Simulation analysis method for main runner flow field of axial plunger pump with conical cylinder body

Abstract

The invention discloses a cone cylinder axial plunger pump main runner flow field simulation analysis method, which is characterized in that a kinematical equation is self-defined, and the kinematical equation of each area of a main fluid domain is established based on the following description: an end cover oil inlet duct inlet, an end cover oil outlet duct outlet and a valve plate oil duct vp are in a static state and do not have position change and volume change; along with the axial rotation of the cylinder body and the axial reciprocating motion of the plunger in the cylinder body hole, the kidney-shaped hole drainage basin cap of the cylinder body axially rotates around a cylinder body rotating shaft, and the volume of the kidney-shaped hole drainage basin cap changes in a zooming mode. An oil duct piston in the plunger axially rotates around a cylinder body rotating shaft and translates along the axial direction of the plunger along with the axial rotation of the cylinder body and the axial reciprocating motion of the plunger in a cylinder body hole, and the volume is not changed; according to the method, the actual motion state and rule of the main fluid domain of the conical cylinder body axial plunger pump are accurately restored, and the internal flow field of the conical cylinder body axial plunger pump can be accurately simulated and calculated.

Description

Technical Field

[0001] The present invention relates to the field of plunger pumps, and particularly to a method for simulating and analyzing the flow field of the main flow channel of a conical cylinder axial plunger pump. Background Art

[0002] During the operation of an axial plunger pump, as the rotating component operates, the working oil in the main fluid domain will undergo pressure pulsation changes. The pressure pulsation affects the working efficiency, operating noise, etc. of the plunger pump. Therefore, it is crucial to obtain the oil pressure pulsation in the main fluid domain of the plunger pump, which is beneficial to the analysis and optimization of product performance. Most flow field simulation software has a built-in professional plunger pump simulation module. However, with the accelerating update and iteration speed of plunger pump products, the built-in plunger pump module is not applicable to the conical cylinder axial plunger pump model, resulting in the inability to perform simulation calculations or the existence of errors in simulation results, affecting data analysis. Summary of the Invention

[0003] Aiming at the problem that the built-in plunger pump simulation module of existing flow field simulation software is not applicable to the conical cylinder axial plunger pump model, the present invention proposes a method for simulating and analyzing the flow field of the main flow channel of a conical cylinder axial plunger pump. The specific technical solutions are as follows:

[0004] A method for simulating and analyzing the flow field of the main flow channel of a conical cylinder axial plunger pump includes the following steps;

[0005] Step 1: Modeling the main fluid domain of the conical cylinder axial plunger pump;

[0006] Step 2: Dividing the main fluid domain and drawing grids; the main fluid domain is divided into: end cover inlet oil passage inlet, end cover outlet oil passage outlet, valve plate oil passage vp, cylinder body kidney-shaped hole basin cap, cylinder body plunger cavity basin cylinder, and plunger internal oil passage piston;

[0007] Step 3: Establishing the kinematic equations of each region of the main fluid domain; among them, the kinematic equations of each region of the main fluid domain are established based on the following description: the end cover inlet oil passage inlet, end cover outlet oil passage outlet, and valve plate oil passage vp are in a static state, without position change and volume change; the cylinder body kidney-shaped hole basin cap undergoes axial rotation around the cylinder body rotation axis and volume scaling change as the cylinder body rotates axially and the plunger reciprocates axially in the cylinder body hole; the plunger internal oil passage piston undergoes axial rotation around the cylinder body rotation axis and translational transformation along the plunger axis as the cylinder body rotates axially and the plunger reciprocates axially in the cylinder body hole, without volume change;

[0008] Step 4: Setting boundary conditions and basic parameters for the overall basin and performing simulation calculations.

[0009] Further, the kinematic equation of the cylinder body kidney-shaped hole basin cap is as follows:

[0010]

[0011] Among them, (pxt_cap, pyt_cap, pzt_cap) represents the real-time position coordinates of each grid point in the cap fluid domain, and (px_cap, py_cap, pz_cap) represents the initial position coordinates of each grid point in the cap fluid domain when the model is imported into the computational fluid dynamics simulation software; R1 is the first spatial rotation transformation matrix.

