Method and device for testing relationship between film vibration frequency and flow rate

Abstract

The present invention discloses a method and device for testing the relationship between film vibration frequency and flow velocity. Based on the principle of triboelectric generation, the method utilizes finite element analysis and linear fitting of a linear function to analyze and calculate the functional relationship between film vibration frequency and flow velocity. The device comprises an airflow supply module, a test cavity, a film vibration unit, and a signal processing and analysis module. The method for testing the relationship between film vibration frequency and flow velocity provided by the present invention simplifies the amount of calculation and is accurate and reliable. The device for testing the relationship between film vibration frequency and flow velocity provided by the present invention can measure the relationship between vibration frequency and flow velocity in real time and has high stability and reliability. At the same time, the device has a simple structure and manufacturing process and is low-cost.

Description

Technical Field

[0001] The present invention relates to the field of sensing technology, and in particular to a method and device for testing the relationship between film vibration frequency and flow velocity. Background Art

[0002] As we all know, membrane structures are widely used in various fields due to their strong adaptability in shape, good mechanical properties, and light weight. This type of structure is very sensitive to the effects of airflow. When the airflow velocity reaches a certain value, the membrane structure can produce a more obvious vibration response. The vibration response of the membrane under the action of airflow can be used to make airflow sensors, wind turbines, etc.

[0003] When a thin film vibrates under the influence of airflow, the vibration frequency is high and the amplitude is small, making the vibration extremely difficult to observe. Currently, methods for observing and calculating the relationship between vibration frequency and flow velocity include: recording with a high-speed camera, or calculating using fluid-structure coupling methods. High-speed camera photography requires very high conditions, is expensive, and difficult to implement. Fluid-structure coupling calculation methods are mostly used for calculating one- and two-dimensional models. When applied to the analysis of three-dimensional thin film vibration models, the calculations are cumbersome and the errors are large. Therefore, the prior art lacks a method and device for measuring the relationship between thin film vibration frequency and flow velocity that is simple to calculate and highly stable and reliable. Summary of the Invention

[0004] The object of the present invention is to address the defects of the prior art and to provide a method and device for testing the relationship between film vibration frequency and flow rate that is simple in calculation and has high stability and reliability.

[0005] According to one aspect of the present invention, a method for testing the relationship between membrane vibration frequency and flow rate is provided, which comprises the following steps:

[0006] Step S100, set the value of m types of air flow Q to a m A constant airflow flows through the test cavity at a unit time t. Driven by the airflow, the vibrating membrane contacts and rubs against at least one electrode, outputting a set of periodic alternating current signals D corresponding to m types of airflow rates Q.

[0007] Step S110: Based on the periodic alternating current signal set D, using the principle of triboelectric generation, analyzing and calculating the vibration frequencies f corresponding to the m types of airflow rates Q, and obtaining m sets of first corresponding values ​​consisting of the m types of airflow rates Q and the corresponding vibration frequencies f;

[0008] Step S120: Establish the model structure of the test cavity and set the value of N airflow flow Q to b n , using the finite element analysis method, the functional relationship between the air flow rate Q and the flow velocity V is analyzed and calculated, where the value of the air flow rate Q b nChange in an arithmetic increasing manner;

[0009] Step S130 , analyzing and calculating the functional relationship between the flow velocity V and the vibration frequency f based on the corresponding relationships between the m types of airflow rates Q and the corresponding vibration frequencies f, and the functional relationship between the airflow rate Q and the flow velocity V;

[0010] Wherein, N≥2, m, n and N are all positive integers.

[0011] Optionally, in step S110, based on the periodic alternating current signal set D, the vibration frequencies f corresponding to the m types of airflow rates Q are analyzed and calculated using the principle of frictional power generation, specifically including:

[0012] According to the periodic AC signal set D corresponding to the m types of airflow flow rates Q, the number of pulse pairs in the periodic AC signal set D corresponding to the m types of airflow flow rates Q within unit time t is analyzed and calculated respectively, and the number is used as the vibration frequency f corresponding to the m types of airflow flow rates Q.

[0013] Optionally, establishing the model structure of the test cavity in step S120 specifically includes:

[0014] An airflow channel of a preset size is established, a vibration film is set as a flat rigid body, and the vibration film is placed inside the airflow channel.

[0015] Optionally, step S100 specifically includes:

[0016] Step S1001: pre-set the value of m types of air flow Q to a m The constant airflow is a1, a2, a m ;

[0017] Step S1002: Set the preset m types of airflow flow rates Q to be a1, a2, ..., a m The constant airflow flows through the test cavity for a unit time t. Driven by the airflow, the vibrating film contacts and rubs with at least one electrode, and outputs a set of periodic AC signals D corresponding to the m types of airflow Q, which are D1, D2, D m .

[0018] Optionally, step S110 specifically includes:

[0019] Step S1101: According to the periodic AC signal set D1, D2...D m , respectively analyze and calculate the periodic AC signal sets D1, D2, D corresponding to the m types of airflow Q in unit time t mThe number of pulse pairs is taken as the vibration frequency f corresponding to the m types of airflow Q, which are f1, f2,...,f m ;

[0020] Step S1102: According to the corresponding relationship between m types of airflow Q and their corresponding vibration frequencies f, m groups of first corresponding values ​​are obtained, namely (a1, f1), (a2, f2)... (a m , f m ).

[0021] Optionally, step S120 specifically includes:

[0022] Step S1201: establishing a model structure of a test cavity;

[0023] Step S1202: Preset the value of N airflow flow Q to b n , followed by b1, b2...b n ; Wherein, the value of the air flow rate Q changes in an arithmetic increasing manner;

[0024] Step S1203: Based on the values ​​b1, b2, ..., b of N airflow rates Q n , using the finite element analysis method, the flow velocities V1, V2, V corresponding to the values ​​of N kinds of air flow Q are analyzed and calculated. n , and obtain N groups of second corresponding values, namely (V1, b1), (V2, b2)...(V n , b n );

[0025] Step S1204: Based on the N sets of second corresponding values, a linear function fitting method is used to analyze and calculate the functional relationship between the airflow rate Q and the flow velocity V:

[0026] V = c1 × Q + d1; or, Q = c2 × V + d2;

[0027] Where V is the flow velocity, Q is the air flow rate, and c1, c2, d1, and d2 are constants.

[0028] Optionally, step S130 specifically includes:

[0029] Step S1301: The values ​​a1, a2, ..., a of the airflow rate Q in the m groups of first corresponding values ​​are m Substitute the functional relationship between the airflow rate Q and the flow velocity V obtained by analysis and calculation in step S1204 respectively, and analyze and calculate the values ​​a1, a2,...a of the airflow rate Q in the first corresponding value. m The corresponding m values ​​of flow velocity V are v1, v2,...v m ;

[0030] Step S1302: Based on the corresponding relationship between the m types of airflow Q and the corresponding vibration frequency f, and the functional relationship between the airflow Q and the flow velocity V, obtain m groups of third corresponding values ​​(v1, f1), (v2, f2)... (v m , f m );

[0031] Step S1303: Based on the obtained m groups of third corresponding values ​​(v1, f1), (v2, f2)...(v m , f m ), using the linear fitting method of a first-order function, the functional relationship between the flow velocity V and the vibration frequency f is analyzed and calculated as follows:

[0032] V = e1 × f + g1; or, f = e2 × V + g2;

[0033] Where V is the flow velocity, f is the vibration frequency, and e1, e2, g1, and g2 are constants.

[0034] According to another aspect of the present invention, there is provided a device for testing the relationship between film vibration frequency and flow rate, comprising: an airflow supply module, a test cavity, a film vibration unit and a signal processing and analysis module; wherein,

[0035] The airflow supply module is connected to the signal processing and analysis module, and is used to output a constant airflow of a preset airflow according to the airflow flow signal output by the signal processing and analysis module;

[0036] The test chamber is a shell with a hollow structure, on which an air inlet and an air outlet are respectively provided, and the air inlet is connected to the air flow supply module;

[0037] The membrane vibration unit is disposed in the test cavity and is configured to generate a periodic alternating current signal when a constant airflow of a preset airflow rate provided by the airflow supply module flows through the test cavity through the air inlet and the air outlet of the test cavity;

[0038] The signal processing and analysis module is connected to the membrane vibration unit and is used to process and analyze the periodic AC signal output by the membrane vibration unit, and analyze and calculate the functional relationship between the vibration frequency and flow rate of the membrane vibration unit based on the processed and analyzed periodic AC signal and the airflow flow signal.

[0039] Optionally, the film vibration unit further comprises: a vibrating film and at least one electrode;

[0040] The vibrating membrane is disposed in the test cavity and has a fixed end and a free end. The fixed end is disposed on the inner wall of the test cavity near the air inlet of the test cavity, and the free end is disposed near the air outlet of the test cavity. At least one electrode is disposed on the inner wall of the test cavity.

