total temperature T of the measured airflow can be calculated using the following formula. g :

[0012]

[0013] This invention provides a thin-film platinum resistance dynamic total temperature probe for measuring transonic flow fields. The technical problems it addresses are: first, it solves the problem of the low frequency response of existing dynamic temperature probes due to the limitations of traditional dynamic temperature sensors; second, it solves the durability problem of existing dynamic temperature probes.

[0014] The technical solution of this invention is:

[0015] 1. A dynamic total temperature probe for measuring transonic flow field using thin-film platinum resistance thermometers, comprising a probe head (1), a probe support (2), an upper thin-film platinum resistance thermometer (3), a lower thin-film platinum resistance thermometer (4), a lead hole (5), and a circular pipe (6), characterized in that: the probe head (1) is a wedge-shaped double-arc prism structure, with an upper thin-film platinum resistance thermometer (3) and a lower thin-film platinum resistance thermometer (4) mounted at the wedge, and the wires of the upper thin-film platinum resistance thermometer (3) and the lower thin-film platinum resistance thermometer (4) being led out through the lead hole (5) and the circular pipe (6) to connect with an external data acquisition device.

[0016] 2. The windward side of the probe head (1) includes the wedge-shaped inclined surface, the symmetrical left side and right side, and the leeward side is the rear cylindrical surface; the angle between the left side and the right side of the probe head (1) is 26° to 78°.

[0017] 3. The leading edge of the probe head (1) at the junction of the left and right sides has an angle of 32° to 56° with the wedge top slope. The probe head is made of heat-insulating material to reduce heat transfer error during measurement and improve probe frequency response and measurement accuracy.

[0018] 4. The upper thin-film platinum resistance (3) and the lower thin-film platinum resistance (4) are miniature four-wire thin-film platinum resistances, which are installed at the wedge of the probe head (1). The length of the thin-film platinum resistance is 0.5 mm to 3 mm, the width is 0.1 mm to 1.5 mm, and the thickness is 0.01 mm to 0.2 mm. The four-wire measurement can effectively eliminate the influence of lead resistance on the measurement results, improve the measurement accuracy, and ensure the stability and accuracy of the data.

[0019] 5. The distance between the upper thin-film platinum resistance (3) and the lower thin-film platinum resistance (4) is x, and the value of x is 0.2 mm ≤ x ≤ 1 mm;

[0020] 6. A lead hole (5) is opened at the junction of the left and right sides of the probe head (1). The lead hole (5) is connected to the circular pipe (6). The diameter of the lead hole is b, and the value of b is 0.2 mm ≤ b ≤ 1 mm.

[0021] 7. The distance between the center of the thin-film platinum resistance (3) and the lowest point of the wedge slope is 1 mm to 3 mm.

[0022] 8. The probe support rod (2) is a columnar structure, which can be a cylinder or a triangular prism. It has a circular channel (6) inside. The diameter of the circular channel (6) is a, and the value of a is 1 mm ≤ a ≤ 8 mm.

[0023] 9. The upper thin-film platinum resistance (3) and the lower thin-film platinum resistance (4) wires are led out from the probe tail through the lead hole (5) and the circular tube (6).

[0024] This invention provides a thin-film platinum resistance dynamic total temperature probe for measuring transonic flow fields, which has the following beneficial effects:

[0025] Benefit 1: This invention, calibrated in a standard wind tunnel, effectively improves measurement accuracy. The precise calibration process ensures accurate and reliable response of the thin-film platinum resistance thermometer at different temperature points, and only the incoming flow parameters are needed during measurement; knowledge of the physical properties of the measured medium is not required.

[0026] Second beneficial effect: This invention is based on the design of a double thin-film platinum resistance thermometer. The two thin-film platinum resistance thermometers compensate for each other during temperature measurement. The temperature analytical transfer function coefficient is obtained through calibration experiments, and the temperature transfer function of the dynamic total temperature probe of the double thin-film platinum resistance thermometer is constructed. The total temperature of the airflow in the measured flow field is reconstructed, which can greatly improve the frequency response of the dynamic total temperature probe.

[0027] Benefit 3: The probe head structure of this invention is simple and compact. The wedge-shaped double-arc prism structure is suitable for transonic flow fields, helping to reduce flow separation and reattachment during flow field measurement, ensuring the smoothness and continuity of the flow. The wedge-shaped double-arc prism structure can form stable shock waves and diffusion waves in transonic flow fields, making the measured flow field characteristics more accurate and predictable. The wedge design helps to reduce shock wave interference, thereby obtaining more accurate flow field temperature information. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of a thin-film platinum resistance dynamic total temperature probe for measuring transonic flow field in an embodiment of the present invention.

