A network compression method and system for solving fluid power system
By compressing the fluid network in series and parallel, replacing the original components with new components, and constructing the reduced resistance equation, the problems of large scale, large storage usage, long calculation time and poor convergence in fluid network solution are solved, and efficient fluid network solution is achieved.
Patent Information
- Application Number
- CN202211151589.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-09-21
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2042-09-21
AI Technical Summary
Existing technologies for solving fluid network models have problems such as large fluid network scale, many variables, large storage space, long calculation time and poor convergence. This is especially difficult to solve efficiently in fluid transportation problems in the fields of petrochemicals, HVAC, water conservancy, aviation, etc.
By performing series and parallel network compression on the fluid network, replacing the original components with new components, constructing the reduced resistance equation, reducing the scale of the network model, simplifying the equation group, and using the fluid network acquisition module, series node acquisition module, series network compression module, parallel network compression module and loop call module to perform network compression.
It reduces the scale of the network model, saves storage space, shortens the calculation time, improves the solution speed and convergence, and optimizes the solution process of the fluid network.
Smart Images
Figure CN115391965B_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the technical field of fluid model construction, and specifically relates to a network compression method and system for solving a fluid power system. Background Art
[0002] Fluid transport problems are often encountered in fields such as petrochemicals, HVAC, water conservancy, measurement and control, and aviation. It is usually necessary to establish a network model of the fluid system, solve its dynamic characteristics, and obtain parameters such as flow, pressure, and temperature at any location in the network. In this way, the loss, efficiency, safety, and reliability of fluid transport in the network can be evaluated, and targeted optimization, improvement, and maintenance can be carried out.
[0003] The fluid network method decomposes and simplifies complex flow paths into a network system composed of a series of components and nodes. Components are used to model the pressure changes generated by fluids. Based on their structural characteristics and flow properties, they can be categorized as pipes, local loss components (such as sudden expansions, contractions, and elbows), flow restrictors (holes, slits, etc.), grates, centrifugal boost components, and special components. The transfer of physical quantities between adjacent components is represented by nodes.
[0004] Solving the fluid network model is a numerical simulation method that forms a nonlinear system of equations by listing the momentum equations for each component, the node continuity equations established based on the network topology, and the necessary energy equations. The system of equations is then solved to determine parameters such as component flow, node pressure, and temperature.
[0005] Existing technical solutions establish a momentum equation for each element in the fluid network and a continuity equation for each internal node. However, achieving a refined solution requires a large network, often containing hundreds of elements and numerous variables, requiring significant storage space, a large number of equations, and lengthy computational time. Furthermore, the biggest challenge in solving nonlinear systems of equations is convergence. The large number of network elements and nodes, coupled with the large number of equations, can easily lead to poor convergence of the entire network due to inappropriate initial values. Summary of the Invention
[0006] In order to solve one of the above problems, the present application provides a network compression method and system for solving a fluid power system to reduce the number of equations in the solution set, thereby shortening the calculation time and accelerating the design iteration cycle.
[0007] In a first aspect, the present application provides a network compression method for solving a fluid power system, mainly comprising:
[0008] Step S1, obtaining a fluid network consisting of components and node topology;
[0009] Step S2, determining a series node in the fluid network that is connected to only two elements;
[0010] Step S3: compress the series node and the two elements connected to the series node into a series network, and replace them with the first type of newly added elements, and construct a flow equation for the first type of newly added elements based on the reduced resistance of the first type of newly added elements;
[0011] Step S4, determining a plurality of parallel elements having the same inlet and the same outlet in the fluid network;
[0012] Step S5: compress the parallel network of the components connected in parallel and replace them with the second type of newly added components, and construct the flow equation of the second type of newly added components based on the reduced resistance of the second type of newly added components;
[0013] Step S6: Repeat the above steps until the series nodes and parallel elements no longer exist in the fluid network.
[0014] Preferably, step S3 further comprises:
[0015] Step S31, determining a first component before the series node and a second component after the series node;
[0016] Step S32: Connect the front node of the first type of newly added component to the front node of the first component, and connect the rear node of the first type of newly added component to the rear node of the second component;
[0017] Step S33: calculating the reduced resistance of the first type of newly added element based on the resistance of the first element and the resistance of the third element, and constructing a flow equation for the first type of newly added element based on the reduced resistance of the first type of newly added element;
[0018] Step S34: Delete the series node, the first element, and the second element in the fluid network.