[0041] When a constant airflow flows through the test cavity through the air inlet and the air outlet of the test cavity, the vibrating film vibrates under the action of the constant airflow, and the vibrating film and at least one electrode contact and rub against each other to generate a periodic alternating current signal; the at least one electrode serves as an output end of the periodic alternating current signal;

[0042] The two surfaces of the vibration film and at least one electrode that are in contact and rub against each other constitute a friction interface.

[0043] Optionally, the center position of the air inlet is opposite to the center position of the air outlet;

[0044] The distance between the fixed end of the vibrating membrane and the end of the test cavity provided with the air inlet is greater than or equal to 1 / 3 of the length of the test cavity.

[0045] Optionally, it further comprises: at least one high molecular polymer layer;

[0046] At least one polymer layer is disposed on at least one electrode, and the at least one polymer layer is disposed opposite to the vibrating film. When a constant airflow flows through the test cavity through the air inlet and the air outlet of the test cavity, the vibrating film vibrates under the action of the constant airflow, and the at least one polymer layer and the vibrating film contact and rub against each other to generate a periodic alternating current signal.

[0047] The two surfaces of at least one high molecular polymer layer and the vibration film that are in contact and friction with each other constitute a friction interface.

[0048] Optionally, an array of protrusions is provided on at least one of the two surfaces constituting the friction interface.

[0049] Optionally, when the test cavity is made of a conductive material, an insulating layer is further provided between the test cavity and at least one electrode, the test cavity is used to shield external interference signals, and the insulating layer is used to prevent conduction between the test cavity and at least one electrode; or,

[0050] When the test cavity is made of insulating material, a shielding layer is further provided on the outside of the test cavity; the shielding layer is used to shield external interference signals.

[0051] Optionally, the signal processing and analysis module further includes: a signal preprocessing module, an airflow control module and an analysis and calculation module; wherein,

[0052] The signal preprocessing module is connected to the thin film vibration unit and is used to preprocess the periodic alternating current signal output by the thin film vibration unit;

[0053] The air flow control module is connected to the air flow supply module and is used to generate an air flow signal and control the air flow supply module to output a constant air flow of a preset air flow according to the air flow signal;

[0054] The analysis and calculation module is connected to the signal preprocessing module and the airflow flow control module respectively, and is used to analyze and calculate the functional relationship between the vibration frequency and flow rate of the thin film vibration unit based on the periodic alternating current signal output by the signal preprocessing module and the airflow flow signal output by the airflow flow control module.

[0055] Optionally, the signal preprocessing module further includes: a rectifier module, an amplifying module, a filtering module and an analog-to-digital conversion module; wherein,

[0056] The rectifier module is connected to the thin film vibration unit and is used to rectify the periodic alternating current signal output by the thin film vibration unit;

[0057] The amplifying module is connected to the rectifier module and is used to amplify the pulsating DC signal output by the rectifier module after rectification;

[0058] The filtering module is connected to the amplifying module and is used to filter out interference noise in the amplified pulsating DC signal output by the amplifying module;

[0059] The analog-to-digital conversion module is connected to the filtering module and is used to convert the analog pulsating DC signal output by the filtering module into a corresponding digital pulsating DC signal and output it to the analysis and calculation module.

[0060] Optionally, the analysis and calculation module applies the above-mentioned method of testing the relationship between the membrane vibration frequency and flow rate based on the periodic alternating current signal output by the signal preprocessing module and the airflow flow signal output by the airflow flow control module to analyze and calculate the functional relationship between the vibration frequency and flow rate of the membrane vibration unit.

[0061] The method for testing the relationship between the film vibration frequency and the flow rate provided by the present invention is based on the principle of friction power generation and uses the finite element analysis method and the linear fitting method of a first-order function to analyze and calculate the functional relationship between the film vibration frequency and the flow rate, which simplifies the amount of calculation and is accurate and reliable. The device for testing the relationship between the film vibration frequency and the flow rate provided by the present invention can measure the relationship between the vibration frequency and the flow rate in real time and has high stability and reliability. At the same time, the device has a simple structure and manufacturing process and is low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 A schematic flow chart of an embodiment of a method for testing the relationship between film vibration frequency and flow rate provided by the present invention;

[0063] Figure 2 A schematic structural diagram of an embodiment of a device for testing the relationship between film vibration frequency and flow rate provided by the present invention;

[0064] Figure 3A schematic structural diagram of an embodiment of a test cavity and a membrane vibration unit in a device for testing the relationship between membrane vibration frequency and flow velocity provided by the present invention;

[0065] Figure 4a Schematic diagram of the functional relationship between air flow rate and flow velocity according to the first embodiment of the present invention;

[0066] Figure 4b Schematic diagram of the functional relationship between vibration frequency and flow velocity according to the first embodiment of the present invention;

[0067] Figure 5a Schematic diagram of the functional relationship between air flow rate and flow velocity in Example 2 of the present invention;

[0068] Figure 5b Schematic diagram of the functional relationship between vibration frequency and flow velocity according to the second embodiment of the present invention;

[0069] Figure 6 Schematic diagram comparing the functional relationship between vibration frequency and flow velocity in Example 1 and Example 2 of the present invention. DETAILED DESCRIPTION

[0070] In order to fully understand the purpose, features and effects of the present invention, the implementation of the technical solution of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited thereto.

[0071] Figure 1 Schematic diagram of the flow chart of an embodiment of the method for testing the relationship between film vibration frequency and flow rate provided by the present invention. Figure 1 As shown, the method includes:

[0072] Step S100: Set the value of the m types of airflow Q to a m A constant airflow flows through the test cavity at a unit time t. Driven by the airflow, the vibrating membrane contacts and rubs against at least one electrode, outputting a set of periodic alternating current signals D corresponding to m types of airflow rates Q.

[0073] Step S110: Based on the periodic AC signal set D, using the principle of frictional power generation, analyzing and calculating the vibration frequencies f corresponding to the m types of airflow rates Q, and obtaining m groups of first corresponding values ​​consisting of the m types of airflow rates Q and the corresponding vibration frequencies f;

[0074] Step S120: Establish the model structure of the test cavity and set the value of N airflow flow Q to b n , using the finite element analysis method, the functional relationship between the air flow rate Q and the flow velocity V is analyzed and calculated; among them, the value of the air flow rate Q b n Change in an arithmetic increasing manner;

[0075] Step S130: Analyze and calculate the functional relationship between the flow velocity V and the vibration frequency f based on the corresponding relationship between the m types of airflow rates Q and the corresponding vibration frequencies f, as well as the functional relationship between the airflow rate Q and the flow velocity V;

[0076] Wherein, N≥2, m, n and N are all positive integers.

[0077] Furthermore, based on the periodic AC signal set D and utilizing the principle of frictional power generation, the vibration frequencies f corresponding to the m types of airflow flow rates Q are analyzed and calculated. Specifically, based on the periodic AC signal set D corresponding to the m types of airflow flow rates Q, the number of pulse pairs in the periodic AC signal set D corresponding to the m types of airflow flow rates Q within unit time t is analyzed and calculated, and the number is used as the vibration frequencies f corresponding to the m types of airflow flow rates Q.

[0078] Specifically, step S100 may include:

[0079] Step S1001: pre-set the value of m types of air flow Q to a m The constant airflow is a1, a2, a m ;

[0080] Step S1002: Set the preset m types of airflow flow rates Q to be a1, a2, ..., a m The constant airflow flows through the test cavity for a unit time t. Driven by the airflow, the vibrating film contacts and rubs with at least one electrode, and outputs a set of m periodic alternating current signals D corresponding to the m airflow rates Q, which are D1, D2, D m .

[0081] Specifically, step S110 may include:

[0082] Step S1101: According to the periodic AC signal set D1, D2...D m , analyze and calculate the periodic AC signal set D1, D2...D corresponding to the m types of airflow Q in unit time t m The number of pulse pairs is taken as the vibration frequency f corresponding to the m types of airflow Q, which are f1, f2,...,f m ;

[0083] Step S1102: According to the corresponding relationship between m types of airflow Q and their corresponding vibration frequencies f, m groups of first corresponding values ​​are obtained, namely (a1, f1), (a2, f2)... (a m , f m ).

[0084] It should be understood that the vibrating film becomes unstable and vibrates back and forth under the drive of the airflow. During the reciprocating vibration process, the vibrating film contacts and rubs against at least one electrode. According to the principle of frictional power generation, the vibrating film outputs an AC signal containing a pulse pair during one reciprocating vibration process. This pulse pair can be a pulse pair containing two in-phase pulses or a pulse pair containing two out-of-phase pulses.