[0012] Furthermore, for the construction of the kinematic equation of the cylinder plunger cavity basin cylinder, first select the reference point RPi_cyl, and then perform position transformation on each grid point in the cylinder plunger cavity basin cylinder. The specific transformation process is as follows:

[0013] (1) The initial position coordinates (px_cyl, py_cyl, pz_cyl) when the model is imported into the computational fluid dynamics simulation software are rotated by the first spatial rotation transformation matrix R1 to obtain the position coordinates (pxt_cyl_0, pyt_cyl_0, pzt_cyl_0);

[0014] (2) Then, with the reference point RPi_cyl as the benchmark, move it to the position (0, 0, 0) to obtain the position coordinates (pxt_cyl_1, pyt_cyl_1, pzt_cyl_1);

[0015] (3) Then, rotate the position at this time by an angle γ with the vector (u_c_t, v_c_t, w_c_t) as the rotation axis to obtain the position coordinates (pxt_cyl_2, pyt_cyl_2, pzt_cyl_2);

[0016] (4) Then, perform length scaling transformation on each grid point to obtain the position coordinates (pxt_cyl_3, pyt_cyl_3, pzt_cyl_3);

[0017] (5) Then, rotate by an angle γ with the vector (u_c_t, v_c_t, w_c_t) as the rotation axis to obtain the position coordinates (pxt_cyl_4, pyt_cyl_4, pzt_cyl_4);

[0018] (6) Finally, move each grid point from (0, 0, 0) to the original position with the reference point RPi_cyl as the benchmark to obtain the coordinate position (pxt_cyl_5, pyt_cyl_5, pzt_cyl_5).

[0019] Further, the real-time position coordinates (rpxt_cyl, rpyt_cyl, rpzt_cyl) of the reference point RPi_cyl in the cylinder of the cylinder plunger cavity are expressed as:

[0020]

[0021] Among them, (rpx0_cyl, rpy0_cyl, rpz0_cyl) is the initial position of the reference point RPi_cyl;

[0022] The position coordinates of each grid point in the cylinder of the cylinder plunger cavity are expressed as follows:

[0023]

[0024]

[0025]

[0026] Among them, (u, v, w) are the coordinates in the Y-axis direction of the local coordinate system of each cylinder fluid domain under the initial position, R2 is the second space rotation transformation matrix, (u_c_t, v_c_t, w_c_t) are the real-time coordinates in the Y-axis direction of the local coordinate system of each cylinder of the cylinder plunger cavity; a is a process variable; R3 is the third space rotation transformation matrix; γ is the plunger inclination angle, in degrees; F is the length expansion coefficient of each cylinder of the cylinder plunger cavity; S0 represents the fluid domain length of the cylinder of the cylinder plunger cavity at the outer dead center, in millimeters; β is the swash plate inclination angle, in degrees; n is the plunger pump speed, in revolutions per minute; θ is the plunger rotation angle, in radians, θ = -ωt; ω is the plunger rotation angular velocity, ω = n / 60*2π, in radians per second; i is the plunger serial number, and the sorting method is that the plunger at the outer dead center position is marked as the No. 1 plunger, and the serial number increases in the plunger rotation direction; Rz is the distance from the center of the plunger ball head to the cylinder main shaft at the inner dead center, in millimeters; R4 is the fourth space rotation transformation matrix.

[0027] Further, the first space rotation transformation matrix R1 and the second space rotation transformation matrix R2 are expressed as:

[0028] When the rotation axis is the X-axis:

[0029]

[0030] When the rotation axis is the Y-axis:

[0031]

[0032] When the rotation axis is the Z-axis,

[0033]

[0034] Wherein, θ is the rotation angle of the plunger, with the unit of radian.

[0035] Furthermore, the initial position of the reference point RPi_cyl is selected as the centroid coordinate value of the interface between the cylinder and the cap when the model is imported into the computational fluid dynamics simulation software.

[0036] Furthermore, when constructing the kinematic equation of the oil passage piston inside the plunger, first select the reference point RPi_pis, and then transform the positions of each grid point inside the oil passage piston of the plunger; the position transformation process of each grid point inside the oil passage piston of the plunger is as follows:

[0037] (1) First, starting from the initial position (px_pis, py_pis, pz_pis) when the model is imported into the computational fluid dynamics simulation software, perform a rotational transformation through the first spatial rotation matrix R1 to obtain the position coordinates (pxt_pis_0, pyt_pix_0, pzt_pis_0);

[0038] (2) Then, move to the position (0, 0, 0) with the reference point RPi_pis as the benchmark to obtain the position coordinates (pxt_pis_1, pyt_pis_1, pzt_pis_1);

