A method for motion flow field simulation and analysis of a dual-motion-degree-of-freedom piston pump

Abstract

The application provides a motion flow field simulation and analysis method of a double-motion-degree-of-freedom piston pump, comprising pretreatment, simulation calculation and analysis processing; the pretreatment comprises the following steps: S11, determining the working state and initial position of each connecting piston and cam according to the operation process of the pump; S12, performing domain modeling on the simulation model, including low-pressure domain modeling, piston domain modeling and high-pressure domain modeling; S13, performing mesh division on each domain; S14, setting each low-pressure flow distribution groove window and piston flow distribution groove opening as Interface, and setting each high-pressure flow distribution groove window and piston flow distribution groove opening as Interface, so as to realize the communication and data exchange of each domain; and S15, cutting the tetrahedral mesh of the low-pressure domain into a low-pressure cavity domain and a cam domain by taking the distance from the cam wall surface as a parameter. The application can comprehensively present the flow field change process of the piston pump, so that the flow field simulation is closer to the actual situation, and the simulation analysis result is more accurate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flow field simulation, and particularly relates to a motion flow field simulation and analysis method of a double-motion-degree-of-freedom piston pump. BACKGROUND

[0002] The motion process of the double-motion-degree-of-freedom piston pump is more complex than that of the conventional crankshaft piston pump, and the motion process includes the rotation and reciprocating motion of the plunger and cam parts, the alternating opening and closing of the plunger flow groove and the cylinder flow window, and the alternating switching of the oil suction and discharge of the upper and lower action chambers of the double-acting plunger. In particular, for the double-motion-degree-of-freedom piston pump with multiple pump cores, the multiple cams and plungers in the pump cavity act at the same time, which greatly affects the flow field in the pump cavity.

[0003] Currently, the flow field simulation of the double-motion-degree-of-freedom piston pump generally has the following two methods: (1) using a one-dimensional simulation method such as AMESim, and a basic mathematical model is used to model and simulate the motion process of the pump in the document “Design Method Research of Two-dimensional Piston Pump”. This method is an approximate representation of the pump motion process, and only the basic rules of pump oil suction and discharge can be obtained. The distribution rules of pressure and flow rate of the pump cavity flow field such as cam oil stirring and plunger window opening and closing cannot be obtained.

[0004] (2) using a CFD flow field simulation method. For example, the document “Flow Characteristics Research of Electric Two-dimensional Piston (2D) Fuel Pump” analyzes the pump oil suction and discharge characteristics through simulation of the plunger motion process. However, the rotation and reciprocating motion of the cam in the low-pressure cavity of the pump, especially the simultaneous motion of multiple cams, causes severe stirring of the flow field in the pump cavity, which directly affects the suction characteristics of the plunger. Therefore, there is a large error in directly using the simulation results of the plunger flow field to analyze the pump oil suction and discharge characteristics without considering the influence of the cam on the flow field in the pump cavity. In addition, currently, when calculating and setting the piston pump, the outlet of the pump is generally directly used as the outlet of the simulation model, and the pressure boundary condition is directly assigned to the outlet. Since the outlet of the model is close to the high-pressure cavity, the pressure of the high-pressure cavity will be automatically adjusted during calculation to match the outlet pressure, which affects the calculation of the flow and pressure, and further affects the pulsation of the flow and pressure. SUMMARY

[0005] The present application aims to at least solve one of the technical problems existing in the prior art.

[0006] The present application provides a motion flow field simulation and analysis method of a double-motion-degree-of-freedom piston pump, which includes pre-processing, simulation calculation and analysis processing; wherein the pre-processing includes:

[0007] S11, determining the working state and initial position of each group of plungers and cams according to the operation process of the pump;

[0008] S12, domain modeling is performed on the simulation model, including low pressure domain modeling, plunger domain modeling and high pressure domain modeling; the low pressure domain includes pump inlet flow pipe, pump low pressure cavity, a plurality of low pressure flow distribution groove windows and a plurality of cams; any plunger corresponds to a plunger domain, and each plunger domain includes upper action scope, plunger movement domain and lower scope; the high pressure domain includes a plurality of high pressure flow distribution groove windows, a plurality of high pressure ring cavity domains and outlet flow pipe, and the outlet flow pipe is provided with a throttle pipe; the plurality of low pressure flow distribution groove windows, the plurality of cams, the plurality of plungers, the plurality of high pressure flow distribution groove windows and the plurality of high pressure ring cavity domains are one-to-one correspondingly arranged;

[0009] S13, meshing is performed on each domain;

[0010] S14, each low pressure flow distribution groove window and plunger flow distribution groove port are arranged as Interface, and each high pressure flow distribution groove window and plunger flow distribution groove port are arranged as Interface, so as to realize the communication and data exchange of each domain;

[0011] S15, the tetrahedral mesh of the low pressure domain is divided into low pressure cavity domain and cam domain by taking the distance from the cam wall surface as a parameter.

[0012] Further, the length Li of the pump inlet flow pipe of the low pressure domain is not less than 6 times the pump inlet diameter Di.

[0013] Further, the distance between the throttle pipe of the high pressure domain and the pump outlet is not less than 6 times the pump outlet diameter Do.

[0014] Further, the diameter determination step of the throttle pipe of the high pressure domain includes:

[0015] S121, determining the theoretical flow of the pump according to the simulated rotating speed;

[0016] S122, estimating the diameter of the throttle pipe according to the orifice throttling formula;

[0017] S123, establishing the model of the outlet flow pipe and the throttle pipe according to the estimated diameter of the throttle pipe, and dividing the mesh;

[0018] S124, giving the flow rate of the outlet flow pipe, and performing CFD simulation, and counting the inlet pressure value of the outlet flow pipe, and comparing with the pressure value of the state to be simulated, if the two values are inconsistent, adjusting the diameter of the throttle pipe, and returning to S123, until the inlet pressure value of the outlet flow pipe is consistent with the pressure value of the state to be simulated, and the diameter of the throttle pipe is determined.

