Method and system for predicting hydrodynamic load loss of deep-sea mining vehicle during water entry process

Abstract

The application provides a kind of hydrodynamic load loss prediction method and system of deep-sea mining vehicle water entry process, method includes: obtaining the related parameters of deep-sea mining vehicle and constructing CFD simulation model, and extracting vehicle speed-time data fitting speed attenuation function;Respectively for the calculation of steady-state total water dynamics of vehicle fully submerged state, for the establishment of transient water dynamics expression based on momentum theorem for vehicle partially submerged and cavity not closed state;Based on the momentum conservation law, the additional mass expression is inverted, and the power law relationship between dimensionless cavity volume and Froude number is constructed and fitted to obtain the cavity volume expression;Cavity volume is substituted into the additional mass expression for correction, and substituted into the transient water dynamics expression to calculate the water dynamics peak before cavity closure, combined with the steady-state water dynamics value to obtain the water dynamics load loss prediction value.The application can accurately predict the water dynamics load loss caused by cavity closure in the water entry process of mining vehicle, and provide data basis for cable tension dynamic control.

Description

Technical Field

[0001] This invention belongs to the field of deep-sea mining technology, specifically relating to a method and system for predicting hydrodynamic load loss during the entry of a deep-sea mining vehicle into the water. Background Technology

[0002] With the increasing depletion of terrestrial mineral resources, deep-sea mining has become an important direction for meeting global resource demands. Deep-sea mining vehicles, as core equipment in mineral extraction, directly determine mining efficiency through their operational safety and reliability. During the deployment of deep-sea mining vehicles, the process of lifting and lowering the vehicle into the water involves several key stages: contact with the water surface, the formation of a cavity as the vehicle enters the water, the gradual closing of the cavity, and complete closure of the cavity and full submersion of the vehicle. Under the influence of strong nonlinear multiphase flow near the free surface, the vehicle's entry into the water generates extremely complex hydrodynamic loads. When the vehicle enters the water and forms a cavity, the volume of the cavity generates additional dynamic buoyancy. However, when the cavity closes, the flow field state experienced by the vehicle abruptly changes from a nonlinear state at a semi-submerged height to a steady-state flow state under full submersion. The additional buoyancy generated by the cavity volume instantly disappears, and the drainage volume becomes only the geometric drainage volume of the vehicle, with buoyancy rapidly returning to static buoyancy. This can cause a sudden and severe loss of transient load and a sudden change in tension on the laying cable in a very short time, which greatly increases the risk of cable breakage and thus poses a serious threat to the safety and reliability of the laying operation.

[0003] Conventional hydrodynamic calculation models for fully submerged flow are widely used to estimate the steady-state loads of conventional underwater equipment due to their high computational efficiency and wide applicability, as a method for evaluating the force state of an object in a flow field. In current research, the paper "Numerical Investigation of Hydrodynamic Coefficients and Wake Characteristics of a Deep-Sea Mining Vehicle" (Machines, 2025, Vol. 13, No. 699) discloses the hydrodynamic parameters of a deep-sea mining vehicle under fully submerged conditions: the vertical water resistance coefficient of the vehicle body. The value is 1.0066, with an additional quality factor. The value is 3.096 (see page 17 of the literature for details). Some studies typically use these fixed constant coefficients and apply specific fluid expressions to predict the conventional hydrodynamic components such as hydrostatic buoyancy, pressure drag, and additional mass inertial force experienced by the vehicle body under full immersion conditions.

[0004] However, existing research largely focuses on hydrodynamic calculations for fully submerged underwater equipment, with limited studies on hydrodynamic loads during cross-interface processes. It lacks precise analysis of the equipment's hydrodynamic characteristics and load losses before and after cavity closure, and suffers from the following shortcomings: First, classical constant-coefficient prediction methods fail when the ingress cavity is not closed and the flow field exhibits high nonlinearity; second, the dynamic added mass during motion is extremely difficult to measure; and third, the mechanical energy dissipation and impact force caused by strong inelastic collisions cannot be ignored. These shortcomings directly prevent existing methods from meeting the high-precision load prediction requirements for cross-interface entry during the mining vehicle deployment stage, thus hindering the engineering application of deep-sea mining technology.