[0039] (3) Then, rotate the current position by an angle γ with (u_p_t, v_p_t, w_p_t) as the rotation axis to obtain the position coordinates (pxt_pis_2, pyt_pis_2, pzt_pis_2);

[0040] (4) Then, translate each grid point by a distance ΔS to obtain the position coordinates (pxt_pis_3, pyt_pis_3, pzt_pis_3);

[0041] (5) Then, rotate by an angle γ with (u_p_t, v_p_t, w_p_t) as the rotation axis to obtain the position coordinates (pxt_pis_4, pyt_pis_4, pzt_pis_4);

[0042] (6) Finally, move each grid point from (0, 0, 0) to the original position with the reference point RPi_pis as the benchmark to obtain the position coordinates (pxt_pis_5, pyt_pis_5, pzt_pis_5).

[0043] Furthermore, the real-time position coordinates (rpxt_pis, rpyt_pis, rpzt_pis) of the reference point RPi_pis of the oil passage piston inside the plunger are expressed as:

[0044]

[0045] Among them, (rpx0_pis, rpy0_pis, rpz0_pis) is the initial position of the reference point RPi_pis;

[0046] The position coordinates of each grid point in the internal oil passage piston of the plunger are represented as follows:

[0047]

[0048] ΔS = Sp - Sp0

[0049]

[0050] Furthermore, the initial position of the reference point RPi_pis selects the centroid coordinate value of the interface between the piston and the cylinder when the model is imported into the computational fluid dynamics simulation software.

[0051] Furthermore, in the fourth step, the setting of the boundary conditions is specifically as follows: Define the inlet end face of the end cover inlet oil passage as the pressure inlet boundary, and define the outlet end face of the end cover outlet oil passage as the pressure outlet boundary; The basic parameters include the plunger pump speed n, the number of plungers N, the swash plate inclination angle β, the plunger inclination angle γ, the distance Rz from the center of the plunger ball head to the main shaft of the cylinder block at the inner dead center, and the cylinder block outer dead center cylinder basin length S0.

[0052] The present invention has the following beneficial effects:

[0053] (1) The present invention solves the problem that some simulation software cannot perform pressure pulsation simulation on the axial piston pump with a conical cylinder block through the built-in plunger pump simulation module; The present invention provides a theoretical data reference basis for the positive design of the valve plate of the axial piston pump with a conical cylinder block.

[0054] (2) The present invention has high universality for the axial piston pump with a conical cylinder block, and is basically applicable to most existing axial piston pump structures with conical cylinder blocks. Only the relevant characteristic dimension parameters need to be obtained on the three-dimensional model to use the simulation method of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a schematic flow chart of the technical solution of the mainstream channel flow field simulation analysis method for the axial piston pump with a conical cylinder block proposed by the present invention;

[0056] Figure 2 It is a schematic diagram of the three-dimensional model of the core area of the plunger pump of the mainstream channel flow field simulation analysis method for the axial piston pump with a conical cylinder block proposed by the embodiment of the present invention;

[0057] Figure 3 Schematic diagram of the main fluid domain of the axial piston pump with a conical cylinder block for the flow field simulation analysis method proposed in the embodiment of the present invention;

[0058] Figure 4 Schematic diagram of the division of each region of the main fluid domain of the axial piston pump with a conical cylinder block for the flow field simulation analysis method proposed in the embodiment of the present invention;

[0059] Figure 5 Schematic diagram of the mesh division of each region of the main fluid domain of the axial piston pump with a conical cylinder block for the flow field simulation analysis method proposed in the embodiment of the present invention;

[0060] Figure 6 Schematic diagram of the pressure distribution of the main fluid domain of the axial piston pump with a conical cylinder block for the flow field simulation analysis method proposed in the embodiment of the present invention;

[0061] Figure 7 Pressure pulsation curve of the cylinder piston cavity of the axial piston pump with a conical cylinder block for the flow field simulation analysis method proposed in the embodiment of the present invention. Detailed implementation manners

[0062] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0063] Referring to Figure 1 as shown, a method for simulating and analyzing the flow field of the main flow channel of an axial piston pump with a conical cylinder block includes the following steps:

[0064] Step 1: Modeling the main fluid domain of the axial piston pump with a conical cylinder block;