[0019] Further, in S13, the meshing of each domain specifically includes: the low pressure domain is divided by tetrahedral meshing, and the cam near wall generates boundary layer mesh; the plunger domain is divided by hexahedral meshing, and the near wall generates boundary layer mesh.

[0020] Further, in S15, the cam boundary layer is completely in the cam domain, and is connected with the low pressure cavity domain by tetrahedron mesh.

[0021] Further, the simulation calculation includes:

[0022] S21, defining the simulation medium property, setting the fluid medium as compressible;

[0023] S22, selecting the turbulence model, setting the boundary condition;

[0024] S23, defining the motion law of the cam and the dynamic mesh method;

[0025] S24, defining the motion law of the plunger and the dynamic mesh method;

[0026] S25, setting the data monitoring surface;

[0027] S26, defining the positive direction of data statistics and the rule of data output;

[0028] S27, setting the time step of unsteady calculation, and starting the simulation calculation.

[0029] Further, in S23, the rotation and reciprocating speed of each cam are defined by UDF respectively, and are applied to the cam domain of each cam, so that the cam domain rotates and reciprocates according to the set law; during the motion, the volume mesh of the cam domain does not change, and the low pressure cavity domain connected with the cam domain realizes mesh change through tetrahedron mesh reconstruction.

[0030] Further, in S24, the entire plunger domain is set as a sliding mesh, and the plunger rotation speed is defined; the reciprocating speed of each plunger is defined by UDF respectively, and is applied to the plunger moving domain; the mesh change of the plunger moving domain, the upper action domain and the lower action domain is realized through the dynamic layer method.

[0031] Further, in S25, the inlet monitoring surface is set on the pump inlet flow pipe, the distance Lid from the pump inlet of the inlet monitoring surface is not less than 4 times the pump inlet diameter Di; the outlet monitoring surface is set on the outlet flow pipe, the distance Lod from the pump outlet of the outlet monitoring surface is not less than 4 times the pump outlet diameter Do; a plurality of high pressure cavity monitoring surfaces are set on the outlet of any high pressure ring cavity domain.

[0032] Further, the analysis and processing includes:

[0033] S31, calculating the oil stirring power G tk of each cam according to the simulation calculation result;

[0034] S32, calculating the power G zk of each plunger according to the simulation calculation result;

[0035] S33, calculate the net output power G of the pump based on the simulation calculation results p ;

[0036] S34, according to the power G of each coupling piston zk and the net output power of the pump G p Calculate the pump's flow resistance power loss G s ;

[0037] S35, calculate the suction and discharge resistance power loss G of each plunger according to the simulation calculation results. zpk .

[0038] Furthermore, in S31, the oil stirring power G of the k-th cam is tk according to Get, where is the rotary stirring power of the kth cam, is the reciprocating oil power of the kth cam; n is the total time step of the pump rotating an integer number of circles after the calculated pressure buildup is stable; T tki is the torque of the k-th cam at the i-th time step, ω k1 is the angular velocity of the kth cam, F tki is the axial force of the k-th cam at the i-th time step, v tki is the reciprocating speed of the k-th cam at the i-th time step, k = 1, 2, ..., m, and m is the number of cams.

[0039] Furthermore, in S32, the power G of the k-th plunger is zk according to Get, where is the rotational power of the kth plunger, is the reciprocating power of the kth plunger; n is the total time step of the pump rotating an integer number of times after the calculated pressure buildup is stable; T zki is the torque of the k-th plunger at the i-th time step, ω k2 is the kth plunger rotation angular velocity, F zki is the axial force of the k-th plunger at the i-th time step, v zki is the reciprocating velocity of the k-th plunger in the i-th time step, k = 1, 2, ..., m, and m is the number of plungers.

[0040] Furthermore, in S33, the net output power G of the pump is p according to Get, where is the pump inlet power, is the pump outlet power; n is the total time step of the pump rotating an integer number of times after the pressure buildup is stabilized; P oi is the pressure of the outlet monitoring surface at the i-th time step, Q oi is the flow rate of the outlet monitoring surface at the i-th time step, Pri is the pressure of the monitoring surface at the inlet at the i-th time step, Q ri is the flow rate of the entrance monitoring surface at the i-th time step.

[0041] Furthermore, in S34, the pump flow resistance power loss G s according to Get.

[0042] Furthermore, in S35, the k-th plunger suction and discharge resistance power loss G zpk according to Get, where is the plunger inlet power, is the plunger outlet power; n is the total time step of the pump rotating an integer number of times after the calculated pressure buildup is stable; P poki is the pressure of the high-pressure distribution channel window of the k-th plunger at the i-th time step, Q poki is the flow rate of the high-pressure distribution channel window of the k-th plunger at the i-th time step, P prki is the pressure of the low-pressure distribution channel window of the k-th plunger at the i-th time step, Q prki is the flow rate of the low-pressure distribution channel window of the k-th plunger at the i-th time step; k = 1, 2, ..., m, where m is the number of plungers.

[0043] By applying the technical solution of the present invention, a motion flow field simulation and analysis method for a dual-motion-freedom piston pump is provided. The motion flow field simulation and analysis method for a dual-motion-freedom piston pump integrates the cam and plunger in the piston pump into a motion flow field for overall modeling, and performs domain-mixed grid division on the cam and plunger. A throttle tube physical model is set at the piston pump outlet, and the simulation of the high-pressure chamber pressure of the piston pump is achieved through the action of the throttle tube, avoiding the influence of the pressure boundary condition directly set at the pump outlet on the simulation of the high-pressure chamber pressure of the piston pump, thereby being able to fully present the flow field change process of the piston pump, making the flow field simulation closer to reality and the simulation analysis results more accurate. Compared with the prior art, the technical solution of the present invention can solve the technical problem that the motion flow field simulation and analysis method in the prior art cannot accurately and effectively simulate and analyze the dual-motion-freedom piston pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings are included to provide a further understanding of the embodiments of the present invention, constitute a part of the specification, illustrate the embodiments of the present invention, and together with the description, explain the principles of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0045] Figure 1A flow chart of simulation modeling and meshing is shown according to the specific embodiments of the present application;