[0005] Therefore, there is an urgent need to propose a method for predicting the hydrodynamic load loss of deep-sea mining vehicles under the cavity closure effect at the water entry interface, so as to accurately determine the dynamic additional mass change, transient impact force and hydrodynamic load loss of the variable mass system before and after cavity closure, thereby providing key hazardous working condition load data for the reliability design of the deployment and recovery system, and improving the safety of vehicle deployment in complex free water environments. Summary of the Invention

[0006] This invention provides a method and system for predicting hydrodynamic load loss during the entry of a deep-sea mining vehicle into the water, in order to solve the technical problem that existing methods cannot meet the high-precision load prediction requirements for cross-interface water entry during the deployment stage of the mining vehicle, thus restricting the engineering application of deep-sea mining technology.

[0007] To achieve the above objectives, a method for predicting hydrodynamic load loss during the entry of a deep-sea mining vehicle into water is provided, comprising the following steps: Obtain the geometric parameters, mass parameters, and initial water entry velocity of the deep-sea mining vehicle, and construct a CFD simulation model of the deep-sea mining vehicle; Based on the CFD simulation model, the vertical velocity-time discrete data of the vehicle body at different times are extracted, and the data are fitted using a preset exponential decay function to obtain a fitting function characterizing the change of vehicle body velocity with time. For a vehicle body that is completely submerged, based on the preset additional mass coefficient and water resistance coefficient, combined with the vehicle body's geometric parameters and the fitting function, the steady-state total hydrodynamic force on the vehicle body after the cavity is closed is calculated, and the steady-state hydrodynamic force value is output. For a vehicle body partially submerged and with the cavity not closed, the vehicle body and the following fluid are considered as a variable mass system. Based on the momentum theorem, the hydrodynamic force on the vehicle body is decomposed into dynamic buoyancy, pressure drag, additional mass inertial force and impact force, and a transient hydrodynamic expression is established. Based on the law of conservation of momentum, the expression for the additional mass of the vehicle body before the cavity is closed is obtained by inverse calculation using the impulse balance relationship between the initial momentum and the peak momentum of the variable mass system. Based on the Logvinovich independent section principle and the inertia-dominated cavity expansion theory, a power-law relationship between dimensionless cavity volume and Froude number and dimensionless time is constructed, and then fitted with CFD simulation data to output a dimensional expression for the volume of the vehicle body drainage cavity. Substitute the dimensional expression into the additional mass expression to obtain the corrected additional mass. Substitute the corrected additional mass into the transient hydrodynamic expression to calculate the peak hydrodynamic force before the cavity closes. By combining the peak hydrodynamic value and the steady-state hydrodynamic value, the predicted value of hydrodynamic load loss is calculated. The predicted value of hydrodynamic load loss is used to evaluate the magnitude of the tension surge when the cable is laid at the moment the cavity closes, and to provide data basis for dynamic control of cable tension.

[0008] In one embodiment, the geometric parameters include the vehicle body volume and the vehicle body bottom area, the mass parameters include the added mass coefficient and the water resistance coefficient, and the steady-state hydrodynamic value is calculated as follows: , in, For still water buoyancy, The density of water, For gravity, Let the geometric volume of the vehicle body be denoted as . The pressure drag when the vehicle body is completely submerged. The coefficient of water resistance. The area facing the water flow perpendicular to the vehicle body when it is completely submerged. , The bottom area of ​​the vehicle body. For the vehicle body The pitch angle at any moment, for The vertical velocity of the vehicle at any given moment, where the vertical direction is perpendicular to the water surface. To add mass force, For the additional quality coefficient, for The vertical acceleration of the vehicle body at any given moment.

[0009] In one embodiment, the process of decomposing the hydrodynamic forces acting on the vehicle body into dynamic buoyancy, pressure drag, additional mass inertial force, and impact force based on the momentum theorem, and establishing a transient hydrodynamic expression, includes: Calculate the force exerted by the fluid reaction on the vehicle body using the momentum theorem. , ,in, The instantaneous momentum of the fluid is given. , Add mass to the vehicle body before the cavity closes. These are dynamic values ​​that change over time. The instantaneous velocity of the vehicle body in the vertical direction; Based on the force of the fluid reaction on the vehicle body Decomposition yields additional mass inertial force and the power of criticism Additional mass inertial force The impact force is the fluid inertial reaction force that the vehicle body must overcome to accelerate the surrounding fluid. This characterizes the additional impact force generated on the vehicle body when there is a drastic change in the vehicle's added mass. The instantaneous acceleration of the vehicle body in the vertical direction. Add a rate of change of mass to the vehicle body; Based on the obtained additional mass inertial force and the power of criticism Establish the transient hydrodynamic expression: , in, This represents dynamic buoyancy, characterizing the transient buoyancy generated by the combined displacement of seawater by the vehicle's geometric volume and the volume of its open cavities. This refers to the volume of the vehicle body's drainage cavity. This represents the pressure difference drag when the cavity is not closed, and characterizes the flow resistance formed by the pressure difference between the front and back surfaces during vehicle movement. This represents the vertical frontal area of ​​the vehicle body when the cavity is not closed, which represents the water resistance of the vehicle body.