[0065] As Figure 2 shown, it is a three-dimensional model diagram of the core region of the axial piston pump with a conical cylinder block used in this embodiment, which is composed of an end cover, a valve plate, a cylinder block, a piston, and a slipper. It can be seen from the figure that the piston pump has 9 pistons, and its rotation axis is located on the Z axis of the three-dimensional coordinate system and rotates from the positive half-axis of the Y axis to the positive half-axis of the X axis. Combining with the swash plate, in the three-dimensional solid direct modeling software, the internal main fluid domain of the piston pump model is obtained by using the method of volume extraction. As Figure 3 shown, in the process of modeling this fluid domain, the small structures such as chamfers at the edges of the model are simplified. Therefore, the flow rate provided by the fluid volume is less than the actual flow rate, but the flow rate difference caused thereby is small, so it will not affect the simulation results. Therefore, the fluid flow in this part can be ignored to simplify the calculation steps.

[0066] Step 2: Region division and mesh drawing of the main fluid domain

[0067] After obtaining the main fluid domain of the plunger pump in the 3D solid direct modeling software, the main fluid domain is divided into the following areas according to the actual situation: end cover oil inlet, end cover oil outlet, valve plate oil channel vp, cylinder waist hole flow domain cap, cylinder plunger cavity flow domain cylinder, plunger internal oil channel piston. The above flow domains and their names are as follows: Figure 4 The divided watersheds are saved in STL format and imported into computational fluid dynamics simulation software for mesh drawing. The mesh drawing results are shown in Figure 5 shown.

[0068] Step 3: Establishment of kinematic equations for each region of the main fluid domain

[0069] Based on the analysis of the movement patterns of various components during the normal operation of the conical cylinder axial piston pump, the flow basins of each part can be described as follows:

[0070] The inlet, outlet, and vp basins are in a static state, with no position or volume changes.

[0071] The cap flow area rotates axially around the cylinder's rotation axis as the cylinder rotates axially, and no volume change occurs;

[0072] The cylinder flow area undergoes axial rotation around the cylinder body's rotation axis and volume scaling changes as the cylinder body rotates axially and the plunger reciprocates axially in the cylinder body hole;

[0073] The piston flow area undergoes axial rotation around the cylinder body rotation axis and translational transformation along the axial direction of the plunger as the cylinder body rotates axially and the plunger reciprocates axially in the cylinder body hole, and no volume change occurs.

[0074] According to the above description of the movement of each basin, the corresponding kinematic equations are established and the readable code of the simulation software is written.

[0075] The basis and process of establishing the kinematic equation code are as follows:

[0076] 1. First, define the independent variables involved in the kinematic equation and assign values ​​to them;

[0077] The number of plungers N, the distance Rz (in millimeters) from the center of the ball head of the plunger to the main axis of the cylinder block at the inner dead center, the length S0 (in millimeters) of the cylinder fluid domain at the outer dead center, the plunger inclination angle γ (in degrees), the swash plate inclination angle β (in degrees), the rotational speed n (in revolutions per minute) of the plunger pump, the angular velocity ω (in radians per second) of the plunger rotation, the rotation angle θ (in radians) of the plunger, the sine function sinθ corresponding to the plunger rotation angle, and the cosine function cosθ corresponding to the plunger rotation angle. Among them, the independent variables N, Rz, S0, γ, β, and n obtain the corresponding values from the model and product manual. The expressions for ω and θ are as follows:

[0078] ω = n / 60 * 2π

[0079] θ = -ωt

[0080] 2. Descriptions of the kinematic equations of each fluid domain;

[0081] inlet, outlet, vp fluid domains

[0082] The inlet, outlet, and vp parts of the river basins are in a static state, without position changes and volume changes, and there is no need to establish kinematic equations.

[0083] cap fluid domain

[0084] The cap fluid domain rotates axially around the rotation axis of the cylinder block as the cylinder block rotates axially, without volume change.

[0085] The expressions for the change of each grid point in the cap fluid domain with time are as follows, where (px_cap, py_cap, pz_cap) are the initial position coordinates of each grid point in the cap fluid domain when importing the computational fluid dynamics simulation software for the example model:

[0086]

[0087] In the above formula, R1 is the first spatial rotation transformation matrix. When the rotation axis is the X-axis,

[0088]

[0089] When the rotation axis is the Y-axis,

[0090]

[0091] When the rotation axis is the Z-axis,

[0092]

[0093] cylinder fluid domain

[0094] The cylinder fluid domain undergoes axial rotation and volume scaling changes around the cylinder's rotation axis as the cylinder rotates axially and the plunger reciprocates axially within the cylinder bore.