[0019] Preferably, the reduced resistance K of the first type of newly added elements is 串 for:
[0020]
[0021] Where R is the ideal gas constant, T is the thermodynamic temperature of the ideal gas, ξ1 and ξ2 are the unit resistance coefficients of the two elements used for series network compression, and A1 and A2 are the pipe cross-sectional areas of the two elements used for series network compression.
[0022] Preferably, step S5 further comprises:
[0023] Step S51: Connect the front node of the second type of newly added element to the front node of the parallel element, and connect the rear node of the second type of newly added element to the rear node of the parallel element;
[0024] Step S52: Calculate the reduced resistance of the second type of newly added element based on the resistance of each parallel element, and construct a flow equation for the second type of newly added element based on the reduced resistance of the second type of newly added element;
[0025] Step S53: Delete the parallel elements in the fluid network.
[0026] Preferably, the reduced resistance K of the second type of newly added element is 并 for:
[0027]
[0028] Where R is the ideal gas constant, T is the thermodynamic temperature of the ideal gas, ξ1 and ξ2 are the unit resistance coefficients of the two elements used for parallel network compression, A1 and A2 are the pipe cross-sectional areas of the two elements used for parallel network compression, and multiple parallel elements are calculated using a pairwise parallel compression method.
[0029] A second aspect of the present application provides a network compression system for solving a fluid power system, mainly comprising:
[0030] A fluid network acquisition module is used to obtain a fluid network consisting of components and node topology;
[0031] A series node acquisition module, configured to determine a series node in the fluid network that is connected to only two elements;
[0032] a series network compression module, configured to perform series network compression on the series node and the two elements connected to the series node, replace them with the first type of newly added elements, and construct a flow equation for the first type of newly added elements using the reduced resistance of the first type of newly added elements;
[0033] A parallel element acquisition module, configured to determine a plurality of parallel elements having the same inlet and the same outlet in the fluid network;
[0034] A parallel network compression module is used to compress the parallel components and replace them with the second type of newly added components, and to construct the flow equation of the second type of newly added components based on the reduced resistance of the second type of newly added components;
[0035] The cyclic calling module is used to call the above modules again until the series nodes and parallel elements no longer exist in the fluid network.
[0036] Preferably, the series network compression module includes:
[0037] a series element marking unit, configured to determine a first element before the series node and a second element after the series node;
[0038] a serial link unit, configured to connect the front node of the first type of newly added element to the front node of the first element, and to connect the rear node of the first type of newly added element to the rear node of the second element;
[0039] a series flow equation construction unit, configured to calculate the reduced resistance of the first type of newly added element using the resistance of the first element and the resistance of the third element, and to construct the flow equation of the first type of newly added element using the reduced resistance of the first type of newly added element;
[0040] The first model updating unit is used to delete the series node, the first element and the second element in the fluid network.
[0041] Preferably, the reduced resistance K of the first type of newly added elements is 串 for:
[0042]
[0043] Where R is the ideal gas constant, T is the thermodynamic temperature of the ideal gas, ξ1 and ξ2 are the unit resistance coefficients of the two elements used for series network compression, and A1 and A2 are the pipe cross-sectional areas of the two elements used for series network compression.
[0044] Preferably, the parallel network compression module includes:
[0045] a parallel link unit, configured to connect the front node of the second type of newly added element to the front node of the parallel element, and to connect the rear node of the second type of newly added element to the rear node of the parallel element;
[0046] a parallel flow equation construction unit, configured to calculate the reduced resistance of the second type of newly added element based on the resistance of each parallel element, and to construct the flow equation of the second type of newly added element based on the reduced resistance of the second type of newly added element;
[0047] The second model updating unit is used to delete parallel elements in the fluid network.
