Density measurement array and method for inverting three-dimensional flow field based on fluid density field change rate

Abstract

The invention discloses a density measurement array and a method for inverting a three-dimensional flow field based on a fluid density field change rate. According to the method, a temperature sensing array comprising temperature probes and an array structure is constructed through a temperature sensor, the temperature probes are arranged with a speed measurement point as the center, and the distance range is unequal from the micron level to the meter level. The array structure can adopt various geometric forms such as a rectangle, a circle and the like. Modeling is carried out by measuring a space distribution field of temperature, combining with calibration of a flow velocity meter and utilizing the relation between the temperature distribution change rate and the flow velocity, so that flow velocity information is inverted. By integrating a plurality of arrays, multi-point measurement of a three-dimensional flow field can be realized. According to the method, high-precision flow velocity measurement can be realized in an environment without scattering particles, and the measurement accuracy is further improved through multi-parameter verification. The range of measuring the fluid scale is wide, and an innovative solution is provided for monitoring the fluid flow speed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of flow velocity measurement, and relates to a density sensor array design for flow velocity measurement and a method for measuring a fluid density field using the density sensor array and then inverting a three-dimensional flow field. BACKGROUND

[0002] Fluid flow plays a crucial role in understanding the dynamic changes of fluid environments, which directly affects climate regulation, nutrient distribution, and the health of ecosystems. Currently, the methods for measuring fluid flow velocity are mainly divided into direct observation methods and indirect observation methods. Common flow velocity measurement principles include mechanical, electromagnetic, acoustic, and optical methods. However, these methods usually rely on suspended particles or bubbles in the fluid for measurement, and perform poorly in areas with few particles or clear water. For example, in deep-sea environments, the fluid has few or almost no particles, making it difficult to measure the flow velocity.

[0003] In nature, fluid flow velocity is a complex phenomenon formed by the combined action of various factors, including wind force, Earth's rotation force, internal density differences of the fluid, atmospheric pressure changes, and tides. In deep fluid environments, surface wind force and atmospheric influence are small, and density changes become the main driving factor of flow velocity changes. In deep fluid regions, the pressure is the same at the same horizontal plane, and the salinity change is also extremely small, so the main factor affecting the density of deep fluid is temperature. By analyzing the rate of change of the temperature field over time, the flow velocity field of the fluid can be inverted. SUMMARY

[0004] The purpose of the present application is to provide a density measurement array that measures the density field based on the correlation between density and temperature through the density measurement array, and a method for inverting a three-dimensional flow field from the rate of change of the fluid density field, which measures the temperature through a temperature sensor array and combines it with the flow velocity measured by a flow velocity sensor for comparative testing, and uses the rate of change of the temperature spatial distribution field over time to fit and invert the flow velocity, providing an innovative solution for fluid flow velocity monitoring.

[0005] To achieve the above purpose, the present application provides the following technical solutions:

[0006] The present application can be used for flow velocity measurement in a fluid environment without scattering particles and with a small range of velocities.

[0007] A temperature sensor array is constructed using temperature sensors, each of which includes a temperature probe, a power management unit, and a data acquisition and processing unit.

[0008] Optionally, the temperature probe includes a thermistor temperature sensor, a platinum resistance temperature sensor, an optical temperature sensor, and other temperature measurement devices not mentioned in the present application.

[0009] Optionally, the temperature probe is encapsulated by a shell for protection, the material includes metal material that can resist pressure, corrosion and is suitable for fluid environment, and the temperature probe can also be encapsulated by other materials according to different use environments.

[0010] Optionally, the power management unit includes a battery compartment and a power management module, and the temperature probe is powered by a transmission line to work, and the entire array can use the same power management and is located on one side of the array.

[0011] Optionally, the data acquisition and processing unit includes a transmission line for transmitting temperature signals, a data acquisition card, a CPU processing unit and the like, and is used for processing and outputting temperature data as a speed signal, and the entire array can use the same data acquisition and processing unit and is located on one side of the array.

