A gas jet velocity measurement system and velocity measurement method based on scalar field measurement data

Abstract

This invention proposes a gas jet velocity measurement system and method based on scalar field measurement data, comprising: determining that the optical diagnostic observation area or sensor is located in the fully developed section of the jet, and then measuring the mass fraction of the light gas jet centerline and radial direction; calculating the radial density data from the measured mass fraction data; fitting the radial density × mass fraction distribution to the given centerline position using a Gaussian distribution function to obtain the jet characteristic width at that centerline position based on the jet characteristic width and the law of conservation of mass.

Description

Technical Field

[0001] This invention belongs to the field of gas dynamics measurement technology, and in particular relates to a gas jet velocity measurement system and method based on scalar field measurement data. Background Art

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Gas jets, as a common fluid dynamics phenomenon, have important applications in aerospace, energy and power, environmental engineering, and many other fields. Traditional gas jet velocity measurement equipment mainly includes hot-wire anemometers, laser Doppler velocimeters (LDV), and particle image velocimeters (PIV).

[0004] However, the aforementioned devices have significant limitations when measuring jets of light gases such as hydrogen and helium. For example, hot-wire anemometers are easily affected by ambient temperature, cause significant disturbance to the flow field, and their measurement range is often limited to low speeds. Laser Doppler velocimeters (LDV) and particle image velocimeters (PIV) rely on particle injection into the flow field, but the drift property of particles in jets of light gases such as hydrogen and helium is very weak, and the particle velocity cannot accurately reflect the flow velocity. Furthermore, the data processing methods are relatively complex. In summary, existing gas jet velocimetry technologies have limitations in terms of accuracy, cost, operational complexity, and environmental adaptability.

[0005] Existing patent documents disclose CN1012533B - a jet velocity measuring device, which is used to measure the velocity of liquid jets. It requires the liquid surface to reflect the light source beam to achieve the measurement, and cannot be used to measure light gas jets. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention provides a gas jet velocity measurement system based on scalar field measurement data. The system uses scalar field (mass fraction or density) measurement data to accurately measure the velocity of the gas jet, which is more efficient, lower cost and more adaptable to the environment.

[0007] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions:

[0008] In the first aspect, a gas jet velocity measurement method based on scalar field measurement data is disclosed, including:

[0009] Determine that the optical diagnostic observation area or sensor is located in the fully developed section of the jet, and then measure the mass fraction or density of the light gas jet centerline and radial direction;

[0010] Density or mass fraction data is calculated from the measured mass fraction or density data;

[0011] Based on the radial density and mass fraction distribution at a given centerline location, a Gaussian distribution function is used to fit the radial density × mass fraction distribution to obtain the jet characteristic width at that centerline location.

[0012] Based on the characteristic width of the jet, the velocity of the jet centerline is calculated according to the law of conservation of mass.

[0013] As a further technical solution, the determination of the location in the fully developed section of the jet is based on whether the distribution of the measured parameters along the axial direction satisfies the reciprocal distribution law and whether the radial distribution satisfies the Gaussian distribution.

[0014] As a further technical solution, the axial measurement parameters satisfy the reciprocal distribution law, in which the mass fraction of light gas in the mixed gas and the density of the mixed gas of light gas are related to the nozzle diameter, the coordinate along the jet axis and the coefficient.

[0015] As a further technical solution, the density or mass fraction data is calculated from the measured mass fraction or density data, and obtained based on the mutual conversion formula between specific mass fraction and density data.

[0016] As a further technical solution, for the fully developed section of the jet, the radial density and mass fraction distribution satisfy a set relationship.

[0017] As a further technical solution, based on the condition that the velocity distribution satisfies the Gaussian distribution, the radial velocity of the jet is further calculated from the velocity of the centerline.

[0018] In a second aspect, a gas jet velocity measurement system based on scalar field measurement data is disclosed, comprising: a booster pump, a pressure stabilizing tank, a nozzle, and a concentration sensor array arranged sequentially;

[0019] The booster pump input is connected to a container containing light gas, and the booster pump output is connected to a pressure stabilizing tank. The booster pump pressurizes the light gas in the container and then delivers it to the pressure stabilizing tank.

