Acoustic network construction method of pipeline system

Abstract

The invention belongs to the field of multi-branch flowing pipelines, and relates to an acoustic network construction method of a pipeline system, which comprises the following steps: segmenting and discretizing a complex pipeline system, determining all component units of the pipeline system, associating all the sound source ends and the middle components through the nodes, and constructing a plurality of acoustic network units of the pipeline system, forming an acoustic network diagram; the method comprises the following steps of: dispersing a complex pipeline system into component units, connecting the component units again in a node form to form an acoustic network diagram, and constructing a scattering relation between sound pressure in a single pipeline in the complex pipeline system and global sound pressure of the system by adopting an acoustic-electric analogy mechanism on the premise of knowing transfer matrixes and sound source characteristics of the component units, according to the method, the mapping matrix of the global sound pressure of the pipeline system and each sound source is established, the internal sound field of the pipeline is obtained, the defects of a classical pipeline acoustic theory and a numerical method are avoided, and a simple and effective means is provided for rapid prediction of complex pipeline noise.

Description

Technical Field

[0001] The present application belongs to the field of multi-branch flow pipelines, and in particular, relates to a method for constructing an acoustic network of a pipeline system. Background Art

[0002] Multi-branch flow pipelines have important application value and research significance in the fields of industrial gas transportation, HVAC and environmental control systems, and aerospace, where the acoustic problems are diverse and complex. Sound waves will propagate along different paths in the pipeline system, resulting in multiple reflections. The reflections in the pipe will cause standing waves, and the corners, bifurcations, and special components of the pipeline will cause scattering, further causing the multi-state propagation of sound waves; long-distance propagation will inevitably cause sound waves to attenuate during the propagation process; the gas flow in the pipeline will not only affect the propagation characteristics of sound waves, but also induce flow-induced noise sources at special components. The interaction and coupling between multiple noise sources will react to the overall sound field distribution in the pipe.

[0003] Traditional classical pipe acoustics theory is based on too many ideal assumptions (such as no friction, uniform materials and simple geometric shapes), which is often quite different from the actual complex pipeline conditions and does not take into account the complex coupling effects of fluid and sound wave propagation.

[0004] Numerical simulation methods, such as finite element analysis, can meet the prediction needs of pipeline flow fields to a certain extent. However, for industrial-grade, large-scale, and highly complex pipeline systems, simulation requires a lot of computing resources and time, which is not conducive to rapid design and optimization. The flow-induced noise induced by special components cannot be accurately analyzed or numerically described.

[0005] Therefore, it is necessary to develop accurate and fast prediction methods for complex pipeline noise, thereby laying a theoretical foundation for the design of low-noise pipeline systems. Summary of the invention

[0006] The purpose of this application is to provide a method for constructing an acoustic network of a pipeline system to solve the problem that existing complex pipeline noise prediction methods occupy large resources and take a long time.

[0007] The technical solution of the present application is: a method for constructing an acoustic network of a pipeline system, comprising: Segment and discretize the complex piping system, determine all component units of the piping system, including the sound source end, nodes and middle section components, and relate all the sound source ends and middle section components to each other through the nodes to form an acoustic network diagram; obtain all acoustic feature data of the middle section components of the acoustic network diagram, and simplify all discretized middle section components into a two-port model; Obtain all acoustic characteristic data of the sound source end, and simplify all discretized sound source ends into a one-port model; Acquiring acoustic characteristic data of each node, including volume flow and cross-sectional area, numbering each two-port model, one-port model and node, and then establishing node scattering matrices according to the volume flow and cross-sectional area of ​​each node; Obtain the two-way pressure amplitudes of all two-port component units, and convert the two-way pressure amplitudes of all two-port component units into a pressure matrix; then construct the scattering matrix of the two-port component unit through the pressure matrix ; Associate all two-port pressure amplitudes with the node scattering matrix to construct a mapping matrix ; According to all the acoustic characteristic data of the one-port component unit and the two-port component unit, through the mapping matrix All two-port component units and one-port component units are associated with each other to form a sound pressure scattering relationship matrix.

