Simulation modeling method for leakage at shaft hole

Abstract

The present invention provides a method for simulating and modeling leakage at an axial hole, comprising: referencing four mechanical translation interfaces in a Modelica system simulation platform using a visual operation; referencing the default variables of the four mechanical translation interfaces to encapsulate a base class model; modifying the default variables of the mechanical translation interfaces in the base class model using declared variables as intermediate variables to calculate the gap length Lp; defining hydraulic ports of a sealed pipeline forming the axial hole to construct a leakage model at the axial hole leakage site based on a set of equations; and simulating and modeling leakage occurring at the axial hole based on the leakage model. The present invention achieves accurate calculation of the liquid mass flow rate at the axial hole leakage site, thereby resolving the technical problem that the basic library provided in the Modelica system simulation platform in the prior art cannot accurately calculate the leaked liquid mass flow rate.

Description

Technical Field

[0001] The present invention relates to the technical field of computer simulation, and in particular to a simulation modeling method for leakage at an axial hole. Background Art

[0002] Modelica is a high-level declarative language used to describe the mathematical properties of things. It is often used in the field of engineering and can easily describe the working characteristics of different types of engineering components (such as springs, resistors, clutches, etc.). In addition, these components can be conveniently combined into subsystems, systems, and even architectural models. In the hydraulic / pneumatic system, if there is no rubber seal at the shaft-hole fitting, the leakage of hydraulic oil cannot be ignored. When the hydraulic library is built based on the Modelica system-level simulation platform in the prior art to build a hydraulic system model, the hydraulic system does not have relevant components to calculate the leakage of hydraulic oil. Therefore, if you want to implement similar shaft hole leakage simulation calculations, you need to use the Modelica language to customize the leakage unit to simulate and calculate the leakage amount of the fluid (for example, hydraulic oil, air, etc.).

[0003] After searching, I discovered that Chinese invention patent publication number CN105067271B discloses a simulation modeling method for an engine cooling system based on the Modelica language. However, this existing technology still fails to define leakage based on the interface parameters of the shaft-hole structure (e.g., radial clearance, shaft-hole fit length), making it impossible to accurately simulate and calculate the impact of potential leakage at the shaft-hole fit on the overall hydraulic / pneumatic system.

[0004] In view of this, it is necessary to improve the existing simulation modeling method for shaft hole leakage in order to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to disclose a simulation modeling method for leakage at an axial hole, so as to solve the problem in the prior art of effectively and accurately evaluating the leakage that may occur at the axial hole using the Modelica system-level simulation platform, thereby accurately evaluating and simulating the potential impact of the leakage that may occur at the axial hole on the entire system, improving the reliability of the calculation results of the leakage at the axial hole, and improving the simplicity of modeling based on the Modelica system-level simulation platform.

[0006] To achieve the above object, the present invention provides a method for simulating and modeling leakage at a shaft hole, comprising:

[0007] Use visual operations to reference four mechanical translation interfaces in the Modelica system simulation platform;

[0008] Reference the default variables of the four mechanical translation interfaces to encapsulate the base class model;

[0009] Modify the default variables of the Mechanical Translation interface in the base model using declared variables as intermediate variables to calculate the gap length Lp;

[0010] Defining a hydraulic port of a sealed pipeline forming an axial hole, constructing a leakage model of the axial hole leakage location according to the following set of equations, and performing simulation modeling of leakage occurring at the axial hole based on the leakage model;

[0011]

[0012] Parameter ρ is the fluid density, parameter r is the diameter of the gap size, parameter Lp is the gap length, μ is the dynamic viscosity of the fluid, parameter c is the gap amount in the diameter direction, parameter e is the eccentricity, parameter abs(dp) is the absolute value of the pressure drop caused by leakage at the shaft hole at the hydraulic port with the gap length Lp, and parameter C dmax is the flow coefficient and is a constant.

[0013] As a further improvement of the present invention, the visual operation method is specifically: referencing four mechanical translation interfaces in a drag-and-drop manner in a graphical user interface formed by a Modelica system simulation platform; the mechanical translation interfaces include: flange_a, flange_b, support_a and support_b.