[0085] Specifically, step S120 may include:

[0086] Step S1201: establishing a model structure of a test cavity, setting an airflow channel of a preset size, setting a vibrating film as a flat rigid body, and placing the vibrating film inside the airflow channel;

[0087] Step S1202: Preset N values ​​b of air flow rate Q n , followed by b1, b2...b n , where the values ​​of N airflow rates Q are b1, b2...b n Change in an arithmetic increasing manner;

[0088] Step S1203: Based on the values ​​b1, b2, ..., b of N airflow rates Q n , using the finite element analysis method, the flow velocities V1, V2, V corresponding to the values ​​of N kinds of air flow Q are analyzed and calculated. n , and obtain N groups of second corresponding values, namely (V1, b1), (V2, b2)...(V n , b n );

[0089] Step S1204: Based on the N sets of second corresponding values, a linear function fitting method is used to analyze and calculate the functional relationship between the airflow rate Q and the flow velocity V:

[0090] V = c1 × Q + d1; or, Q = c2 × V + d2;

[0091] Where V is the flow velocity, Q is the air flow rate, and c1, c2, d1, and d2 are constants.

[0092] Specifically, step S130 may include:

[0093] Step S1301: The values ​​a1, a2, ..., a of the airflow rate Q in the m groups of first corresponding values ​​are m Substitute the functional relationship between the airflow rate Q and the flow velocity V obtained by analysis and calculation in step S1204 respectively, and analyze and calculate the values ​​a1, a2,...a of the airflow rate Q in the first corresponding value. m The corresponding m values ​​of flow velocity V are v1, v2,...v m ;

[0094] Step S1302: Based on the corresponding relationship between the m types of airflow Q and the corresponding vibration frequency f, and the functional relationship between the airflow Q and the flow velocity V, obtain m groups of third corresponding values ​​(v1, f1), (v2, f2)... (v m , f m );

[0095] Step S1303: Based on the obtained m groups of third corresponding values ​​(v1, f1), (v2, f2)...(v m , f m ), using the linear fitting method of a first-order function, the functional relationship between the flow velocity V and the vibration frequency f is analyzed and calculated as follows:

[0096] V = e1 × f + g1; or, f = e2 × V + g2;

[0097] Where V is the flow velocity, f is the vibration frequency, and e1, e2, g1, and g2 are constants.

[0098] In this embodiment, the unit time t can be selected according to the actual needs of those skilled in the art and is not limited here. For example, the unit time t is 1 second.

[0099] It should be noted that the finite element analysis method and linear function fitting method used in the method for testing the relationship between film vibration frequency and flow rate provided by the present invention are both finite element analysis methods and linear function linear fitting methods in the prior art. Those skilled in the art can choose according to actual needs and are not limited here.

[0100] The method for testing the relationship between film vibration frequency and flow velocity provided by the present invention uses the principle of friction power generation and utilizes the finite element analysis method and the linear fitting method of a first-order function to analyze and calculate the functional relationship between the film vibration frequency and flow velocity, thereby simplifying the amount of calculation and being accurate and reliable.

[0101] Figure 2 This is a schematic structural diagram of an embodiment of the device for testing the relationship between film vibration frequency and flow rate provided by the present invention. Figure 3 This is a schematic diagram of the structure of an embodiment of a test cavity and a film vibration unit in a device for testing the relationship between film vibration frequency and flow rate provided by the present invention. Figure 2 and Figure 3As shown, the device includes: an air flow supply module 100 , a test cavity 200 , a film vibration unit 300 and a signal processing and analysis module 400 . Among them, the air flow supply module 100 is connected to the signal processing and analysis module 400, and is used to output a constant air flow of a preset air flow rate according to the air flow rate signal output by the signal processing and analysis module 400; the test cavity 200 is a shell with a hollow structure, on which an air inlet 210 and an air outlet 220 are respectively provided, and the air inlet 210 is connected to the air flow supply module 100; the thin film vibration unit 300 is arranged in the test cavity 200, and is used to generate a periodic alternating current signal when the constant air flow of a preset air flow rate provided by the air flow supply module 100 flows through the test cavity 200 through the air inlet 210 and the air outlet 220 of the test cavity 200; the signal processing and analysis module 400 is connected to the thin film vibration unit 300, and is used to process and analyze the periodic alternating current signal output by the thin film vibration unit 300, and analyze and calculate the functional relationship between the vibration frequency and flow rate of the thin film vibration unit 300 based on the processed and analyzed periodic alternating current signal and the air flow rate signal.

[0102] The airflow supply module 100 adopts an airflow source in the prior art that can output a constant airflow of a preset airflow according to the airflow flow signal output by the signal processing and analysis module 400, which is not limited here.

[0103] Among them, the test cavity 200 is a shell with a hollow structure, and the shape of the shell can be a prism (such as a cuboid, a cube), a sphere, a cylinder, a cone, a pyramid, etc., and the shape of the hollow structure can be a prism (such as a cuboid, a cube), a sphere, a cylinder, a cone, a pyramid, etc. Those skilled in the art can choose according to actual needs, and there is no limitation here.

[0104] It should be understood that the shape of the shell of the test cavity 200 and the shape of the hollow structure can be used in any combination. For example: if the shape of the shell of the test cavity 200 is a rectangular parallelepiped, the shape of the hollow structure of the test cavity 200 can be any one of a prism (such as a rectangular parallelepiped, a cube), a sphere, a cylinder, a cone, and a pyramid; if the shape of the shell of the test cavity 200 is a sphere, the shape of the hollow structure of the test cavity 200 can be any one of a prism (such as a rectangular parallelepiped, a cube), a sphere, a cylinder, a cone, and a pyramid; and so on, which will not be repeated here. Preferably, if Figure 3 As shown, the shell of the test cavity 200 is in the shape of a cuboid, and the hollow structure of the test cavity 200 is in the shape of a cuboid.

[0105] Alternatively, as Figure 3As shown, the center of the air inlet 210 of the test chamber 200 is aligned with the center of the air outlet 220 of the test chamber 200. This arrangement allows a constant airflow to flow through the air inlet 210 of the test chamber 200 and then directly out of the air outlet 220 of the test chamber 200 without turning, thereby reducing the generation of vortices in the test chamber 200 and improving the stability of the airflow in the test chamber 200.

[0106] Among them, the thin film vibration unit 300 is arranged in the test cavity 200, and its setting direction is the same as the flow direction of the constant airflow flowing through the test cavity 200. This can ensure that the thin film vibration unit 300 can better generate a periodic alternating current signal when a constant airflow flows through the test cavity 200.

[0107] Furthermore, the film vibration unit 300 may include: a vibrating film 310 and at least one electrode 320; the vibrating film 310 is arranged in the test cavity, and has a fixed end and a free end, the fixed end is arranged on the inner wall of the test cavity 200 close to the direction of the air inlet 210 of the test cavity 200, and the free end is arranged close to the direction of the air outlet 220 of the test cavity 200; at least one electrode 320 is arranged on the inner wall of the test cavity 200; when a constant air flow passes through the air inlet 210 and the air outlet 220 of the test cavity 200 and flows through the test cavity 200, the vibrating film 310 vibrates under the action of the constant air flow, and the vibrating film 310 and the at least one electrode 320 contact and rub against each other to generate a periodic alternating current signal; at least one electrode 320 serves as the output end of the periodic alternating current signal; wherein, the two surfaces of the vibrating film 310 and the at least one electrode 320 that contact and rub against each other constitute a friction interface.

[0108] The fixed end of the vibrating film 310 is set on the inner wall of the test cavity 200 near the direction of the air inlet 210 of the test cavity 200, and the free end is set near the direction of the air outlet 220 of the test cavity 200 so as to allow a constant airflow to flow from the direction of the fixed end of the vibrating film 310 and act on the vibrating film 310, thereby preventing the vibrating film 310 from curling and / or breaking when vibrating under the action of the constant airflow, and thereby allowing the vibrating film 310 to better contact and rub with at least one electrode 320.

[0109] Optionally, when the center of the air inlet 210 is aligned with the center of the air outlet 220, the distance between the fixed end of the vibrating film 310 and the end of the test cavity 200 where the air inlet 210 is provided is greater than or equal to 1 / 3 of the length of the test cavity 200. This arrangement ensures that when the airflow from the air inlet 210 flows into the fixed end of the vibrating film 310, the flow rate of the constant airflow is stable. In other words, this arrangement ensures that the constant airflow acts on the vibrating film 310 (i.e., the fixed end of the vibrating film 310) at a stable flow rate, thereby ensuring that the vibrating film 310 vibrates stably, improving contact friction, thereby improving the generated periodic AC signal, and reducing the difficulty of processing and analyzing the periodic AC signal. More preferably, when the center of the air inlet 210 is aligned with the center of the air outlet 220, the distance between the fixed end of the vibrating film 310 and the end of the test cavity 200 where the air inlet 210 is provided is equal to 1 / 3 of the length of the test cavity 200.

