Temperature field measurement method and device

Abstract

A temperature field measurement method and device, the temperature field measurement method comprising: acquiring a first fluorescent signal, a second fluorescent signal, a third fluorescent signal and a fourth fluorescent signal; repeatedly performing the process of acquiring the first fluorescent signal and the second fluorescent signal at least once, obtaining at least one first image according to at least one first fluorescent signal; obtaining at least one second image according to at least one second fluorescent signal; repeatedly performing the process of acquiring the third fluorescent signal and the fourth fluorescent signal at least once; obtaining at least one third image according to at least one third fluorescent signal; obtaining at least one fourth image according to at least one fourth fluorescent signal; obtaining the temperature of a detection target according to the fluorescent intensity of at least one first image, the fluorescent intensity of at least one second image, the fluorescent intensity of at least one third image, and the fluorescent intensity of at least one fourth image.

Description

Technical Field

[0001] This invention relates to the field of non-contact temperature measurement, and particularly to a method and apparatus for measuring temperature fields. Background Technology

[0002] Engines are complex thermomechanical machines involving multiple disciplines such as aerodynamics, thermodynamics, mechanics, and materials science. Engine blades are prone to failure and premature degradation in extreme environments, making engine blade testing and diagnostic technology a key technology for ensuring the success of engine development. Temperature is a crucial physical quantity in engine operation monitoring; accurate measurement of the surface temperature of engine blades plays a vital role in assessing their operating status and service life, and ensuring engine safety.

[0003] Engine target blade temperature measurement technologies mainly include two categories: contact and non-contact. Thermocouples are the most basic contact temperature measurement technology. However, traditional thermocouple temperature measurement methods have long response times, making them unsuitable for transient temperature measurements. Furthermore, they can damage the target blade structure and affect the target temperature field distribution. Thin-film temperature sensors (CN201811300429.7) are gradually replacing thermocouples for transient temperature measurement of target blades. The shortcomings of contact temperature measurement technology include weak anti-interference capabilities, intrusive measurement, low spatial and temporal resolution, thermocouple aging, and difficulties in signal lead connections. Compared to contact temperature measurement technology, thermal radiation temperature measurement technology achieves non-contact temperature measurement based on the target's self-heating radiation intensity. It features non-interference, a wide temperature measurement range, and convenient signal transmission. Thermal radiation temperature measurement technology overcomes the shortcomings of traditional contact temperature measurement, measuring surface temperature without contact with the object being measured. However, there are still challenges in measuring the temperature of turbine rotor blades: interference from gas radiation in the test environment; unknown high-temperature emissivity of the blade surface; and the target blade rotation speed exceeding 10,000 rpm. Measuring the radiation temperature field of high-speed blades places stringent requirements on sensors. To prevent motion blur in dynamic blade thermal radiation images, the exposure time for acquiring a single frame of thermal radiation image needs to be less than 500 ns. Within the temperature range of 200–800℃, existing radiation temperature measurement devices, such as infrared thermometers, cannot achieve effective measurement.

[0004] Therefore, in view of the requirements for measuring the temperature field of engine turbine rotor blades under test environment and the limitations of existing technology applications, it is urgent to develop non-contact temperature measurement devices and methods for engine turbine rotor blades. These devices and methods can solve key problems such as gas interference, unknown emissivity, and temperature field measurement of blades with speeds greater than 10,000 rpm in test environment, so as to achieve high-precision measurement of engine turbine rotor blade temperature in test environment. Summary of the Invention

[0005] In view of this, the present invention provides a temperature field measurement method and apparatus to achieve high-precision online measurement of the temperature field of a target.

[0006] According to an embodiment of the present invention, as a first aspect of the invention, a temperature field measurement method is provided, comprising:

[0007] Acquire a first fluorescence signal and a second fluorescence signal, wherein the first fluorescence signal and the second fluorescence signal have different wavelengths, and the first fluorescence signal and the second fluorescence signal are generated by the detection target located in the test area under the excitation of the laser pulse of the measurement pulse laser;

[0008] Acquire a third fluorescence signal and a fourth fluorescence signal; wherein the third fluorescence signal has the same wavelength as the first fluorescence signal, and the fourth fluorescence signal has the same wavelength as the second fluorescence signal, and the third and fourth fluorescence signals are acquired after the laser pulse that excites the target stops.

[0009] The process of acquiring a first fluorescence signal and a second fluorescence signal is repeated at least once to obtain at least one first fluorescence signal and at least one second fluorescence signal; at least one first image is obtained based on at least one first fluorescence signal; and at least one second image is obtained based on at least one second fluorescence signal.

[0010] The process of acquiring a third fluorescence signal and a fourth fluorescence signal is repeated at least once to obtain at least one third fluorescence signal and at least one fourth fluorescence signal; at least one third image is obtained based on at least one third fluorescence signal; at least one fourth image is obtained based on at least one fourth fluorescence signal;

[0011] The temperature of the target is obtained based on the fluorescence intensity of at least one first image, at least one second image, at least one third image, and at least one fourth image.

[0012] According to an embodiment of the present invention, the detection target is in a rotating state.

[0013] Acquiring the first fluorescence signal and the second fluorescence signal includes:

[0014] After detecting that the target has arrived in the test area, the first laser pulse of the measurement pulse laser is emitted to generate the first fluorescence radiation signal;

[0015] The first fluorescence signal and the second fluorescence signal are obtained by acquiring the first fluorescence radiation signal and performing spectral dispersion within a preset time period from the time of emission of the first fluorescence radiation signal.

