A device and method for simultaneous measurement of velocity field and temperature field in water vapor environment

Abstract

The application is a kind of synchronous measuring device and method of water vapor environment velocity field and temperature field, which comprises a first laser emitting 193nm wavelength laser; a light splitting prism splitting the 193nm wavelength laser into two beams and crossing into the object to be measured, forming a micro network and dissociating H2O on the intersection point into ground state OH; a second laser emitting 308nm wavelength laser; a sheet light mirror group converting the 308nm wavelength laser into sheet light and exciting the PLIF fluorescence signal of OH; two cameras respectively matched with 310+5nm and 285+5nm filters receive the fluorescence signal of excited state OH in v'=0 and v'=1 vibration energy level, obtain two kinds of fluorescence intensity information, and inverse the temperature field; then the velocity field is calculated through the distortion of micro grid and the small time difference between 308nm laser and 193nm laser, so that the temperature and flow field information in the compressor model can be measured simultaneously.

Description

Technical Field

[0001] This invention belongs to the field of laser diagnostics and temperature and velocity measurement technology. It uses the measurement of the chemical or physical properties of materials to test or analyze them. In particular, it relates to a device and method for synchronously measuring the velocity field and temperature field in a water vapor environment. Background Technology

[0002] The compressor is a core component of aero-engines and gas turbines, and its characteristics have a significant impact on the performance of the core engine and even the entire machine. During operation, the compressor draws in air from the external atmosphere and progressively pressurizes it, while simultaneously increasing the air temperature. The compressed air is then forced into the combustion chamber where it mixes and burns with injected fuel to generate high-temperature, high-pressure gas. This gas then enters the turbine to expand and perform work. The gas flow field inside the compressor affects the safety, efficiency, and lifespan of the entire machine; therefore, the diagnosis of flow field information is particularly important. Existing flow field measurement technologies have limitations: Velocity vectors and temperature information of the flow field can be obtained using particle image velocimetry (PIV) combined with dual-line planar laser-induced fluorescence (PLIF). However, this PIV velocimetry method requires the injection of tracer particles, which affects the flow field and is not well-suited for measuring micro-gap flow fields at the blade tip. Furthermore, the tracer particles tend to adhere to the blade and wall surfaces, affecting the measurement. Dual-line PLIF thermometry typically uses dual-line OH-PLIF or dual-line NO-PLIF. Dual-line OH-PLIF has a lower limit of 1000K, making it unsuitable for measuring flow fields at room temperature and medium-low temperatures (300-800K), while dual-line NO-PLIF has a wider temperature range but requires additional NO molecule tracers. In addition, the entire experimental system is very complex, requiring at least three lasers, resulting in high experimental costs. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the present invention aims to provide a device and method for synchronously measuring the velocity field and temperature field of a water vapor environment, which can simultaneously measure the velocity field and temperature field of a water vapor environment without the need for external tracer particles.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A device for simultaneously measuring the velocity and temperature fields in a water vapor-containing environment includes a first laser, a beam splitter, a mirror group, a second laser, a sheet mirror group, a first camera, and a second camera.

[0006] The first laser emits a 193nm wavelength laser; the beam splitter is placed in the laser beam path of the first laser to split the 193nm wavelength laser into two laser beams; the mirror group adjusts the optical paths of the two laser beams so that they cross and are incident on a compressor model containing water vapor inside, dissociating the H2O at the intersection point into ground-state OH;

[0007] The second laser emits a 308nm wavelength laser; the sheet light mirror group is arranged in the laser light path of the second laser, converting the 308nm wavelength laser into sheet light and incident it onto the compressor model, exciting the OH in the ground state to the excited state of OH, and then emitting the PLIF fluorescence signal of OH;

[0008] The first camera and the second camera receive fluorescence signals of excited-state OH at different vibrational energy levels to obtain two types of fluorescence intensity information used to invert the temperature field; wherein, the first camera is equipped with a 310±5nm filter and the second camera is equipped with a 285±5nm filter.

