Numerical simulation of self-propulsion of underwater vehicle model

Abstract

The application discloses a numerical simulation research method for self-propulsion of an underwater vehicle model, and relates to the technical field of underwater vehicles. The method comprises the following steps: creating a vehicle model corresponding to an underwater vehicle, and performing mesh block division on the vehicle model to obtain a main body mesh and an appendage mesh corresponding to the vehicle model, wherein the appendage mesh comprises a propeller mesh area and a bow and stern rudder mesh area; controlling rotation of a propeller of the vehicle model based on the propeller mesh area to propel the vehicle model to sail; in the process of sailing of the vehicle model, performing displacement change on the bow and stern rudder mesh area based on a posture deviation between a motion posture of the vehicle model and a target sailing state, so that the vehicle model maintains the target sailing state; obtaining sailing data of the vehicle model in the target sailing state, and performing numerical calculation research based on the sailing data. The method can automatically obtain the sailing data of the vehicle model in the target sailing state to perform numerical calculation of a self-propulsion model.

Description

Technical Field

[0001] This application relates to the field of underwater vehicle technology, and in particular to a numerical simulation research method for the self-propulsion of an underwater vehicle model. Background Technology

[0002] Research on self-propelled underwater vehicles has always been a hot topic in the international hydrodynamics field. For example, research on submarine self-propelled models is an effective way to directly verify the comprehensive hydrodynamic performance of submarines. Early research focused primarily on submarine self-propelled model testing. However, due to the continuous improvement of numerical methods in computational fluid dynamics, the ongoing optimization of high-performance software, and the gradual improvement of hardware facilities in recent years, numerical simulation technology for submarine self-propelled models has been perfected and widely applied. On the one hand, it effectively avoids the disadvantages of long testing cycles and high resource consumption; on the other hand, it can accurately provide information on the surrounding flow field during submarine controlled navigation, providing auxiliary reference for analyzing the submarine's motion attitude and trajectory characteristics. Numerical calculation research on submarine self-propelled models can provide technical support for the prediction and evaluation of submarine maneuverability and seaworthiness, as well as the improvement of submarine self-propelled model testing technology.

[0003] Currently, most numerical implementations of submarine autopilots rely on coupled dynamic analytical data of the propeller and other moving appendages to support the viscous flow calculation of the submarine model's motion. For example, volume force methods or potential flow solving techniques are used to predict propeller thrust and control surface hydrodynamics (moments) in real time, serving as input for the six-degree-of-freedom viscous flow calculation of the submarine model. However, this neglects the three-dimensional vortex flow structure and dynamic characteristics generated by appendage motion. For viscous flow calculations of fully appended submarines, most are limited to constrained models or restricting only some degrees of freedom. This simplifies the six-degree-of-freedom motion attitude changes of the hull and the real-time control of the autopilot, resulting in significant discrepancies with actual submarine autopilot tests and affecting the accuracy of viscous flow calculations. Summary of the Invention

[0004] To address the aforementioned problems and technical requirements, the applicant proposes a numerical simulation method for the self-propulsion of an underwater vehicle model. The technical solution of this application is as follows: A numerical simulation method for studying the self-propulsion of an underwater vehicle model includes the following steps: Create a model of the underwater vehicle and divide the model into grid blocks to obtain the main grid and appendage grids of the vehicle model. The appendage grids include propeller grid regions and bow and stern rudder grid regions. The propeller rotation of the vehicle model is controlled based on the propeller grid area to propel the vehicle model. During the navigation of the vehicle model, based on the attitude deviation between the vehicle model's motion attitude and the target navigation state, the bow and stern rudder grid regions are displaced to ensure that the vehicle model maintains the target navigation state. The navigation data of the vehicle model under the target navigation state is obtained, and numerical calculations are performed based on the navigation data.

[0005] Further methods include: The displacement change of the bow and stern rudder mesh region based on the attitude deviation between the motion attitude of the vehicle model and the target navigation state includes: Based on the attitude deviation of the aircraft model, control parameters are determined, including horizontal control parameters and vertical control parameters. Based on the horizontal control parameters and the vertical control parameters, the bow and stern rudder correction method is determined; The bow and stern rudder grid region is displacement-changed based on the aforementioned bow and stern rudder correction method.

[0006] The attitude deviations include yaw deviation, yaw deviation, heave deviation, and pitch deviation; Based on the attitude deviation of the aforementioned vehicle model, control parameters are determined, including: The horizontal control parameters are determined based on the sway deviation and the yaw deviation of the vehicle model. The vertical control parameters are determined based on the heave deviation and pitch deviation of the aircraft model.