[0046] Figure 2 A flow chart of choke pipe diameter determination is shown according to the specific embodiments of the present application;

[0047] Figure 3 A flow chart of cam moving mesh setting is shown according to the specific embodiments of the present application;

[0048] Figure 4 A flow chart of plunger domain moving mesh setting is shown according to the specific embodiments of the present application;

[0049] Figure 5 A schematic diagram of a piston pump flow field simulation model is shown according to the specific embodiments of the present application;

[0050] Figure 6 A schematic diagram of a low pressure domain simulation model is shown according to the specific embodiments of the present application;

[0051] Figure 7 A schematic diagram of an upper connecting plunger domain simulation model is shown according to the specific embodiments of the present application;

[0052] Figure 8 A schematic diagram of a lower connecting plunger domain simulation model is shown according to the specific embodiments of the present application;

[0053] Figure 9 A schematic diagram of a high pressure domain simulation model is shown according to the specific embodiments of the present application;

[0054] Figure 10 A schematic diagram of a cam domain mesh is shown according to the specific embodiments of the present application;

[0055] Figure 11 A schematic diagram of a plunger domain mesh is shown according to the specific embodiments of the present application;

[0056] Figure 12 An outlet monitoring face pressure curve obtained by simulation is shown according to the specific embodiments of the present application.

[0057] Among the above figures, the following reference signs are included:

[0058] 10, low pressure domain; 1001, low pressure cavity domain; 1002, cam domain; 101, pump low pressure cavity; 102, pump inlet flow tube; 103, upper link cam; 104, lower link cam; 105, first low pressure flow groove window; 106, second low pressure flow groove window; 107, inlet monitoring surface; 20, upper link plunger domain; 201, upper link plunger movement domain; 202, upper link plunger upper action domain; 203, upper link plunger lower action domain; 21, lower link plunger domain; 211, lower link plunger movement domain; 212, lower link plunger upper action domain; 213, lower link plunger lower action domain; 30, high pressure domain; 301, upper link high pressure ring cavity domain; 302, lower link high pressure ring cavity domain; 303, first high pressure flow groove window; 304, second high pressure flow groove window; 305, outlet flow tube; 306, throttle tube; 307, outlet monitoring surface. DETAILED DESCRIPTION

[0059] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict. The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0060] It should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form, unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a presence of the features, steps, operations, devices, components and / or combinations thereof.

[0061] The relative arrangement of parts and steps, numerical expressions, and numerical values set forth in the examples herein are not intended to limit the scope of the application unless specifically so stated. It is to be understood that the drawings are not necessarily to scale as the dimensions of the parts shown are for the purpose of illustration and description only and not to limit the scope of the application. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art can not be discussed in detail but are intended to be part of the specification when appropriate. In all examples shown and discussed herein, any specific values are to be interpreted as illustrative only and not as a limitation. Thus, other examples of exemplary embodiments can have different values. It is noted that like numbers and letters refer to like elements throughout the several views of the drawings and, as such, no further discussion with regard thereto is needed.

[0062] As Figure 1 shown, the motion flow field simulation and analysis method of the dual-motion-degree-of-freedom piston pump according to the specific embodiments of the application comprises pre-processing, simulation calculation and analysis processing; wherein the pre-processing comprises:

[0063] S11, determining the working state and initial position of each connecting piston and cam according to the operation process of the pump;

[0064] S12, performing domain modeling on the simulation model, including low-pressure domain modeling, piston domain modeling and high-pressure domain modeling; the low-pressure domain includes a pump inlet flow pipe, a pump low-pressure oil cavity, a plurality of low-pressure flow distribution groove windows and a plurality of cams; any piston corresponds to a piston domain, and each piston domain includes an upper action scope, a piston movement domain and a lower action scope; the high-pressure domain includes a plurality of high-pressure flow distribution groove windows, a plurality of high-pressure ring cavity domains and an outlet flow pipe, and the outlet flow pipe has a throttle pipe; the plurality of low-pressure flow distribution groove windows, the plurality of cams, the plurality of pistons, the plurality of high-pressure flow distribution groove windows and the plurality of high-pressure ring cavity domains are one-to-one correspondingly arranged;

[0065] S13, performing meshing on each domain;

[0066] S14, setting each low-pressure flow distribution groove window and piston flow distribution groove port as Interface, and setting each high-pressure flow distribution groove window and piston flow distribution groove port as Interface, so as to realize the communication and data exchange of each domain;

[0067] S15, cutting the tetrahedral mesh of the low-pressure domain into a low-pressure cavity domain and a cam domain with the distance from the cam wall surface as a parameter.

[0068] By using the configuration method, a motion flow field simulation and analysis method of the dual-motion-degree-of-freedom piston pump is provided, the motion flow field simulation and analysis method of the dual-motion-degree-of-freedom piston pump integrates the cam and the piston in a motion flow field to model as a whole, performs mixed mesh division on the cam and the piston in different domains, sets a throttle pipe physical model at the outlet of the piston pump, realizes simulation of the high-pressure cavity pressure of the piston pump through the action of the throttle pipe, avoids influence on simulation of the high-pressure cavity pressure of the piston pump caused by directly setting a pressure boundary condition at the outlet of the piston pump, and thus can comprehensively present a change process of the flow field of the piston pump, so that the flow field simulation is closer to the actual situation and the simulation analysis result is more accurate.

[0069] Further, in the application, in S11, a state that each piston port is in communication with the corresponding low-pressure port window and high-pressure port window is selected as an initial state of simulation.

[0070] As a specific embodiment of the application, the length Li of the pump inlet flow pipe in the low-pressure domain is not less than 6 times the diameter Di of the pump inlet. The throttle pipe in the high-pressure domain is not less than 6 times the diameter Do of the pump outlet from the pump outlet.