[0016] Acquiring the third and fourth fluorescence signals, including:

[0017] After detecting that the target has arrived in the test area, a second laser pulse of the measurement pulse laser is emitted to generate a second fluorescent radiation signal;

[0018] The third and fourth fluorescence signals are obtained by acquiring the second fluorescence radiation signal and then splitting it within a preset time after the second laser pulse ends.

[0019] According to an embodiment of the present invention, the process of acquiring a first fluorescence signal and a second fluorescence signal is repeatedly performed at least once to obtain at least one first fluorescence signal and at least one second fluorescence signal, and at least one first image is obtained based on at least one first fluorescence signal; obtaining at least one second image based on at least one second fluorescence signal includes:

[0020] Set at least one first sampling period, where the first sampling period is the unit acquisition time for acquiring one frame of the first image or one frame of the second image;

[0021] For each first sampling period,

[0022] After the target has reached the test area at least once, acquire at least one first fluorescence signal and at least one second fluorescence signal; obtain a first image based on at least one first fluorescence signal and a second image based on at least one second fluorescence signal;

[0023] Repeatedly performing the process of acquiring a third fluorescence signal and a fourth fluorescence signal at least once to obtain at least one third fluorescence signal and at least one fourth fluorescence signal; obtaining at least one third image based on at least one third fluorescence signal; obtaining at least one fourth image based on at least one fourth fluorescence signal, including:

[0024] Set at least one second sampling period, where the second sampling period is the unit acquisition time for acquiring one frame of the third image or one frame of the fourth image;

[0025] For each second sampling period,

[0026] Acquire at least one third fluorescence signal and at least one fourth fluorescence signal after the target has reached the test area at least once; obtain a third image based on the at least one third fluorescence signal and a fourth image based on the at least one fourth fluorescence signal.

[0027] According to an embodiment of the present invention, the wavelengths of the first fluorescence signal and the third fluorescence signal are first wavelengths, and the wavelengths of the second fluorescence signal and the fourth fluorescence signal are second wavelengths;

[0028] The temperature of the target is obtained based on at least one first image, at least one second image, at least one third image, and at least one fourth image, including:

[0029] The objective function is obtained based on the fluorescence intensity of at least one first image, at least one second image, at least one third image, and at least one fourth image.

[0030] By finding the minimum value of the objective function, the temperature of the target can be obtained;

[0031] The objective function is expressed as follows:

[0032]

[0033] in,

[0034]

[0035]

[0036]

[0037]

[0038] Where f represents the objective function, A and B are coefficients; k is the Boltzmann constant; ΔE represents the energy level difference between the first and second thermally coupled energy levels, L(λ1,t0). measure L(λ1,t0) represents the sum of measured fluorescence intensities of at least one first image, L(λ2,t0) represents the theoretical value of fluorescence intensity of the first image, and L(λ2,t0) represents the theoretical value of fluorescence intensity of the first image. measure L(λ2,t0) represents the sum of measured fluorescence intensities of at least one second image, L(λ1,t1) represents the theoretical value of fluorescence intensity of the second image, and L(λ1,t1) represents the theoretical value of fluorescence intensity of the second image. measure L(λ1,t1) represents the sum of measured fluorescence intensities of at least one third image, L(λ2,t1) represents the theoretical value of fluorescence intensity of the third image, and L(λ2,t1) represents the theoretical value of fluorescence intensity of the third image. measure L(λ2,t1) represents the sum of fluorescence intensities of at least one fourth image, where L(λ2,t1) represents the theoretical value of the fluorescence intensity of the fourth image, λ1 represents the first wavelength, λ2 represents the second wavelength, t0 represents the emission time of each laser pulse, and t1 represents the time when the acquisition of the third or fourth fluorescence signal begins after the cessation of each laser pulse. This represents the luminescence lifetime of the fluorescence signal with the first wavelength. Q represents the luminescence lifetime with a fluorescence signal at a second wavelength. measure Q represents the measured value of the fluorescence intensity ratio between the first image and the second image, and Q represents the theoretical value of the fluorescence intensity ratio between the first image and the second image.

[0039] As a second aspect of the present invention, a temperature field measuring device is also provided, comprising:

[0040] A fluorescence module is suitable for emitting a measurement pulse laser and directing the laser pulse of the measurement pulse laser onto a detection target located in the test area to excite a first fluorescence signal and a second fluorescence signal on the detection target; and is also suitable for obtaining a third fluorescence signal and a fourth fluorescence signal after the laser pulse that excites the detection target stops.

[0041] An imaging module is adapted to obtain a first image based on a first fluorescence signal, a second image based on a second fluorescence signal, a third image based on a third fluorescence signal, and a fourth image based on a fourth fluorescence signal;

[0042] The control module is suitable for controlling the fluorescence module and the imaging module to achieve the temperature field measurement method described above.

[0043] According to an embodiment of the present invention, the detection target is in a rotating state.

[0044] The fluorescence module includes:

[0045] The laser unit is suitable for emitting measurement pulse lasers. The laser pulses of the measurement pulse lasers include a first measurement laser pulse and a second laser pulse. The first laser pulse is suitable for exciting a first fluorescence radiation signal on the detection target, and the second laser pulse is suitable for generating a second fluorescence radiation signal on the detection target.

[0046] The spectrometer is adapted to split a first fluorescence radiation signal into a first fluorescence signal of a first wavelength and a second fluorescence signal of a second wavelength; and to split the second fluorescence radiation signal into a third fluorescence signal and a fourth fluorescence signal.

[0047] The signal detection unit is used to issue a trigger signal after detecting that a target has arrived in the test area, so that the control module can control the fluorescence module and the imaging module.