[0007] The stern rudder is an X-shaped rudder; The determination of the bow and stern rudder correction method based on the horizontal control parameters and the vertical control parameters includes: Based on the horizontal control parameters and the vertical control parameters, the rudder correction method is determined, which includes the correction methods of upper left rudder, lower left rudder, upper right rudder and lower right rudder. The bow and rudder correction method is determined based on the vertical control parameters.

[0008] The bow and stern rudder grid area includes a bow rudder grid area and a stern rudder grid area, and the stern rudder grid area includes an upper left rudder grid, a lower left rudder grid, an upper right rudder grid, and a lower right rudder grid; The displacement change of the bow and stern rudder grid region based on the bow and stern rudder correction method includes: The displacement of the upper left rudder grid is adjusted based on the aforementioned upper left rudder correction method. The lower left rudder grid is displacement-changed based on the aforementioned lower left rudder correction method; The upper right rudder grid is displacement-changed based on the correction method of the upper right rudder. The lower right rudder grid is displacement-changed based on the aforementioned lower right rudder correction method; The bow and rudder grid region is displacement-changed based on the aforementioned bow and rudder correction method.

[0009] The control parameters also include quality control parameters, and the method further includes: The mass control parameters are determined based on the heave deviation, and the mass parameters of the vehicle model are adjusted based on the mass control parameters.

[0010] The process of dividing the vehicle model into mesh blocks to obtain the main body mesh and appendage mesh corresponding to the vehicle model includes: An external flow field computational domain is created based on the aforementioned vehicle model; The surface of the aircraft model is divided into main surface meshes and appendage surface meshes by surface meshing, and the external flow field computational domain is divided into main computational domains and appendage computational domains by volume meshing. The method further includes: During the navigation of the vehicle model, flow field information is obtained by solving the computational domain of the vehicle model based on the hydrodynamic model. The computational domain includes the main body computational domain and the appendage computational domain, and the flow field information is the overall flow field information corresponding to the external flow field computational domain. The motion attitude of the vehicle model is determined based on the flow field information.

[0011] The mesh size of the volume mesh in the main computational domain is the same as the mesh size of the main surface mesh, and the mesh size of the volume mesh in the appendage computational domain is the same as the mesh size of the appendage surface mesh.

[0012] The method further includes: The forced self-propulsion method is used to calculate the self-propulsion point and obtain the propeller speed corresponding to the target speed; The control of the propeller rotation of the vehicle model based on the propeller grid region includes: The propeller grid area is rotated based on the propeller speed to make the propeller of the aircraft model rotate.

[0013] The displacement change of the bow and stern rudder mesh region based on the attitude deviation between the motion attitude of the vehicle model and the target navigation state includes: Based on the attitude deviation between the motion attitude of the aforementioned vehicle model and its constant-depth straight-line state, the bow and stern rudder grid regions are subjected to displacement changes. When the vehicle model is in a stable straight-line state, execute the steering command, which is a turn, a Z-shaped steering maneuver, or an emergency reverse. And based on the attitude deviation between the motion attitude of the aircraft model and the navigation state corresponding to the operation command, the bow and stern rudder grid regions are displaced.

[0014] The beneficial technical effects of this application are: In this embodiment, the geometric model of the underwater vehicle is divided into grid blocks. During this process, the main body and appendages of the vehicle are divided into separate grids, so that each part can be independently controlled based on its corresponding independent grid area, thereby improving the realism of the simulated vehicle's motion. Furthermore, during the vehicle's navigation, the navigation state of the vehicle is controlled according to the attitude deviation between the real-time attitude of the vehicle model and the target navigation state, realizing the automatic control process of the vehicle's navigation. This allows the vehicle to automatically maintain the target navigation state without human intervention, thereby automatically acquiring the navigation data of the vehicle model in the target navigation state. This data is then used for numerical calculation research on the self-propulsion model of the underwater vehicle, providing a reference for the actual self-propulsion process of underwater vehicles. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the geometric model of a propeller-equipped, fully appended X-rudder submarine provided in an exemplary embodiment of this application; Figure 2 This is a schematic diagram of the surface meshing of a submarine geometric model provided in an exemplary embodiment of this application; Figure 3 This is a schematic diagram of the external flow field computational domain division provided in an exemplary embodiment of this application; Figure 4 This is a schematic diagram of the overall computational domain mesh partitioning provided in an exemplary embodiment of this application; Figure 5 This is a schematic diagram of a sliding interface and an overlapping interface provided in an exemplary embodiment of this application; Figure 6 This is an exemplary embodiment of the present application, providing a transient flow field distribution around a vehicle and a cloud map showing the development of streamlines on the surface of the vehicle. Figure 7 This is a schematic diagram comparing the underwater gyratory maneuver trajectory with experimental values ​​provided in an exemplary embodiment of this application; Figure 8 This is another exemplary embodiment of the present application, providing a transient flow field distribution around the vehicle and a cloud map showing the development of streamlines on the surface of the vehicle; Figure 9 A flowchart illustrating a numerical simulation research method for an X-rudder submarine self-propelled model provided in an exemplary embodiment of this application is shown. Detailed Implementation

[0016] The specific embodiments of this application will be further described below with reference to the accompanying drawings.