[0071] Further, in the application, as shown in Figure 2 the diameter of the throttle pipe in the high-pressure domain can be determined by the following steps:

[0072] S121, determining the theoretical flow of the pump according to the required simulation speed;

[0073] S122, estimating the diameter of the throttle pipe according to the orifice throttling formula;

[0074] S123, establishing the model of the outlet flow pipe and the throttle pipe according to the estimated diameter of the throttle pipe, and dividing the mesh;

[0075] S124, giving the flow rate of the outlet flow pipe, and performing CFD simulation, counting the inlet pressure value of the outlet flow pipe, and comparing with the pressure value of the required simulation state, if the values are inconsistent, adjusting the diameter of the throttle pipe, and returning to S123, until the inlet pressure value of the outlet flow pipe is consistent with the pressure value of the required simulation state, and the diameter of the throttle pipe is determined.

[0076] In addition, in the application, in S13, the mesh division of each domain specifically includes: the low-pressure domain is divided by tetrahedral mesh, and the boundary layer mesh is generated near the wall of the cam; the piston domain is divided by hexahedral mesh, and the boundary layer mesh is generated near the wall; and the high-pressure domain is divided by mesh, and the form of the mesh is not constrained.

[0077] Further, in the application, in S15, the cam boundary layer should be completely in the cam domain, and is connected with the low-pressure cavity domain by tetrahedral mesh.

[0078] The grid modeling method of the present invention divides the cam and the plunger into mixed grids by domain division and separates the boundary layer of the cam into independent domains, which satisfies the requirements of different dynamic grid change methods for the cam and the plunger and improves the reconstruction accuracy of the cam near-wall grid.

[0079] Furthermore, in the present invention, after completing the pre-processing grid modeling, simulation calculation is performed. The simulation calculation of the present invention includes:

[0080] S21, define the properties of the simulation medium and set the fluid medium to be compressible;

[0081] S22, select the turbulence model and set the boundary conditions;

[0082] S23, defining the motion law of the cam and the dynamic grid method;

[0083] S24, define the motion law of the plunger and the dynamic mesh method;

[0084] S25, setting data monitoring surface;

[0085] S26, defines the positive direction of data statistics and the rules for data output;

[0086] S27, set the time step of unsteady calculation and start simulation calculation.

[0087] As a specific embodiment of the present invention, Figure 3 As shown in Figure 2, in S23, the rotation and reciprocating speeds of each cam link are defined using UDFs and applied to the cam domain of each cam link, causing the cam domain to rotate and reciprocate according to the set rules. During this motion, the volume mesh of the cam domain remains unchanged, while the mesh of the connected low-pressure cavity domain is changed through tetrahedral reconstruction.

[0088] like Figure 4 As shown, in S24, the entire plunger domain is set to a sliding mesh, and the plunger rotational speed is defined. The reciprocating speed of each plunger is defined separately through a UDF and applied to the plunger's moving domain. The mesh changes between the moving domain and the upper and lower domains are implemented using a dynamic layering method, thus achieving reciprocating motion of the plunger. The upper and lower domains have opposite oil suction and discharge processes.

[0089] In the present invention, the low-pressure distribution groove window and the plunger distribution groove opening are set as the interface, and the high-pressure distribution groove window and the plunger distribution groove opening are set as the interface, which are used for the connection and data exchange of each sub-domain, thereby realizing the opening and closing process of the plunger distribution groove and the distribution groove window.

[0090] In S25, an inlet monitoring surface is set on the pump inlet flow pipe, and the distance between the inlet monitoring surface and the pump inlet Lid is not less than 4 times the pump inlet diameter Di; an outlet monitoring surface is set on the outlet flow pipe, and the distance between the outlet monitoring surface and the pump outlet Lod is not less than 4 times the pump outlet diameter Do; multiple high-pressure cavity monitoring surfaces are set at the outlet of any high-pressure annular cavity.

[0091] In S26, the data to be counted include: the torque T of each cam wall t and axial force F t , the torque T on the plunger wall z and axial force F z , the flow rate Q of the entrance monitoring surface r and pressure P r , the flow rate Q of the export monitoring surface o and pressure P o , the flow rate Q of the low-pressure distribution groove window connected to each coupling plunger pr1 , Q pr2 ,…,Q prm and pressure P pr1 、P pr2 ,…,P prm , the flow rate Q of the high-pressure distribution groove window connected to each coupling plunger po1 , Q po2 ,…,Q pom and pressure P po1 、P po2 ,…,P pom The data output rules are set to output once per time step.

[0092] In S27 , according to the simulation status, after the pressure buildup is stabilized, it may be set to calculate at least another 2 revolutions.

[0093] Furthermore, in the present invention, after completing the simulation calculation, an analysis process is performed. The analysis process of the present invention includes:

[0094] S31, calculate the oil stirring power G of each cam according to the simulation calculation results tk ;

[0095] S32, calculate the power G of each coupling plunger based on the simulation calculation results zk ;

[0096] S33, calculate the net output power G of the pump based on the simulation calculation results p ;

[0097] S34, according to the power G of each coupling piston zk and the net output power of the pump G p Calculate the pump's flow resistance power loss G s ;

[0098] S35, calculating the power loss G of each coupling plunger suction and discharge flow resistance according to the simulation calculation result zpk .

[0099] As a specific embodiment of the present application, in S31, the stirring power G of the kth coupling cam tk may be obtained according to , wherein, is the rotating stirring power of the kth coupling cam, is the reciprocating beating oil power of the kth coupling cam; n is the total time step of the pump rotating an integer number of times after the pressure is built and stabilized; T tki is the torque of the kth coupling cam at the i th time step, ω k1 is the angular velocity of the kth coupling cam, F tki is the axial force of the kth coupling cam at the i th time step, v tki is the reciprocating speed of the kth coupling cam at the i th time step, k = 1, 2,..., m, and m is the number of cams.

[0100] In S32, the power G of the kth coupling plunger zk may be obtained according to , wherein, is the rotating power of the kth coupling plunger, is the reciprocating power of the kth coupling plunger; n is the total time step of the pump rotating an integer number of times after the pressure is built and stabilized; T zki is the torque of the kth coupling plunger at the i th time step, ω k2 is the angular velocity of the kth coupling plunger, F zki is the axial force of the kth coupling plunger at the i th time step, v zki is the reciprocating speed of the kth coupling plunger at the i th time step, k = 1, 2,..., m, and m is the number of plungers.

