Multifunctional foamed metal flow parameter measuring device and measuring method

Abstract

The application discloses a multifunctional foam metal flow parameter measuring device and a measuring method, which comprises a test section, an inlet section and a mixing section arranged upstream of the test section, an outlet section arranged downstream of the test section, a foam metal to be measured fixedly arranged on the test section, an inlet pipeline arranged on the inlet section and provided with an expansion mechanism for expanding airflow, a first detection mechanism arranged on the mixing section and used for measuring static pressure upstream of the foam metal to be measured, and a second detection mechanism arranged on the outlet section and used for measuring outlet static pressure. The application can obtain a two-dimensional curve of flow and pressure difference, derive a first-order term and a second-order term coefficient, and convert permeability and inertia coefficient by measuring static pressure before and after the foam metal to be measured, so that flow resistance is measured in a similar way, data is accurate, calculation is simple, and the application provides support for research on engineering application of the foam metal.

Description

Technical Field

[0001] This invention relates to the field of foam metal performance testing technology, and in particular to a multifunctional foam metal flow parameter measuring device and method. Background Technology

[0002] Foamed metal is a special type of metallic material with foam-like pores. It possesses unique structural characteristics and advantages such as low density, good thermal insulation, good sound insulation, high permeability, and good sound damping performance, making it widely used in acoustics, flow control, and other fields. Permeability, inertia coefficient, and flow resistance are three important parameters that determine the fluid flow characteristics when foamed metal is used as a flow medium, and they are of great significance in flow simulation, experiments, and the research of engineering applications of foamed metal.

[0003] Accurate and rapid measurement of permeability and inertia coefficient helps to better utilize the unique properties of foamed metals and apply them to engineering needs. Measurements are typically performed experimentally. The results are then substituted into the Darcy-Forchheimer equation to obtain a functional relationship between fluid velocity and pressure drop within a certain operating range. The coefficients of the first and second terms are then converted to derive the permeability and inertia coefficient.

[0004] In existing technologies, measurements are typically performed using experimental setups. For example, in the book "Determination of Permeability and Inertia Coefficient of Porous Materials Considering Gas Compressibility" by Li Heng, Zhang Xiwen, and He, the experimental setup consists of a flow meter, a pressure gauge, and a sample chamber. This setup determines permeability and inertia coefficient while considering gas compressibility, reducing the requirements for sample thickness and working pressure. Using the gas state equation, continuity equation, and Darcy-Forchheimer equation, calculation expressions for measuring the permeability and inertia coefficient of porous media at higher flow rates are derived. The permeability and inertia coefficient of the porous media can be calculated based on the aerodynamic parameters obtained from two measurements. A pressure-capping method is used to clamp the porous material, static pressure holes are set in the wall, static pressure is measured using an electronic pressure gauge, and a flow meter is connected at the inlet.

[0005] However, the calculation formulas for the above measurement methods are complex. Although theoretically only two measurements are needed to obtain the values ​​of permeability and inertia coefficient, the numerical errors obtained through replication experiments are relatively large. Multiple measurements and fitting curves are required to obtain relatively accurate results. In addition, the end cap clamping method in the experimental device is rather crude, resulting in significant experimental errors and ultimately affecting the accuracy of the experimental data. Summary of the Invention

[0006] To address the aforementioned deficiencies or shortcomings, the present invention aims to provide a multifunctional foam metal flow parameter measuring device and method.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A multifunctional foam metal flow parameter measuring device, comprising:

[0009] The test section includes an inlet section and a mixing section upstream; an outlet section downstream; and a fixed piece of foam metal to be tested within the test section.

[0010] The inlet section includes an inlet pipe, which is equipped with an expansion mechanism for expanding the airflow;

[0011] The mixing section is equipped with a first detection mechanism for measuring the upstream static pressure of the foam metal to be tested. One end of the mixing section is connected to the expansion mechanism, and the other end is connected to the test section.