[0012] Optionally, the installation mode of the power management unit and the data acquisition and processing unit includes multiple modes, for example, the power management unit can be integrated with the data acquisition and processing unit as a module and be fixedly installed together, or can be fixedly installed according to the specific array arrangement, and other installation and fixing modes.

[0013] The temperature sensor array includes temperature probes, array structures, transmission lines, power management units and data acquisition and processing units, multiple temperature sensor probes are arranged in a specific position to form an array with a speed measurement point as a center point, and the flow rate of the fluid at the center point is inversely calculated by using the rate of change of the spatial distribution field of the temperature with time.

[0014] Optionally, the temperature sensor array structure is made of materials that can resist pressure, corrosion and are suitable for fluid environments, and other materials can also be used for production according to different application scenarios, and the materials are not limited to the materials mentioned in the application.

[0015] Optionally, the data acquisition and processing unit and the power management unit are located on one side of the array. A rigid structure can be used to fix the temperature sensor array structure, or the transmission line can be extended to arrange the electrical part on any underwater platform, ship or shore station.

[0016] Optionally, the temperature probes are arranged in an array with a spatial distribution interval of a distance in the range of μm-m, and the entire temperature array can measure turbulent flow of a fluid scale of millimeter to tens of meters.

[0017] Each pair of temperature sensors in the spatial distribution array can form a measurement group, multiple measurement groups can average the measurement data of the same spatial point, remove singular points, improve data accuracy, and also obtain a temperature field spatial distribution and inversely calculate a flow field distribution based on the temperature field spatial distribution.

[0018] Optionally, the temperature sensor array structure can be rectangular, rhombic or circular (cuboid, rhombohedron or sphere), and any other planar or three-dimensional combination arrangement, to achieve the measurement of the temperature spatial distribution of a certain point or a certain space area, and the arrangement is not limited to the way in the examples of the present application.

[0019] The temperature at each point on the array can be measured at different positions in the fluid, and the temperature spatial distribution field can be obtained to construct a flow velocity inversion model.

[0020] According to the temperature values observed at the array point positions, the temperature field distribution analysis is performed.

[0021] Based on the current meter as a calibration tool, the temperature field inversion flow velocity field can be calibrated.

[0022] Optionally, the current meter includes instruments for measuring flow velocity using mechanical principles, electromagnetic principles, acoustic principles, particle imaging principles, laser holographic principles, and optical Doppler principles. The calibration technology based on other types of flow measurement devices is also within the scope of the patent rights of the present invention.

[0023] In the laboratory, a particle-containing fluid is constructed, and the temperature difference-driven fluid velocity field is measured simultaneously using a current meter and a temperature sensor array to perform a comparison fitting.

[0024] Optionally, the fitting method includes polynomial fitting, Boltzmann and other fitting methods, and methods and algorithms for fitting temperature distribution and flow velocity that are not explicitly stated in the present application but can be implemented according to actual measurements.

[0025] According to the current meter observation of the comparison, the relationship between the temperature spatial distribution change rate and the flow velocity is modeled.

[0026] For the density-driven flow field velocity change, the principle is that the density change causes the force change, and the force in fluid mechanics is the direct cause of the flow velocity change, Fb = g·Δρ, where Fb is the buoyancy, g is the gravitational acceleration, and Δρ is the density change. The density change Δρ can be further expressed as: Δρ = ρ·β·ΔT, where ρ is the fluid density, β is the thermal expansion coefficient, and ΔT is the temperature change.

[0027] When the fluid is driven by temperature, its flow velocity v can be approximately inverted by the following formula: where, is the temperature change, and k is a proportional coefficient related to the fluid dynamics parameters. By measuring the temperature and known system parameters, the flow velocity can be inverted.

[0028] The calculation method of the fluid flow velocity is simplified as: y = 3.958 × 10 7 [dΔt] 3-1.675 x 10 5 [dΔt] 2 +432.394 dΔt - 0.1636.