[0101] In S33, the net output power G of the pump p may be obtained according to , wherein, is the pump inlet power, is the pump outlet power; n is the total time step of the pump rotating an integer number of times after the pressure is built and stabilized; P oi is the pressure of the i th time step outlet monitoring surface, Q oi is the flow of the i th time step outlet monitoring surface, P ri is the pressure of the i th time step inlet monitoring surface, Q ri is the flow of the i th time step inlet monitoring surface.

[0102] In S34, the flow resistance power loss G of the pump s may be obtained according to , wherein, k = 1, 2,..., m, and m is the number of plungers.

[0103] In S35, the kth joint plunger suction and discharge flow resistance power loss G zpk According to the above formula, the plunger suction and discharge flow resistance power loss G is obtained, wherein, is the plunger inlet power, is the plunger outlet power; n is the total time step of the pump rotating an integer number of circles after the pressure is built; P poki is the pressure of the high-pressure distribution groove window of the kth joint plunger in the ith time step, Q poki is the flow of the high-pressure distribution groove window of the kth joint plunger in the ith time step, P prki is the pressure of the low-pressure distribution groove window of the kth joint plunger in the ith time step, Q prki is the flow of the low-pressure distribution groove window of the kth joint plunger in the ith time step; k=1, 2,..., m, and m is the number of plungers.

[0104] The analysis processing of the present application can obtain key data such as the oil stirring power of the cam, the plunger power, the net output power of the pump, the flow resistance power loss of the pump, and the suction and discharge flow resistance power loss of the plunger, which has a positive guiding effect on the optimization design of the pump.

[0105] The motion flow field simulation and analysis method of the dual-motion-degree-of-freedom piston pump of the present application can realize the motion simulation of the dual-motion-degree-of-freedom piston pump in the whole motion cycle and the whole fluid domain, and can simultaneously develop the rotary reciprocating motion of the plunger and the cam, so as to obtain the influence law of the two, the flow / pressure characteristics of the piston pump, the oil stirring characteristics of the guide rail, the torque characteristics of the pump, the hydraulic loss of the pump, and other key parameters. The simulation results are more comprehensive than the simulation of the plunger alone.

[0106] In order to further understand the present application, the following will be combined with Figures 1 to 12 The motion flow field simulation and analysis method of the dual-motion-degree-of-freedom piston pump of the present application will be described in detail.

[0107] As Figures 1 to 12 shown, according to the specific embodiment of the present application, a motion flow field simulation and analysis method of a dual-motion-degree-of-freedom piston pump is provided, which comprises pre-processing, simulation calculation, and analysis processing.

[0108] The pre-processing comprises:

[0109] S11: According to the operation process of the pump, the working state and the initial position of the upper and lower joint plungers and the upper and lower joint cams are determined, and the half-open state of the upper and lower joint plunger distribution grooves and the distribution groove windows is selected as the initial state.

[0110] S12: As Figure 5As shown, the simulation model is divided into domains, including a low-pressure domain 10, an upper connecting plunger domain 20, a lower connecting plunger domain 21, and a high-pressure domain 30. Figure 6 As shown, the low-pressure domain 10 includes a pump low-pressure oil cavity 101, a pump inlet flow pipe 102, an upper connecting cam 103, a lower connecting cam 104, a first low-pressure flow groove window 105, and a second low-pressure flow groove window 106. The length Li of the pump inlet flow pipe 102 is not less than 6 times the pump inlet diameter Di. As shown, Figure 7 and Figure 8 As shown, the upper connecting plunger domain 20 is divided into an upper connecting plunger moving domain 201, an upper connecting plunger upper acting domain 202, and an upper connecting plunger lower acting domain 203; the lower connecting plunger domain 21 is divided into a lower connecting plunger moving domain 211, a lower connecting plunger upper acting domain 212, and a lower connecting plunger lower acting domain 213. As shown, Figure 9 As shown, the high-pressure domain 30 includes an upper connecting high-pressure ring cavity domain 301, a lower connecting high-pressure ring cavity domain 302, a first high-pressure flow groove window 303 and a second high-pressure flow groove window 304, and an outlet flow pipe 305. A throttle pipe 306 is arranged on the outlet flow pipe 305. The throttle pipe 306 is not less than 6 times the pump outlet diameter Do from the pump outlet.

[0111] The diameter of the throttle pipe 306 is determined as follows:

[0112] S121: Select 8000 rpm / 8.5 MPa state for piston pump motion flow field simulation, and calculate the theoretical flow rate of 65 L / min at 8000 rpm;

[0113] S122: Estimate the diameter of the throttle pipe 306 according to the small hole throttling formula.

[0114] S123: Establish an outlet flow pipe and throttle pipe model according to the diameter of the throttle pipe 306, and divide the grid.

[0115] S124: The outlet flow pipe 305 is given a flow rate of 65 L / min, and CFD simulation is performed, and the flow pipe inlet pressure is compared with the pressure value required for simulation. If they are not consistent, adjust the diameter of the throttle pipe 306, and perform steps S123 and S124 until the calculated pressure value is consistent with the pressure required for simulation, and the diameter of the throttle pipe 306 is determined.

[0116] S13: Grid division is performed on each domain, wherein the low-pressure domain 10 is divided into tetrahedral grids, and the upper connecting cam 103 and the lower connecting cam 104 are near-wall generated boundary layer grids; as shown, Figure 11 As shown, the upper connecting plunger domain 20 and the lower connecting plunger domain 21 are divided into hexahedral grids, and near-wall generated boundary layer grids; the high-pressure domain 30 is divided into grids without constraints.

[0117] S14: The low-pressure domain 10's porting groove windows 105 and 106 are respectively set as interfaces with the outer cylindrical surfaces of the plunger moving domains 201 and 211, and the high-pressure domain's porting groove windows 303 and 304 are respectively set as interfaces with the outer cylindrical surfaces of the plunger moving domains 201 and 211, for communication and data exchange between the domains.