[0110] In an optional embodiment, in order to make the vibration film 310 more firmly arranged on the inner wall of the test cavity 200, at least one fixing groove 230 for fixing the fixed end of the vibration film 310 is provided on the inner wall of the test cavity 200. In addition, the number of the at least one fixing groove 230 can be one or more. Those skilled in the art can select the number of fixing grooves 230 according to actual needs, and this is not limited here. Specifically, as Figure 3 As shown, two fixing grooves 230 are symmetrically arranged along the length direction on two opposite inner side walls of the test cavity 200 , and both ends of the fixed end of the vibration film 310 along the length direction are respectively arranged in the two fixing grooves 230 .

[0111] More preferably, in order to make the distance between the vibration film 310 and the air inlet 210 of the test cavity 200 easier to adjust, the fixed end of the vibration film 310 is arranged in at least one fixed groove 230 in a detachable and / or slidably adjustable manner, so that the distance between the fixed end of the vibration film 310 and the air inlet 210 of the test cavity 200 can be flexibly adjusted.

[0112] The shape of the vibration film 310 can be polygonal (such as rectangular, triangular, etc.), fan-shaped, etc. Of course, those skilled in the art can also select other shapes of the vibration film 310 according to actual needs, which is not limited here.

[0113] The thickness of the vibration film 310 can be 5μm to 20μm. Of course, those skilled in the art can also choose vibration films 310 of other thicknesses according to actual needs. However, the problem of unstable vibration caused by the thickness of the vibration film 310 being too thin, or the problem of inability to vibrate caused by the thickness of the vibration film 310 being too thick should be avoided.

[0114] Furthermore, the length of the vibrating membrane 310 should be greater than the distance between the vibrating membrane 310 and the at least one electrode 320, while also being less than the distance between the fixed end of the vibrating membrane 310 and the air outlet 220 of the test chamber 200. The reason why the vibrating membrane 310 should be greater than the distance between the vibrating membrane 310 and the at least one electrode 320 ensures that the vibrating membrane 310 can contact and rub against the at least one electrode 320 during vibration is to ensure that the vibrating membrane 310 can vibrate within the test chamber 200.

[0115] The material of the vibration film 310 can be selected from polydimethylsiloxane, polyimide, aniline formaldehyde resin, polyformaldehyde, ethyl cellulose, polyamide, melamine formaldehyde, polyethylene glycol succinate, cellulose, cellulose acetate, polyethylene adipate, polydiallyl phthalate, fiber (regenerated) sponge, polyurethane elastomer, styrene propylene copolymer, styrene butadiene copolymer, synthetic fiber, polymethyl, methacrylate, polyvinyl alcohol, polyvinyl alcohol, polyester, polyisobutylene, polyurethane flexible sponge, polyethylene terephthalate, polyvinyl butyral, formaldehyde phenol, chloroprene rubber, butadiene propylene copolymer, natural rubber, polyacrylonitrile, acrylonitrile vinyl chloride and polyethylene propylene carbonate.

[0116] At least one electrode 320 is disposed on the inner wall of the test cavity 200. It should be noted that when disposing the at least one electrode 320 on the inner wall of the test cavity 200, it is necessary to ensure that the vibrating membrane 310 can contact and rub against the at least one electrode 320. Furthermore, the number of at least one electrode 320 can be one or more. Those skilled in the art can select the location and number of the at least one electrode 320 based on actual needs, and this is not limited here.

[0117] Specifically, if Figure 3 As shown, when the shell and the hollow structure of the test cavity 200 are both in the shape of a cuboid, the vibration film 310 is arranged in the test cavity 200 along the length direction, and at least one electrode 320 can be arranged on the inner wall of the test cavity 200 opposite to the surface of the vibration film 310. Specifically, at least one electrode 320 can be arranged only on the inner top wall of the test cavity 200 opposite to the first side surface of the vibration film 310; it can also be arranged only on the inner bottom wall of the test cavity 200 opposite to the second side surface of the vibration film 310, and can also be arranged on both the inner top wall and the inner bottom wall of the test cavity 200 opposite to the first side surface and the second side surface of the vibration film 310 respectively.

[0118] At least one electrode 320 can be a metal electrode. Specifically, the material of the metal electrode can be a metal or alloy. The metal can be gold, silver, platinum, palladium, aluminum, nickel, copper, titanium, chromium, tin, iron, manganese, molybdenum, tungsten, or vanadium. The alloy can be an aluminum alloy, titanium alloy, magnesium alloy, beryllium alloy, copper alloy, zinc alloy, manganese alloy, nickel alloy, lead alloy, tin alloy, cadmium alloy, bismuth alloy, indium alloy, gallium alloy, tungsten alloy, molybdenum alloy, niobium alloy, or tantalum alloy. In addition, at least one electrode 320 can also be a non-metallic electrode. The material of the non-metallic electrode can be a non-metallic conductive material such as indium tin oxide, graphene, or silver nanowire film.

[0119] In an optional embodiment, the device for testing the relationship between film vibration frequency and flow rate provided by the present invention also includes: at least one polymer layer (not shown in the figure); the at least one polymer layer is arranged on at least one electrode 320, and at least one polymer layer is arranged opposite to the vibrating film 310; when a constant air flow flows through the air inlet 210 and the air outlet 220 of the test cavity 200, the vibrating film 310 vibrates under the action of the constant air flow, and at least one polymer layer and the vibrating film 310 (that is, the free end of the vibrating film 310) contact and rub against each other to generate a periodic alternating current signal; wherein, the two surfaces of the polymer layer and the vibrating film 310 that contact and rub against each other constitute a friction interface.

[0120] Specifically, when the shell and the hollow structure of the test cavity 200 are both in the shape of a rectangular parallelepiped, and the vibrating film 310 is arranged in the test cavity 200 along the length direction, if at least one electrode 320 is arranged on the inner top wall of the test cavity 200 opposite to the first side surface of the vibrating film 310, the first side surface of at least one polymer layer can be arranged on the at least one electrode 320, and its second side surface is arranged opposite to the first side surface of the vibrating film 310. When the free end of the vibrating film 310 vibrates under the action of the airflow, the second side surface of the at least one polymer layer is opposite to the first side surface of the vibrating film 310. The first side surfaces of the vibrating film 310 are in contact and friction with each other; if at least one electrode 320 is arranged on the inner bottom wall of the test cavity 200 opposite to the second side surface of the vibrating film 310, the second side surface of at least one polymer layer can be arranged on at least one electrode 320, and its first side surface is arranged opposite to the second side surface of the vibrating film 310. When the free end of the vibrating film 310 vibrates under the action of the airflow, the first side surface of at least one polymer and the second side surface of the vibrating film 310 are in contact and friction with each other; other situations are similar and will not be repeated here.

[0121] It should be understood that at least one electrode 320 may or may not be provided with at least one polymer layer. In other words, a polymer layer may be provided on all electrodes 320 or on only a portion of the electrodes 320, without limitation herein. For example, if two electrodes 320 are included, a polymer layer may be provided on both electrodes 320 or on either one of the two electrodes 320.

[0122] The material of at least one high molecular polymer layer can be selected from any one of polydimethylsiloxane, polyimide, aniline formaldehyde resin, polyoxymethylene, ethyl cellulose, polyamide, melamine formaldehyde, polyethylene glycol succinate, cellulose, cellulose acetate, polyethylene adipate, polydiallyl phthalate, fiber (regenerated) sponge, polyurethane elastomer, styrene propylene copolymer, styrene butadiene copolymer, artificial fiber, polymethyl, methacrylate, polyvinyl alcohol, polyvinyl alcohol, polyester, polyisobutylene, polyurethane flexible sponge, polyethylene terephthalate, polyvinyl butyral, formaldehyde phenol, chloroprene rubber, butadiene propylene copolymer, natural rubber, polyacrylonitrile, acrylonitrile vinyl chloride and polyethylene glycol carbonate. In addition, the material of at least one high molecular polymer layer can be the same as or different from the material of the vibration film 310. In order to increase the friction power generation effect, preferably, the material of the high molecular polymer layer is different from the material of the vibration film 310.

[0123] In order to increase the friction between the two surfaces constituting the friction interface, a protrusion array structure can be provided on at least one of the two surfaces constituting the friction interface. The protrusion array structure in the present invention adopts the protrusion array structure in the prior art, and the types and quantities of the recesses and protrusions contained in the protrusion array structure are not limited. Those skilled in the art can flexibly set the types and quantities of the recesses and protrusions contained in the protrusion array structure, which are not limited here. For example: the protrusion array structure is composed of a plurality of protrusions arranged in a rectangular or diamond shape, or a plurality of strip structures arranged in a geometric arrangement on both sides, four corners, four edges or the entire surface of at least one surface. Among them, the shape of the protrusions can be cylindrical, quadrangular prism or quadrangular pyramid, etc.; the strip structures can be arranged in the shape of a tic-tac-toe, a cross, a zebra line, a cross or a square.