[0017] To address the aforementioned problems, this application provides a numerical simulation method for the self-propulsion of an underwater vehicle model. The method includes the following steps: S1. Create the underwater vehicle model and divide the vehicle model into grid blocks to obtain the main body grid and appendage grids corresponding to the vehicle model. The appendage grids include the propeller grid area and the bow and stern rudder grid areas.

[0018] The method provided in this application is a numerical research method for an underwater vehicle self-propelled model. The underwater vehicle (such as a submarine) includes a main body and appendages. The main body is the main structure of the vehicle, and the appendages include the vehicle's control structures, such as the bow rudder, stern rudder, and propeller. In the numerical research process, a three-dimensional geometric model (vehicle model) corresponding to the underwater vehicle is first created in 3D modeling software (such as AutoCAD, UG, and Solidworks). In the created geometric model, the appendages are separated from the main body of the underwater vehicle, and each appendage is established as a separate entity from the main body; that is, the bow rudder, stern rudder, propeller, and other appendages are all established separately from the main body. (Illustrative example follows.) Figure 1 As shown, it illustrates the geometric model of a fully appended X-rudder submarine with a propeller, including a side view 101, a front view 102, and a rear view 103 of the geometric model.

[0019] In this embodiment, a self-propelled numerical simulation study is conducted based on an overlapping mesh method. After creating a model of the underwater vehicle, mesh generation is performed based on the model. The mesh generation adopts a block-based approach. During the generation process, the main body of the underwater vehicle and each appendage are meshed separately to achieve independent movement of the main body and appendages. After block-based mesh generation, the main body mesh and appendage mesh are obtained, namely, the overlapping mesh corresponding to the main body and the overlapping mesh corresponding to the appendages.

[0020] For example, the aircraft model created in 3D modeling software is imported into fluid dynamics simulation software (such as CFD software) for mesh generation.

[0021] S2 controls the rotation of the propeller of the vehicle model based on the propeller grid region to propel the vehicle model.

[0022] To enable an underwater vehicle to propel itself, a constant rotational speed can be applied to the propeller of the underwater vehicle when it is stationary, so that the underwater vehicle will start to move forward under the thrust of the propeller.

[0023] In simulating self-propulsion using a vehicle model, the rotation of the propeller in the vehicle model is controlled by the corresponding propeller grid region to propel the vehicle model. In one possible implementation, a sliding mesh technique can be used to control the propeller grid region. This technique allows all grid cells within the sliding region to undergo large-amplitude rigid body rotational motion along with the propeller without deformation or changes in relative position or topology.

[0024] In one possible implementation, propeller speed parameters can be configured in the simulation software. Then, the fluid dynamics simulation software can control the displacement of the propeller grid area according to the configured propeller speed to simulate the propeller rotation process.

[0025] S3. During the navigation of the vehicle model, based on the attitude deviation between the vehicle model's motion attitude and the target navigation state, the bow and stern rudder mesh areas are displaced to ensure that the vehicle model maintains the target navigation state.

[0026] The target navigation state refers to the navigation state to be studied, which may include underwater straight navigation, underwater turning, Z-shaped steering, and emergency reversing.

[0027] During the navigation of the model body, the motion attitude will change continuously due to the interference of unsteady hydrodynamics. In order to keep the model body in the target navigation state, the motion attitude of the model body needs to be adjusted.

[0028] In one possible implementation, during the navigation of the underwater vehicle model, the simulation software can monitor the model's motion attitude in real time. Based on the attitude deviation between the monitored motion attitude and the attitude corresponding to the target navigation state, the software determines the correction method for the vehicle's motion attitude. The correction of the underwater vehicle's motion attitude is achieved by adjusting the rudder angles of the bow and stern. After determining the correction method, the simulation software can adjust the displacement of the bow and stern rudder mesh areas in the vehicle model according to the correction method, thereby achieving the attitude correction process and ensuring the vehicle model maintains the target navigation state.