[0014] As a further improvement of the present invention, the base class model is a Basic base class model, and the shaft hole leakage simulation modeling method further includes: inheriting four mechanical translation interfaces from the Basic base class model.

[0015] As a further improvement of the present invention, it also includes: forming corresponding displacement variables for the mechanical translation interface based on the displacement, using declared variables as intermediate variables to combine with flange_a, flange_b, support_a and support_b to form displacement variables respectively; the displacement variables include: flange_a.s, flange_b.s, support_a.s and support_b.s.

[0016] As a further improvement of the present invention, it also includes: forming corresponding external force variables for the mechanical translation interface based on the external force f, and the external force variables include: flange_a.f, flange_b.f, support_a.f and support_b.f.

[0017] As a further improvement of the present invention, the external force f is the sum of the forces exerted on the mechanical translation interface flange_a, the mechanical translation interface flange_b, the mechanical translation interface support_a, and the mechanical translation interface support_b along the direction of the sealed pipeline by the fluid.

[0018] As a further improvement of the present invention, the hydraulic port includes: a hydraulic inlet port_a through which fluid flows into the sealed pipeline and a hydraulic outlet port_b through which fluid flows out of the sealed pipeline.

[0019] As a further improvement of the present invention, it further includes: introducing a transition length L_trans into the leakage model, so as to use the transition length L_trans as a declared variable.

[0020] As a further improvement of the present invention, the present invention further includes: comparing the gap length Lp with the transition length L_trans;

[0021] If the gap length Lp is less than the transition length L_trans, the fluid mass flow rate m_flow is calculated based on the right-hand formula of the leakage model;

[0022] If the gap length Lp≥transition length L_trans, the fluid mass flow rate m_flow is calculated based on the left-hand formula of the leakage model.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention references the mechanical translation interface in the basic mechanical library provided in the Modelica system simulation platform, establishes a base class model based on the mechanical translation interface, uses the equation for shaft hole leakage in the hydraulic interface, and ultimately achieves accurate calculation of the liquid mass flow rate m_flow at the shaft hole leakage point, thereby solving the technical problem in the prior art that the basic library provided in the Modelica system simulation platform cannot accurately calculate the leaked liquid mass flow rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the geometric model of the closed pipeline in the hydraulic system;

[0026] Figure 2 A schematic diagram of referencing four translational mechanical interfaces in the Modelica system simulation platform based on a drag-and-drop modeling approach in the visual interface of the Modelica system simulation platform;

[0027] Figure 3 Default variables for the mechanical translation interface and define a schematic diagram of the Basic base class model;

[0028] Figure 4In order to generate corresponding displacement variables for the mechanical translation interface based on the displacement, the declared variables are used as intermediate variables to be combined with the four mechanical translation interfaces, flange_a, flange_b, support_a, and support_b, to generate schematic diagrams of the displacement variables respectively.

[0029] Figure 5 Schematic diagram of the mathematical model corresponding to the equation group for calculating the change of the shaft-hole fit length Lp;

[0030] Figure 6 Schematic diagram of the leakage model. DETAILED DESCRIPTION

[0031] The present invention is described in detail below with reference to the various embodiments shown in the accompanying drawings, but it should be noted that these embodiments are not limitations of the present invention, and any equivalent transformations or substitutions in functions, methods, or structures made by ordinary technicians in this field based on these embodiments are all within the scope of protection of the present invention.

[0032] Ginseng Figures 1 to 6 A specific embodiment of a shaft hole leakage simulation modeling method (hereinafter referred to as the "method") of the present invention is shown. The method disclosed in this embodiment is intended to simulate and model the leakage that may occur at the shaft hole fitting of a completely sealed closed pipeline (for example, the hydraulic pipeline of a hydraulic system or the engine system of an internal combustion engine) to evaluate the liquid mass flow loss caused by the leakage at the shaft hole fitting and the pressure loss at both ends of the closed pipeline.