[0020] The pressure stabilizing tank is connected to the nozzle, which sprays the stabilized light gas out in the form of a jet.

[0021] The concentration sensor array is distributed on the upper side of the jet centerline, uniformly distributed along the jet centerline direction, and uniformly distributed in the direction perpendicular to the centerline. As the distance from the nozzle increases, the number of measurement points in the vertical direction on different centerlines gradually increases and extends outward to adapt to the increase in the characteristic width of the jet.

[0022] As a further technical solution, a control valve is installed on the pipeline between the pressure stabilizing tank and the nozzle, and a first pressure sensor and a first temperature sensor are installed on the pipeline between the booster pump and the pressure stabilizing tank.

[0023] A second pressure sensor, a second temperature sensor, and a mass flow meter are installed on the pipeline between the control valve and the nozzle.

[0024] As a further technical solution, a data acquisition device is also included, to which data collected by the first pressure sensor, the first temperature sensor, the second pressure sensor, the second temperature sensor, the mass flow meter, and the concentration sensor array are all transmitted.

[0025] As a further technical solution, the measurement points cover the jet centerline and radial positions perpendicular to the centerline.

[0026] The above one or more technical solutions have the following beneficial effects:

[0027] This invention provides a method for calculating the velocity field of a gas jet using scalar field measurements, i.e., mass fraction or density measurements. This method can accurately, efficiently, and easily calculate velocity data from mass fraction or density measurements. It avoids injecting particles into the flow field or using additional velocity measuring instruments, enabling simultaneous measurement of the scalar and velocity fields, thus reducing measurement complexity and cost. Furthermore, the sensor layout scheme and the method for determining the fully developed stage of the jet allow for the maximum measurement of parameters such as the jet's mass fraction using a limited number of sensors.

[0028] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0030] Figure 1 This is a flowchart of a gas jet velocity measurement method based on scalar field measurement data according to the present invention;

[0031] Figure 2 This is a schematic diagram of an experimental measurement system according to the present invention;

[0032] Figure 3 This is a schematic diagram of the sensor layout scheme of the present invention;

[0033] Figure 4 This is a comparison chart of the jet centerline velocity calculated by the method proposed in this invention and experimental data.

[0034] Figure 5 This is a comparison chart of the jet centerline velocity calculated by the method proposed in this invention and the centerline velocity obtained by numerical simulation.

[0035] Figure 6 This is a comparison chart of the radial velocity of the jet calculated by the method proposed in this invention and the radial velocity obtained by numerical simulation. Detailed Implementation

[0036] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0037] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0038] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0039] Example 1

[0040] The purpose of this embodiment is to provide a gas jet velocity measurement method based on scalar field measurement data, including:

[0041] After determining that the optical diagnostic observation area or sensor is located in the fully developed section of the jet, the mass fraction of the light gas jet centerline and radial direction is measured.

[0042] Density data is calculated from the measured mass fraction data;

[0043] Based on the radial density and mass fraction distribution at a given centerline location, a Gaussian distribution function is used to fit the radial density × mass fraction distribution to obtain the jet characteristic width at that centerline location.

[0044] Based on the characteristic width of the jet, the velocity of the jet centerline is calculated according to the law of conservation of mass.

[0045] It should be noted that several sets of data are measured each time to determine whether the optical diagnostic observation area or sensor is located in the fully developed section, i.e., the flow region where the radial distribution of flow parameters such as velocity and density follows a Gaussian distribution. The fully developed section of the jet is determined based on whether the distribution of measured parameters along the axial direction follows a reciprocal distribution law and whether the radial distribution follows a Gaussian distribution. The axial reciprocal distribution law is as follows:

[0046]

[0047] In the formula, ρ represents the density of the mixed gas after the jet entrains air, Y represents the mass fraction of working gas such as hydrogen or helium in the mixed gas, the subscript cl represents the jet axis (center line), z represents the coordinate along the jet axis, d is the nozzle diameter, and C1, C2 and C3 are all empirical coefficients.

[0048] In one implementation example, scalar information such as the mass fraction or density of the gas jet is measured using optical diagnostic techniques or sensor measurement techniques.