[0095] First, obtain the reference point RPi_cyl (rpx0_cyl, rpy0_cyl, rpz0_cyl) of the cylinder fluid domain at the initial position, which is the coordinate value of the centroid of the upper surface of the cylinder (the interface between the cylinder and the cap) when the example model is imported into the simulation software. The real-time position coordinates (rpxt_cyl, rpyt_cyl, rpzt_cyl) of the reference point RPi_cyl are expressed as;

[0096]

[0097] Each grid point within the cylinder fluid domain rotates around the rotation axis over time, and the resulting position coordinates (pxt_cyl_0, pyt_cyl_0, pzt_cyl_0) are expressed as:

[0098]

[0099] where (px_cyl, py_cyl, pz_cyl) are the initial position coordinates of each grid point within the cylinder fluid domain when the example model is imported into the simulation software.

[0100] The position coordinates (pxt_cyl_1, pyt_cyl_1, pzt_cyl_1) obtained after moving each grid point within the cylinder fluid domain to the position (0, 0, 0) with the reference point RPi_cyl as the reference point are expressed as:

[0101]

[0102] Then, transform the cylinder fluid domain from the inclined state to the state where the Z-axis of the local coordinate system of the cylinder fluid domain coincides with the Z-axis of the global coordinate system, i.e., the vertical state. The expression of the local coordinate system Y-axis direction (u, v, w) of each cylinder fluid domain in the initial position is as follows, where i is the plunger number, and the sorting method is to mark the plunger at the outer dead center position as plunger No. 1, and the serial number increases in the plunger rotation direction:

[0103]

[0104] In the above formula, R2 is the second spatial rotation transformation matrix. When the rotation axis is the X-axis,

[0105]

[0106] When the rotation axis is the Y-axis,

[0107]

[0108] When the rotation axis is the Z-axis,

[0109]

[0110] The expression of the change of the local coordinate system Y-axis direction (u_c_t, v_c_t, w_c_t) of each cylinder fluid domain with time and position is as follows:

[0111]

[0112] The expression of the position coordinates (pxt_cyl_2, pyt_cyl_2, pzt_cyl_2) obtained after rotating each grid point in the cylinder fluid domain by an angle γ around the vector (u_c_t, v_c_t, w_c_t) as the rotation axis is as follows:

[0113]

[0114]

[0115] The calculation formula for the stroke Sp of the plunger in the cylinder bore is as follows:

[0116]

[0117] The calculation formula for the stroke Sp0 of each plunger relative to the plunger at position 1 in the cylinder bore at the initial position is as follows:

[0118]

[0119] Calculate the length expansion coefficient F of each cylinder fluid domain according to the numerical relationship between Sp and Sp0:

[0120]

[0121] From this, the expression of the position coordinates (pxt_cyl_3, pyt_cyl_3, pzt_cyl_3) obtained after the stretching transformation of each grid point in each cylinder fluid domain is as follows:

[0122]

[0123] The expression of the position coordinates (pxt_cyl_4, pyt_cyl_4, pzt_cyl_4) obtained after each grid point in the cylinder fluid domain is rotated by an angle γ around the vector (u_c_t, v_c_t, w_c_t) as the rotation axis again is as follows:

[0124]

[0125]

[0126] Finally, each grid point in the cylinder fluid domain moves from (0, 0, 0) to its original position with the reference point RPi_cyl as the benchmark, and the expressions for the obtained coordinate positions (pxt_cyl_5, pyt_cyl_5, pzt_cyl_5) are as follows:

[0127]

[0128] piston fluid domain

[0129] The piston fluid domain undergoes axial rotation around the cylinder rotation axis and translational transformation along the piston axis as the cylinder rotates axially and the plunger reciprocates axially in the cylinder bore, without volume change. The overall transformation idea is similar to that of the cylinder fluid domain part. The difference is that the piston fluid domain part does not need to consider the scaling transformation but needs to consider the translational transformation.

[0130] First, obtain the reference point RPi_pis (rpx0_pis, rpy0_pis, rpz0_pis) of the piston fluid domain at the initial position, which is the coordinate value of the centroid of the upper surface of each piston (the interface between the piston and the cylinder) when the example model is imported into the simulation software. The real-time position coordinates (rpxt_pis, rpyt_pis, rpzt_pis) of the reference point are expressed as;

[0131]

[0132] Each grid point in the piston fluid domain rotates around the rotation axis with time, and the expressions for the obtained position coordinates (pxt_pis_0, pyt_pis_0, pzt_pis_0) are as follows:

[0133]

[0134] where (px_pis, py_pis, pz_pis) are the initial position coordinates of each grid point in each piston fluid domain when the example model is imported into the simulation software.