[0029] wherein Δt is the temperature distribution difference measured by the temperature sensor group in the spatial distribution field of temperature.

[0030] The multiple temperature sensor arrays are integrated into a laminar flow field velocity measurement array, and the multiple-point flow field velocity measurement in the fluid can be performed.

[0031] Each temperature sensor array has the above characteristics.

[0032] The number N of temperature sensor arrays is increased in the same dimension, and a single-layer flow field can be measured. The single-layer flow field measurement array is fixed by a rigid structure at a specific angle to form flow velocity measurement points with a fixed spacing, and the spacing can be from millimeter level to tens of meters.

[0033] In different depths of fluid, multiple single-layer flow field measurement arrays arranged at equal intervals can be used to realize three-dimensional flow field measurement in the entire fluid.

[0034] In different dimensions, the number N of temperature sensor arrays is increased, and the velocity measurement of a multi-layer three-dimensional flow field can be realized. The multi-layer flow field measurement array is fixed by a rigid structure at a specific angle to form flow velocity measurement points with a fixed spacing, and the spacing can be from millimeter level to tens of meters. The number N is related to the range of the flow field to be measured.

[0035] Compared with the prior art, the present application has the following beneficial effects:

[0036] ① The traditional flow velocity measurement method mostly depends on suspended particles or bubbles in the fluid. However, in deep sea and other areas with few particles or clear water. The present application uses temperature sensor arrays to inversely calculate the flow velocity according to the correlation between temperature and density, and gets rid of the dependence on scattering particles, so that high-precision flow velocity measurement can be realized in a fluid environment without scattering particles.

[0037] ② The temperature sensor array can form multiple sets of measurement data. By averaging the measurement data of the same spatial point, removing singular points, and setting a control group and combining algorithm processing, the reliability of the data and the accuracy of the measurement can be effectively improved.

[0038] ③ The spatial distribution interval of the temperature probe can be adjusted in the range of microns to meters. The entire temperature array can measure the turbulent flow of millimeter to tens of meters of fluid scale. And by integrating multiple temperature sensor arrays, measurement points can be arranged in different dimensions and depths to realize multi-point measurement of three-dimensional flow field. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below only constitute some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0040] Figure 1 Structure diagram of the temperature sensor in the embodiments of the present application;

[0041] Figure 2 Structure diagram of the temperature sensor array in the embodiments of the present application; Figure 2 (a) Structure diagram of the cuboid temperature sensor array; Figure 2 (b) Structure diagram of the spherical temperature sensor array;

[0042] Figure 3 Structure diagram of the flow field measurement array in the embodiments of the present application;

[0043] In the figure: 11, temperature probe; 12, transmission line; 13, power management unit; 14, data acquisition and processing unit; 15, electrical part; 21, array structure. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments only constitute some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0045] Embodiment:

[0046] It should be noted that the terms "comprising" and "having" and any variations thereof in the embodiments of the present application are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device comprising a series of steps or units does not have to be limited to only those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to the process, method, product or device.

[0047] In the following content, for the convenience of description, the terms temperature field, temperature sensing, temperature sensor array, etc. will be used to represent density field, density sensing, density sensor array. In three-dimensional space, if the influence of pressure or concentration (salinity) on density between two points cannot be ignored, density must be used instead of temperature.

[0048] The density of the fluid is determined by its temperature, concentration (such as salinity) and pressure. In the case of the same pressure and concentration, the temperature field can be used to replace the density field to inverse the flow velocity field, and the temperature measurement can be used to replace the density measurement, and the temperature difference can be used to replace the density difference.

[0049] In some embodiments, the temperature probe selects a high-sensitivity thermistor temperature probe with small volume and fast response speed. These temperature probes can accurately capture the small temperature changes in the fluid, thereby providing reliable data support for flow velocity inversion.