[0049] Based on the theory of calculating the physical properties of gas mixtures, the density data is calculated from the measured hydrogen mass fraction data. The conversion formulas between mass fraction and density are as follows:

[0050]

[0051] In the formula, ρ H2 ρ represents the density of hydrogen gas under the specified jet temperature and pressure conditions. air Y represents the air density at the jet temperature and pressure; Y represents the mass fraction of working gases such as hydrogen or helium in the gas mixture.

[0052] Based on the radial density and mass fraction distribution at a given centerline location, a Gaussian distribution function is used to fit the radial density × mass fraction distribution to obtain the jet characteristic width b at that centerline location, which is then used to calculate the velocity at the jet centerline.

[0053] Specifically, according to gas jet theory, for the fully developed section of the jet, the density and mass fraction distributions satisfy the following relationship, which is used to fit b:

[0054]

[0055] In the formula, r represents the radial coordinate of the jet, λ = 1.16 is the empirical coefficient for the hydrogen jet, b is the characteristic width of the jet, and Y... cl ρ represents the mass fraction along the centerline of the jet. cl The centerline density of the jet.

[0056] Calculate the velocity along the centerline of the jet using the law of conservation of mass. For the fully developed section of the jet, the velocity distribution follows a Gaussian distribution:

[0057]

[0058] In the formula, u represents the jet velocity. The law of conservation of mass is as follows:

[0059]

[0060] In the formula, The mass flow rate at the hydrogen jet outlet is represented by a mass flow meter, and φ is the circumferential angle of the jet. Based on the above, the formula for calculating the velocity at the jet centerline can be derived as follows:

[0061]

[0062] Among them, Y cl It is the centerline mass fraction, ρ cl Here, λ represents the centerline density, and λ is an empirical coefficient reflecting the ratio of concentration to radial diffusion rate. denoted by , where b represents the mass flow rate at the hydrogen jet outlet, and b is the characteristic width of the jet.

[0063] Comparison between the jet centerline velocity calculated by the above method and the experimentally measured value Figure 4 As shown.

[0064] Furthermore, based on the condition that the velocity distribution satisfies a Gaussian distribution, the velocity u at the jet centerline can be determined. cl The radial velocity u of the jet was then calculated.

[0065] Example 2

[0066] See Figure 1 and Figure 2 As shown, this embodiment discloses a gas jet velocity measurement system based on scalar field measurement data, which implements the method in the first embodiment above, including: a booster pump, a pressure stabilizing tank, a nozzle and a concentration sensor array arranged in sequence;

[0067] The booster pump's input end is connected to a container containing light gas, and the booster pump's output end is connected to a pressure stabilizing tank. The booster pump pressurizes the light gas in the container and then delivers it to the pressure stabilizing tank.

[0068] The pressure stabilizing tank is connected to the nozzle, which ejects the stabilized light gas in a jet manner;

[0069] Sensor layout scheme as follows Figure 3 As shown, the concentration sensor array is distributed above the center line of the jet, uniformly distributed along the direction of the jet center line, and uniformly distributed in the direction perpendicular to the center line. As the distance from the nozzle increases, the number of measurement points in the vertical direction of different center lines gradually increases and extends outward to adapt to the increase of the jet characteristic width.

[0070] A control valve is installed on the pipeline between the pressure stabilizing tank and the nozzle, and a first pressure sensor and a first temperature sensor are installed on the pipeline between the booster pump and the pressure stabilizing tank.

[0071] A second pressure sensor, a second temperature sensor, and a mass flow meter are installed on the pipeline between the control valve and the nozzle.

[0072] In one embodiment, in order to achieve data acquisition, a data acquisition device is also included. The data collected by the first pressure sensor, the first temperature sensor, the second pressure sensor, the second temperature sensor, the mass flow meter, and the concentration sensor array are all transmitted to the data acquisition device, and the data obtained by the data acquisition device is directly stored on the computer.

[0073] It should be noted that this measurement system is used to measure the mass fraction of a gas jet. The mass fraction of the hydrogen jet is measured along the centerline and radial direction using a sensor. The measurement location must be in the fully developed section of the jet. The measurement points cover the centerline of the jet and the radial position perpendicular to the centerline. It should be noted that the centerline and radial values ​​must be measured simultaneously to determine the jet characteristic width b mentioned below.