[0124] The material of the test chamber 200 can be either conductive or insulating, and this is not limited here. When the test chamber 200 is made of a conductive material, an insulating layer is further provided between the test chamber 200 and the at least one electrode 320. In this case, the test chamber 200 also serves to shield external interference signals, and the insulating layer is used to prevent electrical conduction between the test chamber 200 and the at least one electrode 320. When the test chamber 200 is made of an insulating material, a shielding layer is further provided on the outside of the test chamber 200 to shield external interference signals.

[0125] The shielding layer can be a separately provided conductive shell, which is sleeved on the outside of the test cavity 200 and whose material can be metal or alloy; in addition, the shielding layer can also be a conductive film integrally provided with the test cavity 200, for example, the conductive film can be provided on the outer surface of the test cavity 200 by brushing.

[0126] Among them, such as Figure 2 As shown, the signal processing and analysis module 400 further includes: a signal preprocessing module 410, an airflow flow control module 420 and an analysis and calculation module 430; wherein, the signal preprocessing module 410 is connected to the thin film vibration unit 300, and is used to preprocess the periodic alternating current signal output by the thin film vibration unit 300; the airflow flow control module 420 is connected to the airflow supply module 100, and is used to generate an airflow flow signal, and control the airflow supply module 100 to output a constant airflow with a preset airflow flow according to the airflow flow signal; the analysis and calculation module 430 is respectively connected to the signal preprocessing module 410 and the airflow flow control module 420, and is used to analyze and calculate the functional relationship between the vibration frequency and flow rate of the thin film vibration unit 300 according to the electrical signal output by the signal preprocessing module 410 and the airflow flow signal output by the airflow flow control module 420.

[0127] Specifically, when the thin film vibration unit 300 further includes a vibrating film 310 and at least one electrode 320, the signal preprocessing module 410 is connected to the at least one electrode 320 in the thin film vibration unit 300, and is used to preprocess the periodic alternating current signal output by the at least one electrode 320 in the thin film vibration unit 300; the airflow flow control module 420 is connected to the airflow supply module 100, and is used to generate an airflow flow signal, and control the airflow supply module 100 to output a constant airflow with a preset airflow flow according to the airflow flow signal; the analysis and calculation module 430 is respectively connected to the signal preprocessing module 410 and the airflow flow control module 420, and is used to analyze and calculate the functional relationship between the vibration frequency and flow rate of the vibrating film 310 in the thin film vibration unit 300 according to the electrical signal output by the signal preprocessing module 410 and the airflow flow signal output by the airflow flow control module 420.

[0128] The periodic alternating current signal output by the thin film vibration unit 300 is generally a relatively weak analog alternating current pulse signal, and the periodic alternating current signal output by the thin film vibration unit 300 is usually mixed with industrial frequency interference signals and / or high-frequency noise interference signals, etc. Therefore, after obtaining the periodic alternating current signal output by the thin film vibration unit 300, the electrical signal should be preprocessed so that the subsequent modules can analyze and process the electrical signal. Specifically, the signal preprocessing module 410 may include: a rectifier module 411, an amplifier module 412, a filter module 413 and an analog-to-digital conversion module 414; wherein the rectifier module 411 is connected to the thin film vibration unit 300, and is used to rectify the periodic AC signal output by the thin film vibration unit 300; the amplifier module 412 is connected to the rectifier module 411, and is used to amplify the pulsating DC signal output by the rectifier module 411 after rectification; the filter module 413 is connected to the amplifier module 412, and is used to filter out interference and clutter in the pulsating DC signal output by the amplifier module 412 after amplification; the analog-to-digital conversion module 414 is connected to the filter module 413, and is used to convert the analog pulsating DC signal output by the filter module 413 into a corresponding digital pulsating DC signal and output it to the analysis and calculation module 430.

[0129] More specifically, when the thin film vibration unit 300 further includes a vibrating film 310 and at least one electrode 320, the signal preprocessing module 410 may include: a rectifier module 411, an amplifier module 412, a filter module 413 and an analog-to-digital conversion module 414; wherein the rectifier module 411 is connected to at least one electrode 320 in the thin film vibration unit 300, and is used to rectify the periodic AC signal output by at least one electrode 320 in the thin film vibration unit 300; the amplifier module 412 is connected to the rectifier module 411, and is used to amplify the pulsating DC signal output by the rectifier module 411 after rectification; the filter module 413 is connected to the amplifier module 412, and is used to filter out interference and clutter in the pulsating DC signal output by the amplifier module 412 after amplification; the analog-to-digital conversion module 414 is connected to the filter module 413, and is used to convert the analog pulsating DC signal output by the filter module 413 into a corresponding digital pulsating DC signal and output it to the analysis and calculation module 430.

[0130] It should be noted that the rectifier module 411, amplifier module 412, filter module 413, and analog-to-digital converter module 414 are optional modules. Those skilled in the art may select them based on practical needs and are not specifically limited here. For example, if the rectifier module 411 is not required, the rectifier module 411 may be omitted, and the thin film vibration unit 300 may be connected to the amplifier module 412, or at least one electrode 320 in the thin film vibration unit 300 may be connected to the amplifier module 412. If the amplifier module 412 is not required, the amplifier module 412 may be omitted, and the rectifier module 411 may be connected to the filter module 413. This is analogous and will not be further described here.

[0131] The air flow control module 420 may be a flow meter in the prior art. Those skilled in the art may select a suitable air flow control module 420 according to actual needs, which is not limited here.

[0132] The analysis and calculation module 430 analyzes and calculates the functional relationship between the vibration frequency and flow rate of the membrane vibration unit based on the periodic AC signal output by the signal preprocessing module 410 and the airflow flow signal output by the airflow flow control module 420, and applies the method of testing the relationship between the membrane vibration frequency and flow rate.

[0133] Among them, the method for testing the relationship between the film vibration frequency and the flow rate applied by the analysis and calculation module 430 can be the method for testing the relationship between the film vibration frequency and the flow rate provided by the present invention, or other methods for testing the relationship between the film vibration frequency and the flow rate in the prior art can be used, which is not limited here.

[0134] The device for testing the relationship between film vibration frequency and flow rate provided by the present invention can measure the relationship between vibration frequency and flow rate in real time, with high stability and reliability; at the same time, the structure and manufacturing process of the device for testing the relationship between film vibration frequency and flow rate provided by the present invention are simple and low in cost.

[0135] The following describes in detail the method and device for testing the relationship between film vibration frequency and flow rate provided by the present invention through two specific embodiments. It should be noted that these embodiments are only illustrative and should not be construed as limiting the present invention.

[0136] Example 1

[0137] According to the method and apparatus for testing the relationship between membrane vibration frequency and flow rate provided by the present invention, in this embodiment, the structures of the test cavity 200 and the membrane vibration unit 300 are configured as follows:

[0138] The test chamber 200 is a rectangular parallelepiped test chamber, i.e., the shell and hollow structure of the test chamber 200 are both rectangular parallelepiped in shape, with the center of the air inlet 210 aligning with the center of the air outlet 220 . The shell of the test chamber 200 has a length × width × height of 30 mm × 7 mm × 4 mm and is made of copper. The hollow structure of the test chamber 200 has a length × width × height of 30 mm × 4 mm × 1 mm.

[0139] The film vibration unit 300 includes a vibration film 310 and an electrode 320; wherein,

[0140] The diaphragm 310 is an axisymmetric T-shaped diaphragm. The length × width of its fixed end is 1.5 mm × 4 mm, the length × width of its free end is 10.5 mm × 2.5 mm, and its thickness is 0.01 mm. The distance between the fixed end and the end of the test chamber 200 where the air inlet 210 is located is equal to 1 / 2 the length of the test chamber 200, that is, the distance between the fixed end and the end of the test chamber 200 where the air inlet 210 is located is 15 mm. The diaphragm is made of polyethylene terephthalate.

[0141] The electrode 320 is disposed along the length and width directions on the inner bottom wall of the test cavity 200 opposite to the first side surface of the vibration film 310 and is made of copper. 3M tape is provided between the electrode 320 and the test cavity 200 for insulation.

[0142] When a constant air flow passes through the air inlet 210 and the air outlet 220 of the test cavity 200, the vibrating film 310 vibrates under the action of the constant air flow, and the vibrating film 310 and the electrode 320 contact and rub against each other to generate a periodic alternating current signal, which is output by the electrode 320 as the output end of the periodic alternating current signal to the signal processing and analysis module 400. The signal processing and analysis module 400 processes and analyzes the periodic alternating current signal output by the film vibration unit 300, and analyzes and calculates the functional relationship between the vibration frequency of the film vibration unit 300 and the flow rate.