[0008] Preferably, in the two-port model, the two ports are the inlet port and the outlet port, respectively, indicating the direction in which each port is connected and the direction of sound mass flow, and each port includes the pressure amplitude of the inlet and outlet ports, and each pressure amplitude is expressed as:

[0009] in, , are the output pressure amplitudes at the inlet and outlet ends respectively; , are the input pressure amplitudes at the inlet and outlet ends, respectively; and are the self-noise pressure amplitudes at the inlet and outlet, respectively; Represents the scattering relationship of the pressure amplitude in the two ports.

[0010] Preferably, the one-port model is: In the formula, is a constant pressure source, is the acoustic impedance of the sound source, It is a constant current source.

[0011] Preferably, the node scattering matrix includes a positive scattering matrix and a negative scattering matrix, and the specific method for obtaining the positive scattering matrix and the negative scattering matrix is: Assume that the inlet port and outlet port of the node have the same total area; in this case, the volume flow Defined as: (5) In the formula, p + is the input pressure amplitude of the two-port component unit, p -is the output pressure amplitude of the two-port component unit, and the characteristic impedance ;in is the local speed of sound, is the cross-sectional area of ​​the plane wave propagation, is the density of the medium in the tube; Since the sum of all volume flow rates connected to a node is equal to the total volume flow rate of the node, we have: (6) in , a total of A two-port component unit is connected to the node , is connected to the node Two-port component unit The cross-sectional area of is connected to the node Two-port component unit The input pressure amplitude, Connect to a Node Two-port component unit The output pressure amplitude is obtained by combining equations (5) and (6): (7) Since the pressure is continuous at all nodes, it translates to: (8) Formula (7) and formula (8) together give: (9) In the formula, To connect to a node The input pressure amplitude of any two-port component unit, To connect to a node The output pressure amplitude of the same two-port component unit; Combining equation (7) and equation (9), we can obtain: (10) Its matrix form is: (11) in and The nodes are The positive and negative scattering matrices of : (12) and In and out nodes The pressure amplitude in both directions is is the source strength of a port connected to the node.

[0012] Preferably, the sound pressure scattering relationship matrix is:

[0013] in and Contains all acoustic feature data from one-port and two-port component elements.

[0014] Preferably, the pressure amplitude of the two-port component unit includes an acoustic network matrix ,one Matrix and Two-Port Source Matrix ;in Indicates that the matrix is ​​a complete acoustic network matrix; It indicates that it is the source strength in both ports; Indicates that it is the source strength of the complete network.

[0015] The acoustic network construction method of the pipeline system of the present application discretizes the complex pipeline system into component units and reconnects the component units in the form of nodes to form an acoustic network diagram. By adopting the acoustic-electric analogy mechanism, the scattering relationship between the sound pressure in a single pipeline in the complex pipeline system and the global sound pressure of the system is constructed on the premise that the transfer matrix and sound source characteristics of the component units are known, and a mapping matrix between the global sound pressure of the pipeline system and each sound source is established to obtain the internal sound field of the pipeline, thereby avoiding the defects of classical pipeline acoustic theory and numerical methods and providing a simple and effective means for rapid prediction of complex pipeline noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solution provided by the present application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present application.