[0048] According to an embodiment of the present invention, the imaging module includes:

[0049] Like an intensifier, it amplifies the light of the first, second, third, and fourth fluorescence signals input within a preset time.

[0050] The CCD imaging sensor is suitable for imaging the first, second, third, and fourth fluorescence signals after the light is amplified during the sampling time of the CCD imaging sensor, respectively, to obtain the first image, the second image, the third image, and the fourth image.

[0051] According to an embodiment of the present invention, the control module includes:

[0052] The timing control unit is suitable for receiving trigger signals and issuing timing signals; the timing signals are suitable for controlling the laser unit to emit the first laser pulse and the second laser pulse, and for controlling the image intensifier and the CCD imaging sensor to turn on.

[0053] The calculation unit is adapted to obtain the temperature of the target blade based on at least one first image, at least one second image, at least one third image, and at least one fourth image.

[0054] According to an embodiment of the present invention, the laser unit includes:

[0055] Laser, suitable for emitting initial pulse laser;

[0056] The beam expanding and homogenizing mechanism is suitable for expanding and homogenizing the initial pulse laser beam to obtain the measurement pulse laser.

[0057] The first beam splitter is suitable for reflecting pulsed lasers for measurement.

[0058] The second beam splitter is suitable for reflecting the measurement pulse laser reflected by the first beam splitter to the detection target, as well as transmitting fluorescence radiation signals, wherein the fluorescence radiation signals include a first fluorescence radiation signal and a second fluorescence radiation signal.

[0059] According to an embodiment of the present invention, the detection target is a rotating blade fixed on an impeller, and the preset time is the gating integration time of the image intensifier.

[0060] The gating integral time of the image intensifier is represented as follows:

[0061] △t=D / V

[0062] V=2*π*ω*(W+R) / 60

[0063] Where D is the imaging accuracy of the CCD imaging sensor, ω is the rotational speed of the target, W is the height of the target, and R is the radius of the impeller.

[0064] According to an embodiment of the present invention, the imaging recognition accuracy of the CCD imaging sensor is expressed as follows:

[0065] D = L / (N * 5)

[0066] Where L is the width of the target being detected, and N is the number of effective pixels corresponding to the width of the target being detected on the CCD imaging sensor.

[0067] According to an embodiment of the present invention, the modulation frequency of the measured pulse laser is 10 Hz to 10 kHz.

[0068] According to an embodiment of the present invention, the timing control unit has an accuracy of 1 ns.

[0069] According to embodiments of the present invention, by acquiring the first and second fluorescence signals generated by the target under the excitation of the laser pulse of the measuring pulsed laser, and the third and fourth fluorescence signals obtained after the laser pulse excitation of the target stops, the temperature of the target can be solved based on the first, second, third, and fourth images obtained from the first, second, third, and fourth fluorescence signals, respectively. This combines the fluorescence intensity ratio method with the lifetime method, enabling high-precision online measurement of the target's temperature field. Furthermore, repeating the process of acquiring the first, second, third, and fourth fluorescence signals multiple times reduces noise, resulting in more accurate measurement results. Attached Figure Description

[0070] Figure 1 This is a flowchart of the temperature field measurement method provided in an embodiment of the present invention;

[0071] Figure 2 This is a block diagram of the temperature field measuring device provided in an embodiment of the present invention;

[0072] Figure 3 This is a timing diagram of sampling using a temperature field measuring device provided in an embodiment of the present invention.

[0073] Explanation of reference numerals in the attached figures

[0074] 1 fluorescence module

[0075] 11 laser units

[0076] 111 laser

[0077] 112 Beam Expanding and Beam Homogenizing Mechanism

[0078] 113 First beam splitter

[0079] 114 Second beam splitter

[0080] 12-splitter unit

[0081] 13 signal detection units

[0082] 2 Imaging Modules

[0083] 21-image intensifier

[0084] 22CCD Imaging Sensor

[0085] 3 control modules

[0086] 31 timing control unit

[0087] 32 computing units

[0088] 4 Detection Targets Detailed Implementation

[0089] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0090] Figure 1 This is a flowchart of a temperature field measurement method provided in an embodiment of the present invention.

[0091] like Figure 1 As shown, the temperature field measurement method includes operations S1 to S5.

[0092] In operation S1, a first fluorescence signal and a second fluorescence signal are acquired, wherein the first fluorescence signal and the second fluorescence signal have different wavelengths, and the first fluorescence signal and the second fluorescence signal are generated by the detection target located in the test area under the excitation of the laser pulse of the measurement pulse laser.

[0093] In operation S2, a third fluorescence signal and a fourth fluorescence signal are acquired; wherein, the third fluorescence signal has the same wavelength as the first fluorescence signal, and the fourth fluorescence signal has the same wavelength as the second fluorescence signal. The third fluorescence signal and the fourth fluorescence signal are acquired after the laser pulse that excites the target stops.

[0094] In operation S3, the process of acquiring a first fluorescence signal and a second fluorescence signal is repeated at least once to obtain at least one first fluorescence signal and at least one second fluorescence signal, and at least one first image is obtained based on at least one first fluorescence signal; at least one second image is obtained based on at least one second fluorescence signal.

[0095] In operation S4, the process of acquiring a third fluorescence signal and a fourth fluorescence signal is repeated at least once to obtain at least one third fluorescence signal and at least one fourth fluorescence signal; at least one third image is obtained based on at least one third fluorescence signal; and at least one fourth image is obtained based on at least one fourth fluorescence signal.

[0096] In operation S5, the temperature of the target is obtained based on the fluorescence intensity of at least one first image, at least one second image, at least one third image, and at least one fourth image.