[0012] The outlet section is equipped with a second detection mechanism for measuring the outlet static pressure.

[0013] Preferably, the expansion mechanism includes a replaceable expanding cylindrical pipe connected to the inlet pipe.

[0014] Preferably, a gradually expanding pipe is matched on the gradually expanding cylindrical pipe, and the expansion angle of the gradually expanding pipe is in the range of 6-12 degrees.

[0015] Preferably, the ratio of the inlet pipe diameter to the diameter of the gradually expanding pipe opening is in the range of (1:3). 1:5).

[0016] Preferably, the first detection mechanism includes a first cylindrical pipe connected to the expansion mechanism, a first static pressure hole is provided on the cylindrical pipe, and a first pressure gauge for detecting static pressure is provided on the first static pressure hole.

[0017] Preferably, the second detection mechanism includes a second cylindrical pipe connected to the test section, a second static pressure hole is provided on the cylindrical pipe, and a second pressure gauge for detecting static pressure is provided on the second static pressure hole.

[0018] Preferably, both the first static pressure hole and the second static pressure hole are provided with a pagoda-shaped interface.

[0019] Preferably, the pipeline in the test section has multiple radial fixing points arranged along the axial direction, and each radial fixing point has multiple threaded holes arranged along the circumference. The foam metal to be tested is fixed radially and circumferentially by screws.

[0020] Preferably, the threaded hole is sealed with Blu-Tack.

[0021] In addition, this invention provides a measurement method for a multifunctional foam metal flow parameter measuring device, comprising:

[0022] Set the flow rate values ​​for multiple inlet compressed air inputs;

[0023] At each flow rate, the differential pressure value flowing through the foam metal under test is obtained, recorded, and saved to obtain a set of flow rate value-differential pressure value data;

[0024] By fitting a two-dimensional curve corresponding to the flow rate-pressure difference data set, the coefficients of the first and second terms are obtained;

[0025] The permeability and inertia coefficients are calculated by converting the coefficients of the first and second terms.

[0026] This invention simplifies experimental steps and calculation formulas, and directly uses fitting to obtain permeability and inertia coefficient. Experiments have confirmed the accuracy of this method.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] This invention is a multifunctional flow parameter measuring device for foamed metals. The entire detection process is divided into four sections: an inlet section, a mixing section, a test section, and an outlet section. The test section securely holds the foamed metal to be tested, preventing displacement during testing and eliminating clamping tool errors. The inlet section is equipped with an expansion mechanism for the gas flow, ensuring uniform gas mixing. By measuring the static pressure before and after the foamed metal, a two-dimensional curve of flow rate and pressure difference is obtained, yielding the first and second term coefficients, which can then be used to calculate permeability and inertia. Flow resistance is measured in a similar manner, resulting in accurate data and simplified calculations, providing support for the engineering applications of foamed metals. Furthermore, the inlet section of this invention matches different expansion angles according to different flow velocities to achieve uniform mixing and saves on the length of the experimental platform.

[0029] This invention also provides a multifunctional method for measuring the flow parameters of foamed metal. Based on the detection device of this invention, the foamed metal to be detected can be directly fixed and the data can be directly obtained through the detection mechanism. The obtained two-dimensional curve can be converted to quickly obtain the required parameters. This method is simple and fast. It only requires changing the flow rate of the air inlet under the same device and recording the data to directly obtain the final parameters, resulting in high data accuracy. The method is simple and fast. Finally, after the measurement is completed, CFD calculation is performed and compared with the experimental results to verify the measurement accuracy of this invention. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the multifunctional foam metal flow parameter measuring device of the present invention;

[0031] Figure 2 This is a schematic diagram of the external structure of the multifunctional foam metal flow parameter measuring device of the present invention;

[0032] Figure 3 This is a perspective view of the multifunctional foam metal flow parameter measuring device of the present invention;

[0033] Figure 4 This is a schematic diagram of the test section structure of the multifunctional foam metal flow parameter measuring device of the present invention;

[0034] Figure 5 This is a schematic diagram of the inlet section structure of the multifunctional foam metal flow parameter measuring device of the present invention;

[0035] Figure 6 This is a geometric model diagram of the multifunctional foam metal flow parameter measurement method of the present invention.