[0029] In this way, the simulation software can automatically adjust the self-propulsion attitude of the underwater vehicle model based on the real-time monitored motion attitude, without the need for human intervention during the numerical research process, and can realize the automatic execution of the viscous flow solution of the underwater vehicle self-propulsion model.

[0030] S4: Obtain the navigation data of the navigation body model under the target navigation state, and perform numerical calculations based on the navigation data.

[0031] During the navigation process of the vehicle model in the target navigation state, navigation data can be monitored. The navigation data includes the vehicle's hydrodynamics (dynamic torque), six-degree-of-freedom motion attitude / velocity / acceleration, control surface deflection angle / normal force / torque, propeller thrust / lateral force / torque, etc.

[0032] Furthermore, it can post-process the flow field around the vehicle at different times to obtain calculation results such as the transient flow field distribution around the vehicle, the development of streamlines on the vehicle surface, pressure distribution, and velocity field near the propeller.

[0033] Numerical calculations of navigation data can provide auxiliary references for analyzing the motion attitude and trajectory characteristics of underwater vehicles in the target navigation state.

[0034] In this embodiment, the geometric model of the underwater vehicle is divided into grid blocks. During this process, the main body and appendages of the vehicle are divided into separate grids, so that each part can be independently controlled based on its corresponding independent grid area, thereby improving the realism of the simulated vehicle's motion. Furthermore, during the vehicle's navigation, the navigation state of the vehicle is controlled according to the attitude deviation between the real-time attitude of the vehicle model and the target navigation state, realizing the automatic control process of the vehicle's navigation. This allows the vehicle to automatically maintain the target navigation state without human intervention, thereby automatically acquiring the navigation data of the vehicle model in the target navigation state. This data is then used for numerical calculation research on the self-propulsion model of the underwater vehicle, providing a reference for the actual self-propulsion process of underwater vehicles.

[0035] After establishing the vehicle model, it is also necessary to create a corresponding external flow field computational domain for flow field calculations. During the creation of the external flow field computational domain, it is essential to ensure that the vehicle model's self-propulsion motion does not exceed the domain's range. This external flow field computational domain can be created in simulation software, set as a cuboid with sufficiently large length, width, and height. Of course, the external flow field computational domain can also be a computational domain of other shapes, such as a cylinder; this embodiment does not limit this.

[0036] During the mesh partitioning process, the partitioned mesh includes surface meshes and volume meshes, and a mesh partitioning mode based on quadtree (surface mesh) / octree (volume mesh) is adopted.

[0037] Optionally, the surface of the aircraft model is divided into surface mesh blocks to obtain the main surface mesh and the appendage surface mesh, and the external flow field calculation domain is divided into volume mesh blocks to obtain the main calculation domain and the appendage calculation domain.

[0038] During the surface mesh generation process, a uniform meshing method can be used to obtain the surface mesh corresponding to the entire external flow field computational domain. Furthermore, after meshing the surface of the underwater vehicle model, the main body surface mesh and the appendage surface mesh corresponding to the appendages can be obtained. To improve the solution accuracy of underwater vehicle self-propelled model data calculation research, the main body surface mesh and appendage surface mesh can be refined to increase the mesh density, thereby improving the accuracy of numerical calculations. For example... Figure 2 As shown, it illustrates a schematic diagram of the surface mesh division of a submarine geometric model, including the hull surface mesh (i.e., the main surface mesh) 201 and the stern control surface and propeller surface mesh (attachment surface mesh) 202.

[0039] During the volume mesh generation process, separate solution domains are established for the main body and appendages of the aircraft body model. The resulting computational domain includes the main body computational domain and the appendage computational domains corresponding to each appendage. Optionally, such as... Figure 3 As shown, the external flow field computational domain is divided into 9 regions: the propeller slip grid region (Region_Propeller), the main body overlapping grid region (Region_Submarine), the conning rudder (bow control surface) nested overlapping grid region (Region_PtSail, Region_SbSail), the stern control surface nested overlapping grid region (Region_PtUp, Region_PtDn, Region_SbUp, Region_SbDn), and the external flow field computational domain (Region_Computation).

[0040] To more accurately exchange flow field information between the propeller slip grid region and the external flow field, between the overlapping grid regions of each appendage and the main body overlapping grid region, and between the main body overlapping grid region and the external flow field, local volumetric meshes are established in the background flow field domain or the main body overlapping grid region. Specifically, a volumetric mesh covering the motion traversed by the vehicle model is established in the background flow field domain, and / or a volumetric mesh covering the motion traversed by each appendage is established in the main body overlapping grid region. The mesh size of the local volumetric mesh is similar to or the same as the mesh size of the corresponding surface mesh in its overlapping region. Optionally, the mesh size of the volumetric mesh in the main body computational domain is the same as the mesh size of the main body surface mesh, and the mesh size of the volumetric mesh in the appendage computational domain is the same as the mesh size of the appendage surface mesh. For example... Figure 4 As shown, it illustrates a schematic diagram of an overall computational domain mesh, which includes an external flow field computational domain 401, a main computational domain 402, and an appendage computational domain 403.