[0048] Preferably, the reduced resistance K of the second type of newly added element is 并 for:
[0049]
[0050] Where R is the ideal gas constant, T is the thermodynamic temperature of the ideal gas, ξ1 and ξ2 are the unit resistance coefficients of the two elements used for parallel network compression, A1 and A2 are the pipe cross-sectional areas of the two elements used for parallel network compression, and multiple parallel elements are calculated using a pairwise parallel compression method.
[0051] This application compresses the series and parallel local networks, reduces the scale of the network model that needs to be solved, saves storage space, reduces the number of calculations, speeds up the solution of the fluid network, and improves convergence. BRIEF DESCRIPTION OF THE DRAWINGS
[0052] Figure 1 A flow chart of a preferred embodiment of the network compression method for solving the fluid power system of the present application.
[0053] Figure 2 This is a simplified diagram of the fluid network mode before compression.
[0054] Figure 3 This is a schematic diagram of the model after the first round of compression.
[0055] Figure 4 This is a schematic diagram of the model after the second round of compression. DETAILED DESCRIPTION
[0056] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the implementation of this application will be described in more detail below in conjunction with the drawings in the implementation of this application. In the drawings, the same or similar numbers throughout represent the same or similar elements or elements with the same or similar functions. The described implementation is a part of the implementation of this application, not all of the implementations. The implementation described below with reference to the drawings is exemplary and is intended to be used to explain this application, and should not be understood as a limitation on this application. Based on the implementation in this application, all other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The implementation of this application is described in detail below in conjunction with the drawings.
[0057] The first aspect of the present application provides a network compression method for solving a fluid power system, such as Figure 1 As shown, it mainly includes:
[0058] Step S1: Obtain a fluid network consisting of component and node topology.
[0059] The fluid network consists of components, nodes and their topological relationships. The component numbers and node numbers have designated identifiers. The identifier names can be arbitrarily specified but are unique in the network.
[0060] The fluid network has the following structural characteristics: each element has one inlet and one outlet; an internal node is connected to at least two elements; a boundary node can be connected to one element or to multiple nodes, so it is necessary to specify which ones are boundary nodes.
[0061] Figure 2This is an example of a fluid network diagram, which contains 8 elements: A1, B1, B2, C1, C2, D1, D2, D3, 4 internal nodes - 2 / 3 / 8 / 10, and 3 boundary nodes - 1 / 5 / 12.
[0062] Step S2: determining a series node in the fluid network that is connected to only two elements.
[0063] like Figure 2 In the diagram, node 3 connects two components B1 and B3, and node 8 connects two components C1 and C2.
[0064] Step S3: compress the series network of the series node and the two elements connected to the series node, and replace them with the first type of newly added elements, and construct the flow equation of the first type of newly added elements based on the reduced resistance of the first type of newly added elements.
[0065] like Figure 3 As shown, components B1, B3 and node 3 are compressed in series and replaced by the first type of newly added component K1; components C1, C2 and node 8 are compressed in series and replaced by the first type of newly added component K2.
[0066] Step S4: determining a plurality of parallel elements having the same inlet and the same outlet in the fluid network.
[0067] like Figure 2 As shown, D1, D2, and D3 are three parallel components having the same inlet and the same outlet.
[0068] Step S5: compress the parallel network of the components in parallel and replace them with the second type of newly added components, and construct the flow equation of the second type of newly added components based on the reduced resistance of the second type of newly added components.
[0069] like Figure 3 As shown, the three parallel components D1, D2, and D3 are replaced by the second type of newly added component M1.
[0070] First, the principle of network compression is explained as follows:
[0071] The momentum equation of the element expresses the relationship between flow rate, inlet and outlet parameters, geometric parameters, resistance coefficient, etc.
[0072] For isentropic incompressible fluid, according to Bernoulli equation:
[0073]
[0074] For isentropic flow, considering the loss, the friction equation is:
[0075]
[0076] Where P1 is the total pressure at the unit inlet node, and p1 is the static pressure; P2 is the total pressure at the unit outlet node, and p2 is the static pressure; V is the fluid velocity; ξ is the unit resistance coefficient, which is obtained from the component resistance characteristic test and can also be calculated from the empirical formula for regular structures; ρ is the fluid density.
[0077] The above formula is for incompressible fluid.