[0009] In one embodiment, the first laser is an ArF excimer laser, which emits 193nm wavelength laser light with a frequency of 10-200Hz, and which is an integer multiple of 10Hz.

[0010] In one embodiment, the reflector group includes a first reflector and a second reflector. The first reflector is disposed in the transmission optical path of the beam splitter, and the second reflector is disposed in the reflection optical path of the beam splitter. The reflected light from the first reflector and the reflected light from the second reflector intersect at 120°±5°.

[0011] In one embodiment, the first and second reflectors are both ultraviolet fused silica reflectors with a wavelength range of 120nm-600nm, and the transmittance-to-reflection ratio of the beam splitter is 50%.

[0012] In one embodiment, a first focusing lens and a second focusing lens are respectively provided on the optical paths of the two laser beams obtained by the reflector group, and the first focusing lens and the second focusing lens are DOWN diffraction lenses with a focal length of 300-500mm.

[0013] In one embodiment, the second laser includes an Nd:YAG laser and a dye laser. The Nd:YAG laser emits a 10Hz laser with a wavelength of 532nm, which is incident on the dye laser. The dye laser pumps Rhodamine 590 dye to obtain a 566nm laser, which is then frequency-doubled by two frequency-doubled crystals inside the dye laser to output the 308nm laser.

[0014] In one embodiment, the sheet lens group consists of a convex lens and a plano-concave lens arranged sequentially along the laser beam path, with a focal length of 300-500mm.

[0015] In one embodiment, the angle between the sheet light and the two laser beams intersecting and incident on the compressor model is 120°±5°.

[0016] This invention also provides a measurement method using the aforementioned synchronous measurement device for velocity and temperature fields in a water vapor environment. For temperature field measurement, fluorescence signals S1 and S2 are captured by a first camera and a second camera. Multiple images are taken at each operating point. The portion of each image with a fluorescence intensity greater than 50% of the maximum fluorescence intensity of that image is extracted to obtain high signal-to-noise ratio image information and eliminate the influence of spatial fluctuations of the laser on the experimental data. Then, a pure laser background image under the condition of no water vapor is captured to obtain the laser background signal. The laser background signal is subtracted from each image to eliminate the influence of background noise. Finally, the processed image signals are summed and divided by the number of images to obtain the mean fluorescence intensity information for each operating point. The temperature information of the flow field is calculated by the relationship between the intensity ratio R of S1 and S2 and the temperature T.

[0017] For velocity field measurement, a delay time is set between the 193nm and 308nm wavelength lasers, allowing the OH molecules dissociated by the 193nm laser to undergo a displacement within this delay time. Then, the OH-PLIF signal is excited by the 308nm laser. This displacement is displayed in the form of micro-grid distortion in the captured image. By using the known distance between two points on the calibration plate image and the number of pixels between those two points in the captured image, the actual lengths corresponding to the length and width of a unit pixel are obtained. Thus, the displacement of the OH radicals per unit time is calculated, thereby obtaining the flow field velocity information.

[0018] In one embodiment, the emission time of the 193nm wavelength laser is set as t0, the emission time of the 308nm wavelength laser is set as t1, and the displacement of the OH fluorescence signal (i.e., the S2 position) in the 310nm band relative to the position of the 193nm excitation light emitted by the ArF excimer laser is set as d(x). Then, the formula for calculating the average velocity is as follows:

[0019]

[0020] For the measurement of the temperature field, the OH molecule first moves from the ground state X. 2 The vibrational energy level of Π with v” = 0 is excited to the excited state A. 2The Σ has a v' = 0 vibrational energy level, and vibrational energy transfer (VET) causes some excited OH states to transition from the v' = 0 vibrational energy level to the v' = 1 vibrational energy level. Finally, the spontaneous emission of each particle in these energy levels, i.e., the fluorescence signal from the (1-0) vibrational band and the (0-0) vibrational band, is simultaneously recorded by the ICCD camera. The fluorescence intensity is temperature-dependent and satisfies the following relationship:

[0021] V 01 N0=(V 10 +A1+Q1)N1#Ⅱ

[0022]

[0023] Where V 01 The velocity V represents the rate of propagation from vibrational energy level v' = 0 to vibrational energy level v' = 1; N0 and N1 represent the number of particles in vibrational energy levels v' = 0 and v' = 1, respectively; Q1 represents the rate at which excited-state particles quench to other energy levels; A1 represents the spontaneous emission rate; V 10 This represents the transmission rate from vibrational energy level v' = 1 to vibrational energy level v' = 0; k is the Boltzmann constant, T is the absolute temperature, and ΔE is the velocity. 10 This represents the energy difference between the excited vibrational energy levels. Rearranging the above formula yields the following relationship:

[0024]

[0025] For a given transition (nm), the collected fluorescence satisfies the following equation:

[0026]

[0027] Where ε is the light collection efficiency, η is the quantum efficiency, and V f Let Ω be the laser focusing volume and Ω be the solid-state collection angle. Therefore, the temperature can be expressed by the measured fluorescence:

[0028]

[0029] Where F 0i and F 1j From A 2 From the first two energy levels of the Σ excited state to X 2 Fluorescence signals of energy levels i and j in the ground state of Π; A 0i and A 1j This indicates that the excited state vibrational energy level v'=0 and the vibrational energy level v'=1 migrate to X. 2 The spontaneous emission coefficients of energy levels i and j in the ground state of Π.

[0030] The dissociation process of water is shown in equation VII:

[0031] H2O(X1 A1)+hv λ＝193nm →OH(X 2 Π)+H( 2 S)#Ⅶ

[0032] Where OH(X) 2 Π) represents the ground state OH, H( 2 S) represents the ground state H.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] 1. This invention enables the measurement of the velocity field in a compressor model without the addition of external tracer particles.

[0035] 2. This invention uses only one excitation line (308nm) to obtain the ratio of different narrowband fluorescence signal intensities to measure the temperature field inside the model combustion chamber.

[0036] 3. This invention uses a 193nm wavelength laser to dissociate water vapor to obtain ground-state OH, extending the lower limit of temperature measurement based on OH-PLIF from 1000K to 298K.

[0037] 4. This invention calculates the velocity field by setting different excitation times for 193nm and 308nm wavelength lasers and using an ICCD camera to capture the displacement of OH radicals within that time period.

[0038] 5. This invention uses two ICCD cameras to receive narrowband fluorescence signals of OH at different wavelengths, and calculates the temperature field inside the model combustion chamber by obtaining the ratio of fluorescence intensities.

[0039] 6. This invention obtains high-quality OH fluorescence signals by adding 310±5nm and 285±5nm bandpass filters to filter stray light and other fluorescence signal interference.

[0040] 7. This invention can simultaneously measure the temperature field and velocity field of the object under test. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure of the present invention.

[0042] Figure 2 This is a schematic diagram of the one-dimensional measurement plate arrangement of the present invention.

[0043] Figure 3 This is a schematic diagram of the optical arrangement of the two-dimensional measuring plate of the present invention. Detailed Implementation

[0044] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples.

[0045] The purpose of this invention is to provide a device and method for simultaneously measuring the velocity and temperature fields in a water vapor environment, enabling the simultaneous measurement of the temperature field and flow velocity within a model combustion chamber. This section describes the implementation process and principle.

[0046] like Figure 1 As shown, the synchronous measurement device for velocity and temperature fields in a water vapor environment of the present invention mainly includes a first laser 1, a beam splitter 2, a reflector group, a second laser, a sheet mirror group 12, a first camera 13, and a second camera 15.