[0135] After each grid point in the piston fluid domain is moved to the position of (0, 0, 0) with the reference point RPi_pis as the benchmark,, the expressions for the obtained position coordinates (pxt_pis_1, pyt_pis_1, pzt_pis_1) are as follows:

[0136]

[0137] Then, each piston fluid domain is transformed from an inclined state to a state where the Z-axis of the local coordinate system of each piston fluid domain coincides with the Z-axis of the global coordinate system, that is, a vertical state. The expressions of the Y-axis direction (u, v, w) of the local coordinate system of each piston fluid domain at the initial position are as follows, where i is the plunger serial number, and the sorting method is to mark the plunger at the outer dead center position as plunger No. 1, and the serial number increases in the plunger rotation direction

[0138] direction:

[0139]

[0140] The expression of the change of the Y-axis direction (u_p_t, v_p_t, w_p_t) of the local coordinate system of each piston fluid domain with the time position is

[0141] as follows:

[0142]

[0143] After each grid point in the piston fluid domain rotates by an angle γ around the vector (u_p_t, v_p_t, w_p_t) as the rotation axis, the expressions of the obtained position coordinates (pxt_pis_2, pyt_pis_2, pzt_pis_2) are as follows:

[0144]

[0145] Calculate the translation distance ΔS of each piston fluid domain according to the numerical relationship between Sp and Sp0:

[0146] ΔS = Sp - Sp0

[0147] Thus, the expressions of the position coordinates (pxt_pis_3, pyt_pis_3, pzt_pis_3) obtained after each grid point in each piston fluid domain undergoes a translation transformation are as follows:

[0148]

[0149] Each grid point in the piston fluid domain rotates by an angle γ around the vector (u_p_t, v_p_t, w_p_t) as the rotation axis again, and the expressions of the obtained position coordinates (pxt_pis_4, pyt_pis_4, pzt_pis_4) are as follows:

[0150]

[0151] After all the grid points in the piston fluid domain are moved from (0, 0, 0) to their original positions with reference to the reference point RPi_pis, the expressions for the obtained position coordinates (pxt_pis_5, pyt_pis_5, pzt_pis_5) are as follows:

[0152]

[0153] Step Four: Simulation Calculation

[0154] After establishing the kinematic equations and assigning them to each fluid domain, boundary conditions and basic parameters are set for the overall fluid domain. The inlet end face of the inlet fluid domain is defined as a pressure inlet boundary (Specified Pressure Inlet), and the outlet end face of the outlet fluid domain is defined as a pressure outlet boundary (Specified Pressure Outlet). The basic parameters include the rotational speed n of the piston pump, the number of pistons N, the swash plate angle β, the piston angle γ, the distance Rz from the center of the piston ball head to the main axis of the cylinder block at the inner dead center, and the length S0 of the cylinder fluid domain at the outer dead center of the piston. After completing the above boundary condition settings and technical parameter settings, the simulation example task is submitted for calculation.

[0155] Step Five: Analysis of Simulation Results

[0156] As Figure 6 shown, it is a schematic diagram of the pressure distribution in the main fluid domain; after saving the simulation calculation results at a fixed frequency, a dynamic diagram of the motion state of the fluid domain is generated, and it can be observed that the motion pattern of the fluid domain conforms to the actual situation, and the establishment of the kinematic equation and parameter assignment are verified to be accurate through the numerical value of the volumetric flow rate at the outlet of the fluid domain. After setting data monitoring points in the cylinder fluid domain, the pressure pulsation curve is obtained. As Figure 7 shown, it can be observed that the pressure pulsation curve conforms to the actual change law, verifying that this method can achieve the pressure pulsation simulation of the axial piston pump with a conical cylinder block, making up for the shortcoming that the simulation software cannot accurately simulate the axial piston pump with a conical cylinder block.

[0157] The simulation method of the present invention has high universality and is basically applicable to most of the existing axial piston pump structures with conical cylinder blocks. Only the relevant characteristic dimension parameters need to be obtained on the three-dimensional model to use this set of simulation methods. The present invention solves the problem that some simulation software cannot perform pressure pulsation simulation on the axial piston pump with a conical cylinder block through built-in modules.