[0078] For gas flows with small Ma, the compressibility effect can be ignored. Based on experience, the above formula is applicable. At the same time, the density can be averaged at the inlet and outlet according to the gas state equation P = ρRT. Combined with the continuity equation G = ρVA, the friction equation applicable to gas can be obtained:
[0079]
[0080] Where, is called the flow resistance of the unit.
[0081] For a network with two elements in series, the flow is continuous and temperature changes are ignored, then:
[0082]
[0083] That is, the series flow path can calculate the flow rate by adding up the resistance of each component in the flow path, K 串 It is called the reduced resistance of the first type of newly added element. R is the ideal gas constant, T is the thermodynamic temperature of the ideal gas, ξ1 and ξ2 are the unit resistance coefficients of the two elements used for series network compression, and A1 and A2 are the pipe cross-sectional areas of the two elements used for series network compression.
[0084] Similarly, for a parallel network, the total flow can be calculated using one equation:
[0085]
[0086] Right now Figure 2 The parallel network can also be compressed into Figure 3 A network with only one element M1 is shown.
[0087] Similarly, when multiple elements are connected in series or in parallel, the network can be compressed to a single element using the reduced resistance method. This greatly reduces the number of equations in the fluid network characteristic equations, greatly facilitating the initial field determination and accelerating the solution. Once the solution is complete, the network can be restored.
[0088] Step S6: Repeat the above steps until the series nodes and parallel elements no longer exist in the fluid network.
[0089] For example, Figure 3 On the basis of the formed fluid network, K2 and M2 are further compressed into K3.
[0090] In some optional embodiments, step S3 further includes:
[0091] Step S31, determining a first component before the series node and a second component after the series node;
[0092] Step S32: Connect the front node of the first type of newly added component to the front node of the first component, and connect the rear node of the first type of newly added component to the rear node of the second component;
[0093] Step S33: calculating the reduced resistance of the first type of newly added element based on the resistance of the first element and the resistance of the third element, and constructing a flow equation for the first type of newly added element based on the reduced resistance of the first type of newly added element;
[0094] Step S34: Delete the series node, the first element, and the second element in the fluid network.
[0095] like Figure 2 As shown, find the node in the network that is only connected to two elements. This node and the elements after it can be compressed. The resistance of the elements after the node is calculated together with the resistance of the elements before the node. The relevant information is recorded in the code, such as Figure 2 Node 3 and node 8 in Figure 3 As shown, a new element K1 is added, marked as a compression element of the series flow path, the front node is the rear node of B1, and the rear node is the rear node of B3. The resistances of B1 and B3 are used to calculate the reduced resistance of K1; new record data is added to record the change information of elements and nodes before and after network compression; the information of elements B1 and B3 in the data model is deleted.
[0096] In some optional implementations, step S5 further includes:
[0097] Step S51: Connect the front node of the second type of newly added element to the front node of the parallel element, and connect the rear node of the second type of newly added element to the rear node of the parallel element;
[0098] Step S52: Calculate the reduced resistance of the second type of newly added element based on the resistance of each parallel element, and construct a flow equation for the second type of newly added element based on the reduced resistance of the second type of newly added element;
[0099] Step S53: Delete the parallel elements in the fluid network.
[0100] The embodiment Figure 2As shown, find the components with the same import and export nodes in the network. These components can be compressed into 1, and the resistance is calculated together. The relevant information is recorded in the code, such as Figure 2 Components D1, D2, D3 in. Figure 3 As shown in the figure, a new element M1 is added, marked as a compression element of the parallel flow path, the front and rear nodes remain unchanged, and the resistance is the reduced resistance of elements D1, D2, and D3; new recorded data is added to record the changes in elements and nodes before and after network compression; the information of elements D1, D2, and D3 is deleted.
[0101] exist Figures 3 and 4 During the compression process, a series network compression was performed. The network initially had 8 elements and 7 nodes, but after compression it was reduced to 3 elements and 4 nodes, greatly reducing the number of equations in the system.