[0047] The first laser 1 emits a 193nm wavelength laser beam, and a beam splitter 2 is placed on the path of the 193nm wavelength laser beam to split it into two laser beams. The optical paths of the two laser beams are adjusted by a set of reflectors so that they intersect and are incident on the compressor model 7. The compressor model 7 is filled with air containing water vapor. At the intersection of the two laser beams, H2O is dissociated into ground-state OH.

[0048] The second laser emits a 308nm wavelength laser; the sheet light mirror group 12 is placed in the optical path of the 308nm wavelength laser, converting it into sheet light, which is incident on the compressor model 7 in sheet light form, further exciting the OH in the ground state to the excited state of OH, and then emitting the PLIF fluorescence signal of OH.

[0049] The first camera 13 and the second camera 15 receive fluorescence signals from OH at different ground state energy levels excited by two lasers, and obtain two kinds of fluorescence intensity information, which can be used to invert the temperature field; wherein, the first camera 13 is equipped with a 310±5nm filter and the second camera 15 is equipped with a 285±5nm filter.

[0050] Based on the aforementioned measuring device, this invention first uses two intersecting 193nm wavelength laser beams to forcibly dissociate H2O into OH in the compressor model flow field, thereby extending the experimental conditions to the low-temperature flow field range. Then, a 308nm wavelength laser is used to excite the fluorescence signal of the dissociated OH, obtaining different narrowband fluorescence signals. The temperature field is calculated based on the ratio of these signals. On the other hand, the velocity field can be obtained by measuring and post-processing the micro-distortions of the fluorescence signals on the intersecting grid, thus providing information on the temperature and flow field within the compressor model. This enables the measurement of the velocity and temperature fields in the water vapor environment of the compressor model, providing guidance for setting internal compressor structural parameters. Here, post-processing mainly refers to calculating the velocity using the small time difference between the 308nm and 193nm wavelength laser beams.

[0051] In some embodiments of the present invention, the first laser 1 is an ArF excimer laser, which emits a 193nm wavelength laser with a frequency of 10-200Hz, and which is an integer multiple of 10Hz. A beam splitter 2 splits the 193nm wavelength laser emitted by the ArF excimer laser into two beams, which are then intersected and driven into the object under test, forming a micro-network and dissociating H2O at the intersection points into ground-state OH. For example, the transmittance-to-reflection ratio of the beam splitter 2 is 50%.

[0052] In some embodiments of the present invention, the reflector assembly includes a first reflector 3 and a second reflector 4. The first reflector 3 is disposed in the transmission optical path of the beam splitter 2, and the second reflector 4 is disposed in the reflection optical path of the beam splitter 2. The reflected light from the first reflector 3 and the reflected light from the second reflector 4 intersect at 120°, with an angular error of ±5°. For example, both the first reflector 3 and the second reflector 4 can be ultraviolet fused silica reflectors with a wavelength range of 120-600nm and a diameter of approximately 25.4mm.

[0053] Furthermore, focusing lenses can be set on the optical paths of the two laser beams obtained by adjusting the reflector group. Specifically, a first focusing lens 5 is set on the reflected optical path of the first reflector 3, and a second focusing lens 6 is set on the reflected optical path of the second reflector 4. The first focusing lens 5 and the second focusing lens 6 can be DOE diffraction lenses with a focal length of 300-500mm, so that the two laser beams cross to form a micro grid after passing through the DOE diffraction lens, and dissociate H2O in the 193nm wavelength laser optical path in the flow field of the compressor model 7 into ground state OH.

[0054] In some embodiments of the present invention, the second laser mainly includes an Nd:YAG laser 8 and a dye laser 11. The Nd:YAG laser 8 emits a 10Hz laser with a wavelength of 532nm, which is incident on the dye laser 11. The dye laser 11 pumps Rhodamine 590 dye to obtain a 566nm wavelength laser. This 566nm wavelength laser is then frequency-doubled by two frequency-doubled crystals inside the dye laser to output a 308nm wavelength laser. In the figure, to adjust the optical path, a third reflector 9 and a fourth reflector 10 are placed between the Nd:YAG laser 8 and the dye laser 11. Both reflectors have a diameter of approximately 25.4mm and a designed wavelength of 532nm.