[0050] The temperature probe performs temperature measurement, and the power management unit supplies power to the probe through the transmission line to make it work.

[0051] The signal is returned to the data acquisition and processing unit through the transmission line for speed inversion.

[0052] The power management unit can be integrated with the data acquisition and processing unit as a module, and can be fixed and installed together, or can be fixed and installed separately according to the specific array arrangement.

[0053] The packaging shell of the temperature sensor is made of metal materials that can withstand pressure, corrosion and are suitable for fluid environment. In other use environments, other materials are used for packaging, not limited to pressure-resistant, corrosion-resistant metal materials and other materials mentioned in this invention.

[0054] In some embodiments, based on the reliability verification of temperature measurement, the experiment first calibrates the thermistor, puts the thermistor into a high-precision temperature-controlled water tank (such as temperature fluctuation of 0.4mK) for temperature test, uses a standard platinum resistance temperature sensor as a comparison instrument, collects temperature data under different temperature environments, performs linear fitting of temperature data, and calibrates the thermistor. The temperature measurement accuracy of the thermistor reaches ±0.001℃, which can meet the measurement requirements of small temperature gradient in the experiment.

[0055] In terms of temperature acquisition system, a multi-channel temperature acquisition system (such as TCM) can be used to quickly record data of multiple temperature probes, ensure real-time and accuracy of data, and effectively capture rapidly changing temperature data.

[0056] In some embodiments, in order to verify the accuracy of the flow velocity based on the temperature gradient, the experiment uses a high-precision optical Doppler flowmeter as a comparison standard flow velocity measurement device, with a measurement range of 10μm / s-3m / s and an accuracy of 10μm / s.

[0057] If the flow velocity is low (low flow velocity usually refers to the range of millimeters per second) in the experiment, a higher-precision optical flowmeter can be selected to meet the measurement needs of low-flow velocity environment.

[0058] In some embodiments, two temperature probes are placed in the fluid, with a distance between the center points of the two temperature probes being between millimeters and tens of centimeters, temperature data is collected, and an optical flow meter is placed at the center positions of the two temperature probes to calibrate the reference of the flow rate ratio.

[0059] In some embodiments, the temperature difference between the two points is subjected to a Boltzmann fitting, and the spatial distribution change rate of the temperature is obtained by derivation. Through multiple experiments, the data fitting relationship between the spatial distribution of the temperature and the flow rate is obtained.

[0060] The preferred embodiments of the present application are described below with reference to the accompanying drawings.

[0061] The present application provides a method for measuring the temperature difference gradient using a temperature sensing array, and then inverting the flow rate of the fluid. The schematic structure of the temperature sensor used is shown in Figure 1 .

[0062] The temperature probe 11 is powered by the power management unit 13, and the power is transmitted to the temperature probe 11 by two transmission lines 12.

[0063] The temperature signal is transmitted by the transmission line 12 to the data acquisition and processing unit 14, where the temperature data is collected and processed, and the temperature data is processed and output as a speed signal.

[0064] The overall structure of the temperature sensing array is shown in Figure 2 .

[0065] The sensing array is rectangular, circular or diamond-shaped (cuboid, sphere or rhombohedron), and other ways that can uniformly measure the spatial distribution of the fluid temperature. The gray dots are the temperature probes 11, and the lines are the array structure 21.

[0066] The temperature sensing array structure 21 is made of materials that can withstand pressure, corrosion, and are suitable for fluid environments. Other materials can also be used for production according to different application scenarios, and it is not limited to the materials mentioned in the present application.

[0067] The temperature sensing array extends the transmission line 12, which is connected to the power management unit 13 and the data acquisition and processing unit 14.

[0068] The entire array can use the same power management and the same acquisition and processing part,

[0069] The center red dot is the flow rate measurement point, which is the position point of the inverted flow rate result.

[0070] The data of each pair of temperature sensor measurement groups in the array is taken as a data set, and the measurement data of the same spatial point is subjected to a speed average operation to remove singular points and improve data accuracy.