[0143] The specific steps of testing the relationship between the membrane vibration frequency and the flow rate using the device provided in this embodiment and the method provided in the present invention are as follows:

[0144] The values ​​of 23 air flow rates Q are preset as a m The constant airflow is a1, a2, a 23 ;

[0145] The 23 preset air flow rates Q are set to be a1, a2,...,a 23The constant airflow flows through the test cavity 200 units for 1 second. Driven by the airflow, the vibrating film 310 contacts and rubs against the electrode 320, and outputs a set of periodic AC signals D corresponding to 23 airflow rates Q, which are D1, D2, D 23 ;

[0146] According to the periodic AC signal set D1, D2...D 23 , respectively analyze and calculate the periodic AC signal sets D1, D2, D2 corresponding to the 23 airflow rates Q within a unit time of 1 second. 23 The number of pulse pairs is used as the vibration frequency f corresponding to the 23 airflow rates Q, which are f1, f2,...,f 23 ;

[0147] According to the corresponding relationship between 23 airflow rates Q and their corresponding vibration frequencies f, 23 groups of first corresponding values ​​are obtained, namely (a1, f1), (a2, f2)... (a 23 , f 23 ), wherein Table 1 is a first corresponding numerical table consisting of 23 preset air flow rates Q and the vibration frequencies f corresponding to the 23 preset air flow rates Q, the unit of the air flow rate Q is liters / minute, and the unit of the vibration frequency f is Hertz;

[0148] Table 1

[0149] <![CDATA[(a1,f1)]]> <![CDATA[(a2,f2)]]> <![CDATA[(a3,f3)]]> <![CDATA[(a4,f4)]]> <![CDATA[(a5,f5)]]> <![CDATA[(a6,f6)]]> <![CDATA[(a7,f7)]]> (6.1,1773) (5.9,1575) (5.46,1454) (5.22,1333) (4.88,1260) (4.44,1147) (4.21,1099) <![CDATA[(a8,f8)]]> <![CDATA[(a9,f9)]]> <![CDATA[(a 10 ,f 10 )]]> <![CDATA[(a 11 ,f 11 )]]> <![CDATA[(a 12 ,f 12 )]]> <![CDATA[(a 13 ,f 13 )]]> <![CDATA[(a 14 ,f 14 )]]> (3.91,1034) (3.56,855) (3.46,771) (3.29,701) (2.38,518) (5.79,1545) (5.52,1444) <![CDATA[(a 15 ,f 15 )]]> <![CDATA[(a 16 ,f 16 )]]> <![CDATA[(a 17 ,f 17 )]]> <![CDATA[(a 18 ,f 18 )]]> <![CDATA[(a 19 ,f 19 )]]> <![CDATA[(a 20 ,f 20 )]]> <![CDATA[(a 21 ,f 21 )]]> (5.2,1368) (4.93,1298) (4.84,1242) (4.62,1182) (4.13,1069) (3.93,1019) (3.41,789) <![CDATA[(a 22 ,f 22 )]]> <![CDATA[(a 23 ,f 23 )]]> (2.98,625) (2.1,459)

[0150] Establishing a model structure of the test cavity 200;

[0151] The preset values ​​of 5 air flow rates Q are b n , which are b1, b2...b5 in sequence; wherein the value of the air flow rate Q changes in an arithmetic increasing manner;

[0152] According to the values ​​b1, b2, ..., b5 of the five airflow flow rates Q, the finite element analysis method is used to analyze and calculate the flow velocities V1, V2, ..., V5 corresponding to the five airflow flow rates Q, and obtain five sets of second corresponding numerical values, namely (V1, b1), (V2, b2), ..., (V5, b5). Table 2 is a second corresponding numerical table consisting of the five preset airflow flow rates Q and the flow velocities V corresponding to the five preset airflow flow rates Q. The unit of the airflow flow rate Q is liters per minute, and the unit of the flow velocity V is meter per second.

[0153] Table 2

[0154] <![CDATA[(V1,b1)]]> <![CDATA[(V2,b2)]]> <![CDATA[(V3,b3)]]> <![CDATA[(V4,b4)]]> <![CDATA[(V5,b5)]]> (13.8902,2) (19.3052,3) (24.7202,4) (30.1352,5) (35.5502,6)

[0155] Figure 4aFIG. 1 is a schematic diagram showing the functional relationship between the air flow rate Q and the flow velocity V according to the first embodiment of the present invention. Figure 4a As shown, the airflow rate Q in the five groups of second corresponding values ​​is first plotted as the horizontal coordinate and the flow velocity V as the vertical coordinate in the coordinate system. Then, based on the five groups of second corresponding values, the linear fitting method of a first function is used to analyze and calculate the functional relationship between the airflow rate Q and the flow velocity V:

[0156] V = 5.415 × Q + 3.0602;

[0157] The values ​​a1, a2,...a of the airflow rate Q in the 23 sets of first corresponding values ​​are 23 Substitute the functional relationship between the airflow rate Q and the flow velocity V into the equation respectively, and analyze and calculate the values ​​a1, a2,...a of the airflow rate Q in the first corresponding value. 23 The corresponding 23 flow velocity V values ​​are v1, v2,...v 23 ;

[0158] According to the corresponding relationship between 23 kinds of air flow Q and the corresponding vibration frequency f, as well as the functional relationship between air flow Q and flow velocity V, 23 sets of third corresponding values ​​(v1, f1), (v2, f2)... (v 23 , f 23 );

[0159] Figure 4b FIG. 1 is a schematic diagram showing the functional relationship between the vibration frequency f and the flow velocity V according to the first embodiment of the present invention. Figure 4b As shown, the vibration frequency f in the 23 sets of third corresponding values ​​is first plotted as the horizontal coordinate and the flow velocity V as the vertical coordinate in the coordinate system, and then the 23 sets of third corresponding values ​​(v1, f1), (v2, f2)... (v 23 , f 23 ), using the linear fitting method of a first-order function, the functional relationship between the flow velocity V and the vibration frequency f is analyzed and calculated as follows:

[0160] V = 0.0169 × f + 7.8688.

[0161] Example 2

[0162] According to the method and apparatus for testing the relationship between membrane vibration frequency and flow rate provided by the present invention, in this embodiment, the structures of the test cavity 200 and the membrane vibration unit 300 are configured as follows:

[0163] The test chamber 200 is a rectangular parallelepiped test chamber. That is, the shell and hollow structure of the test chamber 200 are both rectangular parallelepiped in shape. The center of the air inlet 210 is directly opposite the center of the air outlet 220. The shell of the test chamber 200 has a length × width × height of 30 mm × 7 mm × 4 mm and is made of copper. The length × width × height of the hollow structure of the test chamber 200 is 30 mm × 4 mm × 0.6 mm.

[0164] The film vibration unit 300 includes a vibration film 310 and an electrode 320; wherein,

[0165] The diaphragm 310 is an axisymmetric T-shaped diaphragm. The length × width of its fixed end is 1.5 mm × 4 mm, the length × width of its free end is 10.5 mm × 2.5 mm, and its thickness is 0.01 mm. The distance between the fixed end and the end of the test chamber 200 where the air inlet 210 is located is equal to 1 / 2 the length of the test chamber 200, that is, the distance between the fixed end and the end of the test chamber 200 where the air inlet 210 is located is 15 mm. The diaphragm is made of polyethylene terephthalate.

[0166] The electrode 320 is disposed along the length and width directions on the inner bottom wall of the test cavity 200 opposite to the first side surface of the vibration film 310 and is made of copper. 3M tape is provided between the electrode 320 and the test cavity 200 for insulation.

[0167] When a constant air flow passes through the air inlet 210 and the air outlet 220 of the test cavity 200, the vibrating film 310 vibrates under the action of the constant air flow, and the vibrating film 310 and the electrode 320 contact and rub against each other to generate a periodic alternating current signal, which is output by the electrode 320 as the output end of the periodic alternating current signal to the signal processing and analysis module 400. The signal processing and analysis module 400 processes and analyzes the periodic alternating current signal output by the film vibration unit 300, and analyzes and calculates the functional relationship between the vibration frequency of the film vibration unit 300 and the flow rate.