[0055] In some embodiments of the present invention, the sheet light lens group 12 is composed of a convex lens and a plano-concave lens arranged sequentially along the laser light path, with a focal length of 300-500mm, which can convert 308nm wavelength laser into sheet light and excite the PLIF fluorescence signal of OH.

[0056] Furthermore, the angle between the sheet beam and the two laser beams incident on the compressor model 7 is 120°, with a possible angular error of ±5°, but the sum of the angles of the three beams should obviously be 360°. By changing the positions of the three sheet beams within the compressor model 7, the ground state OH at different positions within the compressor model 7 can be excited to the excited state OH, emitting fluorescence signals in different narrow bands.

[0057] In some embodiments of the present invention, the first camera 13 and the second camera 15 are both ICCD cameras.

[0058] In this invention, although the laser wavelength is a necessary characteristic for excitation, it is obviously not necessary to be completely precise to the defined parameters. Generally, the ArF laser used for water dissociation has a fixed wavelength of 193 nm, while the Nd:YAG laser + dye laser used for OH excitation emits wavelengths around 308 nm. A scan within a certain range (307-309 nm) is needed to obtain a suitable excitation peak, thereby determining the actual excitation wavelength.

[0059] Continue to refer to Figure 1 The measurement process of this invention is as follows:

[0060] The first laser 1 emits a 193nm wavelength laser beam, which enters the beam splitter prism 2 and is split into two beams. The two beams are then adjusted by a mirror assembly and a focusing lens to form a miniature network, which is then directed to intersect within the test object. At the intersection, the H₂O at the intersection points dissociates into ground-state OH and ground-state H. Simultaneously, a second laser emits a 308nm wavelength laser beam, which passes through the beam mirror assembly 12 to form a sheet beam, exciting the PLIF fluorescence signal of the OH on the 193nm wavelength laser miniature network. The three laser beams are distributed as follows: Figure 2 As shown. Finally, using the first camera 13 and the second camera 15, PLIF narrowband fluorescence signals at different wavelengths are received to obtain fluorescence intensity information. The flow field temperature is calculated by the ratio of the signal intensities of the two narrowband wavelengths. Figure 2 The line measurement method has been transformed into Figure 3 The surface measurement method shown enables the transition from 2D to 3D measurement. Three laser beams are positioned on the same plane. Two 193nm wavelength lasers intersect to form a microgrid, and then a 308nm wavelength laser is injected to excite the PLIF fluorescence signal of the OH. The velocity field is then calculated using the distortion of the microgrid and the small time difference between the 308nm and 193nm wavelength lasers.

[0061] Specific measurement methods:

[0062] For temperature field measurement, fluorescence signals S1 and S2 are captured by the first camera 13 and the second camera 15. Multiple images are taken at each operating point. The portion of each image with a fluorescence intensity greater than 50% of the maximum fluorescence intensity of that image is extracted to obtain high signal-to-noise ratio image information and eliminate the influence of spatial fluctuations of the laser on the experimental data. Then, pure laser background images under the condition of no water vapor introduction are taken and averaged to obtain the laser background signal. The laser background signal is subtracted from each image to eliminate the influence of background noise. Finally, the processed image signals are summed and divided by the number of images to obtain the mean fluorescence intensity information for each operating condition. The temperature field information in the flow field is obtained by formula VI. Since the pump light band is very close to the fluorescence band of the 0-0 vibration zone, a clean flow field is required and stray light is blocked to prevent it from interfering with the fluorescence signal.

