A method and system for active source towbody simulation

Abstract

The application discloses an active sound source towed body simulation method and system, and belongs to the technical field of ocean exploration equipment simulation.The simulation method comprises the following steps: S1, determining a reference towed point of the towed body according to static water posture analysis; S2, judging the stability of the towed body through hydrodynamic force and stability analysis; S3, calculating the working depth of the towed body, and outputting a simulation result.The simulation system comprises the following units: a model establishing unit, which is used for constructing a three-dimensional model of the towed body; a static water posture analysis module, which is used for calculating the positions of the center of gravity, the center of buoyancy and the towed point; a hydrodynamic force analysis module, which is used for analyzing the hydrodynamic force center and the stability; a towed depth analysis module, which is used for simulating the dynamic behavior of the towing system; and a simulation output module, which is used for outputting the simulation result.The simulation precision and efficiency are greatly improved through full-process correlation modeling, node stress analysis and pre-judgment, the simulation system is suitable for ocean environment risks, and the performance of the towed body can be accurately verified.

Description

Technical Field

[0001] This invention relates to the field of marine exploration equipment simulation technology, specifically to an active acoustic source towed body simulation method and system. Background Technology

[0002] Active acoustic towed bodies are important equipment for marine acoustic detection. Their still water attitude, motion stability and tow depth directly affect the detection accuracy.

[0003] The existing technology has the following drawbacks: the still water attitude analysis is crude, and traditional methods rely on experience to set the towing point without precise calculation through mechanical equilibrium equations, resulting in initial attitude deviations of roll or pitch, which affects the accuracy of subsequent simulations; the hydrodynamic stability judgment is ambiguous, the relative positional relationship between the hydrodynamic center and the towing point is not clearly defined, and stability is inferred only from the shape, which cannot quantify the critical pitch angle and is prone to actual instability; the towing depth simulation is oversimplified, the modeling of the towing cable system ignores the details of the force at the nodes, and the pre-judgment of total buoyancy and total gravity is not considered, resulting in a large deviation between the simulation results and the actual working depth.

[0004] Therefore, there is an urgent need for a method and system that can achieve accurate simulation throughout the entire process in order to improve design efficiency and reliability. Summary of the Invention

[0005] In view of this, the main objective of the present invention is to provide an active sound source towing body simulation method and system, in order to at least partially solve the above-mentioned technical problems.

[0006] To achieve the above objectives, as a first aspect of the present invention, a method for simulating an active sound source towed body is proposed, comprising:

[0007] S1: Determine the reference towing point of the towing body based on still water attitude analysis;

[0008] S2: Determine the stability of the towed body through hydrodynamic and stability analysis;

[0009] S3: Calculate the working depth of the towed body and output the simulation results.

[0010] In this invention, preferably, the still water attitude analysis includes the following steps:

[0011] S11: Obtain the mass M and center of gravity coordinates (x) of the towed body through the 3D model of the towed body. G y G );

[0012] S12: Set the material properties of the 3D model to water to obtain the mass of fluid discharged by the towed body, M. b and the coordinates of the center of buoyancy (x) B y B), calculate buoyancy F 浮 =M b ×g, where g represents the acceleration due to gravity;

[0013] S13: Using the drag point as the origin Along the bow of the towed body, pointing towards the stern. The axis, vertically upward is The first coordinate system is constructed using axes, with the x-direction distance from the dragging point to the center of gravity denoted as 'a', and the x-direction distance between the center of gravity and the center of buoyancy denoted as 'l=x'. G -x B ;

[0014] S14: Solve for the value of a to ensure that the towed body has zero roll, zero pitch and is in force balance in still water.

[0015] In this invention, preferably, the value of 'a' is obtained through the force balance equation T+F. 净 =G and the torque balance equation G×a=|F 净 Solving the system of equations |×(a+l) simultaneously yields the result, where T represents the tension in the towing cable, and F... 净 G represents the net buoyancy of the towed body in the water, and G represents the weight of the towed body.