[0097] According to embodiments of the present invention, by acquiring the first and second fluorescence signals generated by the target under the excitation of the laser pulse of the measuring pulsed laser, and the third and fourth fluorescence signals obtained after the laser pulse excitation of the target stops, the temperature of the target can be solved based on the first, second, third, and fourth images obtained from the first, second, third, and fourth fluorescence signals, respectively. This combines the fluorescence intensity ratio method with the lifetime method, enabling high-precision online measurement of the target's temperature field. Furthermore, repeating the process of acquiring the first, second, third, and fourth fluorescence signals multiple times reduces noise, resulting in more accurate measurement results.

[0098] Meanwhile, the temperature field measurement method provided in this embodiment of the invention does not require contact measurement, which solves the problems of gas interference in the test environment where the target is located and the unknown emissivity of the target. It has the advantages of clear principle, technical feasibility, good test accuracy, practical feasibility and scalability.

[0099] According to an embodiment of the present invention, the wavelengths of the first fluorescence signal and the third fluorescence signal are first wavelengths, and the wavelengths of the second fluorescence signal and the fourth fluorescence signal are second wavelengths;

[0100] The temperature of the target is obtained based on at least one first image, at least one second image, at least one third image, and at least one fourth image, including:

[0101] The objective function is obtained based on the fluorescence intensity of at least one first image, at least one second image, at least one third image, and at least one fourth image.

[0102] The temperature of the target is obtained by finding the minimum value of the objective function.

[0103] The objective function is expressed as follows:

[0104]

[0105] in,

[0106]

[0107]

[0108]

[0109]

[0110] Where f represents the objective function, A and B are coefficients; k is the Boltzmann constant; ΔE represents the energy level difference between the first and second thermally coupled energy levels, L(λ1,t0). measure L(λ1,t0) represents the sum of measured fluorescence intensities of at least one first image, L(λ2,t0) represents the theoretical value of fluorescence intensity of the first image, and L(λ2,t0) represents the theoretical value of fluorescence intensity of the first image. measure L(λ2,t0) represents the sum of measured fluorescence intensities of at least one second image, L(λ1,t1) represents the theoretical value of fluorescence intensity of the second image, and L(λ1,t1) represents the theoretical value of fluorescence intensity of the second image. measure L(λ1,t1) represents the sum of measured fluorescence intensities of at least one third image, L(λ2,t1) represents the theoretical value of fluorescence intensity of the third image, and L(λ2,t1) represents the theoretical value of fluorescence intensity of the third image. measure L(λ2,t1) represents the sum of fluorescence intensities of at least one fourth image, where L(λ2,t1) represents the theoretical value of the fluorescence intensity of the fourth image, λ1 represents the first wavelength, λ2 represents the second wavelength, t0 represents the emission time of each laser pulse, and t1 represents the time when the acquisition of the third or fourth fluorescence signal begins after the cessation of each laser pulse. This represents the luminescence lifetime of the fluorescence signal with the first wavelength. Q represents the luminescence lifetime with a fluorescence signal at a second wavelength. measure Q represents the measured value of the fluorescence intensity ratio between the first image and the second image, and Q represents the theoretical value of the fluorescence intensity ratio between the first image and the second image.

[0111] According to embodiments of the present invention, the detection target can be in a stationary state or a rotating state. When the detection target is in a stationary state, at least one first fluorescence signal, a second fluorescence signal, a third fluorescence signal, and a fourth fluorescence signal can be acquired. Each first fluorescence signal can be used to obtain a first image, each second fluorescence signal can be used to obtain a second image, each third first fluorescence signal can be used to obtain a third image, and each fourth fluorescence signal can be used to obtain a fourth image. The temperature of the detection target can then be obtained from the fluorescence intensity of at least one first image, at least one second image, at least one third image, and at least one fourth image.

[0112] The following is a detailed explanation of the target being rotated.

[0113] When the target being detected is rotating:

[0114] The acquisition of the first fluorescence signal and the second fluorescence signal in operation S1 includes:

[0115] After detecting that the target has arrived in the test area, the first laser pulse of the measurement pulse laser is emitted to generate a first fluorescent radiation signal.

[0116] The first fluorescence signal and the second fluorescence signal are obtained by acquiring the first fluorescence radiation signal and performing spectral dispersion within a preset time period from the time of emission of the first fluorescence radiation signal.

[0117] The acquisition of the third and fourth fluorescence signals in operation S2 includes:

[0118] After detecting that the target has arrived in the test area, a second laser pulse of the measurement pulse laser is emitted to generate a second fluorescent radiation signal;

[0119] The third and fourth fluorescence signals are obtained by acquiring the second fluorescence radiation signal and then splitting it within a preset time after the second laser pulse ends.

[0120] In operation S3, the process of acquiring a first fluorescence signal and a second fluorescence signal is repeated at least once to obtain at least one first fluorescence signal and at least one second fluorescence signal, and at least one first image is obtained based on the at least one first fluorescence signal; obtaining at least one second image based on the at least one second fluorescence signal includes:

[0121] Set at least one first sampling period, where the first sampling period is the unit acquisition time for acquiring one frame of the first image or one frame of the second image;

[0122] For each first sampling period,

[0123] After the target has reached the test area at least once, acquire at least one first fluorescence signal and at least one second fluorescence signal; obtain a first image based on at least one first fluorescence signal and a second image based on at least one second fluorescence signal.