[0074] Specifically, the concentration sensor outputs a voltage signal, which is recorded and saved by a data acquisition instrument. The saved voltage value is then converted into a mass fraction value using a formula provided by the sensor manufacturer.

[0075] "Radial" refers to the direction perpendicular to the jet centerline, and the radial distribution follows a Gaussian distribution (where Y... cl It is the centerline mass fraction, ρ cl Where Y is the radial mass fraction, ρ is the radial density, and λ is the empirical coefficient reflecting the ratio of concentration to velocity radial diffusion rate.

[0076]

[0077] When the system is working, the specific usage or working process is as follows:

[0078] First, the nitrogen cylinder is opened to serve as the driving gas for the booster pump, and the hydrogen cylinder is opened to introduce hydrogen into the booster pump for pressurization and injection into the pressure stabilizing tank. Therefore, the pressure stabilizing tank contains either hydrogen or helium, both of which are pure gases and are called the "working gas".

[0079] Second, stop pressurizing when the pressure inside the pressure stabilizing tank reaches 1.2 times the required release pressure for the experiment. The pressure in the pressure stabilizing tank is slightly higher than the required release pressure to maintain pressure stability during the release process.

[0080] Third, open the control valve, and high-pressure hydrogen gas is sprayed out from the nozzle. After the jet is sprayed out, it mixes with air, and the pressure is controlled by the control valve.

[0081] Fourth, the data acquired by the data acquisition instrument is used to collect and record the data measured by the sensor.

[0082] Verification Example

[0083] To further verify the accuracy and applicability of the method proposed in this invention, the calculation results of the method proposed in this invention were compared with the results of computational fluid dynamics numerical simulation, specifically including the following steps:

[0084] A high-pressure hydrogen jet simulation model was established using computational fluid dynamics software, with the hydrogen source pressure set to 1 MPa, the nozzle diameter to 1 mm, and the ambient temperature to 293.15 K.

[0085] The mass fraction and density distribution of the jet are derived from the numerical simulation results, which are then used to calculate parameters such as the characteristic width of the jet.

[0086] Based on the radial density and mass fraction distribution at a given centerline location, a Gaussian distribution function is used to fit the radial density × mass fraction distribution to obtain the characteristic width of the jet at that centerline location. According to gas jet theory, for the fully developed section of the jet, the density and mass fraction distributions satisfy the following relationship:

[0087]

[0088] In the formula, r represents the radial coordinate of the jet, λ = 1.16 is the empirical coefficient of the hydrogen jet, b is the characteristic width of the jet, and the subscript "cl" indicates the centerline of the jet;

[0089] Calculate the velocity along the centerline of the jet using the law of conservation of mass. For the fully developed section of the jet, the velocity distribution follows a Gaussian distribution:

[0090]

[0091] In the formula, u represents the jet velocity. The law of conservation of mass is as follows:

[0092]

[0093] In the formula, The mass flow rate at the hydrogen jet outlet is represented by φ, calculated using numerical simulation software, where φ is the circumferential angle of the jet. Based on the above, the formula for calculating the velocity at the jet centerline can be derived as follows:

[0094]

[0095] Based on the condition that the velocity distribution satisfies the Gaussian distribution, the radial velocity of the jet can be further calculated from the centerline velocity.

[0096] Comparison between the jet centerline velocity calculated by the above method and the numerical simulation results Figure 5 As shown, the comparison between the radial velocity distribution of the jet at different locations calculated by the above method and the numerical simulation results is as follows: Figure 6 As shown.

[0097] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computer devices. Optionally, they can be implemented using computer-executable program code, thereby allowing them to be stored in a storage device for execution by a computer device, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. The present invention is not limited to any particular combination of hardware and software.