[0158] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A method for simulating and analyzing the flow field of the main channel of a tapered cylinder axial piston pump, characterized in that: The steps include: Step 1: Modeling the main fluid domain of the tapered cylinder axial piston pump; Step 2: Divide the main fluid domain and draw the grid; the main fluid domain is divided into: end cover oil inlet channel inlet, end cover oil outlet channel outlet, valve plate oil channel vp, cylinder waist hole flow area cap, cylinder plunger cavity flow area cylinder, plunger internal oil channel piston; Step 3: Establish the kinematic equations of each region of the main fluid domain; wherein, the kinematic equations of each region of the main fluid domain are established based on the following description: the end cover oil inlet, the end cover oil outlet, and the distribution plate oil channel vp are in a static state, and no position change and volume change occur; the cylinder waist hole flow basin cap undergoes axial rotation around the cylinder rotation axis and volume scaling change as the cylinder body rotates axially and the plunger moves axially back and forth in the cylinder hole; the plunger internal oil channel piston undergoes axial rotation around the cylinder rotation axis and translational transformation along the plunger axis as the cylinder body rotates axially and the plunger moves axially back and forth in the cylinder hole, and no volume change occurs; Step 4: Set boundary conditions and basic parameters for the entire watershed and perform simulation calculations.

2. The method for simulating and analyzing the flow field of the main channel of a tapered cylinder axial piston pump according to claim 1 is characterized in that: The kinematic equation of the cylinder waist hole flow basin cap is as follows: Among them, (pxt_cap, pyt_cap, pzt_cap) represent the real-time position coordinates of each grid point in the cap fluid domain, (px_cap, py_cap, pz_cap) represent the initial position coordinates of each grid point in the cap fluid domain when the model is imported into the computational fluid dynamics simulation software; R1 is the first space rotation transformation matrix.

3. The method for simulating and analyzing the flow field of the main channel of a tapered cylinder axial piston pump according to claim 2 is characterized in that: The kinematic equation of the cylinder plunger cavity flow domain cylinder is constructed by first selecting the reference point RPi_cyl, and then transforming the positions of the grid points in the cylinder plunger cavity flow domain cylinder. The specific transformation process is as follows: (1) The initial position coordinates (px_cyl, py_cyl, pz_cyl) when the model is imported into the computational fluid dynamics simulation software are rotated by the first spatial rotation transformation matrix R1 to obtain the position coordinates (pxt_cyl_0, pyt_cyl_0, pzt_cyl_0); (2) Then move to the position (0,0,0) based on the reference point RPi_cyl, and obtain the position coordinates (pxt_cyl_1, pyt_cyl_1, pzt_cyl_1); (3) Then rotate the current position by an angle γ with the vector (u_c_t, v_c_t, w_c_t) as the rotation axis to obtain the position coordinates (pxt_cyl_2, pyt_cyl_2, pzt_cyl_2); (4) Then each grid point is stretched and resized to obtain the position coordinates (pxt_cyl_3, pyt_cyl_3, pzt_cyl_3); (5) Then, after rotating the vector (u_c_t, v_c_t, w_c_t) by an angle γ, the position coordinates (pxt_cyl_4, pyt_cyl_4, pzt_cyl_4) are obtained; (6) Finally, each grid point is moved from (0,0,0) to its original position based on the reference point RPi_cyl to obtain the coordinate position (pxt_cyl_5, pyt_cyl_5, pzt_cyl_5).

4. The method for simulating and analyzing the flow field of the main channel of a tapered cylinder axial piston pump according to claim 3 is characterized in that: The real-time position coordinates (rpxt_cyl, rpyt_cyl, rpzt_cyl) of the reference point RPi_cyl in the cylinder plunger cavity flow field are expressed as: Among them, (rpx0_cyl, rpy0_cyl, rpz0_cyl) is the initial position of the reference point RPi_cyl; The position coordinates of each grid point in the cylinder plunger cavity flow domain are expressed as follows: Among them, (u, v, w) is the coordinate of the local coordinate system of each cylinder fluid domain in the Y-axis direction at the initial position, R2 is the second space rotation transformation matrix, (u_c_t, v_c_t, w_c_t) is the real-time coordinate of the local coordinate system of each cylinder plunger cavity flow domain cylinder in the Y-axis direction; a is the process variable; R3 is the third space rotation transformation matrix; γ is the plunger inclination angle, in degrees; F is the length expansion coefficient of each cylinder plunger cavity flow domain cylinder; S0 represents the cylinder plunger cavity flow domain cylinder at the outer dead point The fluid domain length of the domain cylinder, in millimeters; β is the inclination angle of the swash plate, in degrees; n is the speed of the plunger pump, in revolutions per minute; θ is the plunger rotation angle, in radians, θ=-ωt; ω is the plunger rotation angular velocity, ω=n / 60*2π, in radians per second; i is the plunger serial number, the sorting method is to mark the plunger at the outer dead point position as plunger No. 1, and the plunger rotation direction is the serial number increasing direction; Rz is the distance from the center of the plunger ball head to the main axis of the cylinder body at the inner dead point, in millimeters; R4 is the fourth space rotation transformation matrix.