[0016] In this invention, preferably, step S2 specifically includes the following steps:

[0017] S21: The towing point is determined by constructing a second coordinate system, and the pitching moment generated by the hydrodynamic force on the towing point is obtained by constructing a third coordinate system, with the towing point as the origin of the coordinate system. Pointing towards the tail of the towed body Direction, vertically upwards. Direction, pointing towards the port side of the towed hull. Construct a second coordinate system With the centroid as the origin of the coordinate system The head of the towed body is Direction, vertically upwards. Direction, pointing towards the starboard side of the towed hull. Direction, constructing a third coordinate system - ;

[0018] S22: Calculate the coordinates of the hydrodynamic center in the second coordinate system using empirical formulas;

[0019] S23: Analyze the restoring torque and critical pitch angle when the pitch angle changes based on the relative position of the hydrodynamic center coordinates and the towing point, thereby obtaining the restoring torque and critical pitch angle when the towing body is stable.

[0020] In this invention, preferably, step S3 specifically includes the following steps:

[0021] S31: Simplify the towing system into a concentrated mass spring system;

[0022] S32: Divide the system into several nodes and perform force analysis;

[0023] S33: Establish motion equations for simulation.

[0024] In this invention, preferably, step S33 specifically includes the following steps:

[0025] S331: Initialize node parameters, determine whether the total buoyancy is greater than the total gravity. If yes, end the simulation; otherwise, proceed to step S332.

[0026] S332: Calculate and obtain the elastic elongation between nodes based on the tension and pitch angle of the nodes;

[0027] S333: Calculate the location of the node based on the elastic elongation;

[0028] S334: Determine whether the towed body can sink. If yes, end the simulation; otherwise, correct the node parameters and return to step S332.

[0029] In this invention, preferably, the node parameters include gravity, buoyancy, water resistance, inertial force, and tension.

[0030] In this invention, preferably, the stability judgment criterion for the towed body in S23 is: if the hydrodynamic center is located behind the tow point, the towing is stable; if the hydrodynamic center is located in front of the tow point, the towing is unstable.

[0031] In this invention, preferably, the concentrated mass spring system includes a tugboat, a towline, and a tow body, the towline being divided into n segments, and the number of nodes being n+1.

[0032] As a second aspect of the present invention, an active sound source towed body simulation system is proposed, the system comprising:

[0033] The model building unit is used to construct the three-dimensional model of the dragged body;

[0034] The still water attitude analysis module is used to calculate the center of gravity, center of buoyancy, and towing point position;

[0035] The hydrodynamic analysis module is used to analyze the hydrodynamic center and stability.

[0036] The drag depth analysis module is used to simulate the dynamic behavior of the dragging system;

[0037] And a simulation output module, used to output simulation results.

[0038] Based on the above technical solution, the active sound source towed body simulation method and system of the present invention has at least one of the following beneficial effects compared with the prior art:

[0039] 1. By simultaneously solving the force and moment balance equations, the drag point is calculated. The center of gravity and the center of buoyancy work together to ensure zero deviation in the initial attitude, making the still water attitude analysis more accurate and laying a high-precision foundation for subsequent simulations.

[0040] 2. Hydrodynamic analysis decomposes spatial motion and considers the influence of pitch angle, clarifies the positional relationship between the hydrodynamic center and the towing point, and can accurately calculate the critical pitch angle, avoiding errors in empirical judgment and quantifying stability assessment.

[0041] 3. A centralized mass spring system is used for modeling, taking into account the details of the force at the nodes and the pre-judgment, which reduces the simulation deviation. Taking the reference towing point as the core, the simulation of still water attitude, hydrodynamic stability and towing depth are connected in series to avoid the accumulation of errors caused by independent calculation of each link and achieve accurate verification of the whole process. Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a flowchart illustrating an active sound source dragging body simulation method according to the present invention.

[0044] Figure 2 This is a schematic diagram showing the relative positions of the center of gravity, center of buoyancy, and towing point of a towing body simulation method for an active sound source towing body according to the present invention.