[0033] Ginseng Figure 1 As shown in the figure, in a completely sealed closed pipeline, under the action of the pressure difference Δp upstream of the closed pipeline, the volume flow rate Q in the closed pipeline can be determined because the flow resistance in the closed pipeline is also determined. However, in some special closed pipelines, there is a clearance between the shaft hole, such as the clearance between the piston and the cylinder. The aforementioned clearance is Figure 1 As shown in the figure, the presence of clearance prevents a closed pipeline from being completely sealed. Consequently, the volume flow rate Q is lost compared to a completely sealed closed pipeline. Consequently, a small amount of fluid flowing or temporarily stored within the cavities of hydraulic components and systems may cross the cavity boundary and flow from the high-pressure side to the low-pressure side due to factors such as shaft-hole clearance, which is defined as leakage.

[0034] The embodiment discloses a method for simulating and modeling leakage at a shaft hole to Figure 1The sealed pipeline shown is simulated and modeled for leakage at the shaft hole to accurately assess the adverse effects of leakage of the fluid (e.g., hydraulic oil or gas) objectively present at the shaft hole on the entire hydraulic or pneumatic system. The method disclosed in this embodiment utilizes the mechanical translation interface (i.e., the basic library) in the basic mechanical library of the Modelica language, establishes a Basic base class model based on the mechanical translation interface, and uses the equation set for shaft hole leakage at the hydraulic port to ultimately detect and calculate shaft hole leakage (i.e., the fluid mass flow rate m_flow generated by the leakage at the shaft hole). This solves the technical problem in the prior art that the basic library included in the Modelica system simulation platform based on the Modelica language cannot accurately calculate the leaked fluid mass flow rate m_flow.

[0035] A method for simulating and modeling leakage at an axial hole disclosed in this embodiment includes the following steps.

[0036] Four mechanical translation interfaces are referenced in the Modelica system simulation platform in a visual operation manner. Specifically, the so-called visual operation manner is: four mechanical translation interfaces are referenced in a drag-and-drop manner in the graphical user interface 100 formed by the Modelica system simulation platform. The mechanical translation interfaces introduced in this embodiment include: flange_a, flange_b, support_a and support_b. Specifically, Modelica interfaces, such as mechanical translation interfaces, rotation interfaces, hydraulic ports and other components are all ready-made, but can only implement the most basic functions, so the user only needs to manually drag them directly into the base class model. The default variables of the four mechanical translation interfaces are referenced to encapsulate the base class model. The base class model is the Basic base class model. The shaft hole leakage simulation modeling method also includes: the Basic base class model inherits the four mechanical translation interfaces, and specifically inherits the four mechanical translation interfaces of flange_a, flange_b, support_a and support_b at the same time.

[0037] There are many basic elements in Modelica, and the basic elements are defined by the language types contained in Modelica. There are many language types that form basic elements, for example, base class model: Basic model; model: model; class: class, etc., and can be formed based on base class model, model or class, etc. to define different non-basic elements. At the same time, in order to improve the readability of the computer code formed by the Modelica language, before calculating the leakage, pressure drop and other variables caused by the shaft hole parameters, it is necessary to put the mechanical translation interface, intermediate variables, etc. into a base class model (that is, the Basic base class model below). The model in this embodiment refers to the Basic model type. The computer programming method starts with Basic model and ends with End Basic. When the formal calculation begins later, it is sufficient to directly inherit and reference the above four mechanical translation interfaces in the Modelica system simulation platform. The specific parameters are: Figure 2 shown.

[0038] Use declared variables as intermediate variables to modify the default variables of the mechanical translation interface in the base class model to calculate the gap length Lp. Corresponding displacement variables are generated for the mechanical translation interface based on the displacement, and the declared variables are used as intermediate variables to combine with flange_a, flange_b, support_a, and support_b to form displacement variables. Specifically, the displacement variables include: flange_a.s, flange_b.s, support_a.s, and support_b.s, and all are vectors. In this embodiment, the shaft hole leakage simulation modeling method also includes: generating corresponding external force variables for the mechanical translation interface based on the external force f, and the external force variables include: flange_a.f, flange_b.f, support_a.f, and support_b.f. The external force f is the vector sum of the forces generated by the fluid on the mechanical translation interface flange_a, the mechanical translation interface flange_b, the mechanical translation interface support_a, and the mechanical translation interface support_b along the direction of the sealed pipeline.