[0102] The second aspect of the present application provides a network compression system for solving a fluid power system corresponding to the above method, mainly comprising:
[0103] A fluid network acquisition module is used to obtain a fluid network consisting of components and node topology;
[0104] A series node acquisition module, configured to determine a series node in the fluid network that is connected to only two elements;
[0105] a series network compression module, configured to perform series network compression on the series node and the two elements connected to the series node, replace them with the first type of newly added elements, and construct a flow equation for the first type of newly added elements using the reduced resistance of the first type of newly added elements;
[0106] A parallel element acquisition module, configured to determine a plurality of parallel elements having the same inlet and the same outlet in the fluid network;
[0107] A parallel network compression module is used to compress the parallel components and replace them with the second type of newly added components, and to construct the flow equation of the second type of newly added components based on the reduced resistance of the second type of newly added components;
[0108] The cyclic calling module is used to call the above modules again until the series nodes and parallel elements no longer exist in the fluid network.
[0109] In some optional embodiments, the series network compression module includes:
[0110] a series element marking unit, configured to determine a first element before the series node and a second element after the series node;
[0111] a serial link unit, configured to connect the front node of the first type of newly added element to the front node of the first element, and to connect the rear node of the first type of newly added element to the rear node of the second element;
[0112] a series flow equation construction unit, configured to calculate the reduced resistance of the first type of newly added element using the resistance of the first element and the resistance of the third element, and to construct the flow equation of the first type of newly added element using the reduced resistance of the first type of newly added element;
[0113] The first model updating unit is used to delete the series node, the first element and the second element in the fluid network.
[0114] In some optional embodiments, the reduced resistance K of the first type of newly added element is 串 for:
[0115]
[0116] Where R is the ideal gas constant, T is the thermodynamic temperature of the ideal gas, ξ1 and ξ2 are the unit resistance coefficients of the two elements used for series network compression, and A1 and A2 are the pipe cross-sectional areas of the two elements used for series network compression.
[0117] In some optional embodiments, the parallel network compression module includes:
[0118] a parallel link unit, configured to connect the front node of the second type of newly added element to the front node of the parallel element, and to connect the rear node of the second type of newly added element to the rear node of the parallel element;
[0119] a parallel flow equation construction unit, configured to calculate the reduced resistance of the second type of newly added element based on the resistance of each parallel element, and to construct the flow equation of the second type of newly added element based on the reduced resistance of the second type of newly added element;
[0120] The second model updating unit is used to delete parallel elements in the fluid network.
[0121] In some optional embodiments, the reduced resistance K of the second type of newly added element is 并 for:
[0122]
[0123] Where R is the ideal gas constant, T is the thermodynamic temperature of the ideal gas, ξ1 and ξ2 are the unit resistance coefficients of the two elements used for parallel network compression, A1 and A2 are the pipe cross-sectional areas of the two elements used for parallel network compression, and multiple parallel elements are calculated using a pairwise parallel compression method.
[0124] This application compresses the series and parallel local networks, reduces the scale of the network model that needs to be solved, saves storage space, reduces the number of calculations, speeds up the solution of the fluid network, and improves convergence.
[0125] Although the present application has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications or improvements may be made based on the present application. Therefore, such modifications or improvements, which do not depart from the spirit of the present application, are within the scope of protection claimed in the present application.
Claims
1. A network compression method for solving a fluid dynamic system, characterized in that: include: Step S1, obtaining a fluid network consisting of components and node topology; Step S2, determining a series node in the fluid network that is connected to only two elements; Step S3: compress the series node and the two elements connected to the series node into a series network, and replace them with the first type of newly added elements, and construct a flow equation for the first type of newly added elements based on the reduced resistance of the first type of newly added elements; Step S4, determining a plurality of parallel elements having the same inlet and the same outlet in the fluid network; Step S5: compress the parallel network of the components connected in parallel and replace them with the second type of newly added components, and construct the flow equation of the second type of newly added components based on the reduced resistance of the second type of newly added components; Step S6, repeat the above steps until the series nodes and parallel elements no longer exist in the fluid network; Step S3 further comprises: Step S31, determining a first component before the series node and a second component after the series node; Step S32: Connect the front node of the first type of newly added component to the front node of the first component, and connect the rear node of the first type of newly added component to the rear node of the second component; Step S33: Calculate the reduced resistance of the first type of newly added element based on the resistance of the first element and the resistance of the second element, and construct a flow equation for the first type of newly added element based on the reduced resistance of the first type of newly added element; Step S34, deleting the series node, the first element, and the second element in the fluid network; Step S5 further comprises: Step S51: Connect the front node of the second type of newly added element to the front node of the parallel element, and connect the rear node of the second type of newly added element to the rear node of the parallel element; Step S52: Calculate the reduced resistance of the second type of newly added element based on the resistance of each parallel element, and construct a flow equation for the second type of newly added element based on the reduced resistance of the second type of newly added element; Step S53: Delete the parallel elements in the fluid network.