[0168] The specific steps of testing the relationship between the membrane vibration frequency and the flow rate using the device provided in this embodiment and the method provided in the present invention are as follows:

[0169] The values ​​of 15 air flow rates Q are preset as a m The constant airflow is a1, a2, a 15 ;

[0170] The 15 preset air flow rates Q are set to be a1, a2,...,a 15The constant airflow flows through the test cavity 200 units for 1 second. Driven by the airflow, the vibrating film 310 contacts and rubs against the electrode 320, and outputs a set of periodic AC signals D corresponding to 15 airflow rates Q, which are D1, D2, D 15 ;

[0171] According to the periodic AC signal set D1, D2...D 15 , respectively analyze and calculate the periodic AC signal sets D1, D2, D corresponding to the 15 airflow rates Q within a unit time of 1 second. 15 The number of pulse pairs is used as the vibration frequency f corresponding to 15 airflow rates Q, which are f1, f2,...,f 15 ;

[0172] According to the corresponding relationship between 15 airflow rates Q and their corresponding vibration frequencies f, 15 groups of first corresponding values ​​are obtained, namely (a1, f1), (a2, f2)... (a 15 , f 15 ), wherein Table 3 is a first corresponding numerical table consisting of 15 preset air flow rates Q and the vibration frequencies f corresponding to the 15 preset air flow rates Q, the unit of the air flow rate Q is liters / minute, and the unit of the vibration frequency f is Hertz;

[0173] Table 3

[0174] <![CDATA[(a1,f1)]]> <![CDATA[(a2,f2)]]> <![CDATA[(a3,f3)]]> <![CDATA[(a4,f4)]]> <![CDATA[(a5,f5)]]> <![CDATA[(a6,f6)]]> <![CDATA[(a7,f7)]]> (3.44,858) (3.34,1823) (3.06,1615) (2.55,1293) (2.06,1026) (1.57,750) (1.05,488) <![CDATA[(a8,f8)]]> <![CDATA[(a9,f9)]]> <![CDATA[(a 10 ,f 10 )]]> <![CDATA[(a 11 ,f 11 )]]> <![CDATA[(a 12 ,f 12 )]]> <![CDATA[(a 13 ,f 13 )]]> <![CDATA[(a 14 ,f 14 )]]> (3.5,1868) (3.25,1750) (2.97,1493) (2.88,1417) (2.68,1377) (2.02,994) (1.97,934) <![CDATA[(a 15 ,f 15 )]]> (1.43,634)

[0175] Establishing a model structure of the test cavity 200;

[0176] The preset values ​​of 5 air flow rates Q are b n , which are b1, b2...b5 in sequence; wherein the value of the air flow rate Q changes in an arithmetic increasing manner;

[0177] Based on the values ​​b1, b2, ..., b5 of the five airflow flow rates Q, the finite element analysis method is used to analyze and calculate the flow velocities V1, V2, ..., V5 corresponding to the five airflow flow rates Q, and five sets of second corresponding numerical values ​​are obtained, namely (V1, b1), (V2, b2), ..., (V5, b5). Table 4 is a second corresponding numerical table consisting of the five preset airflow flow rates Q and the flow velocities V corresponding to the five preset airflow flow rates Q. The unit of the airflow flow rate Q is liters per minute, and the unit of the flow velocity V is meter per second.

[0178] Table 4

[0179] <![CDATA[(V1,b1)]]> <![CDATA[(V2,b2)]]> <![CDATA[(V3,b3)]]> <![CDATA[(V4,b4)]]> <![CDATA[(V5,b5)]]> (19.9024,1.5) (24.8177,2) (29.733,2.5) (34.6483,3) (39.5636,3.5)

[0180] Figure 5aFIG. 1 is a schematic diagram showing the functional relationship between the air flow rate Q and the flow velocity V according to the second embodiment of the present invention. Figure 5a As shown, the airflow rate Q in the five groups of second corresponding values ​​is first plotted as the horizontal coordinate and the flow velocity V as the vertical coordinate in the coordinate system. Then, based on the five groups of second corresponding values, the linear fitting method of a first function is used to analyze and calculate the functional relationship between the airflow rate Q and the flow velocity V:

[0181] V = 9.8306 × Q + 5.1565;

[0182] The values ​​a1, a2,...a of the airflow rate Q in the 15 groups of first corresponding values ​​are 15 Substitute the functional relationship between the airflow rate Q and the flow velocity V into the equation, and calculate and obtain the values ​​a1, a2, ..., a1 of the airflow rate Q in the first corresponding value. 15 The corresponding 15 flow velocity V values ​​are v1, v2,...v 15 ;

[0183] According to the corresponding relationship between 15 kinds of air flow Q and the corresponding vibration frequency f, as well as the functional relationship between air flow Q and flow velocity V, 15 sets of third corresponding values ​​(v1, f1), (v2, f2)... (v 15 , f 15 );

[0184] Figure 5b FIG. 1 is a diagram showing the functional relationship between the vibration frequency f and the flow velocity V according to the second embodiment of the present invention. Figure 5b As shown, the vibration frequency f in the 15 sets of third corresponding values ​​is first plotted as the horizontal coordinate and the flow velocity V as the vertical coordinate in the coordinate system, and then the 15 sets of third corresponding values ​​(v1, f1), (v2, f2)... (v 15 , f 15 ), using the linear fitting method of a first-order function, the functional relationship between the flow velocity V and the vibration frequency f is analyzed and calculated as follows:

[0185] V=0.0167×f+8.3504.

[0186] The only difference between the first embodiment and the second embodiment is that the height of the hollow structure of the test cavity 200 in the first embodiment is 1 mm, while the height of the hollow structure of the test cavity 200 in the second embodiment is 0.6 mm.

[0187] Depend on Figure 4b and Figure 5bIt can be seen that the vibration frequency f of Example 1 or Example 2 increases with the increase of flow velocity V, and it can also be seen that there are differences between the test data of Example 1 and Example 2. In order to avoid errors caused by the test cavity 200 and the vibrating film unit 300, after fitting using a linear function linear fitting method, it is found that the straight lines formed by Example 1 and Example 2 coincide with each other, that is, the vibration frequency f and flow velocity V of Example 1 and Example 2 are both linearly positively correlated.

[0188] like Figure 4b and Figure 5b As shown in FIG. 1 , when the flow velocity V is 35 m / s, the vibration frequency f in Example 1 is rounded to 1605 Hz; the vibration frequency f in Example 2 is rounded to 1596 Hz. Therefore, it can be seen that when the flow velocity is the same, the corresponding vibration frequencies of Example 1 and Example 2 are different, and there is an error caused by the test cavity 200 and the vibrating film unit 300. However, according to Figure 6 As shown in the schematic diagram comparing the functional relationship between the vibration frequency f and the flow velocity V of Example 1 and Example 2, it can be seen that the straight lines formed by linear fitting of the test data of Example 1 and Example 2 overlap, which shows that Example 1 and Example 2 have good consistency. In other words, the method and device for testing the relationship between the vibration frequency and flow velocity of the film provided by the present invention can not only measure the relationship between the vibration frequency and flow velocity in real time, but also have high stability and reliability. In addition, since the only difference between Example 1 and Example 2 is the size of the test cavity 200, it can be clearly seen that the vibration frequency f of the vibrating film 310 is independent of the size of the test cavity 200 in which it is located.

[0189] The method for testing the relationship between the film vibration frequency and the flow rate provided by the present invention is based on the principle of friction power generation and uses the finite element analysis method and the linear fitting method of a first-order function to analyze and calculate the functional relationship between the film vibration frequency and the flow rate, which simplifies the amount of calculation and is accurate and reliable. The device for testing the relationship between the film vibration frequency and the flow rate provided by the present invention can measure the relationship between the vibration frequency and the flow rate in real time and has high stability and reliability. At the same time, the device has a simple structure and manufacturing process and is low in cost.

[0190] Those skilled in the art will appreciate that, although the above description uses a sequential description of the steps of the method for ease of understanding, it should be noted that the order of the steps is not strictly limited.

[0191] Those skilled in the art will understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a program, and the program can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc.

[0192] It is also understood that the device structures shown in the drawings or embodiments are merely schematic, representing logical structures, wherein modules shown as separate components may or may not be physically separate, and components shown as modules may or may not be physical modules.

[0193] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for testing the relationship between film vibration frequency and flow rate, characterized in that: The method is implemented by a device for testing the relationship between the film vibration frequency and the flow rate, the device comprising: Airflow supply module, test cavity, film vibration unit and signal processing and analysis module; wherein, The airflow supply module is connected to the signal processing and analysis module, and is used to output a constant airflow of a preset airflow according to the airflow flow signal output by the signal processing and analysis module; The test chamber is a shell with a hollow structure, on which an air inlet and an air outlet are respectively provided, and the air inlet is connected to the air flow supply module; The membrane vibration unit is disposed in the test cavity and is configured to generate a periodic alternating current signal when a constant airflow of a preset airflow rate provided by the airflow supply module flows through the test cavity through the air inlet and the air outlet of the test cavity; The signal processing and analysis module is connected to the thin film vibration unit and is used to process and analyze the periodic alternating current signal output by the thin film vibration unit, and analyze and calculate the functional relationship between the vibration frequency and flow velocity of the thin film vibration unit based on the processed and analyzed periodic alternating current signal and the airflow flow signal; The thin film vibration unit further comprises: a vibration film and at least one electrode; The vibrating membrane is disposed in the test cavity and has a fixed end and a free end. The fixed end is disposed on the inner wall of the test cavity in a direction close to the air inlet of the test cavity, and the free end is disposed in a direction close to the air outlet of the test cavity. The at least one electrode is disposed on the inner wall of the test cavity. When the constant airflow flows through the test cavity through the air inlet and the air outlet of the test cavity, the vibrating film vibrates under the action of the constant airflow, and the vibrating film and the at least one electrode contact and rub against each other to generate the periodic alternating current signal; the at least one electrode serves as an output end of the periodic alternating current signal; Wherein, the two surfaces of the vibrating film and the at least one electrode that are in contact and friction with each other constitute a friction interface; The method comprises the following steps: Step S100: Set the value of the m types of airflow Q to a m A constant airflow flows through the test cavity at a unit time t. Driven by the airflow, the vibrating membrane contacts and rubs against at least one electrode, outputting a set of periodic alternating current signals D corresponding to m types of airflow rates Q. Step S110: Based on the periodic AC signal set D, using the principle of frictional power generation, analyzing and calculating the vibration frequencies f corresponding to the m types of airflow rates Q, and obtaining m groups of first corresponding values ​​consisting of the m types of airflow rates Q and the corresponding vibration frequencies f; Step S120: Establish the model structure of the test cavity and set the value of N airflow flow Q to b n , using the finite element analysis method, the functional relationship between the air flow rate Q and the flow velocity V is analyzed and calculated; among them, the value of the air flow rate Q b n Change in an arithmetic increasing manner; Step S130: Analyze and calculate the functional relationship between the flow velocity V and the vibration frequency f based on the corresponding relationship between the m types of airflow rates Q and the corresponding vibration frequencies f, as well as the functional relationship between the airflow rate Q and the flow velocity V; Wherein, N≥2, m, n and N are all positive integers.