[0045] Figure 3 This is a schematic diagram showing the change of the g-coordinate value of the hydrodynamic center of a towed body at different submerged angles as the flow velocity increases, according to an active sound source towed body simulation method of the present invention.

[0046] Figure 4 This is a simplified coordinate diagram of a towed body system for an active sound source towed body simulation method according to the present invention.

[0047] Figure 5 This is a schematic diagram of the force analysis of a node in an active sound source towing body simulation method according to the present invention;

[0048] Figure 6 This is a schematic diagram of the simulation process of S33 of the active sound source dragging body simulation method of the present invention. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0050] The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of the invention. The singular forms “a,” “the,” and “the” used in embodiments of the invention are also intended to include the plural forms unless the context clearly indicates otherwise.

[0051] Existing technologies suffer from problems such as coarse still-water attitude analysis, ambiguous hydrodynamic stability judgment, and large deviations in towing depth simulation in active sound source towed body simulation. Through in-depth research, it was discovered that by accurately determining the reference towing point based on the towed body's three-dimensional model and equilibrium equations to ensure zero still-water attitude, establishing a dual coordinate system, and calculating the hydrodynamic center coordinates using empirical formulas to quantify the restoring torque and critical pitch angle, the towed system is simplified into a concentrated mass spring system. Through a complete design process involving nodal force analysis, pre-judgment, and iterative simulation to predict towing depth, this method can solve the problems of low accuracy, unquantified stability judgment, large depth prediction deviations, and inability to verify the entire process in existing active sound source towed body simulations. Therefore, this invention proposes an active sound source towed body simulation method, such as... Figure 1 As shown, it includes:

[0052] S1: Determine the reference towing point of the towing body based on still water attitude analysis; By performing detailed calculations and simulations on the force balance, buoyancy distribution and gravity line position of the towing body under different placement states in still water, and combining the principles of hydrostatics, accurately determine the reference towing point corresponding to the natural equilibrium attitude of the towing body when there is no water flow interference. This point is a key reference for the subsequent towing system design, ensuring uniform force during towing and avoiding unnecessary attitude deviation.

[0053] S2: Determine the stability of the towed body through hydrodynamic and stability analysis; comprehensively consider the hydrodynamic coefficient, inertial moment and restoring moment of the towed body under different speeds and water depths to conduct numerical simulation, analyze its attitude response characteristics when subjected to external disturbances (such as wave impact and water flow changes), evaluate its stability in the longitudinal, lateral and vertical directions, and ensure that the towed body can maintain the predetermined attitude in actual operation to avoid the risk of violent swaying or capsizing;

[0054] S3: Calculate the working depth of the towed body and output simulation results; Based on the traction force parameters of the towing system, the elastic characteristics of the towing cable, and the influence of water density and depth on hydrodynamics, establish a mathematical model for iterative calculation to determine the target depth range in which the towed body can work stably under specific working conditions. At the same time, generate visualized simulation results containing key information such as attitude parameters, force distribution, and motion trajectory through simulation software to provide data support for the design optimization and practical application of the towed body.

[0055] The present invention will be further illustrated below through specific embodiments. It should be noted that the following embodiments are merely illustrative and not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the embodiments shown below without inventive effort are within the scope of protection of the embodiments of the present invention.

[0056] Example 1

[0057] In this embodiment, the still water attitude analysis further includes the following steps:

[0058] S11: The 3D model of the towed body is constructed using 3D modeling software (such as SolidWorks). The model accuracy meets the requirement that the calculation error of the center of gravity and center of buoyancy is ≤0.1%. The mass M and the coordinates of the center of gravity (x, y, y) of the towed body are obtained from the 3D model. G y G In this embodiment, the mass is 367.663 kg and the center of gravity is located at (92.736, 39.943).

[0059] S12: Set the material properties of the 3D model to water to obtain the mass of fluid discharged by the towed body, M. b and the coordinates of the center of buoyancy (x) B y B ), calculate buoyancy F 浮 =M b ×g, where g represents the acceleration due to gravity, and in this embodiment, the mass of the towed body discharging fluid is M. b The weight is 254.351 kg, the buoyancy of the towed body is 254.351 kg × 9.81 N / kg = 1111.59 N, and the position of the center of buoyancy is (62.625, 12.852).