5. The method for simulating and analyzing the flow field of the main channel of a tapered cylinder axial piston pump according to claim 4 is characterized in that: The first spatial rotation transformation matrix R1 and the second spatial rotation transformation matrix R2 are expressed as: When the rotation axis is the X axis: When the rotation axis is the Y axis: When the rotation axis is the Z axis, Where θ is the plunger rotation angle in radians.

6. The method for simulating and analyzing the flow field of the main channel of a tapered cylinder axial piston pump according to claim 5, characterized in that: The initial position of the reference point RPi_cyl is the face-center coordinate value of the interface between the cylinder and the cap when the model is imported into the computational fluid dynamics simulation software.

7. The method for simulating and analyzing the flow field of the main channel of a tapered cylinder axial piston pump according to claim 6, characterized in that: When constructing the kinematic equation of the piston's internal oil passage, first select the reference point RPi_pis, and then transform the positions of the grid points in the piston's internal oil passage; the position transformation process of the grid points in the piston's internal oil passage is as follows: (1) First, the initial position (px_pis, py_pis, pz_pis) when the model is imported into the computational fluid dynamics simulation software is rotated by the first spatial rotation transformation matrix R1 to obtain the position coordinates (pxt_pis_0, pyt_pis_0, pzt_pis_0); (2) Then move to the position (0,0,0) based on the reference point RPi_pis, and obtain the position coordinates (pxt_pis_1, pyt_pis_1, pzt_pis_1); (3) Then rotate the current position by an angle γ with (u_p_t, v_p_t, w_p_t) as the rotation axis to obtain the position coordinates (pxt_pis_2, pyt_pis_2, pzt_pis_2); (4) Then translate each grid point by a distance ΔS to obtain the position coordinates (pxt_pis_3, pyt_pis_3, pzt_pis_3); (5) Then rotate the angle γ with (u_p_t, v_p_t, w_p_t) as the rotation axis to obtain the position coordinates (pxt_pis_4, pyt_pis_4, pzt_pis_4); (6) Finally, each grid point is moved from (0,0,0) to its original position based on the reference point RPi_pis to obtain the position coordinates (pxt_pis_5, pyt_pis_5, pzt_pis_5).

8. The method for simulating and analyzing the flow field of the main channel of a tapered cylinder axial piston pump according to claim 7 is characterized in that: The real-time position coordinates (rpxt_pis, rpyt_pis, rpzt_pis) of the reference point RPi_pis of the piston internal oil passage are expressed as: Among them, (rpx0_pis, rpy0_pis, rpz0_pis) is the initial position of the reference point RPi_pis; The position coordinates of each grid point in the piston's internal oil passage are expressed as follows:

9. The method for simulating and analyzing the flow field of the main channel of a tapered cylinder axial piston pump according to claim 8, characterized in that: The reference point RPi_pis initial position selects the face center coordinate value of the piston and cylinder interface when the model is imported into the computational fluid dynamics simulation software.

10. The method for simulating and analyzing the flow field of the main channel of a tapered cylinder axial piston pump according to claim 9, characterized in that: In the step 4, the boundary conditions are specifically set as follows: the inlet end face of the end cover oil inlet passage inlet is defined as the pressure inlet boundary, and the outlet end face of the end cover oil outlet passage outlet is defined as the pressure outlet boundary; the basic parameters include the plunger pump speed n, the number of plungers N, the swash plate inclination angle β, the plunger inclination angle γ, the distance Rz between the center of the plunger ball head and the cylinder main axis at the inner dead point, and the cylinder flow field length S0 at the outer dead point of the plunger.

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