[0039] like Figure 2 As shown, the drag-and-drop modeling is used in the Modelica system simulation platform, and specifically in Figure 2 The visualization interface 100 of the Modelica system simulation platform shown references four mechanical translation interfaces (flange / support): flange_a, flange_b, support_a and support_b. Figure 3As shown. In Modelica, there is a default relationship that the flow variables at the same point are 0 and the potential variables are the same. Therefore, by defining parameters, defining variables (i.e., flange_a, flange_b, support_a and support_b), and defining equations, we can get Figure 2 The flow variables and potential variables of the four mechanical translation interfaces in produce corresponding results, such as Figure 3 The following table shows the default variables corresponding to the four mechanical translation interfaces in Modelica.

[0040] based on Figure 3 , directly reference the default variables corresponding to the four mechanical translation interfaces, and uniformly define them into a Basic base class model. The Basic base class model in this embodiment is used to convert the displacement between the four mechanical translation interfaces (i.e., flange_a, flange_b, support_a, support_b) (for example, Figure 3 flange_a.s in , etc.) and forces (e.g., Figure 4 The flange_a.f, flange_b.f, etc. in the equation are combined to form an equation, and a new variable f is defined. The variable f parameter Figure 4 As shown. The four mechanical translation interfaces mentioned above are all interfaces, and the flange_a.s, flange_b.s, support_a.s, and support_b.s involved in the following are all variables. The variable f here is an external force, which is different from the force of the interface itself such as flange_a.f. The variable f will form an equation with a flow variable of 0 with the force of the interface such as flange_a.f and flange_b.f. The vector s_rel_a and vector s_rel_ab are used in subsequent calculations, as shown in the following example. Figure 4 . Figure 4 In the example, s_rel_a is the position of the variable flange_a.s, the default variable of flange_a itself, relative to the vector support_a.s. flange_a.s - support_a.s = s_rel_a.

[0041] A hydraulic port of a sealing pipeline forming an axial hole is defined to construct a leakage model of the axial hole leakage location according to the following set of equations (hereinafter referred to as "equation set (1)"), and a simulation model of the leakage occurring at the axial hole is performed based on the leakage model;

[0042]

[0043] The meanings of the parameters in equation group (1) are defined as follows: parameter ρ is the fluid density, parameter r is the diameter of the gap size, parameter Lp is the gap length, μ is the dynamic viscosity of the fluid, parameter c is the gap amount in the diameter direction, parameter e is the eccentricity, parameter abs(dp) is the absolute value of the pressure drop caused by the leakage of the fluid at the shaft hole of the gap length Lp at the hydraulic port, parameter C dmax The hydraulic ports include: a hydraulic inlet port_a for fluid to flow into the sealed pipeline and a hydraulic outlet port_b for fluid to flow out of the sealed pipeline.

[0044] The main code of the Basic base class model is shown in the following equation group (2). The Basic base class model in equation group (2) defines an additional switch variable. As a declared variable, the switch variable can be used as an intermediate variable in this embodiment, and specifically: in the fixed area of ​​the Modelica language, enter protected, start a new line, enter the Boolean type, and name it switch to complete the definition of this switch. Use this additional switch variable as an intermediate variable to define the subtraction of the two vector variables flange_a.s and flange_b.s, that is, the direction represented by the vector s_rel_ab. Due to the relative position of the shaft hole, the gap length Lp formed in the sealed pipeline may change. Finally, the equation group for calculating the change in the shaft hole fitting length based on the Modelica computer code is shown in the following equation group (2).

[0045]

[0046] The axial hole leakage simulation modeling method disclosed in this embodiment further includes: introducing a transition length L_trans into the leakage model (i.e., the aforementioned equation group (1)), using the transition length L_trans as a declared variable. The method further includes: comparing the gap length Lp with the transition length L_trans; if the gap length Lp is less than the transition length L_trans, calculating the fluid mass flow rate m_flow based on the right-hand side formula of the leakage model (i.e., see the following equation (2)).