[0010] In one embodiment, the mass parameter includes the vehicle body mass. The expression for the additional mass of the vehicle body before cavity closure is obtained by inversion calculation based on the law of conservation of momentum and utilizing the impulse balance relationship between the initial momentum and the peak momentum of the variable mass system. This includes: Calculate the initial momentum of the variable mass system at the moment the vehicle body enters the water. , ,in, For vehicle body mass, The speed at which the vehicle just touches the water surface; Calculate the peak moment momentum of the variable mass system when the vertical force on the vehicle body reaches its peak during water immersion. , ,in, The velocity at the peak of the vertical force experienced by the vehicle body during its immersion in water; The external impulse of the variable mass system is calculated based on dynamic buoyancy, pressure resistance when the cavity is not closed, and the integral of gravity over time. , ,in, For dynamic buoyancy, This refers to the pressure differential resistance when the cavity is not closed. According to the external impulse The initial momentum and the peak moment momentum The inversion calculation yields the expression for the additional mass of the car body before the cavity closes: .

[0011] In one embodiment, the geometric parameters further include vehicle body feature dimensions. The method involves constructing a power-law relationship between dimensionless cavity volume and Froude number and dimensionless time, based on the Logvinovich independent section principle and the inertia-dominated cavity expansion theory, and fitting this relationship with CFD simulation data to output a dimensional expression for the vehicle body drainage cavity volume, including: Based on the Logvinovich independent section principle and the inertia-driven cavity expansion theory, the parameters affecting the cavity volume evolution during water entry are dimensionless, including: constructing the Froude number. Characterizing the ratio of inertial force to gravity, constructing a dimensionless time. Characterizes the ratio of vehicle diving distance to vehicle feature dimensions, and expresses this relationship in terms of vehicle volume. Based on the volume of the vehicle body drainage cavity Dimensionless transformation ,in, These are the characteristic dimensions of the vehicle body. The initial velocity of the vehicle body upon entering the water. The time measured from the moment the vehicle body touches the water surface; Establish dimensionless cavity volume The power-law relationship is as follows: ; Using CFD simulation data of several sets of vehicles with different initial water entry velocities as calibration samples, the least squares method was used for fitting, and the empirical coefficients in the power-law relationship were obtained through calibration. , , The specific values ​​are used to obtain the volume of the vehicle body drainage cavity. Dimensional expression .

[0012] In one embodiment, the preset velocity decays exponentially over time as a function is: ,in, The velocity in the vertical direction of the vehicle body is [value]. The initial velocity of the vehicle body upon entering the water. The time measured from the moment the vehicle body touches the water surface; The decay exponent is used to fit and extract the function by minimizing the mean square error between the exponential decay function and the vertical velocity-time discrete data points of the CFD simulation. Substituting the dimensional expression for the volume of the vehicle body drainage cavity into the expression for the additional mass, we obtain the corrected additional mass as follows:

[0013] in, This is the moment when the vertical force on the vehicle reaches its peak during the process of the vehicle entering the water.

[0014] In one embodiment, the modified additional mass is substituted into the transient hydrodynamic expression to obtain the modified peak value of the total hydrodynamic force on the vehicle body before cavity closure. , ; The hydrodynamic load loss experienced by the vehicle body before and after the cavity is closed is as follows: ,in, This represents the hydrodynamic load loss value experienced by the vehicle body before and after the cavity is closed. This represents the peak value of the total hydrodynamic force acting on the vehicle body before the cavity closes. This refers to the hydrodynamic force exerted on the vehicle body after the cavity is closed.