[0124] In operation S4, the process of acquiring a third fluorescence signal and a fourth fluorescence signal is repeated at least once to obtain at least one third fluorescence signal and at least one fourth fluorescence signal; at least one third image is obtained based on the at least one third fluorescence signal; at least one fourth image is obtained based on the at least one fourth fluorescence signal, including:

[0125] Set at least one second sampling period, where the second sampling period is the unit acquisition time for acquiring one frame of the third image or one frame of the fourth image;

[0126] For each second sampling period,

[0127] Acquire at least one third fluorescence signal and at least one fourth fluorescence signal after the target has reached the test area at least once; obtain a third image based on the at least one third fluorescence signal and a fourth image based on the at least one fourth fluorescence signal.

[0128] Figure 2 A block diagram of a temperature field measuring device according to an embodiment of the present invention is shown.

[0129] like Figure 2 As shown, the temperature field measuring device includes: a fluorescence module 1, an imaging module 2, and a control module 3.

[0130] The fluorescence module 1 is adapted to emit a measurement pulse laser and direct the laser pulse onto the detection target 4 located in the test area to excite a first fluorescence signal and a second fluorescence signal on the detection target 4; and to obtain a third fluorescence signal and a fourth fluorescence signal after the laser pulse stimulating the detection target 4 stops. The imaging module 2 is adapted to obtain a first image based on the first fluorescence signal, a second image based on the second fluorescence signal, a third image based on the third fluorescence signal, and a fourth image based on the fourth fluorescence signal. The control module 3 is adapted to control the fluorescence module and the imaging module to realize the temperature field measurement method described above.

[0131] According to an embodiment of the present invention, the detection target 4 is in a rotating state, and the fluorescence module 1 includes: a laser unit 11, a beam splitting unit 12 and a signal detection unit 13.

[0132] Laser unit 11 is adapted to emit measurement pulse lasers, including a first measurement laser pulse and a second laser pulse. The first laser pulse is adapted to excite a first fluorescence radiation signal on the detection target 4, and the second laser pulse is adapted to generate a second fluorescence radiation signal on the detection target 4. Spectrometer unit 12 is adapted to split the first fluorescence radiation signal into a first fluorescence signal of a first wavelength and a second fluorescence signal of a second wavelength; and to split the second fluorescence radiation signal into a third fluorescence signal and a fourth fluorescence signal. Signal detection unit 13 is adapted to emit a trigger signal after detecting that the detection target 4 has arrived in the test area, so that the control module 3 controls the fluorescence module 1 and the imaging module 2. This signal detection unit can be a position trigger.

[0133] According to an embodiment of the present invention, the imaging module 2 includes an image intensifier 21 and a CCD imaging sensor 22, which together form an image-intensified CCD imaging sensor. The image intensifier 21 is adapted to amplify the light of a first fluorescence signal, a second fluorescence signal, a third fluorescence signal, and a fourth fluorescence signal input within a preset time period. The CCD imaging sensor 22 is adapted to image the received amplified first fluorescence signal, second fluorescence signal, third fluorescence signal, and fourth fluorescence signal respectively within the sampling time of the CCD imaging sensor, to obtain a first image, a second image, a third image, and a fourth image.

[0134] According to an embodiment of the present invention, the control module 3 includes a timing control unit 31 and a calculation unit 32.

[0135] The timing control unit 31 is adapted to receive trigger signals and issue timing signals; the timing signals are adapted to control the laser unit to issue a first laser pulse and a second laser pulse, and to control the activation of the image intensifier and the CCD imaging sensor. The calculation unit 32 is adapted to obtain the temperature of the target blade based on at least one first image, at least one second image, at least one third image, and at least one fourth image.

[0136] According to an embodiment of the present invention, the laser unit 11 includes: a laser 111, a beam expanding and homogenizing mechanism 112, a first beam splitter 113, and a second beam splitter 114. The laser 111 is adapted to emit an initial pulsed laser, and this laser 111 is a pulsed laser. The beam expanding and homogenizing mechanism 112 is adapted to expand and homogenize the initial pulsed laser to obtain a measurement pulsed laser. The first beam splitter 113 is adapted to reflect the measurement pulsed laser. The second beam splitter 114 is adapted to reflect the measurement pulsed laser reflected by the first beam splitter to the detection target 4, and to transmit a fluorescence radiation signal, wherein the fluorescence radiation signal includes a first fluorescence radiation signal and a second fluorescence radiation signal.

[0137] According to an embodiment of the present invention, the detection target 4 is a rotating blade fixed on the impeller, and the preset time is the gating integration time of the image intensifier.

[0138] The gating integration time of enhancer 21 is represented as follows:

[0139] △t=D / V (6)

[0140] V = 2πω(W+R) / 60 (7)

[0141] Where D is the imaging accuracy of the CCD imaging sensor, ω is the rotational speed of the target, W is the height of the target, and R is the radius of the impeller.

[0142] According to an embodiment of the present invention, the imaging recognition accuracy of the CCD imaging sensor 22 is expressed as follows:

[0143] D = L / (N * 5) (8)

[0144] Where L is the width of the target being detected, and N is the number of effective pixels corresponding to the width of the target being detected on the CCD imaging sensor.

[0145] The following are specific embodiments, and in conjunction with Figure 2 This invention describes a method for measuring the temperature field of rotating blades fixed on an impeller using the temperature field measuring device provided in this embodiment. In this embodiment, the impeller is an engine impeller with an optical window. The first beam splitter 113 and the second beam splitter 114 in the fluorescence unit 11 form an integrated beam splitter structure with three optical interfaces. The first interface is mounted to the engine's optical window via a flange, the second interface is connected to the imaging module 2, and the third interface 3 is connected to the beam expanding and homogenizing mechanism 112. The beam expanding and homogenizing mechanism 112 is connected to the laser 111 in the laser unit 11 via a flange.