[0060] S13: To maintain the towed body's equilibrium in still water under the influence of the cable (i.e., ensuring the towed body is in a state of zero roll, zero pitch, and force balance), a suitable towing point needs to be selected at the top cover of the towed body. The towing point, center of gravity, and center of buoyancy should be abstracted, such as... Figure 2 The diagram illustrates the relative positions of the towing center of gravity (G), the center of buoyancy (B), and the towing point (O) of this invention, with the towing point as the origin. Along the bow of the towed body, pointing towards the stern. The axis, vertically upward is The first coordinate system is constructed using axes, with the x-direction distance from the dragging point to the center of gravity denoted as 'a', and the x-direction distance between the center of gravity and the center of buoyancy denoted as 'l=x'. G -x B ;

[0061] S14: Solve for the value of a. In this embodiment, the value of a is 13.41, which means that the still water attitude of the towed body obtained by towing at this point is zero roll, zero pitch and force balance.

[0062] In this embodiment, the value of 'a' is further determined by the force balance equation T+F. 净 =G and the torque balance equation G×a=|F 净 Solving the system of equations |×(a+l) simultaneously yields the result, where T represents the tension in the towing cable, and F... 净 G represents the net buoyancy of the towed body in the water, and G represents the weight of the towed body.

[0063] In this embodiment, step S2 further includes the following steps:

[0064] S21: When a towed body is suspended at rest in water, it is acted upon by three forces: gravity, weight, and weight. Secondly, buoyancy. Thirdly, the drag force acting on the drag point. When the towed body is at zero tilt and zero nose-up position, the origin of the coordinate system is the tow point. Pointing towards the tail of the towed body Direction, vertically upwards. Direction, pointing towards the port side of the towed hull. Construct the second coordinate system by direction Based on the assumption of submarine planar motion, the spatial motion of the towed body is decomposed into two planar motions: one is the horizontal plane motion, which does not change depth and mainly studies the maintenance and change of course; the other is the vertical plane motion, which does not change course and mainly studies the maintenance and change of depth. During towing motion, the towed body is subjected to static forces and velocity-related hydrodynamic forces in the vertical plane. If the towed body experiences an additional attitude angle due to disturbance, the static restoring torque still plays a stabilizing role. Whether the towed body can remain stable depends on the effect of the hydrodynamic torque. If the hydrodynamic force generates a capsizing torque that is greater than the static restoring torque, the towed body is definitely unstable. Since the hydrodynamic force and its generated torque increase rapidly with increasing speed, while the static restoring torque remains constant, when the speed is sufficiently high, the torque generated by the hydrodynamic force will definitely exceed the static restoring torque. Therefore, for the towed body to be towed stably, the hydrodynamic force must generate a restoring torque. (Center of gravity coordinates) (a, b, c), coordinates of the floating center (d,e,f). When suspended at rest, the coordinates of the center of gravity are (-0.015, -0.193, 0) and the coordinates of the center of buoyancy are (-0.045, -0.22, 0). , , .

[0065] With the center of gravity as the origin The head of the towed body is Direction, vertically upwards. Direction, pointing towards the starboard side of the towed hull. Direction, construct the third coordinate system - Hydrodynamics in coordinate system - The projections of the upper force are respectively , , The projections of the torques are respectively , , ;

[0066] S22: Calculate the coordinates of the hydrodynamic center in the second coordinate system according to the well-known empirical formula for the longitudinal trim hydrodynamic center in the field of ship hydrodynamics. The empirical formula is as follows: ,in: This is represented as the x-axis coordinate of the hydrodynamic center in the second coordinate system, where L represents the total length of the towed body. Indicates the pitch angle. The positive sign indicates that the dragging body is burying its head. A negative value indicates that the dragging body raises its head;