[0017] Figure 1 This is a schematic diagram of the overall process of this application; Figure 2 This is a schematic diagram of the four-source, four-node, five-element pipeline system of this application; Figure 3 Acoustic network diagram of the piping system for this application; Figure 4 This is the acoustic scattering relationship of the two-port element numbered m in this application. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] A method for constructing an acoustic network of a pipe system, such as Figure 1 As shown, the specific steps include: Step S100, segmenting and discretizing the complex pipeline system, determining all component units of the pipeline system, the component units including the sound source end, the node and the middle section component, and correlating all the sound source ends and the middle section components with each other through the node to form an acoustic network diagram; Acquire all acoustic feature data of the middle section components of the acoustic network diagram, simplify all discretized middle section components into a two-port model. The specific judgment standard is to simplify the component units whose two ports can act on the acoustic network into a two-port model. The component units such as straight pipes, variable cross-section pipes and valves can all be represented as two ports, and a total of Two-port component unit, Each component unit interacts with the entire pipe network with two ports. The two ports are the inlet port and the outlet port, indicating the direction of each port connection and the direction of sound mass flow. Each port has two state variables, which are the pressure amplitudes of the inlet and outlet ports. Each pressure amplitude is expressed as: (1) in, , are the output pressure amplitudes at the inlet and outlet, respectively. , are the input pressure amplitudes at the inlet and outlet ends, respectively, which are also passive and unknown variables. and are the self-noise pressure amplitudes at the inlet and outlet, respectively, flowing out from the two ports and are active known variables. It represents the scattering relationship of the pressure amplitude in the two ports, namely transmission and reflection. There is a required passive part and an optional active part at the inlet and outlet.

[0020] Step S200, obtaining all acoustic feature data of the sound source end, and simplifying all discretized sound source ends into a one-port model; One port means that it contains only one port and acts on the entire acoustic network through this single port, that is, the sound source end. One port represents one component, such as a power unit or an exhaust end. Similar to two ports, one port is described by two state variables, but in this case they are pressure p and volume flow rate . Pressure amplitude at a node connected to a port It can be described using two different models: constant voltage source and constant current source.

[0021] The constant pressure source model is described as: (2) The constant current source model is described as: (3) in is a constant voltage source (the active part of one port), is the acoustic impedance of the sound source, is the volume flow rate, is a constant current source. The combination of equation (2) and equation (3) yields: (4).

[0022] Step S300, obtaining acoustic characteristic data of each node, the acoustic characteristic data including volume flow and cross-sectional area, numbering each two-port model, one-port model and node, and then establishing a node scattering matrix according to the volume flow and cross-sectional area of ​​each node, the node scattering matrix including a positive scattering matrix and a negative scattering matrix; A node is a connection point between various components in an acoustic network. It can connect any number of one-port models and two-port models. A node determines how to divide the acoustic mass flow between the ports connected to the node.

[0023] Preferably, the specific method for obtaining the positive scattering matrix and the negative scattering matrix is: assuming that the inlet port and the outlet port of the node have the same total area. Defined as: (5) In the formula, p + is the input pressure amplitude of the two-port component unit, p - is the output pressure amplitude of the two-port component unit, and the characteristic impedance ;in is the local speed of sound, is the cross-sectional area of ​​the plane wave propagation, is the density of the medium in the tube.

[0024] Since the sum of all volume flow rates connected to a node is equal to the total volume flow rate of the node, we can get: (6) in , a total of A two-port component unit is connected to the node , is connected to the node Two-port component unit The cross-sectional area of Connect to a Node Yes Two-port component unit The input pressure amplitude, Connect to a Node Two-port component unit The output pressure amplitude is obtained by combining equations (5) and (6): (7) Since the pressure is continuous at all nodes, it can be transformed into: (8) Formula (7) and formula (8) together give: (9) In the formula, To connect to a node The input pressure amplitude of any two-port component unit, To connect to a node The output pressure amplitude of the same two-port component unit.

[0025] Combining equation (7) and equation (9), we can obtain: (10) Its matrix form is: (11) in and The nodes are The positive and negative scattering matrices of : (12) and In and out nodes The pressure amplitude in both directions is is the source strength of a port connected to the node.

[0026] Step S400, obtaining the two-way pressure amplitudes of all two-port component units, and converting the two-way pressure amplitudes of all two-port component units into a pressure matrix: the pressure amplitudes of the two-port component units are expressed as an acoustic network matrix ,one Matrix and Two-Port Source Matrix .in Indicates that the matrix is ​​the complete acoustic network matrix, It means it is the source strength in both ports. Indicates that it is the source strength of the complete network.