[0146] In use Figure 2 When using the temperature measuring device in the system, the specific steps are as follows:

[0147] First, determine the measurement bandwidth of fluorescence radiation of the target leaf (i.e., the gating integration time of image intensifier 21).

[0148] Assuming the target blade's rotational speed is ω = 12000 rpm, the height of a single blade is W = 44 mm, the impeller radius is R = 275 mm, and the number of target blades is N = 100, then the blade's linear velocity is V = 2*π*ω*(W+R) / 60 (m / s) ≈ 400 m / s. The CCD imaging sensor 22 has a spatial resolution of D = 0.1 mm for the object-side blade, and the minimum imaging accuracy is α (m), typically α = D / 5 = 0.02 mm. Therefore, the maximum integration time (i.e., exposure time) of the image intensifier 21 is Δt = α / V = 50 ns, which is the measurement time bandwidth of the target blade's fluorescence radiation. Meeting this condition allows for the effective measurement of blades rotating at 12000 rpm.

[0149] Figure 3 This is a timing diagram of the temperature field measurement device provided in the embodiment of the present invention performing sampling.

[0150] To better understand the process of the embodiments of the present invention, the first sampling period for the first fluorescence signal and the second fluorescence signal, and the second sampling period for the third fluorescence signal and the fourth fluorescence signal, can use the same sampling period (i.e., as shown in the figure). Figure 3 (As shown in part a) for illustration. Figure 3 As shown in section a, this can be viewed as multiple sampling periods, where the high level represents the sampling time and the low level represents the non-sampling time. The sampling time of each sampling period is the exposure time of the CCD imaging sensor 22, which is also the imaging time of one frame of image.

[0151] The temperature field measurement of the target blade using the aforementioned temperature field measuring device includes two scenarios, which will be explained in detail below.

[0152] When the target blade can reach the test area once within the sampling time (10ms) of each frame of the CCD imaging sensor 22, the specific sampling process is as follows:

[0153] like Figure 3 As shown in section b, the timing sequence of the acquisition of the first and second fluorescence signals is illustrated. Figure 3 Part b includes multiple first sampling cycles. Taking one first sampling cycle as an example, at time t0, the target blade rotates to the test area, and the position trigger sends a signal. At this time, the timing control unit 31 sends a timing signal to turn on the pulsed laser and emit the first laser pulse. At the same time, the timing control unit 31 sends a timing signal to control the imaging module 2 to start acquiring the first and second fluorescence signals generated by the target blade. The gating integration time (Δt) of the image intensifier 21 in each first sampling cycle is the actual acquisition time of each fluorescence signal.

[0154] Since the target leaf only reaches the test area once during the sampling time of each image frame, meaning the target leaf emits only the first and second fluorescence signals once, the imaging module 2 obtains one first image based on the first fluorescence signal and one second image based on the second fluorescence signal image during the acquisition time of each image frame. The gating integration time of the image intensifier 21 is set to Δt = 50 ns, meaning the actual acquisition time for each fluorescence signal is Δt = 50 ns. Following this procedure, the target leaf rotates for multiple cycles, and the CCD imaging sensor 22 can obtain M = 100 first images and M = 100 second images. The fluorescence intensities of the M first and second images are summed to obtain the steady-state fluorescence intensity measurement values ​​for fluorescence signals at different wavelengths, thereby enhancing the signal intensity.

[0155] like Figure 3 As shown in section c, the acquisition timing of the third and fourth fluorescence signals is illustrated. Figure 3Part b includes multiple second sampling periods, corresponding to the first sampling period. For each second sampling period, at time t0, the target blade reaches the test area, the position trigger sends a signal, and at this time, the timing control unit 31 sends a timing signal to turn on the pulsed laser, emitting a second laser pulse. At time t1, after one pulse width ends, the imaging module 2 begins to acquire the third and fourth fluorescence signals generated by the target blade. Similarly, since the target blade only reaches the test area once, the imaging module 2 can only acquire the third and fourth fluorescence signals once within the acquisition time of each frame. Within one sampling period, one frame of the third image is obtained using one acquired third fluorescence signal, and one frame of the fourth image is obtained using one acquired fourth fluorescence signal. The gating integration time of the image intensifier 21 is set to Δt = 50 ns, meaning the actual acquisition time for each fluorescence signal is Δt = 50 ns. Following this procedure, the target blade 1 rotates for multiple cycles, and the image-enhanced CCD sensor 2 acquires M=100 frames of the third image and M frames of the fourth image. The fluorescence intensity of the M frames of the third and fourth images is summed to obtain the attenuation intensity measurement value of the fluorescence signal at different wavelengths.

[0156] When the target blade can reach the test area multiple times within the sampling time of each frame, the specific sampling process is as follows:

[0157] The modulation frequency of the measurement pulsed laser is set to 1kHz. During each frame acquisition time (i.e., 10ms) of the CCD imaging sensor 22, the target blade can reach the test area multiple times.

[0158] like Figure 3 As shown in section d, the timing sequence of the acquisition of the first and second fluorescence signals is illustrated. Figure 3 The middle part (d) includes multiple first sampling periods. In each first sampling period, the target blade reaches the test area multiple times, triggering a position trigger. At this moment, the timing control unit 31 sends a timing signal to activate the pulsed laser, emitting a first laser pulse. Since the target blade only reaches the test area multiple times, the pulsed laser can emit N=10 first laser pulses within the sampling time of one sampling period. This results in N=10 first fluorescence signals and second fluorescence signals. The imaging module uses the 10 acquired first fluorescence signals to obtain one first image frame, and uses the 10 acquired second fluorescence signals to obtain one second image frame. Thus, N=10 cumulative measurements of steady-state fluorescence intensity are achieved within the acquisition time of each image frame. The gating integration time of the image intensifier 21 is set to Δt=50ns each time a pulsed laser is emitted.