[0041] After establishing the computational domain, the simulation software can calculate the flow field information based on the fluid dynamics model, obtain the flow field dynamics, and then control the motion attitude of the vehicle model according to the flow field dynamics.

[0042] After applying a constant rotational speed to the vehicle model and enabling it to begin sailing, the flow field information is obtained by solving the computational domain of the vehicle model based on the fluid dynamics model. The computational domain includes the main computational domain and the appendage computational domain, and the flow field information is the overall flow field information corresponding to the external flow field computational domain.

[0043] First, a fluid dynamics model is established. In this embodiment, the governing equations for the flow field are the Reynolds Average Navier-Stokes Equations (RANS), which include the continuity equation and the momentum equation:

[0044]

[0045] in, and It is the time-averaged velocity component. and It is the pulsating velocity component. For fluid density, Represents the fluid's kinematic viscosity coefficient and related terms for fluctuating velocity. This is called Reynolds stress. Indicates the flow field pressure. and Indicates components in different directions.

[0046] And introduce The turbulence model closes the above RANS equations, where the turbulent kinetic energy... With dissipation rate The equation is:

[0047]

[0048] in, For turbulent kinetic energy, For dissipation rate, , For turbulent kinetic energy generation, , Represents the Prandtl number for turbulence. This indicates the effect of compressible turbulent fluctuating expansion on the total dissipation rate. , For source terms, Represents the turbulent viscosity coefficient. This represents the kinematic viscosity coefficient of the fluid, and , , , , .

[0049] In calculating the flow field information, the governing equations are discretized using the finite volume method. The convection term in the momentum equation uses a second-order upwind difference scheme, the diffusion term uses a central difference scheme, the turbulence model equations use a second-order upwind difference scheme, and the time term uses a second-order implicit scheme. The pressure-velocity coupling method can be achieved using a semi-implicit method for pressure-linked equations (SIMPLE) to obtain the pressure and velocity fields of the computational domain. Furthermore, the velocity and pressure field information within the grid cells at the overlapping grid interface between adjacent regions is obtained by weighted distance differences between the velocity and pressure fields between adjacent grid cells on both sides of the interface. Specifically, the propeller slip grid region exchanges flow field data with the external flow field computational domain through the slip interface; and each overlapping grid region exchanges flow field data with the external flow field computational domain through the overlapping grid interface. (Illustrative example follows.) Figure 5 As shown, there is a slip interface 501 between the propeller slip mesh region and the external flow field computational domain, and there is an overlapping interface 502 between the nested overlapping mesh region of the stern control surface and the external flow field computational domain.

[0050] Furthermore, an unsteady calculation method is used to update the flow field information during the calculation process. The time step in the unsteady calculation process is determined based on the propeller speed; illustratively, it can be set to a time step where the propeller rotates 20 degrees in each time step. ,Right now , where n is the propeller speed, in RPS.

[0051] After obtaining the flow field information, the motion attitude of the vehicle model can be determined based on the flow field information.

[0052] The flow field information includes the velocity field and pressure field of each grid. The flow field dynamics can be determined based on the velocity field and pressure field, and then the control force on the vehicle model can be determined based on the flow field dynamics, thereby determining the motion attitude of the vehicle model and controlling the navigation of the vehicle model.

[0053] In this embodiment, to automatically position the vehicle model in the target navigation state, a PD controller is used to correct the vehicle model's attitude. Specifically, the method of adjusting the bow and stern rudder mesh regions based on the attitude deviation between the vehicle model's motion attitude and the target navigation state to maintain the vehicle model in the target navigation state includes the following steps: Step S31: Based on the attitude deviation of the vehicle model, determine the control parameters, which include horizontal control parameters and vertical control parameters.

[0054] To ensure the vehicle model maintains the target navigation state, horizontal and vertical controls can be applied. Specifically, the horizontal and vertical control parameters are determined based on the attitude deviation between the motion attitude determined by the aforementioned flow field information and the target navigation state. The specific method for determining these control parameters is as follows:

[0055] in, The actual control elements (horizontal control and vertical control, etc.) are applied. and , Transient value, The target value is the attitude value corresponding to the target navigation state, and the transient value is the attitude value corresponding to the motion attitude.