[0027] Then the scattering matrix of the two-port component unit is constructed through the pressure matrix , The dimension is Diagonal matrix. At this time, equation (11) is transformed into the correlation matrix : (13) Used to describe the correlation between various pressure amplitudes in the entire sound source network.

[0028] The one-port model has a simple working principle and does not require additional construction of a scattering matrix.

[0029] Step S500, associating all two-port pressure amplitudes with the node scattering matrix to construct a mapping matrix; according to all acoustic feature data of the one-port component unit and the two-port component unit, associating all the two-port component units with the one-port component unit through the mapping matrix to form a sound pressure scattering relationship matrix; In order to connect all two-port component units to each other through nodes, this method introduces the mapping matrix . Contains nodes Whether it is connected to both ports is key information. The information in also contains whether the node is an outlet or an import, which describes the relationship between the local pressure amplitude and the pressure amplitude of the entire network. Should meet: (14) in, represent or ; The value of each position is 0 or 1, if the node is connected to both ports, it is 1, otherwise it is 0. It can be expressed as: (15) Then the equations of all nodes are transformed into the acoustic pressure scattering relationship matrix: (16) The above formula describes the sound pressure scattering relationship in the complete acoustic network, forming a total of Equation. and Contains all acoustic characteristic data from one-port component units and two-port component units, which can be calculated by understanding the geometric shape of the acoustic network body. Combined with formula (1), the local scattering equations of each of the M two-ports are constructed to form another The equation can be formed equations, and find the , at this point the sound field solution of the entire complex piping system is completed.

[0030] As a specific implementation method, a specific example is used to illustrate: 1) Segment the complex piping system, such as Figure 2 The piping system contains four sound source ends, four nodes, and five mid-section "two-port" components, which can be simplified as follows Figure 3 Acoustic network diagram of the piping system; For the two-port model, each element interacts with the entire pipe network with two ports. The two ports are divided into inlet and outlet ports, which represent the direction of each port connection and the direction of acoustic mass flow. Each port has two state variables, which are the pressure amplitudes at the inlet and outlet ports, such as Figure 4 As shown, the output , and input , is the pressure amplitude in the pipe, which is also a passive term and an unknown variable. and is the source pressure amplitude, flowing out of the two ports, and is the active term and known variable.

[0031] 2) Simplify the sound source end and outlet end of the pipeline into a one-port model. The acoustic characteristic data of the one-port model includes sound mass flow information, sound source intensity (specific to the sound source end) and port impedance. The one-port model is connected to a node, such as Figure 3 .

[0032] 3) Number each two-port model, one-port model and each node to obtain the positive scattering matrix and negative scattering matrix of each node. Establish the global sound pressure scattering relationship , the overall scattering matrix is a diagonal matrix with diagonal elements ; 4) Construct the node scattering matrix to Figure 3 For example, the heat dissipation matrix of node 3 in for: (17) The first number in the index is 1 if the connection is an entry port, and 2 if it is an exit port. The second number describes which port the connection is to. is the sound pressure amplitude from the node (+), through the outlet port (2) and connected to the two ports 5. The mapping matrix can be The statement is as follows

[0033] 6) Substitute the node scattering matrix, overall scattering matrix and mapping matrix into , for A two-port element piping system is constructed. equations, and solve them to get the corresponding , complete the acoustic field solution of the pipeline system.

[0034] Through the above design, the complex piping system is discretized into component units and the component units are reconnected in the form of nodes to form an acoustic network diagram. The acoustic-electric analogy mechanism is used. Under the premise of known transfer matrix and sound source characteristics of the component units, the scattering relationship between the sound pressure in a single pipe in the complex piping system and the global sound pressure of the system is constructed, and the mapping matrix between the global sound pressure of the piping system and each sound source is established to obtain the internal sound field of the pipeline. This avoids the defects of classical pipeline acoustics theory and numerical methods, and provides a simple and effective means for rapid prediction of complex pipeline noise.