[0159] like Figure 3 As shown in section e, the acquisition timing of the third and fourth fluorescence signals is illustrated. Figure 3Part e includes multiple second sampling periods, corresponding to the previous sampling periods. For each second sampling period, the target blade reaches the test area multiple times, triggering a position trigger. At this moment, the timing control unit 31 sends a timing signal to activate the pulsed laser, emitting a second laser pulse. Since the target blade only reaches the test area multiple times, the pulsed laser can emit N=10 second laser pulses within one sampling period. This results in N=10 third and fourth fluorescence signals. Imaging module 2 uses the 10 third fluorescence signals acquired within one sampling period to obtain one third image frame, and uses the 10 fourth fluorescence signals acquired within one sampling period to obtain one fourth image frame. Thus, N=10 cumulative measurements of fluorescence attenuation intensity are achieved within each image frame acquisition time. The gating integration time of image intensifier 21 is set to Δt=50ns each time a pulsed laser is emitted.

[0160] It should be noted that in this embodiment, the acquisition of the first fluorescence signal, the second fluorescence signal, the third fluorescence signal, and the fourth fluorescence signal are two processes. It is understood that, if the equipment allows, the two processes can also be completed in one process.

[0161] Finally, the temperature field of the target blade is solved by combining the fluorescence intensity ratio method and the lifetime method, i.e., by using formulas (1)-(5). This step is achieved by calculation unit 32.

[0162] The above is the basic principle of the temperature solution method that combines fluorescence intensity ratio and lifetime method.

[0163] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A temperature field measurement method, comprising: acquiring a first fluorescent signal and a second fluorescent signal, wherein the first fluorescent signal and the second fluorescent signal have different wavelengths, and the first fluorescent signal and the second fluorescent signal are generated by a detection target located in a test region under excitation of a laser pulse of a measurement pulsed laser; acquiring a third fluorescent signal and a fourth fluorescent signal, wherein the third fluorescent signal has the same wavelength as the first fluorescent signal, the fourth fluorescent signal has the same wavelength as the second fluorescent signal, and the third fluorescent signal and the fourth fluorescent signal are acquired after a laser pulse for exciting the detection target stops; repeating the process of acquiring the first fluorescent signal and the second fluorescent signal at least once to obtain at least one first fluorescent signal and at least one second fluorescent signal, and obtaining at least one first image according to the at least one first fluorescent signal and obtaining at least one second image according to the at least one second fluorescent signal; repeating the process of acquiring the third fluorescent signal and the fourth fluorescent signal at least once to obtain at least one third fluorescent signal and at least one fourth fluorescent signal, and obtaining at least one third image according to the at least one third fluorescent signal and obtaining at least one fourth image according to the at least one fourth fluorescent signal; obtaining a temperature of the detection target according to a fluorescent intensity of the at least one first image, a fluorescent intensity of the at least one second image, a fluorescent intensity of the at least one third image, and a fluorescent intensity of the at least one fourth image.

2. The temperature field measurement method according to claim 1, characterized in that, the detection target is in a rotating state, acquiring the first fluorescent signal and the second fluorescent signal comprises: after detecting that the detection target reaches the test region, emitting a first laser pulse of the measurement pulsed laser to generate a first fluorescent radiation signal; acquiring the first fluorescent signal and the second fluorescent signal obtained by spectrally analyzing the first fluorescent radiation signal within a preset time from a time when the first fluorescent radiation signal is emitted; acquiring the third fluorescent signal and the fourth fluorescent signal comprises: after detecting that the detection target reaches the test region, emitting a second laser pulse of the measurement pulsed laser to generate a second fluorescent radiation signal; acquiring the third fluorescent signal and the fourth fluorescent signal obtained by spectrally analyzing the second fluorescent radiation signal within the preset time after the second laser pulse ends. 3.The temperature field measurement method of claim 2, wherein: the process of acquiring the first fluorescent signal and the second fluorescent signal is repeated at least once to obtain at least one first fluorescent signal and at least one second fluorescent signal, and at least one first image is obtained according to the at least one first fluorescent signal; the at least one second image is obtained according to the at least one second fluorescent signal, comprising: setting at least one first sampling period, wherein the first sampling period is a unit acquisition time for acquiring one frame of the first image or one frame of the second image; for each of the first sampling periods, acquiring at least one first fluorescent signal and at least one second fluorescent signal obtained after the detection target reaches the test region at least once; obtaining a first image according to the at least one first fluorescent signal and obtaining a second image according to the at least one second fluorescent signal; repeating the process of acquiring the third fluorescent signal and the fourth fluorescent signal at least once to obtain at least one third fluorescent signal and at least one fourth fluorescent signal; obtaining at least one third image according to the at least one third fluorescent signal; and obtaining at least one fourth image according to the at least one fourth fluorescent signal, comprising: setting at least one second sampling period, wherein the second sampling period is a unit acquisition time for acquiring one frame of the third image or acquiring one frame of the fourth image; for each of the second sampling periods, acquiring at least one third fluorescent signal and at least one fourth fluorescent signal obtained after the detection target reaches the test region at least once; obtaining a third image according to the at least one third fluorescent signal and obtaining a fourth image according to the at least one fourth fluorescent signal.