[0098] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A gas jet velocity measurement method based on scalar field measurement data, characterized in that, include: After determining that the optical diagnostic observation area or sensor is located in the fully developed section of the jet, the mass fraction of the light gas jet centerline and radial direction is measured. The sensor layout scheme is as follows: the concentration sensor array is distributed above the centerline of the jet, evenly distributed along the direction of the centerline, and evenly distributed in the direction perpendicular to the centerline. As the distance from the nozzle increases, the number of measurement points in the vertical direction of different centerlines gradually increases and extends outward to adapt to the increase of the jet characteristic width. Radial density data were calculated from the measured mass fraction data; Based on the radial density and mass fraction distribution at a given centerline location, a Gaussian distribution function is used to fit the radial density × mass fraction distribution to obtain the jet characteristic width at that centerline location. Based on the characteristic width of the jet, the velocity of the jet centerline is calculated according to the law of conservation of mass. Specifically, the determination of whether the jet is located in the fully developed stage is based on whether the distribution of measured parameters along the axial direction satisfies the inverse distribution law, and whether the radial distribution satisfies the Gaussian distribution law; the inverse distribution law along the axial direction is as follows: In the formula, This indicates the density of the gas mixture after the jet entrains air. Indicates the mass fraction of hydrogen in the gas mixture, subscript Indicates the jet axis, Represents the coordinates along the jet axis. Nozzle diameter, and All are empirical coefficients; The mass fraction or density scalar information of the gas jet is measured using optical diagnostic technology or sensor measurement technology; based on the calculation theory of gas mixture properties, the density data is calculated from the measured hydrogen mass fraction data; the conversion formulas between mass fraction and density are as follows: In the formula, This represents the density of hydrogen gas under the specified jet temperature and pressure conditions. This indicates the air density at the jet temperature and pressure. This indicates the mass fraction of hydrogen in the gas mixture; Based on the radial density and mass fraction distribution at a given centerline location, a Gaussian distribution function is used to fit the radial density × mass fraction distribution to obtain the characteristic jet width at that centerline location. , used to calculate the velocity of the jet centerline; Specifically, according to gas jet theory, for the fully developed section of the jet, the density and mass fraction distributions satisfy the following relationship, which is used for fitting. : In the formula, Represents the radial coordinates of the jet. This is the empirical coefficient for hydrogen jet. The characteristic width of the jet. Indicates the mass fraction along the centerline of the jet. The centerline density of the jet; Calculate the velocity along the centerline of the jet according to the law of conservation of mass; for the fully developed section of the jet, the velocity distribution satisfies the following Gaussian distribution: In the formula, Indicates the jet velocity; The law of conservation of mass is as follows: In the formula, The mass flow rate at the hydrogen jet outlet is indicated by a mass flow meter. Let be the circumferential angle of the jet; based on the above, the formula for calculating the velocity along the centerline of the jet can be derived as follows: in, It is the centerline mass fraction. For centerline density, An empirical coefficient reflecting the ratio of concentration to radial diffusion rate, This indicates the mass flow rate at the hydrogen jet outlet. The characteristic width of the jet.

2. A system for implementing the gas jet velocity measurement method based on scalar field measurement data as described in any one of claims 1, characterized in that, include: A booster pump, a pressure stabilizing tank, nozzles, and a concentration sensor array are arranged in sequence. The booster pump input is connected to a container containing light gas, and the booster pump output is connected to a pressure stabilizing tank. The booster pump pressurizes the light gas in the container and then delivers it to the pressure stabilizing tank. The pressure stabilizing tank is connected to the nozzle, which sprays the stabilized light gas out in the form of a jet. The concentration sensor array is distributed on the upper side of the jet centerline, uniformly distributed along the jet centerline direction, and uniformly distributed in the direction perpendicular to the centerline. As the distance from the nozzle increases, the number of measurement points in the vertical direction on different centerlines gradually increases and extends outward to adapt to the increase in the characteristic width of the jet.

3. The system for a gas jet velocity measurement method based on scalar field measurement data as described in claim 2, characterized in that, A control valve is installed on the pipeline between the pressure stabilizing tank and the nozzle, and a first pressure sensor and a first temperature sensor are installed on the pipeline between the booster pump and the pressure stabilizing tank. A second pressure sensor, a second temperature sensor, and a mass flow meter are installed on the pipeline between the control valve and the nozzle.

4. The system for gas jet velocity measurement based on scalar field measurement data as described in claim 3, characterized in that, It also includes a data acquisition device, to which data collected by the first pressure sensor, the first temperature sensor, the second pressure sensor, the second temperature sensor, the mass flow meter, and the concentration sensor array are transmitted.

5. The system for a gas jet velocity measurement method based on scalar field measurement data as described in claim 2, characterized in that, The measurement points cover the jet centerline and radial positions perpendicular to the centerline.

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