[0056] P is the proportional control parameter, which is a gain factor of the controller. The larger the value, the faster the proportional control response. D is the derivative control parameter, which is a lag factor of the controller. It adds a lag effect to the application of control commands to prevent sudden changes in the controlled variable from affecting the control system. The values ​​of P and D can be selected based on historical numerical calculations and empirical values ​​from model tests.

[0057] Attitude deviations include y-sway deviation and y-sway deviation. Deviation, heave z-deviation and pitch deviation.

[0058] Optionally, the horizontal control parameters can be determined based on the sway and yaw deviations of the vehicle model.

[0059]

[0060] in, For horizontal control parameters, For sway deviation, This is the bow roll deviation.

[0061] Optionally, vertical control parameters can be determined based on the heave and pitch deviations of the vehicle model.

[0062]

[0063] in, For vertical control parameters, For heave deviation, This refers to pitch deviation.

[0064] Step S32: Determine the bow and stern rudder correction method based on the horizontal control parameters and the vertical control parameters.

[0065] The horizontal and vertical control of the aircraft model is actually achieved by adjusting the bow and stern control surfaces. Optionally, the stern rudder correction method is determined based on the horizontal and vertical control parameters. In this embodiment, the stern rudder is an X-rudder, and the stern rudder correction method includes correction methods for the upper left rudder, lower left rudder, upper right rudder, and lower right rudder. As shown in the following formula:

[0066]

[0067] in, These are the left-side rudder correction parameters, corresponding to the left-side rudder correction method. These are the left-side rudder correction parameters, corresponding to the left-side rudder correction method. These are the upper right rudder correction parameters, corresponding to the upper right rudder correction method. These are the parameters for the lower right rudder correction, corresponding to the lower right rudder correction method.

[0068] The bow and rudder correction method is determined based on the vertical control parameters. That is:

[0069] in, These are the bow and rudder correction parameters, corresponding to the bow and rudder correction methods.

[0070] Step S33: Displacement change of the bow and stern rudder grid region based on the bow and stern rudder correction method.

[0071] During the adjustment of the bow and stern rudders, adjustments are made based on the corresponding bow and stern rudder grid regions. These grid regions include both the bow rudder grid region and the stern rudder grid region. In the above embodiment, the bow rudder grid region is the nested and overlapping grid region of the sail and rudder, and the stern rudder grid region is the nested and overlapping grid region of the stern control surfaces. The stern rudder grid region includes the upper left rudder grid (Region_PtUp, lower left rudder grid Region_PtDn, upper right rudder grid Region_SbUp, and lower right rudder grid Region_SbDn).

[0072] During the adjustment process, the left-side rudder mesh can be displaced based on the left-side rudder correction method; the left-side rudder mesh can be displaced based on the left-side rudder correction method; the right-side rudder mesh can be displaced based on the right-side rudder correction method; the right-side rudder mesh can be displaced based on the right-side rudder correction method; and the bow-side rudder mesh region can be displaced based on the bow-side rudder correction method. It should be noted that the displacement of the mesh region includes the displacement of both the surface meshes and the volume meshes within that region. For example, when displacing the left-side rudder mesh, both the surface meshes and the volume meshes within that region are displaced. Optionally, the DFBI rotation and translation motion technique can be used to achieve the mesh displacement process. During this process, the mesh elements within the overlapping region achieve six-degree-of-freedom rigid body motion together with the main body and all attachments, without deformation or changes in relative position or topology.

[0073] In the above process, horizontal and vertical controls are applied to the model of the underwater vehicle. However, when the initial gravity and buoyancy of the actual underwater vehicle differ significantly, excessive vertical displacement can lead to problems with the vertical control parameters. The distortion caused by the buoyancy cannot be completely offset by the PD control of the bow and stern control surfaces alone. Furthermore, increasing the rudder angle to maintain the target heading state will further lead to a continuous deterioration of the pitch. Therefore, in one possible implementation, in addition to vertical control, the process of filling and draining ballast tanks can be further simulated, and the mass m of the ship model can be controlled by a PD controller, that is, the control parameters include mass control parameters.

[0074] Optionally, mass control parameters can be determined based on heave deviation, and the mass of the vehicle model can be adjusted according to these parameters. The mass control parameters are determined as follows:

[0075] in, This refers to the heave deviation.

[0076] Optionally, the target navigation state can be a constant depth straight navigation state.

[0077] In one possible implementation, the forced propulsion method can be used to calculate the self-centering point, thereby obtaining the propeller speed corresponding to the target speed. Furthermore, the forced propulsion method using a towed pool restraint model can be employed to calculate the self-centering point and obtain the propeller speed corresponding to the target speed.