[0063] Velocity measurement requires acquiring reference marker images to determine the positional information within the flow field; velocity marker images, i.e., micro-grid distortion, are used for calculating flow field velocities; and calibration plate images are used to determine spatial distances and other information. After preprocessing the data obtained from the above experiments, including spatial filtering and noise removal, the processed images need to extract positional information. The marker positions are identified using the previously captured reference marker and calibration plate images. Then, the magnification of the captured images is calculated to determine the displacement of the OH base over a certain time period, thereby calculating the displacement information per unit time and ultimately obtaining the velocity field information of the measured object.

[0064] In an embodiment of the present invention, an OH-PLIF signal is excited by a 308nm wavelength laser with a laser energy of 20mJ and a frequency of 10Hz. At this time, the OH is in multiple laser resonant frequency excitation states. The wavelengths of fluorescence emitted by the OH in different laser resonant frequency excitation states are different. The present invention selects two relatively strong fluorescence signal bands, namely 305-315nm and 280-290nm. An ICCD camera with appropriate filters, namely the first camera 13 and the second camera 15, is used to capture these two signals. 150-200 images are taken at each working point. The maximum fluorescence intensity of each image is determined, and half of the intensity is taken as the lower limit value for extracting the signal of that image. The portion of the fluorescence intensity of each image in the obtained data that is greater than half of its maximum fluorescence intensity is extracted, thereby obtaining image information with a high signal-to-noise ratio.

[0065] To ensure that the images captured by the two ICCD cameras have the same resolution and cover the same area, temporal and spatial matching of the cameras is necessary. This can be achieved by simultaneously triggering both cameras with the laser's Q-factor, while maintaining identical settings for the camera gate width, delay, and intensifier, thus achieving timing matching. Furthermore, the calibration board is placed stationary at the test location, and images of the calibration board are captured by both ICCD cameras for subsequent spatial matching during image processing.

[0066] Specifically, for velocity field measurement, a delay time (typically 1-40 μs) is set between the 193 nm and 308 nm wavelength lasers. This allows the OH radicals dissociated from water molecules by the 193 nm laser to undergo a displacement within this delay time, before being excited by the 308 nm laser to generate an OH-PLIF signal, which is captured by an ICCD camera. This displacement is displayed as a micro-grid distortion in the captured image. The image is then post-processed using spatial filtering and noise reduction techniques. By using the known distance between two points on the calibration plate image and the number of pixels between those two points in the captured image, the actual length of each pixel is obtained, thus calculating the displacement of the OH radicals per unit time and obtaining the flow field velocity information.

[0067] In an embodiment of the present invention, a fluorescence signal S1 near the 310nm wavelength is captured by a first camera 13. There is a delay of μs between the 193nm and 308nm wavelength lasers. The emission time of the 193nm laser is set as t0, and the emission time of the 308nm laser is set as t1. The displacement of the OH fluorescence signal (S2) within the 310nm wavelength band relative to the position of the 193nm excitation light emitted by the ArF excimer laser is set as d(x). Here, H2O on the excitation light is dissociated into ground state OH and H, where OH is subsequently excited to an excited state by the 308nm laser, emitting a fluorescence signal which is then received by the ICCD camera. The average velocity calculation formula is as follows:

[0068]

[0069] The second camera 15 is positioned opposite the first camera 13, capturing fluorescence signals F excited by a 308nm wavelength laser and located near the 285nm wavelength band. 0i Since the molecular number density in different quantum states of a gas follows a Boltzmann distribution when the rotational energy levels of the molecules are in thermal equilibrium, two different laser resonance frequency excitation states were selected, and the fluorescence signals F in the corresponding wavelength bands (310 nm and 285 nm) were measured. 0i and F 1j Fluorescence signal F 0i and F 1j It satisfies equation VI with temperature T:

[0070]

[0071] Where Q1 represents the rate at which an excited-state particle quenches to other energy levels; T is the absolute temperature, and ΔE 10 It is the energy difference between the excited vibrational energy levels; F 0i and F 1j From A 2 From the first two energy levels of the Σ excited state to X 2 Fluorescence signals of energy levels i and j in the ground state of Π; A 0i and A 1j This indicates that the excited state vibrational energy level v'=0 and the vibrational energy level v'=1 migrate to X. 2 The spontaneous emission coefficients of energy levels i and j in the ground state of Π.