[0036] In the diagram, 1—inlet section; 2—mixing section; 3—test section; 4—outlet section; 5—foam metal to be tested; 6—touchscreen; 11—inlet pipe; 12—expansion mechanism; 21—first cylindrical pipe; 22—first static pressure hole; 31—threaded hole; 41—second cylindrical pipe; 42—second static pressure hole. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the protection scope of the present invention.

[0038] To obtain the parameters of foamed metal and understand its properties, it is necessary to design a device that can fix the foamed metal to be tested and quickly obtain the upstream and downstream static pressure difference under gas compressibility. In order to obtain the static pressure difference, this invention provides a multifunctional foamed metal flow parameter measuring device.

[0039] To solve the above problems, specifically as follows: Figure 1-3 As shown, a multifunctional foam metal flow parameter measuring device of the present invention includes:

[0040] Test section 3 is equipped with an inlet section 1 and a mixing section 2 upstream; an outlet section 4 is installed downstream of test section 3; and the foam metal to be tested 5 is fixedly installed in test section 3.

[0041] The inlet section 1 includes an inlet pipe 11, on which an expansion mechanism 12 for expanding airflow is provided;

[0042] The mixing section 2 is equipped with a first detection mechanism for measuring the upstream static pressure of the foam metal 5 to be tested. One end of the mixing section 2 is connected to the expansion mechanism 12, and the other end is connected to the test section 3.

[0043] The outlet section 4 is equipped with a second detection mechanism for measuring the outlet static pressure.

[0044] like Figure 4 As shown, to solve the problem of fixing the foam metal 5 to be tested, the third section of the invention is the test section 3, which is equipped with a second cylindrical pipe for fixing the foam metal 5 to be tested. For example, the dimensions of the foam metal 5 to be tested selected in this invention are: a cylindrical foam metal with a diameter of 30mm and a length of 25mm. Therefore, a second cylindrical pipe with an inner diameter of 30mm and a length of 100mm is used, and multiple radial fixing points are arranged along the axial direction. Each radial fixing point has multiple threaded holes 31 arranged circumferentially. The foam metal to be tested is fixed radially and circumferentially by screws. For example, in the axial direction, threaded holes of size m3 are opened every 25mm, with four evenly distributed circumferential threaded holes corresponding to one axial position, which can simultaneously achieve radial and circumferential fixing. The diameter of the fixing section is 30mm, and the diameters of the inlet and outlet sections are 29mm, thus achieving axial fixing and enabling lossless clamping. Sealing is ensured by the threaded holes and Blu-Tack adhesive. It achieves automatic fixation of the foam metal through threaded holes and threads, while maintaining good sealing. It should be noted that the size of the foam metal used in the experiment in this invention is only an example given in this embodiment and is not limited thereto.

[0045] To ensure successful data measurement, the selection of pipes at each stage of this invention needs to be set according to the foam metal 5 to be measured. For example... Figure 5 As shown, the inlet section 1 of the first segment includes an inlet pipe 11, which is a cylindrical pipe. An expansion mechanism 12 for expanding the airflow is provided on the inlet pipe 11. In this invention, the expansion mechanism 12 includes a replaceable gradually expanding cylindrical pipe, which is connected to the inlet pipe 11. It should be noted that the expansion angle of the gradually expanding cylindrical pipe in this invention can be adjusted according to the flow velocity. For example, depending on the diameter of the inlet pipe, an inlet pipe with a larger expansion angle can be used when the flow velocity is low, and an inlet pipe with a smaller expansion angle can be used when the flow velocity is high. A gradually expanding cylindrical pipe with a matching expansion angle can be selected.