[0015] Based on the same inventive concept, this invention also proposes a hydrodynamic load loss prediction system for the deep-sea mining vehicle entering the water, comprising: The simulation model construction module is used to obtain the geometric parameters, mass parameters and initial water entry velocity of the deep-sea mining vehicle, and to construct the CFD simulation model of the deep-sea mining vehicle. The vehicle speed fitting module is used to extract the vertical velocity-time discrete data of the vehicle body at different times based on the CFD simulation model, and to fit it using a preset exponential decay function to obtain a fitting function that characterizes the change of vehicle speed with time. The steady-state hydrodynamic calculation module is used to calculate the steady-state total hydrodynamic force on the vehicle body after the cavity is closed, based on the preset additional mass coefficient and water resistance coefficient, combined with the vehicle body's geometric parameters and the fitting function, and output the steady-state hydrodynamic force value for the vehicle body in a fully submerged state. The transient hydrodynamics construction module is used to treat the vehicle body and the following fluid as a variable mass system when the vehicle body is partially submerged and the cavity is not closed. Based on the momentum theorem, the hydrodynamic force on the vehicle body is decomposed into dynamic buoyancy, pressure drag, additional mass inertial force and impact force, and a transient hydrodynamic expression is established. The additional mass inversion module is used to invert and calculate the expression of the additional mass of the vehicle body before the cavity is closed, based on the law of conservation of momentum and the impulse balance relationship between the initial momentum and the peak momentum of the variable mass system. The cavity volume fitting module is used to construct a power-law relationship between dimensionless cavity volume and Froude number and dimensionless time based on the Logvinovich independent section principle and the inertia-dominated cavity expansion theory. It then combines CFD simulation data for fitting and outputs a dimensional expression for the volume of the vehicle body drainage cavity. The dynamic peak calculation module is used to substitute the dimensional expression into the additional mass expression to obtain the corrected additional mass, and then substitute the corrected additional mass into the transient hydrodynamic expression to calculate the hydrodynamic peak before the cavity is closed. The load loss calculation module is used to combine the peak hydrodynamic value and the steady-state hydrodynamic value to calculate the predicted value of hydrodynamic load loss. The predicted value of hydrodynamic load loss is used to evaluate the magnitude of the tension surge when the cable is laid at the moment the cavity closes and to provide data basis for dynamic control of cable tension.

[0016] Based on the same inventive concept, the present invention also proposes an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the prediction method as described above.

[0017] Based on the same inventive concept, embodiments of the present invention also propose a computer storage medium storing at least one executable instruction that causes a processor to execute the prediction method described above.

[0018] Compared with existing technologies, the beneficial effects of this invention are as follows: Addressing the complex dynamic phenomenon of drastic hydrodynamic changes before and after cavity closure during vehicle immersion, a high-precision predictive calculation model of the hydrodynamic forces acting on the vehicle body before and after cavity closure is constructed. This model accurately captures the peak impact value and evolution law of water immersion, strictly controlling the prediction calculation error of hydrodynamic load loss to within 5%. It not only fills the gap in related fluid-structure interaction dynamics rapid prediction models, but also provides core theoretical basis and data support for fluid load assessment during the deployment and diving process of deep-sea mining vehicles, dynamic control of umbilical cable / wire rope tension in deep water, and analysis of system motion stability. It has significant engineering practical value and broad application prospects for ensuring the safe deployment and stable operation of deep-sea heavy-duty equipment. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1This is a flowchart of the method for predicting hydrodynamic load loss during the entry of a deep-sea mining vehicle into water, as described in this embodiment of the invention. Figure 2 This is a schematic diagram of a three-dimensional model of the deep-sea mining vehicle in an embodiment of the present invention; Figure 3 This is a time-series diagram showing the characteristics of a deep-sea mining vehicle entering the water under a certain working condition in a physics experiment; Figure 4 This is a time-series diagram showing the characteristics of a deep-sea mining vehicle entering the water under the corresponding working conditions in the simulation. Figure 5 This is statistical data on the vehicle body tilt angle when the cavity closes at different initial release tilt angles when the release height is 500mm; Figure 6 This is a comparison chart of theoretical calculations and simulation results of the vertical hydrodynamic forces experienced by the vehicle body under different initial water entry velocities after the cavity is closed. Figure 7 This is a comparison chart of theoretical calculations and simulation results of the peak vertical hydrodynamic force on the vehicle body under different initial water entry velocities before the cavity is closed. Figure 8 This is a schematic diagram of the hydrodynamic load loss prediction system for the deep-sea mining vehicle entering the water process in an embodiment of the present invention; Figure 9 This is a schematic diagram of an electronic device in an embodiment of the present invention. Detailed Implementation

[0021] 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.