[0118] S15: As shown in Figure 10 , the tetrahedral mesh of the low-pressure domain 10 is divided into a low-pressure cavity domain 1001 and a cam domain 1002 with the distance from the wall surface of the upper and lower connecting cams 103 and 104 as the parameter. The cam boundary layer should be completely within the cam domain 1002 and connected with the low-pressure cavity domain 1001 in tetrahedral mesh.

[0119] The simulation calculation includes:

[0120] S21: The simulation medium is defined as liquid kerosene, and the fluid medium is set as compressible.

[0121] S22: The turbulent flow model k-w SST is selected, and the boundary conditions are set.

[0122] S23: The motion law of the upper and lower connecting cams 103 and 104 and the dynamic mesh method are defined. The rotation and reciprocating speed variation law of the upper and lower connecting cams are respectively defined by UDF and applied to the cam domains 1002 of the upper and lower connecting cams 103 and 104, so that the cam domains 1002 rotate and reciprocate according to the set law. During the motion, the volume mesh of the cam domain 1002 does not change, and the low-pressure cavity domain 1001 connected therewith realizes mesh change through tetrahedral mesh reconstruction.

[0123] S24: define the movement law of the upper and lower connecting plunger domains 20 and 21 and the dynamic mesh method. The entire upper and lower connecting plunger domains 20 and 21 are set as sliding meshes, and the plunger rotation speed variation law is defined. The outer circular surfaces of the upper and lower connecting plunger moving domains 201 and 211 are respectively set as Interfaces with the low-pressure distribution groove windows 105 and 106, and the outer circular surfaces of the upper and lower connecting plunger moving domains 201 and 211 are respectively set as Interfaces with the high-pressure distribution groove windows 303 and 304, so as to exchange data and realize the opening and closing process of the plunger distribution groove and the outer circular surface of the distribution groove window. Further, the reciprocating speed law of each connecting plunger is defined through UDF and applied to the upper and lower connecting plunger moving domains 201 and 211. The grid changes of the upper connecting plunger moving domain 201 and the upper and lower connecting plunger active domains 202 and 203 are realized through the dynamic layer method, and the grid changes of the lower connecting plunger moving domain 211 and the upper and lower connecting plunger active domains 212 and 213 are realized through the dynamic layer method, so as to realize the reciprocating movement of the plunger, and the suction / drainage processes of the upper and lower active domains are opposite.

[0124] S25: set the data monitoring surface, set the inlet monitoring surface 107 on the pump inlet flow pipe 102, the distance Lid from the pump inlet is not less than 4 times the inlet diameter Di; set the outlet monitoring surface 307 on the outlet flow pipe 305, the distance Lod from the pump outlet is not less than 4 times the pump outlet diameter Do.

[0125] S26: define the positive direction of data statistics and the rule of data output. The positions and data types that need to be counted include: the torque T t and the axial force F t of the wall surfaces of the upper and lower connecting cams 103 and 104 z and the axial force F z of the wall surfaces of the upper and lower connecting plunger moving domains 201 and 211 r and the pressure P r of the inlet monitoring surface 107 r and the pressure P r of the outlet monitoring surface 307 pr1 and the pressure P pr1 of the first low-pressure distribution groove window 105 communicated with the upper connecting plunger pr2 and the pressure P pr2 of the second low-pressure distribution groove window 106 communicated with the lower connecting plunger po1 and the pressure P po1 of the first high-pressure distribution groove window 303 communicated with the upper connecting plunger po2and pressure P po2 The above data is output once per time step.

[0126] S27: Set the time step of unsteady calculation, calculate 200 time steps per revolution of the pump. According to the state of simulation, after the pressure is stable, at least 2 revolutions are calculated.

[0127] The analysis process includes:

[0128] S31: Calculate the oil stirring power of the upper and lower connecting cams 103 and 104, and the data statistics and analysis method is as follows:

[0129]

[0130] wherein, is the rotating oil stirring power of the kth connecting cam, is the reciprocating oil stirring power of the kth connecting cam; n takes the time step of the last simulation revolution, a total of 200 time steps; T tki is the torque of the kth connecting cam at the ith time step, ω k1 is the angular velocity of the kth connecting cam, F tki is the axial force of the kth connecting cam at the ith time step, v tki is the reciprocating speed of the kth connecting cam at the ith time step; k = 1, 2, the first connecting cam is the upper connecting cam, and the second connecting cam is the lower connecting cam. The calculated oil stirring power of the upper connecting cam 103 is 108 W, and the oil stirring power of the lower connecting cam 104 is 107 W.

[0131] S32: Calculate the power of the upper and lower connecting plungers, and the data statistics and analysis method is as follows:

[0132]

[0133] wherein, is the rotating power of the plunger, is the reciprocating power of the plunger; n takes the time step of the last simulation revolution, a total of 200 time steps; T zki is the torque of the kth connecting plunger at the ith time step, ω k2 is the angular velocity of the kth connecting plunger, F zki is the axial force of the kth connecting plunger at the ith time step, v zki is the reciprocating speed of the kth connecting plunger at the ith time step; k = 1, 2, the first connecting plunger is the upper connecting plunger, and the second connecting plunger is the lower connecting plunger. The calculated oil stirring power of the upper connecting plunger is 4579 W, and the oil stirring power of the lower connecting plunger is 4555 W.

[0134] S33: Calculate the net output power G p of the pump, and the data statistics and analysis method is as follows:

[0135]

[0136] in, is the pump inlet power, is the pump outlet power; n is the time step of the last revolution of the simulation, a total of 200 time steps; P oi is the pressure of the outlet monitoring surface at the i-th time step, Q oi is the flow rate of the outlet monitoring surface at the i-th time step, P ri is the pressure of the monitoring surface at the inlet at the i-th time step, Q ri is the flow rate at the inlet monitoring surface at time step i. The net output power of the piston pump is calculated to be 8612W.

[0137] S34: Calculate the pump flow resistance loss G s , the data statistics and analysis methods are as follows:

[0138]

[0139] The flow resistance loss of the piston pump is calculated to be 522W.