4. The temperature field measurement method of claim 1, wherein, The wavelength of the first fluorescent signal and the third fluorescent signal is a first wavelength, and the wavelength of the second fluorescent signal and the fourth fluorescent signal is a second wavelength; obtaining the temperature of the detection target according to the at least one first image, the at least one second image, the at least one third image, and the at least one fourth image, comprising: obtaining an objective function according to the fluorescence intensity of the at least one first image, the fluorescence intensity of the at least one second image, the fluorescence intensity of the at least one third image, and the fluorescence intensity of the at least one fourth image; obtaining the temperature of the detection target by finding the minimum value of the objective function; wherein the objective function is represented as follows: wherein, wherein denotes an objective function, and are coefficients; is the Boltzmann constant; denotes an energy level difference between a thermally coupled energy level of the first wavelength and a thermally coupled energy level of the second wavelength, denotes a sum of measured values of the fluorescence intensity of the at least one first image, denotes a theoretical value of the fluorescence intensity of the first image, denotes a sum of measured values of the fluorescence intensity of the at least one second image, denotes a theoretical value of the fluorescence intensity of the second image, denotes a sum of measured values of the fluorescence intensity of the at least one third image, denotes a theoretical value of the fluorescence intensity of the third image, denotes a sum of the fluorescence intensity of the at least one fourth image, denotes a theoretical value of the fluorescence intensity of the fourth image, denotes the first wavelength, denotes the second wavelength, denotes a time of emission of each laser pulse, denotes a time of starting the acquisition of the third fluorescence signal or the fourth fluorescence signal after stopping each laser pulse, denotes a luminescence lifetime of the fluorescence signal having the first wavelength, denotes a luminescence lifetime of the fluorescence signal having the second wavelength, denotes a measured value of the fluorescence intensity ratio of the first image and the second image, denotes a theoretical value of the fluorescence intensity ratio of the first image and the second image.

5. A temperature field measurement device, comprising: a fluorescence module adapted to emit a measurement pulsed laser and to cause laser pulses of the measurement pulsed laser to be incident on a detection target located in a test region to excite first and second fluorescent signals on the detection target, and to obtain third and fourth fluorescent signals after the laser pulses exciting the detection target have ceased; an imaging module adapted to obtain a first image from the first fluorescent signal and a second image from the second fluorescent signal, a third image from the third fluorescent signal and a fourth image from the fourth fluorescent signal; a control module adapted to control the fluorescence module and the imaging module to implement the temperature field measurement method of any one of claims 1-4.

6. The temperature field measurement device of claim 5, wherein, The detection target is in a rotating state, The fluorescence module comprises: a laser unit adapted to emit the measurement pulsed laser, laser pulses of the measurement pulsed laser comprising first and second laser pulses, the first laser pulse being adapted to excite a first fluorescent radiation signal on the detection target, and the second laser pulse being adapted to generate a second fluorescent radiation signal on the detection target; a light splitting unit, adapted to split the first fluorescent radiation signal into a first fluorescent signal of a first wavelength and a second fluorescent signal of a second wavelength, and to split the second fluorescent radiation signal into a third fluorescent signal and a fourth fluorescent signal; a signal detection unit, adapted to send a trigger signal after detecting that the probe target reaches the test region, so as to control the fluorescence module and the imaging module by the control module.

7. The temperature field measurement device of claim 6, wherein, The imaging module comprises: an image intensifier, which realizes light amplification on the first fluorescent signal, the second fluorescent signal, the third fluorescent signal and the fourth fluorescent signal input within a preset time; a CCD imaging sensor, which is adapted to image the first fluorescent signal, the second fluorescent signal, the third fluorescent signal and the fourth fluorescent signal received after light amplification within the sampling time of the CCD imaging sensor, to obtain the first image, the second image, the third image and the fourth image.

8. The temperature field measurement device of claim 7, wherein, The control module comprises: a timing control unit, adapted to receive the trigger signal and send a timing signal, wherein the timing signal is adapted to control the laser unit to send the first laser pulse and the second laser pulse, and to control the opening of the image intensifier and the CCD imaging sensor; a calculation unit, adapted to obtain the temperature of the probe target according to at least one of the first image, at least one of the second image, at least one of the third image and at least one of the fourth image.

9. The temperature field measuring device according to claim 7, wherein The laser unit comprises: a laser, adapted to send an initial pulse laser; a beam expander and light homogenizer mechanism, adapted to expand and homogenize the initial pulse laser to obtain the measuring pulse laser; a first light splitter, adapted to reflect the measuring pulse laser; a second light splitter, adapted to reflect the measuring pulse laser reflected by the first light splitter to the probe target, and to transmit the fluorescent radiation signal, wherein the fluorescent radiation signal comprises a first fluorescent radiation signal and a second fluorescent radiation signal.

10. The temperature field measurement device of claim 7, wherein, The probe target is a rotating blade fixed on an impeller, and the preset time is the gating integration time of the image intensifier, wherein the gating integration time of the image intensifier is represented as follows: wherein D is the imaging resolution of the CCD imaging sensor, ω is the rotating speed of the probe target, W is the height of the probe target, and R is the radius of the impeller.

11. The temperature field measurement device of claim 10, wherein, The imaging resolution of the CCD imaging sensor is represented as follows: wherein L is the width of the probe target, and N is the number of effective pixels corresponding to the width of the probe target on the CCD imaging sensor.

12. The temperature field measurement device of claim 7, wherein, The modulation frequency of the measuring pulse laser is 10 Hz to 10 kHz.

13. The temperature field measurement device of claim 8, wherein, The precision of the timing control unit is 1 ns.

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