2. The method for testing the relationship between film vibration frequency and flow rate according to claim 1, characterized in that: The step S110 of analyzing and calculating the vibration frequencies f corresponding to the m types of airflow rates Q based on the periodic AC signal set D using the principle of frictional power generation specifically includes: According to the periodic AC signal set D corresponding to the m types of airflow flow rates Q, the number of pulse pairs in the periodic AC signal set D corresponding to the m types of airflow flow rates Q within a unit time t is analyzed and calculated respectively, and the number is used as the vibration frequency f corresponding to the m types of airflow flow rates Q.

3. The method for testing the relationship between film vibration frequency and flow rate according to claim 1 or 2, characterized in that: The step S120 of establishing the model structure of the test cavity specifically includes: An airflow channel of a preset size is established, a vibration film is set as a flat rigid body, and the vibration film is arranged inside the airflow channel.

4. The method for testing the relationship between film vibration frequency and flow rate according to claim 1 or 2, characterized in that: The step S100 specifically includes: Step S1001: pre-set the value of m types of air flow Q to a m The constant airflow is a1, a2, a m ; Step S1002: Set the preset m types of airflow flow rates Q to be a1, a2, ..., a m The constant airflow flows through the test cavity for a unit time t. Driven by the airflow, the vibrating film contacts and rubs with the at least one electrode, and outputs a set of periodic alternating current signals D corresponding to the m types of airflow flow rates Q, which are D1, D2, D m .

5. The method for testing the relationship between film vibration frequency and flow rate according to claim 4, characterized in that: The step S110 specifically includes: Step S1101: According to the periodic AC signal set D1, D2...D m , respectively analyze and calculate the periodic AC signal sets D1, D2, D corresponding to the m types of airflow Q in unit time t m The number of pulse pairs in the middle is taken as the vibration frequency f corresponding to the m types of airflow Q, which are f1, f2...f m ; Step S1102: According to the corresponding relationship between m types of airflow Q and their corresponding vibration frequencies f, m groups of first corresponding values ​​are obtained, namely (a1, f1), (a2, f2)... (a m , f m ).

6. The method for testing the relationship between film vibration frequency and flow rate according to claim 5, characterized in that: The step S120 specifically includes: Step S1201: establishing a model structure of a test cavity; Step S1202: Preset the value of N airflow flow Q to b n , followed by b1, b2...b n ; Wherein, the value of the air flow rate Q changes in an arithmetic increasing manner; Step S1203: Based on the values ​​b1, b2, ..., b of N airflow rates Q n , using the finite element analysis method, the flow velocities V1, V2, V corresponding to the values ​​of N kinds of air flow Q are analyzed and calculated. n , and obtain N groups of second corresponding values, namely (V1, b1), (V2, b2)...(V n , b n ); Step S1204: Based on the N sets of second corresponding values, a linear function fitting method is used to analyze and calculate the functional relationship between the airflow rate Q and the flow velocity V: V = c1 × Q + d1; or, Q = c2 × V + d2; Where V is the flow velocity, Q is the air flow rate, and c1, c2, d1, and d2 are constants.

7. The method for testing the relationship between film vibration frequency and flow rate according to claim 6, characterized in that: The step S130 specifically includes: Step S1301: The values ​​a1, a2, ..., a of the airflow rate Q in the m groups of first corresponding values ​​are m Substitute the functional relationship between the airflow rate Q and the flow velocity V obtained by analysis and calculation in step S1204 respectively, and analyze and calculate the values ​​a1, a2,...a of the airflow rate Q in the first corresponding value. m The corresponding m values ​​of flow velocity V are v1, v2,...v m ; Step S1302: Based on the corresponding relationship between the m types of airflow Q and the corresponding vibration frequency f, and the functional relationship between the airflow Q and the flow velocity V, obtain m groups of third corresponding values ​​(v1, f1), (v2, f2)... (v m , f m ); Step S1303: Based on the obtained m groups of third corresponding values ​​(v1, f1), (v2, f2)...(v m , f m ), using the linear fitting method of a first-order function, the functional relationship between the flow velocity V and the vibration frequency f is analyzed and calculated as follows: V = e1 × f + g1; or, f = e2 × V + g2; Where V is the flow velocity, f is the vibration frequency, and e1, e2, g1, and g2 are constants.

8. The method for testing the relationship between film vibration frequency and flow rate according to claim 1, characterized in that: The center position of the air inlet is directly opposite to the center position of the air outlet; The distance between the fixed end of the vibrating membrane and the end of the test cavity provided with the air inlet is greater than or equal to 1 / 3 of the length of the test cavity.

9. The method for testing the relationship between film vibration frequency and flow rate according to claim 1, characterized in that: The device further comprises: at least one high molecular polymer layer; The at least one polymer layer is disposed on the at least one electrode, and the at least one polymer layer is disposed opposite to the vibrating film; when the constant airflow flows through the test cavity through the air inlet and the air outlet of the test cavity, the vibrating film vibrates under the action of the constant airflow, and the at least one polymer layer and the vibrating film contact and rub against each other to generate the periodic alternating current signal; The two surfaces of the high molecular polymer layer and the vibration film that are in contact and friction with each other constitute a friction interface.

10. The method for testing the relationship between film vibration frequency and flow rate according to claim 9, characterized in that: At least one of the two surfaces constituting the friction interface is provided with a protrusion array structure.

11. The method for testing the relationship between film vibration frequency and flow rate according to claim 1, 9 or 10, characterized in that: When the test cavity is made of a conductive material, an insulating layer is further provided between the test cavity and the at least one electrode; the test cavity is used to shield external interference signals; the insulating layer is used to prevent conduction between the test cavity and the at least one electrode; or, When the test cavity is made of insulating material, a shielding layer is further provided on the outside of the test cavity; the shielding layer is used to shield external interference signals.

12. The method for testing the relationship between film vibration frequency and flow rate according to claim 1, characterized in that: The signal processing and analysis module further includes: a signal preprocessing module, an airflow control module and an analysis and calculation module; The signal preprocessing module is connected to the thin film vibration unit and is used to preprocess the periodic alternating current signal output by the thin film vibration unit; The airflow control module is connected to the airflow supply module, and is used to generate the airflow signal and control the airflow supply module to output a constant airflow with a preset airflow according to the airflow signal; The analysis and calculation module is connected to the signal preprocessing module and the airflow flow control module respectively, and is used to analyze and calculate the functional relationship between the vibration frequency and flow rate of the thin film vibration unit based on the periodic alternating current signal output by the signal preprocessing module and the airflow flow signal output by the airflow flow control module.

13. The method for testing the relationship between film vibration frequency and flow rate according to claim 12, characterized in that: The signal preprocessing module further includes: a rectifier module, an amplifying module, a filtering module and an analog-to-digital conversion module; The rectifier module is connected to the thin film vibration unit and is used to rectify the periodic alternating current signal output by the thin film vibration unit; The amplifying module is connected to the rectifying module and is used to amplify the pulsating DC signal output by the rectifying module after rectification; The filtering module is connected to the amplifying module and is used to filter out interference noise in the amplified pulsating DC signal output by the amplifying module; The analog-to-digital conversion module is connected to the filtering module and is used to convert the analog pulsating DC signal output by the filtering module into a corresponding digital pulsating DC signal and output it to the analysis and calculation module.

14. The method for testing the relationship between film vibration frequency and flow rate according to claim 12 or 13, characterized in that: The analysis and calculation module analyzes and calculates the functional relationship between the vibration frequency and flow rate of the thin film vibration unit according to the periodic alternating current signal output by the signal preprocessing module and the airflow flow signal output by the airflow flow control module.

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