[0072] In this invention, the dissociation process of water is shown in equation VII:

[0073] H2O(X 1 A1)+hv λ＝193nm →OH(X 2 Π)+H( 2 S)#Ⅶ

[0074] Where OH(X) 2 Π) represents the ground state OH, H( 2 S) represents the ground state H.

Claims

1. A device for simultaneously measuring the velocity field and temperature field in a water vapor-containing environment, characterized in that, It includes a first laser (1), a beam splitter (2), a mirror group, a second laser, a beam splitter group (12), a first camera (13), and a second camera (15); The first laser (1) emits a 193nm wavelength laser; the beam splitter (2) is set in the laser beam path of the first laser (1) to split the 193nm wavelength laser into two laser beams; the reflector group adjusts the optical paths of the two laser beams so that they cross and are incident on the compressor model (7) which is filled with water vapor air, and dissociates the H2O at the intersection point into ground state OH; The second laser emits a 308nm wavelength laser; the sheet light mirror group (12) is set in the laser light path of the second laser, converts the 308nm wavelength laser into sheet light and incident it on the compressor model (7), excites the OH in the ground state to the excited state of the OH, and then emits the PLIF fluorescence signal of the OH; The first camera (13) and the second camera (15) receive PLIF fluorescence signals from the spontaneous emission of excited state OH at different vibrational energy levels, and obtain two fluorescence intensity information for inverting the temperature field; wherein, the first camera (13) is equipped with a 310±5nm filter and the second camera (15) is equipped with a 285±5nm filter.

2. The device for synchronously measuring the velocity field and temperature field of a water vapor-containing environment according to claim 1, characterized in that, The first laser (1) is an ArF excimer laser, which emits a 193nm wavelength laser with a frequency of 10-200Hz, and is an integer multiple of 10Hz.

3. The device for synchronously measuring the velocity field and temperature field in a water vapor-containing environment according to claim 1, characterized in that, The reflector group includes a first reflector (3) and a second reflector (4). The first reflector (3) is disposed in the transmission light path of the beam splitter (2), and the second reflector (4) is disposed in the reflection light path of the beam splitter (2). The reflected light from the first reflector (3) and the reflected light from the second reflector (4) intersect at 120°±5°.

4. The device for synchronously measuring the velocity field and temperature field of a water vapor-containing environment according to claim 3, characterized in that, The first reflector (3) and the second reflector (4) are both ultraviolet fused silica reflectors with a wavelength range of 120-600nm, and the transmittance-to-reflection ratio of the beam splitter (2) is 50%.

5. The device for synchronously measuring the velocity field and temperature field of a water vapor-containing environment according to claim 1, characterized in that, The optical paths of the two laser beams obtained by the mirror group are respectively provided with a first focusing lens (5) and a second focusing lens (6), and the first focusing lens (5) and the second focusing lens (6) are DEE diffraction lenses with a focal length of 300-500mm.

6. The device for synchronously measuring the velocity field and temperature field in a water vapor-containing environment according to claim 1, characterized in that, The second laser includes an Nd:YAG laser (8) and a dye laser (11). The Nd:YAG laser (8) emits a 10Hz laser with a wavelength of 532nm, which is incident on the dye laser (11). The dye laser (11) pumps Rhodamine 590 dye to obtain a 566nm laser, and then the 566nm laser is frequency doubled by two frequency doubling crystals inside the dye laser to output the 308nm laser.

7. The device for synchronously measuring the velocity field and temperature field of a water vapor-containing environment according to claim 1, characterized in that, The sheet lens group (12) consists of a convex lens and a plano-concave lens arranged sequentially along the laser beam path, with a focal length of 300-500mm.