[0140] S35: Calculate the k-th plunger suction and discharge resistance power loss G zpk , the data statistics and analysis methods are as follows:

[0141]

[0142] in, is the plunger inlet power, is the plunger outlet power; n is the time step of the last revolution of the simulation, a total of 200 time steps; P poki is the pressure of the high-pressure distribution channel window of the k-th plunger at the i-th time step, Q poki is the flow rate of the high-pressure distribution channel window of the k-th plunger at the i-th time step, P prki is the pressure of the low-pressure distribution channel window of the k-th plunger at the i-th time step, Q prki is the flow rate through the low-pressure distribution slot window at the kth plunger at the i-th time step; k = 1, 2. The calculated power loss for the upper plunger's suction and discharge resistance is 161 W, and the lower plunger's suction and discharge resistance is 173 W.

[0143] like Figure 12 As shown, the outlet monitoring surface piston pump pressure surface is obtained by applying the motion flow field simulation and analysis method of the dual-motion freedom piston pump of the present invention. The pressure pulsation of the outlet monitoring surface is calculated to be 3.82%, and the pulsation frequency is 1066.7 Hz.

[0144] In summary, the application provides a motion flow field simulation and analysis method of a dual-motion-degree-of-freedom piston pump, which integrates the cam and the plunger in the piston pump in a motion flow field for overall modeling, performs mixed grid division on the cam and the plunger in different domains, sets a throttle pipe physical model at the outlet of the piston pump, realizes simulation of the high-pressure cavity pressure of the piston pump through the action of the throttle pipe, avoids the influence of directly setting a pressure boundary condition at the outlet of the piston pump on the simulation of the high-pressure cavity pressure of the piston pump, so as to comprehensively present the flow field change process of the piston pump, make the flow field simulation more close to the actual situation, and make the simulation analysis result more accurate.

[0145] The application can realize motion simulation of the dual-motion-degree-of-freedom piston pump in a full motion cycle and a full fluid domain, simultaneously perform rotary reciprocating motion of the plunger and the cam, and obtain key parameters such as influence law of the plunger and the cam, flow rate / pressure characteristics of the piston pump, oil stirring characteristics of the guide rail, torque characteristics of the pump, and hydraulic loss of the pump. The simulation result is more comprehensive than that of the plunger simulation alone.

[0146] For the purposes of the description hereinafter, the terms "upper", "lower", "right", "left", "rear", "front", "vertical", "horizontal", and derivatives thereof (e.g., "vertical ly", "horizontally", etc.) can be used herein for ease of description to describe the assumptions under which the applications were used or tested. These terms are used interchangeably, without intending as limitations, to broadest coverage. For purposes of the description hereinafter, spatially relative terms, such as "above", "below", "up", "down", "between", "within", "left", "right", "rear", "front", "rearward", "forward", "upward", "downward", "vertical", "horizontal", and the like, can be used herein for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if a device described herein is turned over, elements described as "above" or "up" other elements or features would then be oriented "below" or "down" the other elements or features. Thus, the exemplary term "above" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if a device described herein is turned over, elements described as "above" or "up" other elements or features would then be oriented "below" or "down" the other elements or features. Thus, the exemplary term "above" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0147] In addition, it should be noted that the use of "first", "second", and the like words of similar meaning to define the components, is only for the convenience of distinguishing the corresponding components, and the above words have no special meaning unless otherwise stated, and therefore cannot be understood as a limitation on the scope of protection of the application.

[0148] The above only describes the preferred embodiments of the application and is not intended to limit the application. The application can be variously changed and modified by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the scope of protection of the application.

Claims

1. A motion flow field simulation and analysis method for a dual-motion-freedom piston pump, characterized in that: The motion flow field simulation and analysis method of the dual-motion-freedom piston pump includes pre-processing, simulation calculation and analysis processing; wherein the pre-processing includes: S11, determining the working state and initial position of each coupling plunger and cam according to the operation process of the pump; S12, performing domain modeling on the simulation model, including low-pressure domain modeling, plunger domain modeling, and high-pressure domain modeling; the low-pressure domain includes a pump inlet flow pipe, a pump low-pressure oil chamber, a plurality of low-pressure distribution groove windows, and a plurality of cams; each plunger corresponds to a plunger domain, and each plunger domain includes an upper action domain, a plunger movement domain, and a lower action domain; the high-pressure domain includes a plurality of high-pressure distribution groove windows, a plurality of high-pressure annular cavity domains, and an outlet flow pipe, wherein the outlet flow pipe has a throttling tube; the plurality of low-pressure distribution groove windows, the plurality of cams, the plurality of plungers, the plurality of high-pressure distribution groove windows, and the plurality of high-pressure annular cavity domains are arranged in a one-to-one correspondence; S13, grid division of each sub-domain; S14, each low-pressure distribution slot window and the plunger distribution slot opening are set as an interface, and each high-pressure distribution slot window and the plunger distribution slot opening are set as an interface to achieve connectivity and data exchange between each sub-domain; S15, using the distance from the cam wall as a parameter, the tetrahedral mesh of the low-pressure domain is divided into the low-pressure cavity domain and the cam domain.

2. The motion flow field simulation and analysis method of a dual-motion-freedom piston pump according to claim 1 is characterized in that: The pump inlet flow pipe length Li of the low-pressure region is not less than 6 times the pump inlet diameter Di.

3. The motion flow field simulation and analysis method of a dual-motion-freedom piston pump according to claim 1 is characterized in that: The distance between the throttling pipe in the high-pressure region and the pump outlet is not less than 6 times the pump outlet diameter Do.

4. The motion flow field simulation and analysis method of a dual-motion-freedom piston pump according to claim 1, characterized in that: The step of determining the diameter of the throttling tube in the high-pressure region includes: S121, determining the theoretical flow rate of the pump according to the rotational speed to be simulated; S122, estimate the throttling tube diameter based on the small hole throttling formula; S123, establishing an outlet flow pipe and a throttle pipe model according to the estimated throttle pipe diameter, and dividing the mesh; In step S124, a flow rate is given to the outlet flow pipe, and CFD simulation is performed. The outlet flow pipe inlet pressure value is calculated and compared with the pressure value of the desired simulation state. If they are inconsistent, the throttle pipe diameter is adjusted, and the process returns to step S123 until the outlet flow pipe inlet pressure value is consistent with the pressure value of the desired simulation state, and the throttle pipe diameter is determined.