[0078] Subsequently, the obtained propeller speed can be applied to the stationary vehicle model, i.e., the rotation of the propeller grid region is controlled based on the propeller speed. A sliding mesh technique can be used to rotate the propeller grid region, thereby causing the propeller of the vehicle model to rotate. After the vehicle model enters the navigation state, unsteady calculations can be performed using a hydrodynamic model to obtain the flow field information within each time step. Then, based on the flow field information within each time step, the motion attitude of the vehicle model within each time step is determined. Furthermore, based on the target attitude corresponding to the constant-depth straight-ahead state, the attitude deviation within each time step is determined, and the displacement changes of the bow, stern, and rudder grid regions are adjusted. During this process, the time-history changes of dynamic and kinematic parameters can be recorded, and the results of these changes can be processed to obtain the time-history change curves of the vehicle's hydrodynamic (moment), six-degree-of-freedom motion attitude / velocity / acceleration, control surface deflection angle / normal force / torque, propeller thrust / lateral force / torque, etc., under constant-depth straight-ahead state. Furthermore, it can post-process the flow field around the model of the vehicle at different times under constant depth and straight-line conditions to obtain the calculation results of the transient flow field distribution around the vehicle, as well as the development of streamlines on the surface of the vehicle, pressure distribution, and velocity field near the propeller.

[0079] Furthermore, the target navigation state can be underwater turning, Z-shaped steering, or emergency reversing. After the navigation model is in a stable straight-line state, steering commands can be executed, including turning, Z-shaped steering, or emergency reversing, to conduct numerical calculation studies under different working conditions.

[0080] After the operation command is executed, the vehicle model will transition from a stable straight-line state to the navigation state corresponding to the steering command. During this process, the PD controller also needs to adjust the motion attitude of the vehicle model to maintain the navigation state corresponding to the operation command. That is, based on the attitude deviation between the motion attitude of the vehicle model and the navigation state corresponding to the operation command, the bow, stern, and rudder mesh areas are displaced.

[0081] Indicatively, when the operational command is underwater turning, the bow and stern rudder mesh regions can be displaced based on the attitude deviation between the vehicle model's motion attitude and its underwater turning state to maintain the vehicle model's underwater turning state. Furthermore, during underwater turning, the surrounding flow field at different times can be acquired and post-processed to obtain the transient flow field distribution around the vehicle and the streamline development cloud map of the vehicle's surface, such as... Figure 6 As shown. Furthermore, the underwater turning maneuver trajectory can be determined based on navigation data during underwater turning, and compared with experimental values ​​to determine whether the turning maneuver requirements are met. For example... Figure 7 As shown, the diameter error between the underwater slewing maneuver trajectory 701 and the experimental value 702 is less than 5%, confirming that the requirements are met.

[0082] Indicatively, when the operating command is Z-shaped maneuvering, the bow and stern rudder mesh regions can be displaced based on the attitude deviation between the vehicle model's motion attitude and the Z-shaped maneuvering state to maintain the vehicle model in the Z-shaped maneuvering state. Furthermore, in the Z-shaped maneuvering state, the surrounding flow field at different times can be acquired and post-processed to obtain the transient flow field distribution around the vehicle and the streamline development cloud map of the vehicle surface, such as... Figure 8 As shown.

[0083] In one possible implementation, such as Figure 9 As shown, the numerical simulation research method for the X-rudder submarine self-propelled model includes the following steps: Step 901: Establish a three-dimensional geometric model of a fully attached X-rudder submarine with a propeller.

[0084] Step 902: Mesh the geometric model to obtain the overlapping mesh corresponding to the hull / control surfaces and the slip mesh corresponding to the propeller.

[0085] Step 903: Solve the RANS equations for hydrodynamic attitude.

[0086] Step 904, attitude correction of the autopilot PD controller.

[0087] Step 905: Control the movement of the hull / control surfaces based on overlapping mesh technology.

[0088] Step 906: Control propeller rotation based on sliding grid technology.

[0089] Step 907: Numerical calculation of the propeller rotation speed of the submarine self-propelled model.

[0090] The above descriptions are merely preferred embodiments of this application, and this application is not limited to the above embodiments. It is understood that other improvements and variations that can be directly derived or conceived by those skilled in the art without departing from the spirit and concept of this application should be considered to be included within the protection scope of this application.