8. The device for synchronously measuring the velocity field and temperature field in a water vapor-containing environment according to claim 1, characterized in that, The angle between the sheet light and the two laser beams that cross-incidentally incident on the compressor model (7) is 120°±5°.

9. A measurement method using the synchronous measurement device for velocity and temperature fields in a water vapor-containing environment as described in claim 1, characterized in that, For the measurement of the temperature field, fluorescence signals S1 and S2 are captured by the first camera (13) and the second camera (15). Multiple pictures are taken at each working point. The part of each picture that is greater than 50% of the maximum fluorescence intensity of that picture is extracted to obtain image information with high signal-to-noise ratio and eliminate the influence of laser fluctuations in space on the experimental data. Then, the influence of background noise is eliminated and the mean information of fluorescence intensity at each working point is calculated. The temperature information of the flow field is deduced by the relationship between the intensity ratio R of S1 and S2 and the temperature T. For velocity field measurement, a delay time is set between the 193nm wavelength laser and the 308nm wavelength laser, so that the OH radicals dissociated by the 193nm wavelength laser move a certain distance within this delay time, and are then excited by the 308nm wavelength laser to generate an OH-PLIF signal. This displacement is displayed in the form of micro-grid distortion in the captured image. The displacement of the OH radicals per unit time is calculated, thereby obtaining the flow field velocity information.

10. The measurement method according to claim 9, characterized in that, Let t0 be the emission time of the 193nm wavelength laser, t1 be the emission time of the 308nm wavelength laser, and d(x) be the displacement of the OH fluorescence signal (S2 position) in the 310nm band relative to the position of the 193nm excitation light emitted by the ArF excimer laser. Then, the formula for calculating the average velocity is as follows: For the measurement of the temperature field, the OH molecule first moves from the ground state X. 2 The vibrational energy level of Π with v” = 0 is excited to the excited state A. 2 The Σ has a v' = 0 vibrational energy level, and vibrational energy transfer (VET) causes some excited OH states to transition from the v' = 0 vibrational energy level to the v' = 1 vibrational energy level. Finally, the spontaneous emission of each particle in these energy levels, i.e., the fluorescence signal from the (1-0) vibrational band and the (0-0) vibrational band, is simultaneously recorded by the ICCD camera. The fluorescence intensity is temperature-dependent and satisfies the following relationship: V 01 N0=(V 10 +A1+Q1)N1#Ⅱ Where V 01 The velocity V represents the rate of propagation from vibrational energy level v' = 0 to vibrational energy level v' = 1; N0 and N1 represent the number of particles in vibrational energy levels v' = 0 and v' = 1, respectively; Q1 represents the rate at which excited-state particles quench to other energy levels; A1 represents the spontaneous emission rate; V 10 This represents the transmission rate from vibrational energy level v' = 1 to vibrational energy level v' = 0; k is the Boltzmann constant, T is the absolute temperature, and ΔE is the velocity. 10 It is the energy difference between the excited vibrational energy levels; rearranging the above formula, we get the following relationship: For a given transition (nm), the collected fluorescence satisfies the following equation: Where ε is the light collection efficiency, η is the quantum efficiency, and V f Let Ω be the laser focusing volume and Ω be the solid-state collection angle; therefore, the temperature can be expressed by the measured fluorescence: Where F 0i and F 1j From A 2 From the first two energy levels of the Σ excited state to X 2 Fluorescence signals of energy levels i and j in the ground state of Π; A 0i and A 1j This indicates that the excited state vibrational energy level v'=0 and the vibrational energy level v'=1 migrate to X. 2 The spontaneous emission coefficients of energy levels i and j in the ground state of Π; The dissociation process of water is shown in equation VII: H2O(X 1 A1)+hv λ＝193nm →OH(X 2 Π)+H( 2 S)#Ⅶ Where OH(X) 2 Π) represents the ground state OH, H( 2 S) represents the ground state H.

Images