[0022] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this invention should have the ordinary meaning understood by those skilled in the art. The terms "first," "second," and similar terms used in the embodiments of this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0023] like Figure 1 As shown in the figure, this embodiment of the invention provides a method for predicting hydrodynamic load loss during the entry of a deep-sea mining vehicle into the water, including the following steps.

[0024] S1: Obtain the geometric parameters, mass parameters, and initial velocity upon entering the water of the deep-sea mining vehicle, and construct a CFD simulation model of the deep-sea mining vehicle.

[0025] S2: Based on the CFD simulation model, extract the vertical velocity-time discrete data of the vehicle body at different times, and use the preset exponential decay function to fit it to obtain the fitting function characterizing the change of vehicle body velocity with time.

[0026] S3: For the vehicle body in a fully submerged state, based on the preset additional mass coefficient and water resistance coefficient, combined with the vehicle body's geometric parameters and fitting function, calculate the steady-state total hydrodynamic force on the vehicle body after the cavity is closed, and output the steady-state hydrodynamic force value.

[0027] S4: For the vehicle body partially submerged and the cavity not closed, the vehicle body and the following fluid are regarded as a variable mass system. Based on the momentum theorem, the hydrodynamic force on the vehicle body is decomposed into dynamic buoyancy, pressure drag, additional mass inertial force and impact force, and a transient hydrodynamic expression is established.

[0028] S5: Based on the law of conservation of momentum, the expression for the additional mass of the car body before the cavity is closed is obtained by inversion calculation using the impulse balance relationship between the initial momentum and the momentum at the peak moment of the variable mass system.

[0029] S6: Based on the Logvinovich independent section principle and the inertia-dominated cavity expansion theory, a power-law relationship between dimensionless cavity volume and Froude number and dimensionless time is constructed, and then fitted with CFD simulation data to output a dimensional expression for the volume of the vehicle body drainage cavity.

[0030] S7: Substitute the dimensional expression into the additional mass expression to obtain the corrected additional mass. Substitute the corrected additional mass into the transient hydrodynamic expression to calculate the peak hydrodynamic force before the cavity closes.

[0031] S8: Combining the peak hydrodynamic value and the steady-state hydrodynamic value, the predicted value of hydrodynamic load loss is calculated. The predicted value of hydrodynamic load loss is used to evaluate the tension surge of the cable during the moment of cavity closure and to provide data basis for dynamic control of cable tension.

[0032] In step S1, the geometric parameters include the vehicle body volume V. V Vehicle body bottom area A z And the vehicle body characteristic dimension D. Mass parameters include vehicle body mass, added mass coefficient, and water resistance coefficient.

[0033] In this embodiment, in conjunction with reference to Figure 2 According to Table 1, the parameter settings for the deep-sea mining vehicle model used in the experiment are as follows: Table 1:

[0034] In this embodiment, the criterion for determining cavity closure is that the buoyancy of the vehicle body is found in the CFD to recover to the buoyancy generated by the displacement of the vehicle body volume at a certain moment, thus determining that the cavity is closed. In other embodiments, the criterion for determining cavity closure may also be that, according to the flow field diagram, the cavity begins to detach from the upper surface of the vehicle body, thus determining that the cavity is closed.

[0035] In this embodiment, before step S2, the accuracy of computational fluid dynamics (CFD) simulation in predicting the vehicle body's water entry attitude and cavity change patterns is verified through physical experiments.

[0036] The verification test used a scaled-down model, conducted in a transparent sidewalled water tank with a water depth of 0.4m. The model was released from a set height via an electromagnetic release device, and the water entry speed was controlled by adjusting the release height. The initial release angle ranged from -60° to 60° horizontally. A high-speed camera (1280×800 resolution, 5000fps sampling frequency) recorded the water entry process, and the vehicle tilt angle was extracted through image post-processing.