[0046] For example, the ratio of the inlet pipe diameter to the diameter of the gradually expanding pipe opening can be selected, and the range can be 1:3. The ratio is 1:5, preferably 1:3. A cylindrical foam metal 5 with a diameter of 30mm and a length of 25mm is selected for testing. The inlet pipe 11 is set to have a diameter of 10mm. The airflow expands from the 10mm pipe to the cylindrical pipe with an inner diameter of 30mm, ensuring uniform gas mixing and providing stable data for subsequent measurements. Furthermore, this ensures the accuracy of parameter acquisition. Alternatively, a corresponding expansion angle of the gradually expanding pipe can be selected, with the expansion angle ranging from 6 to 12 degrees.

[0047] Specifically, in this invention, the second stage is the mixing section 2. This stage requires measuring the upstream static pressure of the foam metal to be tested, i.e., the gas static pressure after passing through the expanding pipe. Therefore, a first detection mechanism is established. This first detection mechanism includes a first cylindrical pipe 21 connected to the expansion mechanism 12. A first static pressure orifice 22 is provided on the first cylindrical pipe 21. The first cylindrical pipe 21 is a smooth cylindrical pipe with a diameter of 30 mm. Furthermore, a first pressure gauge for detecting static pressure is provided on the first static pressure orifice 22. A pressure gauge is an instrument used to measure fluid pressure. It typically compares the pressure to be measured with a reference pressure (such as atmospheric pressure or other given pressure), thus measuring the relative pressure or pressure difference. It can be a digital pressure gauge, a mechanical pressure gauge, or a pressure sensor. For higher measurement accuracy, a pressure sensor or a precision digital pressure gauge can be selected.

[0048] Preferably, in order to facilitate accurate testing, a pagoda-shaped interface and an air pipe are provided on the first static pressure port 22. The pagoda-shaped interface and the air pipe are connected to the first pressure gauge to measure the static pressure of the cylindrical pipe.

[0049] After the airflow passes through the foam metal 5 under test, it reaches the fourth section: the outlet section 4. The outlet section 4 is equipped with a second detection mechanism for measuring the outlet static pressure. Specifically, the second detection mechanism includes a second cylindrical pipe 41 connected to the test section 3. A second static pressure hole 42 is provided on the cylindrical pipe, and a second pressure gauge for measuring static pressure is provided on the second static pressure hole. Similarly, in this stage, the second cylindrical pipe 41 is also a smooth cylindrical pipe with a diameter of 30mm. Preferably, in order to facilitate accurate testing, a pagoda-shaped interface and an air pipe are provided on the second static pressure hole 42. The pagoda-shaped interface and the air pipe are connected to the second pressure gauge to measure the static pressure of the cylindrical pipe.

[0050] In another embodiment, in order to measure the static pressure difference between the upstream and downstream, a pressure gauge can be connected to the pagoda-shaped interface of the two static pressure holes to directly measure the static pressure difference data. This method is more convenient and reduces experimental measurement steps.

[0051] The multifunctional foam metal flow parameter measuring device in this invention mainly obtains permeability, inertia coefficient, and flow resistance parameters. After obtaining the differential pressure value, it is also necessary to obtain the inlet flow rate value through a flow meter. Each inlet flow rate value corresponds to a differential pressure value. By changing the outlet valve opening of the flow regulating valve multiple times, the flow rate value can be adjusted, and the differential pressure value flowing through the foam metal at the corresponding flow rate (velocity) can be measured and the data recorded to provide basic data for subsequent parameter acquisition.

[0052] For example, in specific data processing, the coefficients of the first and second terms can be obtained by fitting a two-dimensional curve of flow rate and pressure difference, which can then be used to calculate the permeability and inertia coefficient. Flow resistance was also measured in a similar way with good results.