[0047]

[0048] If the gap length Lp ≥ the transition length L_trans, the fluid mass flow rate m_flow is calculated based on the left-hand side formula of the aforementioned leakage model (ie, see the following formula (3)).

[0049]

[0050] The parameters contained in the aforementioned formula (2) and formula (3) have the same meaning as the parameters contained in the aforementioned equation group (1).

[0051] Figure 4 s_rel_ab, that is, the change in the shaft-hole length when calculating leakage (i.e., Figure 5 The gap length Lp in the formula is defined in Basic. By defining two additional hydraulic ports (i.e., hydraulic port port_a and hydraulic port port_b) based on the Basic base class model referenced by Basic, the gap between the shaft hole and the shaft hole can be changed to produce different leakage amounts after the shaft hole is subjected to force or displacement. By coupling the aforementioned features (i.e., Basic base class model, hydraulic ports, etc.), and defining a set of equations in Modelica, the calculation of variables between mechanics and hydraulics is realized, and finally a leakage model (i.e., leakage model) is formed. The specific parameters are Figure 6 As shown. The specific computer code of the equation group (1) in Modelica is shown in the following code (1) and code (2). The equation group (1) for calculating leakage and characterizing the leakage model is shown above. The calculation formula on the left side of the equation group (1) (i.e., formula (3)) is the calculation formula for calculating the fluid mass flow rate m_flow of the leakage, and the calculation formula on the right side of the equation group (1) (i.e., formula (2)) is the calculation formula for the liquid volume flow rate Q considering the intercepting hole.

[0052] The left side of equation group (1) is the formula for calculating the leakage fluid mass flow rate m_flow, and the right side of equation group (1) is the formula for calculating the fluid mass flow rate of the clearance hole. The leakage caused by the shaft-hole fit is related to the gap length Lp. Figure 6 The variables related to the key mechanical translation interface have been explained above and will not be repeated here. The specific parameters / variables are explained as follows: The parameters contained in the left side of the equation group (1) include: the density ρ of the hydraulic oil, the gap size (diameter r) is a known input quantity, the dynamic viscosity μ is a known input quantity, the gap length Lp is a quantity to be determined, the gap in the diameter direction c is a known input quantity, the eccentricity e is a known input quantity, and the pressure drop abs (dp) is a known input quantity or a quantity transmitted from the relevant interface of other components (the equation referred to by code (2) refers to the difference between the hydraulic port port_a.p and the hydraulic port port_b.p, i.e. dp), C dmax is the flow coefficient, which is a constant, equivalent to the Modelica code,

[0053] Parameter C in code (1) and code (2) dmaxis a constant. Under normal circumstances, by substituting this gap length Lp into the calculation formula on the right side of the equation group (1), the fluid mass flow rate m_flow of the gap hole can be calculated. The gap length Lp in the calculation formula on the right side of the equation group (1) is in the denominator position of the equation group. Obviously, when the gap length Lp tends to 0, it means that the gap length Lp is very small, and the fluid mass flow rate m_flow calculated in the calculation formula on the right side of the equation group (1) will be distorted. At this time, since the left side of the equation group (1) is the calculation formula for the fluid mass flow rate m_flow of the throttle hole, it has nothing to do with the gap length Lp. Therefore, in the parameter C dmax When the parameters ρ, r, c, and abs(dp) are all known, the fluid mass flow rate m_flow of the orifice can be calculated. If the calculated result of the fluid mass flow rate m_flow of the orifice (i.e., the calculation formula on the left side of equation group (1)) is forcibly assigned to the fluid mass flow rate m_flow of the right clearance hole, that is, the fluid mass flow rate m_flow of the right clearance hole is forced to be equal to the fluid mass flow rate m_flow of the orifice, the critical Lp can be easily obtained and defined as the transition length L_trans.