[0029] Figure 2 yes Figure 1 Top view.

[0030] Figure 3 yes Figure 1 Sectional view and enlarged view along direction A.

[0031] Figure 4 yes Figure 1 Sectional view along direction B.

[0032] Figure 5 yes Figure 1 Side view.

[0033] The components are: 1-probe head, 2-probe support, 3-upper thin-film platinum resistance, 4-lower thin-film platinum resistance, 5-lead hole, and 6-circular tube. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments, 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 explicit definition of the scope of protection of the present invention.

[0035] like Figures 1-5 The image shows a dynamic total temperature probe for measuring transonic flow field using a thin-film platinum resistance thermometer. It consists of a probe head (1), a probe support (2), an upper thin-film platinum resistance thermometer (3), a lower thin-film platinum resistance thermometer (4), a lead hole (5), and a circular pipe (6). The probe head (1) is a wedge-shaped double-arc prism structure. The upper thin-film platinum resistance thermometer (3) and the lower thin-film platinum resistance thermometer (4) are mounted at the wedge. The wires of the upper thin-film platinum resistance thermometer (3) and the lower thin-film platinum resistance thermometer (4) are led out through the lead hole (5) and the circular pipe (6) to connect with external data acquisition equipment.

[0036] The windward side of the probe head (1) includes a wedge-shaped inclined surface, a symmetrical left side and a right side, and a rear cylindrical surface on the leeward side; the angle between the left side and the right side of the probe head (1) is 45°.

[0037] The leading edge of the probe head (1) at the junction of the left and right sides forms an angle of 30° with the wedge top slope. The probe head is made of heat-insulating material to reduce heat transfer error during measurement and improve probe frequency response and measurement accuracy.

[0038] The upper thin-film platinum resistance (3) and the lower thin-film platinum resistance (4) are miniature four-wire thin-film platinum resistances, which are installed at the wedge of the probe head (1). The length of the thin-film platinum resistance is 3 mm, the width is 1 mm, and the thickness is 0.05 mm. The four-wire measurement can effectively eliminate the influence of lead resistance on the measurement results, improve the measurement accuracy, and ensure the stability and accuracy of the data.

[0039] The distance between the upper thin-film platinum resistance (3) and the lower thin-film platinum resistance (4) is x, and the value of x is 0.5 mm.

[0040] A lead hole (5) is opened at the junction of the left and right sides of the probe head (1). The lead hole (5) is connected to the circular pipe (6). The diameter of the lead hole is b, and the value of b is 0.2 mm.

[0041] The distance between the center of the thin-film platinum resistance (3) and the lowest point of the wedge slope is 3 mm.

[0042] The probe support rod (2) is a columnar structure with a diameter of 10 mm. It has a circular channel (6) inside, and the diameter of the circular channel (6) is a, where a is 8 mm.

[0043] The upper thin-film platinum resistance (3) and the lower thin-film platinum resistance (4) are made of miniature four-wire thin-film platinum resistance wires that are led out from the probe tail through the lead hole (5) and the circular tube (6).

[0044] This invention proposes a data processing method based on a thin-film platinum resistance thermometer (PTT) dynamic total temperature probe for measuring transonic flow fields. In a calibration wind tunnel, the PTT dynamic total temperature probe is calibrated over a wide range, with calibration speeds ranging from Mach 0.8 to Mach 2 (in 0.1 Mach intervals), deflection angles ranging from -60° to 60° (in 5° intervals), and pitch angles ranging from -30° to 30° (in 5° intervals). During wind tunnel calibration, temperature measurements are simultaneously performed using two thin-film platinum resistance thermometers. The two thermometers are supplied with different constant currents by a signal generator. While the initial temperatures of the two thermometers differ, they possess the same convective heat transfer surface heat transfer coefficient h. This allows the obtaining of the ratio of heat flux densities between the two thermometers under different operating conditions. This ratio of heat flux densities is defined as B and satisfies the following equation:

[0045] q1=h(T t -T w1 )

[0046] q2=h(T t -T w2 )

[0047]

[0048] In the formula, q1 and q2 represent the heat flux density of the thin-film platinum resistance thermometer, in W / m³. 2 Tw1, Tw2 — Temperature measured by thin-film platinum resistance thermometer, in K; Tt — Total incoming flow temperature of the calibration wind tunnel, in K. The ratio B of heat flux density under different calibration conditions can be obtained through the above calibration method.