5. The motion flow field simulation and analysis method of a dual-motion-freedom piston pump according to claim 1, characterized in that: In S13, meshing of each sub-domain specifically includes: using tetrahedral meshing for the low-pressure domain, generating boundary layer meshes near the cam wall; and using hexahedral meshing for the plunger domain, generating boundary layer meshes near the wall.

6. The motion flow field simulation and analysis method of a dual-motion-freedom piston pump according to claim 1, characterized in that: In S15, the cam boundary layer is completely within the cam domain and is connected to the low-pressure cavity domain with a tetrahedral mesh.

7. The motion flow field simulation and analysis method of a dual-motion-freedom piston pump according to claim 1, characterized in that: The simulation calculation includes: S21, define the simulation medium properties and set the fluid medium to be compressible; S22, select the turbulence model and set the boundary conditions; S23, defining the motion law of the cam and the dynamic grid method; S24, define the motion law of the plunger and the dynamic mesh method; S25, setting data monitoring surface; S26, defines the positive direction of data statistics and the rules for data output; S27, set the time step of unsteady calculation and start simulation calculation.

8. The motion flow field simulation and analysis method of a dual-motion-freedom piston pump according to claim 7, characterized in that: In S23, the rotation and reciprocating speeds of each cam link are defined separately through UDF and applied to the cam domain of each cam link, so that the cam domain rotates and reciprocates according to the set rules. During the movement, the volume mesh of the cam domain does not change, and the low-pressure cavity domain connected to the cam domain realizes mesh change through tetrahedral mesh reconstruction.

9. The motion flow field simulation and analysis method of a dual-motion-freedom piston pump according to claim 7, characterized in that: In S24, the entire plunger domain is set as a sliding mesh and the plunger rotation speed is defined; Define the reciprocating speed of each plunger separately through UDF and apply it to the plunger movement domain; The mesh changes of the piston movement domain and the upper and lower scopes of the piston are realized by the dynamic layer method.

10. The motion flow field simulation and analysis method of a dual-motion-freedom piston pump according to claim 7, characterized in that: In S25, an inlet monitoring surface is set on the pump inlet flow pipe, and the distance between the inlet monitoring surface and the pump inlet Lid is not less than 4 times the pump inlet diameter Di; an outlet monitoring surface is set on the outlet flow pipe, and the distance between the outlet monitoring surface and the pump outlet Lod is not less than 4 times the pump outlet diameter Do; multiple high-pressure cavity monitoring surfaces are set at the outlet of any high-pressure annular cavity.

11. The motion flow field simulation and analysis method of a dual-motion-freedom piston pump according to claim 1, characterized in that: The analysis process includes: S31, calculate the oil stirring power G of each cam according to the simulation calculation results tk ; S32, calculate the power G of each coupling plunger according to the simulation calculation results zk ; S33, calculate the net output power G of the pump based on the simulation calculation results p ; S34, according to the power G of each coupling piston zk and the net output power of the pump G p Calculate the pump's flow resistance power loss G s ; S35, calculate the suction and discharge resistance power loss G of each plunger according to the simulation calculation results. zpk .

12. The motion flow field simulation and analysis method of a dual-motion-freedom piston pump according to claim 11, characterized in that: In S31, the oil stirring power G of the kth cam is tk according to Get, where is the rotary oil stirring power of the kth cam, is the reciprocating oil power of the kth cam; n is the total time step of the pump rotating an integer number of circles after the calculated pressure buildup is stable; T tki is the torque of the k-th cam at the i-th time step, ω k1 is the angular velocity of the kth cam, F tki is the axial force of the k-th cam at the i-th time step, v tki is the reciprocating speed of the k-th cam at the i-th time step, k = 1, 2, ..., m, and m is the number of cams.

13. The motion flow field simulation and analysis method of a dual-motion-freedom piston pump according to claim 11, characterized in that: In S32, the power G of the kth plunger zk according to Get, where is the rotational power of the kth plunger, is the reciprocating power of the kth plunger; n is the total time step of the pump rotating an integer number of times after the calculated pressure buildup is stable; T zki is the torque of the k-th plunger at the i-th time step, ω k2 is the kth plunger rotation angular velocity, F zki is the axial force of the k-th plunger at the i-th time step, v zki is the reciprocating velocity of the k-th plunger in the i-th time step, k = 1, 2, ..., m, and m is the number of plungers.

14. The motion flow field simulation and analysis method of a dual-motion-freedom piston pump according to claim 13, characterized in that: In S33, the net output power of the pump G p according to Get, where is the pump inlet power, is the pump outlet power; n is the total time step of the pump rotating an integer number of times after the pressure buildup is stabilized; P oi is the pressure of the outlet monitoring surface at the i-th time step, Q oi is the flow rate of the outlet monitoring surface at the i-th time step, P ri is the pressure of the monitoring surface at the inlet at the i-th time step, Q ri is the flow rate of the entrance monitoring surface at the i-th time step.

15. The motion flow field simulation and analysis method of a dual-motion-freedom piston pump according to claim 14, characterized in that: In S34, the pump's flow resistance power loss G s according to Get.

16. The motion flow field simulation and analysis method of a dual-motion-freedom piston pump according to claim 11, characterized in that: In S35, the kth plunger suction and discharge resistance power loss G zpk according to Get, where is the plunger inlet power, is the plunger outlet power; n is the total time step of the pump rotating an integer number of times after the calculated pressure buildup is stable; P poki is the pressure of the high-pressure distribution channel window of the k-th plunger at the i-th time step, Q poki is the flow rate of the high-pressure distribution channel window of the k-th plunger at the i-th time step, P prki is the pressure of the low-pressure distribution channel window of the k-th plunger at the i-th time step, Q prki is the flow rate of the low-pressure distribution channel window of the k-th plunger at the i-th time step; k = 1, 2, ..., m, where m is the number of plungers.

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