[0053] For example, when acquiring the flow resistance parameter, pressure difference and velocity are also measured, only the velocity range is smaller, and the flow resistance parameter... ,in, d The diameter of the cross section, △p For pressure differential, within the set velocity range of 0.02-0.23 m / s, d= 0.075 m. Two PPI (pores per inch) values ​​were selected for testing, and the experimental data are shown in Tables 1 and 2:

[0054] Table 1 Experimental data of PPI50

[0055]

[0056] Table 2 Experimental data for PPI35

[0057]

[0058] In summary, the multifunctional foam metal flow parameter measuring device of this invention enables convenient and rapid measurement; it automatically fixes the foam metal using screws and a perforated method, thereby eliminating clamping tool errors and ensuring good sealing. The device has a simple structure and operation, simplifies the detection method, and provides accurate detection data. By avoiding the end cap clamping method of the foam metal to be measured, it avoids data errors and thus enables accurate and rapid acquisition of parameters.

[0059] In another embodiment, the present invention also provides a multifunctional method for measuring the flow parameters of foamed metal, comprising:

[0060] S1, Set the flow rate values ​​for multiple inlet compressed air inputs;

[0061] To obtain multiple sets of data, both to facilitate two-dimensional curve fitting and to reduce data errors, it is necessary to change the outlet valve opening of the flow regulating valve multiple times to change the flow rate value.

[0062] Specifically, you can first select several different specific flow rates, and then adjust the opening of the compressor outlet valve according to the selected flow rate until the inlet section reaches the corresponding flow rate.

[0063] S2. Obtain the differential pressure value flowing through the foam metal under each flow rate value, and record and save it to obtain a set of flow rate value-differential pressure value data;

[0064] When the inlet section reaches the corresponding flow rate value, the pressure difference value flowing through the foam metal at the corresponding flow rate (flow velocity) is measured by the first and second detection mechanisms, the data is recorded, and the volumetric flow rate value minus the pressure difference value data is obtained.

[0065] ;

[0066] in, Q For volumetric flow rate, The flow rate measured by the first testing agency. The cross-sectional area at the point tested by the first testing agency. The flow rate measured by the second testing agency. This refers to the cross-sectional area of ​​the area tested by the second testing agency.

[0067] Repeat this step until the pressure difference value corresponding to all selected flow rates has been measured. At this point, a set of flow rate-pressure difference data is obtained: for example, the data set provided in Table 3 is the flow rate-pressure difference data set.

[0068] Table 3. Flow velocity-pressure difference data set

[0069]

[0070] S3. Fit the two-dimensional curve corresponding to the flow rate-pressure difference data set to obtain the coefficients of the first and second terms;

[0071] The data in Table 1 are fitted to obtain a two-dimensional curve. The coefficients of the first and second terms are obtained by performing calculations on the two-dimensional curve.

[0072] S4. Calculate the permeability and inertia coefficient based on the coefficients of the first and second terms.

[0073]

[0074] in, For pressure difference, U For flow rate, dx Taking -0.075m, the experimentally measured value is... and Then, calculate using the intermediate equations. K and These are the permeability and inertia coefficient.

[0075] The permeability and inertia coefficient were calculated, and the flow resistance was measured in a similar manner.

[0076] Finally, to test the multifunctional foam metal flow parameter measurement device and testing method of this invention, Fluent simulation was performed. Fluent is a popular international commercial CFD (Computational Fluid Dynamics) software package. It has rich physical models, advanced numerical methods, and powerful pre- and post-processing capabilities, and has wide applications in aerospace, automotive design, oil and gas, and turbine design. CFD is a product of the combination of modern fluid mechanics, numerical mathematics, and computer science. It approximates the integral and differential terms in the governing equations of fluid mechanics as discrete algebraic forms, making them a system of algebraic equations. Then, a computer solves these discrete algebraic equations to obtain numerical solutions at discrete time / space points.