[0067] Assuming the towed body generates a submerged angle after being disturbed Then the hydrodynamic force on the towing body is a resistance force that is opposite to the direction of the water flow velocity. and lift force perpendicular to the velocity direction Assume the hydrodynamic center of the towed body is at... If the coordinates in the coordinate system are (g, h, i), then the distance from the hydrodynamic center to the towing point is... , The pitching moment generated by the hydrodynamic force on the towing point is:

[0068]

[0069] set up , These are the coordinate values ​​in the second coordinate system of the hydrodynamic center. Take the height of the centroid of the towed body. This can be obtained using empirical formulas. To calculate the coordinates of the hydrodynamic center, the extent of the hydrodynamic center can be determined, such as... Figure 3The curves showing the variation of the x-coordinate of the hydrodynamic center of the towed body with the flow velocity under different pitch angles α are shown. The horizontal axis represents the flow velocity, and the vertical axis represents the x-coordinate value of the hydrodynamic center. The curves correspond to the working conditions of α = -10°, -8°, -6°, -4°, -2°, 2°, 4°, 6°, 8°, and 10°, respectively.

[0070] S23: Analyze the restoring torque and critical pitch angle when the pitch angle changes based on the relative position of the hydrodynamic center coordinates and the towing point, thereby obtaining the restoring torque and critical pitch angle when the towing body is stable. The pitch angle α ranges from -10° to 10°, where a positive α indicates that the towing body is bowed (i.e., the head is downward) and a negative α indicates that the towing body is bowed (i.e., the head is upward), corresponding to the typical postures of the towing body in actual operation, namely bowed and bowed postures.

[0071] In this embodiment, the stability judgment of the towed body in S23 is further based on the following criteria: if the hydrodynamic center is located behind the tow point, the towing is stable; if the hydrodynamic center is located in front of the tow point, the towing is unstable.

[0072] Specifically, if the calculated hydrodynamic center is after the towing point, then the lift... The resulting moment attempts to reduce the submerged angle caused by the disturbance; that is, lift generates a trim-restoring moment. Conversely, if the hydrodynamic center is ahead of the towing point, the lift... The generated torque aims to reduce the submerged angle caused by the disturbance. Increased. Because the towed body is streamlined, drag... The resistance is relatively small; when the pitch angle is 0, the hydrodynamic center is below the towing point, and as the pitch angle increases, the hydrodynamic center moves upward, resulting in increased drag. The lever arm at the drag point decreases rapidly, and the torque generated by the resistance also decreases rapidly. When the pitch angle... When it increases, lift As the pitch increases, the lever arm of the lift relative to the towing point also increases. Therefore, as long as the hydrodynamic center is behind the towing point, there must exist a critical pitch angle. This makes the angle of the head tilt downwards... Greater than At that time, the total hydrodynamic torque A value greater than 0 indicates the tilting restoring moment. The inherent drag angle corresponds to different speeds. Unlike before, in this case, the towed body is towed stably. If the initial posture of the towed body is with its head raised, the resistance... The resulting torque is also a restoring torque. Similarly, when the towed body pitches up, the lift increases with the increase of the pitch angle. As the lift increases in the opposite direction, the lever arm of the lift relative to the towing point also increases in the opposite direction. This creates a restoring torque in the opposite direction on the towed body, stabilizing its movement.

[0073] The towed system is an integrated detection system mainly composed of a tugboat, towline, and towed body. It can be applied to underwater operations such as seabed topographic exploration and marine resource exploration. It has advantages such as high work efficiency and good operational performance. The towline is the link between the tugboat and the towed body, providing power from the tugboat and bearing the main hydrodynamic forces. In the study of the towline, the mass concentration method is used to transform the main components into a single point mass, thus ensuring the accuracy of the calculated parameters of important components in principle. In this embodiment, step S3 further includes the following steps:

[0074] S31: The towing body (including tugboats, towing cables, and towing bodies) is simplified into a concentrated mass spring system. Specifically, different cables are simplified into point masses and massless springs, with the springs and point masses connected by a hinge, such as... Figure 4 As shown, the towing cable is divided into n segments, with a total of (n+1) nodes on the cable, the first being the tugboat and the last being the towing body. A fourth coordinate system is constructed with the tugboat's center of mass as the origin, the two mutually perpendicular directions at sea level as the horizontal and vertical axes, and the water depth direction as the vertical axis. To describe the attitude of each node of the towing system in the fourth coordinate system, orientation angles are introduced. and pitch angle The coordinates of node i were established by combining the node's position information, orientation angle, and pitch angle.