[0054] Another innovative technical concept of the method disclosed in this embodiment is the introduction of a transition length, L_trans, into the leakage model, using it as a declarative variable. Based on the equations for the mechanical translation interface and the orifice mass flow rate, m_flow, L_trans is used as a declarative variable to constrain the gap length, Lp, to a minimum or smaller value. This prevents errors in the calculation of the fluid mass flow rate, m_flow, caused by an excessively small gap length, Lp. After obtaining the transition length, L_trans, two methods are available for determining the fluid mass flow rate, m_flow.

[0055] The first calculation method: If only the calculation formula on the right side of equation group (1) is used to calculate the fluid mass flow rate m_flow of the gap hole, when the gap length Lp is long enough (for example, much larger than the gap amount c in the diameter direction), the calculated value s_rel_ab in the previous mechanical translation interface is used to represent the gap length Lp; if the gap length Lp is very small (for example, close to 0), the transition length L_trans is directly assigned to the gap length Lp.

[0056] The second calculation method: When the gap length Lp ≥ the transition length L_trans, the gap calculation formula on the right side of equation group (1) is used to calculate the gap hole fluid mass flow rate m_flow. When the gap length Lp < the transition length L_trans, the calculation formula on the left side of equation group (1) is used to calculate the gap hole fluid mass flow rate m_flow. This ensures that the gap hole fluid mass flow rate m_flow can still be output when the gap length Lp approaches 0. Therefore, the calculation of the critical value of the gap length Lp (i.e., the transition length L_trans) is crucial.

[0057] The computer program code written based on Modelica code in equation group (1) (hereinafter referred to as "code (1)") is as follows:

[0058]

[0059] Finally, when Modelica calculates the fluid leakage occurring at the axial hole of the sealed pipeline, the computer program code of the Modelica equation group (hereinafter referred to as "Code (2)") is as follows, taking into account other main defined parameters and variables:

[0060]

[0061] The relevant parameters and variables of the Modelica code equations are explained below. dmax : Flow coefficient; when calculating leakage, Figure 1 In the geometric model of the closed pipeline in the hydraulic system shown, the diameter of the hole r; the clearance c in the diameter direction of the shaft hole; the eccentricity e of the shaft hole; the gap length Lp; Figure 1 The pressure of the hydraulic port on the left side of the middle seal line is p_a, Figure 1 The pressure at the hydraulic port on the right side of the sealed pipeline is p_b. The value of the fluid mass flow m_flow in code (1) is related to the transition length L_trans. The sealed pipeline and the closed pipeline have the same technical meaning.

[0062] By using Modelica's steps of defining a mechanical translation interface, establishing a base class model, referencing the base class model, defining hydraulic ports, and defining related variables, and finally implementing equations between interfaces and variables, the calculation of complex problems can be achieved. Therefore, one of the significant features of the Modelica language is the definition of flow variables and potential variables between interfaces, specifically: the potential variables at the connection are equal and the sum of the flow variables at the connection is 0. Therefore, the four mechanical translation interfaces defined in the present invention, namely flange_a, support_a, flange_b, and support_b, and the hydraulic ports (i.e., port_a and port_b) will also have this relationship (i.e., the potential variables at the connection are equal and the sum of the flow variables at the connection is 0). The equation port_a.m_flow + port_b.m_flow = 0 in code (2) is an application of the flow variable being 0.

[0063] This method is based on the mathematical model description of axial hole leakage, uses the Modelica system simulation platform and the Modelica language to establish a set of equations, uses the characteristics of Modelica's inherent flow variables and potential variables, and based on the influence of the transition length L_trans on the leaking fluid mass flow rate, finally uses the Modelica language to calculate the leaking fluid mass flow rate m_flow, the pressure drop dp at both ends of the sealed pipeline, and other variables to construct a leakage model. Through the axial hole leakage simulation modeling method disclosed by the present invention, leakage can be defined based on the relevant axial hole dimensional parameters (for example, the density of the pressure oil (ρ), the gap size (diameter r) is a known input quantity, and the dynamic viscosity (μ)), and creatively takes into account the fluid mass flow rate of the leakage element under the critical length L_trans of the axial hole, thereby improving the reliability of the fluid leakage calculation results at the axial hole. At the same time, it can also calculate the pressure loss on both sides of the leakage element. Finally, the four mechanical translation interfaces and two hydraulic ports (i.e., port_a and port_b) of the leakage element can be coupled with other components in the hydraulic / pneumatic system for calculation, ultimately achieving an assessment of the impact of the entire hydraulic / pneumatic system.