[0077] Firstly, as Figure 6 As shown, the geometric model was drawn using UG, and then the mesh was created using ICEM. The generated mesh file was imported into Fluent, and the values ​​of permeability and inertia coefficient were filled into the porous material model. Iterative calculations were then started, and after stabilization, the simulation results were imported into CFD-post for observation. FLUENT is a general-purpose CFD software package used to simulate complex flows ranging from incompressible to highly compressible. Finally, the experimental pressure difference value and the numerically calculated pressure difference value were found to be very close, indicating that the experimental setup has high reliability, as shown in Table 2. Table 4 shows the simulation data and the actual test data.

[0078] Table 4 Simulation data and actual test data

[0079]

[0080] The device of this invention can quickly and accurately measure parameters such as permeability, inertia coefficient, and flow resistance, and obtain the corresponding relationship between airflow velocity and pressure difference across the two ends of the foam metal. Through Fluent numerical calculation and comparison verification, when the flow velocity varies in the range of 0-97.72 m / s, the difference between the CFD results and the experimental results is about 1%, indicating that the experimental device has high measurement accuracy and can achieve the purpose of measuring the required experimental parameters.

[0081] It will be apparent to those skilled in the art that the above specific examples are merely preferred embodiments of the present invention. Therefore, any improvements or modifications that may be made by those skilled in the art to certain parts of the present invention still embody the principles of the present invention and achieve the objectives of the present invention, and all fall within the scope of protection of the present invention.

Claims

1. A multi-functional foamed metal flow parameter measuring device, characterized by, The utility model relates to a kind of experimental section, including: Test section, the test section upstream is provided with import section, mixing section;The test section downstream is provided with outlet section;The test section is fixedly provided with to be measured foam metal;The pipeline of the test section is uniformly arranged with multiple radial fixed points along the axial direction, and each radial fixed point is uniformly arranged with multiple threaded holes along the circumferential direction, and the to-be-measured foam metal is fixed by screw and screw in radial direction, circumferential direction; The import section includes inlet pipeline, and the inlet pipeline is provided with expansion mechanism for expanding airflow; The mixing section is provided with first detection mechanism for measuring static pressure upstream of to-be-measured foam metal, and one end of the mixing section is communicated with the expansion mechanism, and the other end is connected with the test section; The first detection mechanism includes first cylindrical pipeline communicated with the expansion mechanism, and the cylindrical pipeline is provided with first static pressure hole, and the first static pressure hole is provided with first pressure gauge for detecting static pressure; The outlet section is provided with second detection mechanism for measuring outlet static pressure; The second detection mechanism includes second cylindrical pipeline communicated with the test section, and the cylindrical pipeline is provided with second static pressure hole, and the second static pressure hole is provided with second pressure gauge for detecting static pressure.

2. The multi-functional foamed metal flow parameter measurement device of claim 1, wherein, The expansion mechanism includes replaceable diverging cylindrical pipeline, and the diverging cylindrical pipeline is connected with the inlet pipeline.

3. The multi-functional foamed metal flow parameter measurement device of claim 2, wherein, The diverging cylindrical pipeline is matched with diverging pipeline, and the expansion angle of the diverging pipeline ranges from 6 to 12 degrees.

4. The multi-functional foamed metal flow parameter measurement device of claim 1, wherein, The ratio of the diameter of the inlet pipeline to the diameter of the diverging pipeline ranges from 1:3 to 1:

5.

5. The multi-functional foamed metal flow parameter measurement device of claim 1, wherein, The first static pressure hole and the second static pressure hole are both provided with pagoda-shaped interface.

6. The multi-functional foamed metal flow parameter measurement device of claim 1, wherein, Blue silicone is arranged outside the threaded hole for sealing.

7. A measuring method based on the multifunctional foamed metal flow parameter measuring device according to claim 1, characterized in that, Including: Set multiple inlet air input flow values; Obtain differential pressure value of to-be-measured foam metal under each flow value, and record saving, obtain a group of flow value-differential pressure value data group; Fit two-dimensional curve corresponding to flow value-differential pressure value data group, obtain linear term and quadratic term coefficients; Convert permeability and inertia coefficient according to the linear term and quadratic term coefficients.

Images