[0037] CFD simulations use a VOF multiphase flow model to track changes in the free surface, and employ k-... The SST turbulence model captures the flow field changes during vehicle entry into the water. The boundary conditions of the simulated fluid domain are a velocity inlet, a pressure outlet, and a wall, with the wall being a symmetrical plane. A cut-volume mesh generation scheme is used, with refinement applied to the free interface (water surface) and the vehicle's motion region, resulting in a total mesh count of 7 million and a minimum mesh size of 0.0625m. The simulation time compensation is set to 0.0025s, and the vehicle motion and force data collected are the changes in the vehicle's center of mass, sampled at a frequency of 400Hz.

[0038] Specifically, will Figure 3 Experimental test records and Figure 4 Comparative analysis of numerical simulations reveals a high degree of agreement between the simulated cavity variation patterns and vehicle attitude and the experimental results, validating the accuracy of the CFD simulation model. During the entire water entry process from t=0.00s to t=0.20s, the simulation not only accurately captured the complex motion of the vehicle body under the influence of hydrodynamic torque, including clockwise deflection and downward and rightward submersion, but also reproduced with high precision the large deformation evolution of the air-water two-phase flow interface, including the formation of open cavities, asymmetric stretching, and cavitation morphology attached to the vehicle surface. This highly consistent comparison fully validates the reliability of the numerical calculation method, laying a solid data foundation for subsequent accurate extraction of cavity features and prediction of hydrodynamic load losses.

[0039] With a release height of 500mm, experimental and simulation comparison data of the vehicle body tilt angle when the cavity is closed are shown below for different initial release tilt angles of the vehicle body. Figure 5 As shown, the relative error between the two is between 4.0% and 9.0%, with an average error of approximately 6.8%. This error mainly originates from angle measurement errors in image post-processing and manufacturing errors in the scaled-down model. For a highly nonlinear water entry process, this error is within an acceptable engineering range, indicating that the simulation model has good predictive ability in simulating highly nonlinear water entry processes. Figure 5 The vehicle tilt angle prediction error data shown further supports the reliability of the CFD simulation model for subsequent cavity evolution and hydrodynamic load prediction.

[0040] In this embodiment, step S2 is to fit a vehicle speed expression based on CFD speed change data.

[0041] First, assume that the velocity of an object decelerating in water decreases exponentially with time, that is: (1) Then, the velocity change data of the CFD was fitted and extracted using MATLAB. The fitting used 1920 data points, and R0 was calculated. 2 =0.931. Time in this embodiment In seconds (s), the formula The exponent in the equation is a dimensionless quantity.

[0042] In step S3 of this embodiment, for the fully submerged state, the additional buoyancy generated by the cavity volume of the vehicle body disappears, and the vehicle body's drainage volume becomes only the geometric drainage volume, restoring the vehicle body's buoyancy to static buoyancy. Simultaneously, as the vehicle body enters the fully submerged state, the additional mass generated during the vehicle's movement in water tends to stabilize. Based on existing research: the coefficient of additional mass in water... Water resistance coefficient Calculate the total hydrodynamic forces (including hydrostatic buoyancy, pressure drag, and additional mass forces) acting on the vehicle body when the cavity is closed: (2) in, It is the total hydrodynamic force experienced by the vehicle body when it is completely submerged. The buoyancy force is in still water, directed upwards, and is taken as a positive value. The pressure drag caused by the vehicle body being completely submerged is in the opposite direction to the direction of motion. As an additional mass force, when the vehicle body decelerates downwards, the direction is upwards, and a positive value is taken; The density of water, For gravity, The geometric volume of the vehicle body is expressed in units of 1000 liters. , for The vertical velocity of the vehicle at any given time, in units of In this embodiment The timeframe is when the vehicle's buoyancy recovers to a volume of 44.31m³ in the CFD calculation data. 3 The moment when steady-state buoyancy is generated is the moment when the vehicle body is completely submerged. for The vertical acceleration of the vehicle body at time t, in units of t. ; The area facing the water resistance in the vertical direction when the vehicle body is completely submerged is calculated using equation (3): (3) in, This refers to the bottom area of ​​the vehicle body; For the vehicle body The pitch angle at any given moment is obtained by directly reading the vehicle's rotation angle around the y-axis from the CFD.

[0043] Additional quality coefficient Water resistance coefficient The method is applicable to mining vehicles with the geometry shown in this embodiment. For vehicles with other shapes or different scale ratios, the same method can be used for calibration.