[0064] The method disclosed in this embodiment realizes the accurate calculation of the liquid mass flow m_flow at the shaft hole leakage, thereby solving the technical problem that the basic library provided in the Modelica system simulation platform in the prior art cannot accurately calculate the leaking liquid mass flow.

[0065] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

[0066] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0067] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A simulation modeling method for leakage at an axial hole, characterized in that: include: Use visual operations to reference four mechanical translation interfaces in the Modelica system simulation platform; Reference the default variables of the four mechanical translation interfaces to encapsulate the base class model; Modify the default variables of the Mechanical Translation interface in the base model using declared variables as intermediate variables to calculate the gap length Lp; Defining a hydraulic port of a sealed pipeline forming an axial hole, constructing a leakage model of the axial hole leakage location according to the following set of equations, and performing simulation modeling of leakage occurring at the axial hole based on the leakage model; Parameter ρ is the fluid density, parameter r is the diameter of the gap size, parameter Lp is the gap length, μ is the dynamic viscosity of the fluid, parameter c is the gap amount in the diameter direction, parameter e is the eccentricity, parameter abs(dp) is the absolute value of the pressure drop caused by leakage at the shaft hole at the hydraulic port with the gap length Lp, and parameter C dmax is the flow coefficient and is a constant.

2. The shaft hole leakage simulation modeling method according to claim 1, characterized in that: The visualization operation method is specifically as follows: referencing four mechanical translation interfaces in a drag-and-drop manner in a graphical user interface formed by a Modelica system simulation platform; The mechanical translation interface includes: flange_a, flange_b, support_a and support_b.

3. The shaft hole leakage simulation modeling method according to claim 2, characterized in that: The base class model is a Basic base class model, and the shaft hole leakage simulation modeling method further includes: inheriting four mechanical translation interfaces from the Basic base class model.

4. The shaft hole leakage simulation modeling method according to claim 3, characterized in that: Also includes: The mechanical translation interface forms corresponding displacement variables based on the displacement, and uses declared variables as intermediate variables to combine with flange_a, flange_b, support_a and support_b to form displacement variables respectively; the displacement variables include: flange_a.s, flange_b.s, support_a.s and support_b.s.

5. The shaft hole leakage simulation modeling method according to claim 3, characterized in that: Also includes: Corresponding external force variables are generated for the mechanical translation interface based on the external force f, and the external force variables include: flange_a.f, flange_b.f, support_a.f and support_b.f.

6. The shaft hole leakage simulation modeling method according to claim 5, characterized in that: The external force f is the sum of the forces exerted on the mechanical translation interface flange_a, the mechanical translation interface flange_b, the mechanical translation interface support_a, and the mechanical translation interface support_b along the direction of the sealed pipeline by the fluid.

7. The shaft hole leakage simulation modeling method according to claim 1, characterized in that: The hydraulic port includes a hydraulic inlet port_a through which fluid flows into the sealed pipeline and a hydraulic outlet port_b through which fluid flows out of the sealed pipeline.

8. The shaft hole leakage simulation modeling method according to claim 1, characterized in that: Also includes: A transition length L_trans is introduced into the leakage model so as to take the transition length L_trans as a declared variable.

9. The shaft hole leakage simulation modeling method according to claim 8, characterized in that: Also includes: Compare the gap length Lp and the transition length L_trans; If the gap length Lp is less than the transition length L_trans, the fluid mass flow rate m_flow is calculated based on the right-hand formula of the leakage model; If the gap length Lp≥transition length L_trans, the fluid mass flow rate m_flow is calculated based on the left-hand formula of the leakage model.

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