[0075] S32: Divide the system into several nodes and perform force analysis. Each node is subjected to gravity, buoyancy, water resistance, tension, and inertial forces, such as... Figure 5 As shown, the kinematic equations of node i are obtained:

[0076]

[0077] In the formula: The mass of node i; Let be the acceleration vector of node i; Let i be the buoyancy force acting on node i. ; Let be the gravitational force acting on node i. ; In the water flow The water resistance vector experienced by the lower node i; Let be the vector of the inertial force acting on node i; , Let be the tension vector of the rope acting on node i;

[0078] S33: Establish motion equations for simulation.

[0079] Node i is subjected to tension force and The function of this is based on the coordinate system established above. , , By decomposing the directions, we obtain the analytical equations for the tension force in the three directions:

[0080]

[0081] Since the tugboat and the towing body experience different forces at the intermediate nodes of the cable, the tension of the first and last nodes is set to 0.

[0082] Water resistance is the velocity. and the speed of movement of components Coupling effect. Based on the formula for calculating fluid water resistance, the expression for the fluid water resistance of component i is obtained:

[0083]

[0084] Let be the fluid resistance coefficient at node i; Let be the area of ​​node i facing the flow direction; The velocity vector at the depth of node i; Let i be the velocity vector of node i.

[0085] The inertial force at a node mainly consists of the added mass of the node and the inertial force caused by the volume of water displaced by the node. The inertial force at node i... The mathematical expression:

[0086]

[0087] For the additional quality coefficient, ; Added mass to the overall mass, ;

[0088] Based on the above force analysis, substitute the above formula into the equation.

[0089] Based on the above equations of motion, a simulation model was established to analyze and study the changes in tension, attitude, and angle of the cable under different flow velocities.

[0090] In this embodiment, further, as Figure 6 As shown, step S33 specifically includes the following steps:

[0091] S331: Initialize node parameters and determine whether the total buoyancy is greater than the total gravity. If so, it means that the towing system is not heavy enough to dive and the simulation ends. Otherwise, proceed to step S332. The pre-judgment step can avoid a certain proportion of invalid iterations. By setting the iteration termination condition, such as coordinate difference ≤ 0.1m, the convergence speed can be greatly improved.

[0092] S332: Calculate parameters such as water resistance, tension, and pitch angle for each node;

[0093] S333: And using tension and pitch angle, calculate the elastic elongation between each node, thereby obtaining the actual position of each node;

[0094] S334: Determine whether the towed body can sink, that is, determine whether the depth change of the towed body in three consecutive iterations is less than or equal to a preset threshold. In this embodiment, the preset threshold is set to 0.1m, and is adjusted to 0.05m-0.2m according to the actual ocean current speed and water depth. If yes, it is determined that the towed body can sink to a stable working depth and the simulation ends. Otherwise, the node parameters are corrected, that is, the ocean current speed and tugboat speed are adjusted according to the actual situation, and the process returns to step S332.

[0095] In this simulation, the towed body mass was selected as 380 kg, the buoyancy as 1100 N, the cable diameter as 20 mm, the cable mass as 1250 g / m, the cable buoyancy as 28 N / m, the rated working tensile force as 50 kN, the minimum breaking strength as 150 kN, and the minimum bending radius as 300 mm. The cable length was 800 m, divided into 80 segments of 10 meters each. The first node was the tugboat, the last node was the towed body, and the rest were the cable.