[0035] Finally, it should be noted that: the drawings of the embodiments disclosed in the present invention only involve structures related to the embodiments disclosed in the present invention, and other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other; Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for constructing an acoustic network of a pipeline system, characterized in that: include: Segment and discretize the complex piping system, determine all component units of the piping system, including the sound source end, nodes and middle section components, and relate all the sound source ends and middle section components to each other through the nodes to form an acoustic network diagram; obtain all acoustic feature data of the middle section components of the acoustic network diagram, and simplify all discretized middle section components into a two-port model; Obtain all acoustic characteristic data of the sound source end, and simplify all discretized sound source ends into a one-port model; Acquiring acoustic characteristic data of each node, including volume flow and cross-sectional area, numbering each two-port model, one-port model and node, and then establishing node scattering matrices according to the volume flow and cross-sectional area of ​​each node; Obtain the two-way pressure amplitudes of all two-port component units, and convert the two-way pressure amplitudes of all two-port component units into a pressure matrix; then construct the scattering matrix of the two-port component unit through the pressure matrix ; Associate all two-port pressure amplitudes with the node scattering matrix to construct a mapping matrix ; According to all the acoustic characteristic data of the one-port component unit and the two-port component unit, through the mapping matrix All two-port component units and one-port component units are associated with each other to form a sound pressure scattering relationship matrix.

2. The method for constructing an acoustic network of a pipeline system according to claim 1, characterized in that: In the two-port model, the two ports are the inlet port and the outlet port, respectively, indicating the direction of connection of each port and the direction of sound mass flow. Each port includes the pressure amplitude of the inlet and outlet ports, and each pressure amplitude is expressed as: ； in, , are the output pressure amplitudes at the inlet and outlet ends respectively; , are the input pressure amplitudes at the inlet and outlet ends, respectively; and are the self-noise pressure amplitudes at the inlet and outlet, respectively; Represents the scattering relationship of the pressure amplitude in the two ports.

3. The method for constructing an acoustic network of a pipeline system according to claim 1, characterized in that: The one-port model is: ； In the formula, is a constant pressure source, is the acoustic impedance of the sound source, It is a constant current source.

4. The method for constructing an acoustic network of a pipeline system according to claim 3, characterized in that: The node scattering matrix includes a positive scattering matrix and a negative scattering matrix. The specific method for obtaining the positive scattering matrix and the negative scattering matrix is: Assume that the inlet port and outlet port of the node have the same total area; in this case, the volume flow Defined as: (5) In the formula, p + is the input pressure amplitude of the two-port component unit, p - is the output pressure amplitude of the two-port component unit, and the characteristic impedance ;in is the local speed of sound, is the cross-sectional area of ​​the plane wave propagation, is the density of the medium in the tube; Since the sum of all volume flow rates connected to a node is equal to the total volume flow rate of the node, we have: (6) in , a total of A two-port component unit is connected to the node , is connected to the node Two-port component unit The cross-sectional area of is connected to the node Two-port component unit The input pressure amplitude, is connected to the node Two-port component unit The output pressure amplitude is obtained by combining equations (5) and (6): (7) Since the pressure is continuous at all nodes, it translates to: (8) Formula (7) and formula (8) together give: (9) In the formula, To connect to a node The input pressure amplitude of any two-port component unit, To connect to a node The output pressure amplitude of the same two-port component unit; Combining equation (7) and equation (9), we can obtain: (10) Its matrix form is: (11) in and The nodes are The positive and negative scattering matrices of : (12) and In and out nodes The pressure amplitude in both directions is is the source strength of a port connected to the node.

5. The method for constructing an acoustic network of a pipeline system according to claim 4, characterized in that: The acoustic pressure scattering relationship matrix is: ； in and Contains all acoustic feature data from one-port and two-port component elements.

6. The method for constructing an acoustic network of a pipeline system according to claim 2, characterized in that: The pressure amplitude of the two-port component unit includes the acoustic network matrix ,one Matrix and Two-Port Source Matrix ;in Indicates that the matrix is ​​a complete acoustic network matrix; It indicates that it is the source strength in both ports; Indicates that it is the source strength of the complete network.

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