2. The network compression method for solving a fluid power system according to claim 1, characterized in that: The reduced resistance K of the first type of new components 串 for: Where R is the ideal gas constant, T is the thermodynamic temperature of the ideal gas, ξ1 and ξ2 are the unit resistance coefficients of the two elements used for series network compression, and A1 and A2 are the pipe cross-sectional areas of the two elements used for series network compression.
3. The network compression method for solving a fluid power system according to claim 1, characterized in that: The reduced resistance K of the second type of new components 并 for: Where R is the ideal gas constant, T is the thermodynamic temperature of the ideal gas, ξ1 and ξ2 are the unit resistance coefficients of the two elements used for parallel network compression, A1 and A2 are the pipe cross-sectional areas of the two elements used for parallel network compression, and multiple parallel elements are calculated using a pairwise parallel compression method.
4. A network compression system for solving a fluid dynamic system, characterized in that: include: A fluid network acquisition module is used to obtain a fluid network consisting of components and node topology; A series node acquisition module, configured to determine a series node in the fluid network that is connected to only two elements; a series network compression module, configured to perform series network compression on the series node and the two elements connected to the series node, replace them with the first type of newly added elements, and construct a flow equation for the first type of newly added elements using the reduced resistance of the first type of newly added elements; A parallel element acquisition module, configured to determine a plurality of parallel elements having the same inlet and the same outlet in the fluid network; A parallel network compression module is used to compress the parallel components and replace them with the second type of newly added components, and to construct the flow equation of the second type of newly added components based on the reduced resistance of the second type of newly added components; a cyclic calling module, used for re-calling the above modules until the series nodes and parallel elements no longer exist in the fluid network; The series network compression module includes: a series element marking unit, configured to determine a first element before the series node and a second element after the series node; a serial link unit, configured to connect the front node of the first type of newly added element to the front node of the first element, and to connect the rear node of the first type of newly added element to the rear node of the second element; a series flow equation construction unit, configured to calculate a reduced resistance of the first type of newly added element using the resistance of the first element and the resistance of the second element, and to construct a flow equation for the first type of newly added element using the reduced resistance of the first type of newly added element; a first model updating unit, configured to delete the series node, the first element, and the second element in the fluid network; The parallel network compression module includes: a parallel link unit, configured to connect the front node of the second type of newly added element to the front node of the parallel element, and to connect the rear node of the second type of newly added element to the rear node of the parallel element; a parallel flow equation construction unit, configured to calculate the reduced resistance of the second type of newly added element based on the resistance of each parallel element, and to construct the flow equation of the second type of newly added element based on the reduced resistance of the second type of newly added element; The second model updating unit is used to delete parallel elements in the fluid network.
5. The network compression system for solving a fluid power system according to claim 4, characterized in that: The reduced resistance K of the first type of new components 串 for: Where R is the ideal gas constant, T is the thermodynamic temperature of the ideal gas, ξ1 and ξ2 are the unit resistance coefficients of the two elements used for series network compression, and A1 and A2 are the pipe cross-sectional areas of the two elements used for series network compression.
6. The network compression system for solving a fluid power system according to claim 4, characterized in that: The reduced resistance K of the second type of new components 并 for: Where R is the ideal gas constant, T is the thermodynamic temperature of the ideal gas, ξ1 and ξ2 are the unit resistance coefficients of the two elements used for parallel network compression, A1 and A2 are the pipe cross-sectional areas of the two elements used for parallel network compression, and multiple parallel elements are calculated using a pairwise parallel compression method.