[0049] During the test measurement, under known incoming flow conditions, the corresponding heat flux density ratio B can be obtained from the calibration data. Using the measured Tw1 and Tw2 data, the total temperature T of the measured airflow can be calculated using the following formula. g :

[0050]

[0051] This invention is based on a dynamic total temperature probe using a thin-film platinum resistance thermometer. By obtaining the temperature analytical transfer function coefficients through calibration experiments, the temperature transfer function of the dynamic total temperature probe is constructed, and the total temperature of the airflow in 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 data processing method based on a thin-film platinum resistance dynamic total temperature probe for measuring across the acoustic flow field, the probe is composed of a probe head (1), a probe stem (2), an upper thin-film platinum resistance (3), a lower thin-film platinum resistance (4), a lead hole (5), a circular pipe (6), characterized in that: The probe head (1) is a wedge top double circular arc prism structure, and an upper thin film platinum resistance (3) and a lower thin film platinum resistance (4) are arranged at the sharp split part of the probe head (1); the lead wires of the upper thin film platinum resistance (3) and the lower thin film platinum resistance (4) are led out through the lead hole (5) and the circular pipeline (6) and connected with an external collecting device; The windward surface of the probe head (1) comprises a wedge top inclined surface, symmetrical left and right side surfaces, and the leeward surface is a rear cylindrical surface; The included angle between the left side surface and the right side surface of the probe head (1) is 26° to 78°; The included angle between the front edge line at the junction of the left side surface and the right side surface of the probe head (1) and the wedge top inclined surface is 32° to 56°; the probe head is made of heat insulation material, so as to reduce the heat transfer error during measurement, improve the frequency response and measurement accuracy of the probe; The upper thin film platinum resistance (3) and the lower thin film platinum resistance (4) are micro four-wire thin film platinum resistances, which are arranged at the sharp split part of the probe head (1); the length of the thin film platinum resistance is 0.5 mm to 3 mm, the width is 0.1 mm to 1.5 mm, and the thickness is 0.01 mm to 0.2 mm; the four-wire measurement can effectively eliminate the influence of lead resistance on the measurement result, improve the measurement accuracy, and ensure the stability and accuracy of the data; The interval distance between the upper thin film platinum resistance (3) and the lower thin film platinum resistance (4) is x, and the value range of x is 0.2 mm≤x≤1 mm; The lead hole (5) is opened at the junction of the left side surface and the right side surface of the probe head (1) and communicates with the circular pipeline (6); the diameter of the lead hole is b, and the value range of b is 0.2 mm≤b≤1 mm; The distance between the center of the upper thin film platinum resistance (3) and the lowest point of the wedge top inclined surface of the probe head (1) is 1 mm to 3 mm; The probe stem (2) is a columnar structure, a cylinder or a triangular prism, and a circular pipeline (6) is arranged in the probe stem (2); the diameter of the circular pipeline (6) is a, and the value range of a is 1 mm≤a≤8 mm; The lead wires of the upper thin film platinum resistance (3) and the lower thin film platinum resistance (4) are led out from the probe tail through the lead hole (5) and the circular pipeline (6); A thin film platinum resistance dynamic total temperature probe for measuring transonic flow field is calibrated in a wide range in a calibration wind tunnel; the calibration speed range is 0.8 Mach to 2 Mach, the deflection angle range is -60° to 60°, and the pitch angle range is -30° to 30°; during the wind tunnel test calibration, two thin film platinum resistances are used to measure the temperature at the same time; the two thin film platinum resistances are provided with different constant currents by a signal generator; the initial temperatures of the two resistances are different, but they have the same convective heat transfer surface heat transfer coefficient h, so that the heat flux density ratio of the two thin film platinum resistances under different working conditions is obtained, the heat flux density ratio is defined as B, and the following equation is satisfied: q1 = h(T t - T w1 ) q2 = h(T t - T w2 ) In the formula, q1, q2 are heat flux densities of the thin-film platinum resistance, in units of W / m 2 ; Tw1, Tw2 are temperatures measured by the thin-film platinum resistance, in units of K; Tt is the total temperature of the incoming flow of the calibration wind tunnel, in units of K, and the ratio B of the heat flux densities under different calibration conditions can be obtained through the above calibration method. During the test measurement, the corresponding heat flux ratio B can be found from the calibration data under the known inflow condition. The total temperature T of the measured air flow is calculated from the measured Tw1, Tw2 data through the following formula g : Based on the thin film platinum resistance dynamic total temperature probe, the temperature analytical transfer function coefficient is obtained through the calibration test, the temperature measurement transfer function of the thin film platinum resistance dynamic total temperature probe is constructed, the total temperature of the measured flow field is reconstructed, and only the incoming flow parameters need to be obtained during the measurement, without the need to understand the physical parameters of the measured medium.

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