[0096] As the flow velocity increases, the drag coefficient gradually decreases, but the decreasing trend is small. To ensure a safety margin, the maximum drag coefficient of 0.126 for the towed body is selected. The drag coefficient of the cylinder at different flow velocities is typically between 1.1 and 1.4. To ensure a safety margin in the simulation results, the subsequent simulation of the cable section uses the drag coefficient. Calculate the depth change of the towed body node, i.e., the last node. The depth change is the difference between the current iteration depth and the previous iteration depth. If the difference is ≤0.1 meters, it means that the towed body depth is stabilizing and can sink to the target depth, and the simulation ends. If the difference is >0.1 meters, correct the node parameters, such as adjusting the ocean current velocity and the tugboat speed, and return to step S332 to iterate until the working depth stabilizes.

[0097] In this embodiment, the node parameters further include gravity, buoyancy, water resistance, inertial force, and tension.

[0098] In this embodiment, the concentrated mass spring system further includes a tugboat, a towline, and a tow body. The towline is divided into n segments, and the number of nodes is n+1.

[0099] An active sound source towed body simulation system, the system comprising:

[0100] The model building unit is used to build a 3D model of the dragged body using 3D modeling software such as SolidWorks. The model must include the dragged body shell, internal equipment, drag point interface structure, and support the export of parameters such as mass, center of gravity, and center of buoyancy.

[0101] The still water attitude analysis module is used to import the mass, center of gravity, and center of buoyancy parameters output by the model building unit, and automatically calculate the buoyancy F. 浮 Gravity G, Net buoyancy F 净 Solve the equilibrium equations to find the reference towing point position and output the still water attitude parameters, which include the center of gravity, center of buoyancy and towing point coordinates.

[0102] The hydrodynamic analysis module is used to import parameters such as the total length L of the towed body and the pitch angle α, calculate the coordinates of the hydrodynamic center based on empirical formulas, analyze the relative position of the hydrodynamic center and the tow point, and output stability parameters, including the position of the hydrodynamic center, the restoring moment, and the critical pitch angle.

[0103] The towing depth analysis module is used to set parameters such as the number of towing cable segments n, ocean current speed u, and tugboat speed to simulate the dynamic behavior of the towing system. Through node force analysis and iterative calculation, it outputs the curve of the towing depth changing with time or ocean current speed.

[0104] It also includes a simulation output module, which integrates the output results of the above modules and outputs simulation reports in the form of tables, curves, and 3D model annotations, including still water attitude verification results, stability assessment results, and drag depth prediction results, and supports exporting to PDF or Excel format.

[0105] This invention accurately solves for the reference towing point by simultaneously solving the force balance equation and torque balance equation in the still water attitude analysis stage. This effectively avoids the initial roll and pitch deviations caused by traditional empirical setting of the towing point, laying a high-precision foundation for subsequent simulations. By constructing a multi-coordinate system and calculating the coordinates of the hydrodynamic center using clear empirical formulas, it quantitatively analyzes the restoring torque and critical roll angle when the pitch angle changes, clearly defining the impact of the relative position of the hydrodynamic center and the towing point on stability. This solves the problems of ambiguous hydrodynamic stability judgment and inability to quantify critical parameters in existing technologies. The towing system is simplified into a concentrated mass spring system. Through pre-judgment by comparing nodal force analysis with total buoyancy and total gravity, and iterative simulation with depth change threshold control, the simulation deviation of towing depth is significantly reduced. At the same time, the entire process of still water attitude, hydrodynamic stability, and towing depth simulation is connected in series with the reference towing point as the core, avoiding the accumulation of errors from independent calculations in each stage, significantly improving the overall simulation accuracy and efficiency. It can better adapt to marine environmental risks, accurately verify the still water attitude, motion stability, and working depth performance of the active acoustic source towed body, and provide reliable support for towed body design optimization.

[0106] In the description of the embodiments of the present invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In the embodiments of the present invention, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in the embodiments of the present invention, as well as the features of the different embodiments or examples.