[0044] Figure 6 The theoretical calculation and simulation results of the vertical hydrodynamic force on the vehicle body under eight different initial water entry velocities after the cavity is closed are compared. The data show that the hydrodynamic values ​​under each condition are stable at around 500kN, and the trend of the two shows a high degree of consistency. From the relative error distribution on the right vertical axis, the error scatter points of all conditions are strictly controlled within the range of [-4.83%, +3.3%]. The theoretical calculation and simulation results of condition 3 are almost completely consistent, which shows that formula (2) has extremely high accuracy and reliability in predicting the hydrodynamic characteristics of the vehicle body after the cavity is closed.

[0045] In step S4 of this embodiment, for a variable mass system, the hydrodynamic components are solved according to Newton's second law and the fluid momentum theorem, and the additional mass inertial force during the cross-interface water entry process is decomposed.

[0046] Because the vehicle body was not completely submerged and carried an expanding dynamic cavity, the surrounding fluid boundary was undergoing drastic changes. The instantaneous momentum of this moving fluid... for: (4) in, Added mass to the vehicle body, in units of , The instantaneous velocity of the vehicle body in the vertical direction, in units of .

[0047] In this invention, Defined as the equivalent mass of the surrounding fluid forced to move along with the vehicle body during acceleration or deceleration. This differs from the constant additional mass in classical potential flow theory, which is based on the assumption of an infinite-domain flow field. It is a dynamic equivalent added mass that takes into account the effects of free surface and cavity evolution, and its value varies with the vehicle body immersion depth and cavity volume.

[0048] According to the momentum theorem, the force exerted by the vehicle body on the fluid to change the state of motion of the surrounding fluid is equal to the rate of change of the fluid's momentum with time. According to Newton's third law, the force of the fluid's reaction on the vehicle body is the negative of the above force. (5) in, The force exerted on the vehicle body by the reaction of the fluid. This refers to the instantaneous acceleration of the vehicle body in the vertical direction.

[0049] As the vehicle enters the water, the volume of fluid displaced increases dramatically, resulting in a rapid increase in its added mass. This impact hydrodynamic component caused by the surge in mass and the dramatic transformation of momentum is called the impact force. To ensure that its upward direction hinders the movement of the vehicle, the formula introduces the absolute value of the velocity, namely: (6) Specifically, when the vehicle body moves downwards and the added mass increases, The upward direction hinders the movement of the vehicle, creating a strong upward pulling impact effect.

[0050] Because the vehicle body is in a state of violent deceleration at the moment of entering the water, its vertical acceleration The value is negative, therefore the added mass inertial force is... for: (7) Since the bottom surface of the vehicle body is mostly submerged in water during partial immersion, this invention assumes that the water resistance coefficient of the vehicle body in the partially submerged state is still [value missing]. The expression for the total hydrodynamic force acting on the vehicle body at this time is: (8) in, Indicates dynamic buoyancy. This refers to the volume of the vehicle body's drainage cavity, in units of... , This represents the pressure differential resistance when the cavity is not closed. This refers to the vertical frontal area of ​​the vehicle body when the cavity is not closed, which represents the water resistance. , For the vehicle body The pitch angle at any given moment.

[0051] In this embodiment, dynamic buoyancy represents the transient buoyancy force generated by the combined displacement of seawater by the vehicle's geometric volume and the volume of the open cavities surrounding its surface. Its magnitude changes in real time with the expansion and contraction of the cavities. Pressure drag represents the flow resistance generated during the vehicle's entry into the water due to the pressure buildup of fluid in front and the separation of fluid behind, creating a low-pressure zone. This resistance is proportional to the square of the vehicle's velocity and the area facing the current. Added mass inertial force represents the fluid inertial reaction force that the vehicle must overcome during deceleration upon entering the water, as it accelerates the surrounding fluid. This force is proportional to the instantaneous acceleration of the vehicle in the vertical direction and is opposite to the direction of acceleration. Impact force represents the additional impact force generated on the vehicle during entry into the water due to the rapid expansion of the cavities and the sharp increase in the volume of water displaced, causing a drastic change in added mass within a very short time. This force is proportional to the rate of change of added mass and the absolute value of the vehicle's instantaneous velocity.

[0052] Step S5 in this embodiment is to calculate the expression for the additional mass during the cross-interface water entry process based on the law of conservation of momentum.

[0053] This invention assumes that the vehicle body and the additional mass resulting from its motion constitute a dynamic system, allowing for the calculation of the equivalent mass of the variable mass system without the influence of internal energy dissipation. When the vehicle body is on the water surface, the initial momentum of the system is: (9) in, For vehicle body mass, This is the speed at which the vehicle just touches the water surface.