[0071] The power management unit 13 and the data acquisition and processing unit 14 can be fixed to the array structure 21 in a rigid structure, located on one side of the array, or can be extended transmission lines, and the electrical part 15 is arranged to any underwater platform, ship or shore base site.

[0072] The calculation method of the fluid flow rate is simplified as: y = 3.958 x 10 7 [dΔt] 3 -1.675 x 10 5 [dΔt] 2 + 432.394 dΔt - 0.1636.

[0073] The schematic diagram of the flow field measurement array is shown in Figure 3 .

[0074] N temperature sensor arrays are arranged to form a set, forming flow rate measurement points with fixed intervals of millimeter to tens of meters, becoming a laminar flow field velocity measurement array;

[0075] In this example, multiple temperature sensor array sets are arranged at different depths of the fluid to form a laminar flow field velocity measurement array, and multi-point flow field velocity measurement is performed in the fluid, and the flow rate measurement point interval is 10 cm;

[0076] In this example, the number N of temperature sensor arrays is increased in different dimensions to realize multi-layer three-dimensional flow field velocity measurement, and the flow rate measurement point interval is 10 cm, and the theoretical interval of the present application can be from millimeter to tens of meters.

[0077] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, different embodiments or examples described in the present specification and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0078] The above embodiments are only for the purpose of illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made in accordance with the essence of the present application should be covered within the protection scope of the present application.

Claims

1. A density measurement array, characterized in that, include: A temperature sensing array includes temperature probes, an array structure, transmission lines, a power management unit, and a data acquisition and processing unit. Multiple temperature probes are arranged in an array with a speed measurement point as the center point and at a set position. The temperature probes are fixed on the array structure and are electrically connected to the power management unit and the data acquisition and processing unit respectively through the transmission lines.

2. A method for inverting a three-dimensional flow field based on the rate of change of fluid density field, characterized in that, Including the following steps: Construct a temperature sensing array using temperature sensors; Temperature spatial distribution field is obtained by measuring the temperature of fluid using a temperature sensing array. Each point on the array is located at a different position in the fluid, and the temperature at each point is measured to construct the temperature spatial distribution field. Based on the temperature values ​​observed at the array point locations, the spatial distribution field of temperature is analyzed; Using a flow meter as a calibration tool, a calibration basis is provided for the inversion of the flow velocity field from the temperature field. A fluid containing particles is constructed in the laboratory, and the fluid velocity field driven by the temperature difference is measured simultaneously using a flow meter and a temperature sensor array, and then compared and fitted. Based on the flow velocity measurements, a model was developed to represent the relationship between the spatial distribution rate of temperature change and the flow velocity. For density-driven flow field velocity changes, the flow velocity of the fluid under temperature-driven conditions is approximately inverted using a preset formula; Multiple temperature sensor arrays are integrated into a laminar flow field velocity measurement array. The number of temperature sensor arrays is increased in the same dimension to measure the single-layer flow field. In fluids at different depths, multiple single-layer flow field measurement arrays are arranged at equal intervals, or the number of temperature sensor arrays is increased in different dimensions to measure the three-dimensional flow field in the entire fluid.

3. The method for inverting a three-dimensional flow field based on the rate of change of fluid density field according to claim 1, characterized in that, The preset formula includes Fb=g·Δρ, where Fb is buoyancy, g is gravitational acceleration, and Δρ is density change. The density change Δρ can be further expressed as: Δρ=ρ·β·ΔT, where ρ is fluid density, β is the coefficient of thermal expansion, and ΔT is temperature change.

4. The method for inverting a three-dimensional flow field based on the rate of change of fluid density field according to claim 1, characterized in that, The preset formula includes y = 3.958 × 10 7 [dΔt] 3 -1.675×10 5 [dΔt] 2 +432.394dΔt-0.1636, where Δt is the temperature distribution difference and y is the fluid velocity.

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