[0107] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of embodiments of the present invention, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0108] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for simulating an active sound source towed body, characterized in that, include: S1: Determine the reference towing point of the towing body based on still water attitude analysis; S11: Obtain the towed body structural parameters through the three-dimensional model of the towed body. The towed body structural parameters include the mass M and the coordinates of the center of gravity (x). G y G ); S12: Set the material properties of the 3D model to water to obtain the mass of fluid discharged by the towed body, M. b and the coordinates of the center of buoyancy (x) B y B ), calculate buoyancy F 浮 =M b ×g, where g represents the acceleration due to gravity; S13: Construct the first coordinate system, denoting the distance in the x-direction from the dragging point to the center of gravity as 'a', and the distance in the x-direction between the center of gravity and the center of buoyancy as 'l=x'. G -x B ; S14: Solve for the value of a to ensure that the towed body has zero roll, zero pitch and is in force balance in still water. S2: Determine the stability of the towed body through hydrodynamic and stability analysis; S21: Determine the towing point by constructing a second coordinate system, and obtain the pitching moment generated by the hydrodynamic force on the towing point by constructing a third coordinate system; S22: Calculate the coordinates of the hydrodynamic center in the second coordinate system based on the pitching moment, towed body structural parameters, and empirical formulas. S23: Analyze the restoring torque and critical pitch angle when the pitch angle changes based on the relative position of the hydrodynamic center coordinates and the towing point, so as to obtain the restoring torque and critical pitch angle when the towing body is stable; S3: Calculate the working depth of the towed body and output the simulation results; Using the drag point as the origin of the coordinate system Pointing towards the tail of the towed body Direction, vertically upwards. Direction, pointing towards the port side of the towed hull. Construct the second coordinate system by direction With the centroid as the origin of the coordinate system The head of the towed body is Direction, vertically upwards. Direction, pointing towards the starboard side of the towed hull. Direction, construct the third coordinate system - .

2. The active sound source towed body simulation method according to claim 1, characterized in that, Using the drag point as the origin Along the bow of the towed hull, pointing towards the stern. The axis, vertically upward is The first coordinate system is constructed using axes.

3. The active sound source towed body simulation method according to claim 1, characterized in that, The value of 'a' is obtained from the force balance equation T+F. 净 =G and the torque balance equation G×a=|F 净 Solving the system of equations |×(a+l) simultaneously yields the result, where T represents the tension in the towing cable, and F... 净 G represents the net buoyancy of the towed body in the water, and G represents the weight of the towed body.

4. The active sound source towed body simulation method according to claim 1, characterized in that, The stability judgment criteria for the towed body in S23 are as follows: if the hydrodynamic center is located behind the tow point, the towing is stable; if the hydrodynamic center is located in front of the tow point, the towing is unstable.

5. The active sound source towed body simulation method according to claim 1, characterized in that, S3 specifically includes the following steps: S31: Simplify the towing system into a concentrated mass spring system; S32: Divide the system into several nodes and perform force analysis; S33: Establish motion equations for simulation.

6. The active sound source towed body simulation method according to claim 5, characterized in that, The centralized mass spring system includes a tugboat, a towline, and a tow body. The towline is divided into n segments, and there are n+1 nodes.

7. The active sound source towed body simulation method according to claim 5, characterized in that, S33 specifically includes the following steps: S331: Initialize node parameters, determine whether the total buoyancy is greater than the total gravity. If yes, end the simulation; otherwise, proceed to step S332. S332: Calculate and obtain the elastic elongation between nodes based on the tension and pitch angle of the nodes; S333: Calculate the location of the node based on the elastic elongation; S334: Determine whether the towed body can sink. If yes, end the simulation; otherwise, correct the node parameters and return to step S332.

8. The active sound source towed body simulation method according to claim 7, characterized in that, The node parameters include gravity, buoyancy, water resistance, inertial force, and tension.

9. An active sound source towed body simulation system, employing the simulation method as described in any one of claims 1 to 8, the system comprising: The model building unit is used to construct the three-dimensional model of the dragged body; The still water attitude analysis module is used to calculate the center of gravity, center of buoyancy, and towing point position; The hydrodynamic analysis module is used to analyze the hydrodynamic center and stability. The drag depth analysis module is used to simulate the dynamic behavior of the dragging system; as well as The simulation output module is used to output simulation results.

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