Claims

1. A numerical simulation method for the self-propulsion of an underwater vehicle model, characterized in that, The method includes: Create a model of the underwater vehicle and divide the model into grid blocks to obtain the main grid and appendage grids of the vehicle model. The appendage grids include propeller grid regions and bow and stern rudder grid regions. The propeller rotation of the vehicle model is controlled based on the propeller grid area to propel the vehicle model. During the navigation of the vehicle model, based on the attitude deviation between the vehicle model's motion attitude and the target navigation state, the bow and stern rudder grid regions are displaced to ensure that the vehicle model maintains the target navigation state. Acquire the navigation data of the vehicle model under the target navigation state, and perform numerical calculations based on the navigation data; The step of adjusting the bow and stern rudder grid region based on the attitude deviation between the motion attitude of the vehicle model and the target navigation state includes: determining control parameters based on the attitude deviation of the vehicle model, the control parameters including horizontal control parameters and vertical control parameters; determining the bow and stern rudder correction method based on the horizontal control parameters and the vertical control parameters; and adjusting the bow and stern rudder grid region based on the bow and stern rudder correction method. The method of dividing the vehicle model into mesh blocks to obtain the main body mesh and appendage mesh corresponding to the vehicle model includes: creating an external flow field computational domain corresponding to the vehicle model; dividing the surface of the vehicle model into surface mesh blocks to obtain the main body surface mesh and appendage surface mesh; and dividing the external flow field computational domain into volume mesh blocks to obtain the main body computational domain and appendage computational domain; the method further includes: during the navigation of the vehicle model, solving the computational domain of the vehicle model based on a fluid dynamics model to obtain flow field information, wherein the computational domain includes the main body computational domain and the appendage computational domain, and the flow field information is the overall flow field information corresponding to the external flow field computational domain; and determining the motion attitude of the vehicle model based on the flow field information.

2. The method according to claim 1, characterized in that, The attitude deviations include yaw deviation, yaw deviation, heave deviation, and pitch deviation; Based on the attitude deviation of the aforementioned vehicle model, control parameters are determined, including: The horizontal control parameters are determined based on the sway deviation and the yaw deviation of the vehicle model. The vertical control parameters are determined based on the heave deviation and pitch deviation of the aircraft model.

3. The method according to claim 1, characterized in that, The stern rudder is an X-shaped rudder; The determination of the bow and stern rudder correction method based on the horizontal control parameters and the vertical control parameters includes: Based on the horizontal control parameters and the vertical control parameters, the rudder correction method is determined, which includes the correction methods of upper left rudder, lower left rudder, upper right rudder and lower right rudder. The bow and rudder correction method is determined based on the vertical control parameters.

4. The method according to claim 3, characterized in that, The bow and stern rudder grid area includes a bow rudder grid area and a stern rudder grid area, and the stern rudder grid area includes an upper left rudder grid, a lower left rudder grid, an upper right rudder grid, and a lower right rudder grid; The displacement change of the bow and stern rudder grid region based on the bow and stern rudder correction method includes: The displacement of the upper left rudder grid is adjusted based on the aforementioned upper left rudder correction method. The lower left rudder grid is displacement-changed based on the aforementioned lower left rudder correction method; The upper right rudder grid is displacement-changed based on the correction method of the upper right rudder. The lower right rudder grid is displacement-changed based on the aforementioned lower right rudder correction method; The bow and rudder grid region is displacement-changed based on the aforementioned bow and rudder correction method.

5. The method according to claim 2, characterized in that, The control parameters also include quality control parameters, and the method further includes: The mass control parameters are determined based on the heave deviation, and the mass parameters of the vehicle model are adjusted based on the mass control parameters.

6. The method according to claim 1, characterized in that, The mesh size of the volume mesh in the main computational domain is the same as the mesh size of the main surface mesh, and the mesh size of the volume mesh in the appendage computational domain is the same as the mesh size of the appendage surface mesh.

7. The method according to any one of claims 1 to 5, characterized in that, The method further includes: The forced self-propulsion method is used to calculate the self-propulsion point and obtain the propeller speed corresponding to the target speed; The control of the propeller rotation of the vehicle model based on the propeller grid region includes: The propeller grid area is rotated based on the propeller speed to make the propeller of the aircraft model rotate.

8. The method according to claim 7, characterized in that, The displacement change of the bow and stern rudder mesh region based on the attitude deviation between the motion attitude of the vehicle model and the target navigation state includes: Based on the attitude deviation between the motion attitude of the aforementioned vehicle model and its constant-depth straight-line state, the bow and stern rudder grid regions are subjected to displacement changes. When the navigation model is in a stable straight-line state, execute the operation command, which is to turn, zigzag steering, or emergency reverse. And based on the attitude deviation between the motion attitude of the aircraft model and the navigation state corresponding to the operation command, the bow and stern rudder grid regions are displaced.

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