[0054] At the peak of the vertical force on the vehicle body, the peak moment momentum of the system is: (10) in, This represents the velocity at the peak of the vertical force experienced by the vehicle body during its descent into the water. In this embodiment, the peak moment... This represents the moment when the vehicle body's drainage volume is at its maximum in the CFD calculation data.

[0055] Since the impact force and the inertial force due to the added mass are internal forces in this dynamic system, they need to be excluded from the calculation of the system's momentum change. Therefore, the system's impulse... The following can be calculated by integrating gravity, dynamic buoyancy, and pressure drag over time: (11) in, Indicates dynamic buoyancy. This represents the pressure resistance when the cavity is not closed.

[0056] From the law of conservation of momentum, we can obtain: (12) Simplifying the above equation, we can obtain the expression for the additional mass of the vehicle body: (13) The calculation can be performed based on formula (13). .

[0057] Step S6 in this embodiment involves calculating the volume of the vehicle body drainage cavity based on the Logvinovich independent section principle and the inertia-dominated cavity expansion theory, combined with CFD data fitting. .

[0058] Based on the Logvinovich independent section principle and the theory of inertia-driven cavity expansion, this paper analyzes the nondimensional growth law of cavity volume during vehicle immersion in water. Based on existing research, during the cavity inertial expansion stage, the axial dimension of the cavity... It approximately increases linearly with the distance the object moves, that is... The lateral dimensions of the cavity It satisfies the Rayleigh-type inertial expansion law, that is... ; This refers to the characteristic dimension of the vehicle body in the vertical direction. Therefore, the cavity volume can be approximately expressed as a coupling function of vehicle velocity, time, and characteristic dimensions of the vehicle body, i.e. The volume of the nondimensional cavity was further derived. satisfy: (14) Among them, Froude number Nondimensionalized time parameters initial velocity , These are empirical coefficients, related to the vehicle body geometry, cavity type, and free surface effect. Using CFD simulation data of several sets of vehicles under different initial water entry velocities as calibration samples, the least squares method was employed for fitting to calibrate the empirical coefficients in the power-law relationship. , , The specific numerical values. The number of data points used for fitting was 1920, and R... 2 =0.914.

[0059] The following data was extracted by fitting CFD data using MATLAB: (15) That is, the volume of the vehicle body drainage cavity The expression is: (16) Formula (16) can be directly substituted into the subsequent dynamic buoyancy calculation, so that the calculation of the vehicle body's additional mass is coupled with the cavity evolution.

[0060] The above empirical coefficients , , This method is only applicable to mining vehicles with geometry similar to this embodiment, and only before the cavity is closed. For other shapes or different water entry stages, the parameters should be refitted according to the framework of formula (14), rather than directly applying the values ​​in this embodiment.

[0061] In this embodiment, the vehicle body feature dimensions , is a key geometric parameter used for dimensionless time and constructing Froude numbers, and its physical significance lies in characterizing the influence of the lateral dimension of the vehicle body on the cavity expansion.

[0062] Those skilled in the art will understand that for different vehicle models, the equivalent feature size D can be determined according to the above principles, and the prediction method of the present invention can be directly applied without changing the methodological framework. In other words, the value of D varies with the vehicle model, but the principles for determining D and the subsequent prediction method are universal.

[0063] Then, based on the parameters obtained above, the additional mass of the vehicle body before the water-entry cavity closes is adjusted. And the hydrodynamic expression, and predict the hydrodynamic load loss before and after cavity closure: Combining equations (1), (8), (13), and (16), the expression for the additional mass of the vehicle body before the closure of the water-entry cavity, corrected by a semi-empirical formula, is as follows: (17) Formula (17) is a semi-empirical model based on the Logvinovich principle and the theory of inertial expansion. Substituting formula (17) into formula (7) yields the modified expression for the total hydrodynamic force on the vehicle body before the closure of the water-entry cavity (taking the vertical upward direction as positive): (18) Figure 7 The theoretical calculation and simulation results of the peak vertical hydrodynamic force on the vehicle body under eight different initial water entry speeds before the cavity is closed are compared. The eight different initial water entry speeds are detailed in Table 2.

[0064] Table 2:

[0065] Data shows that as the operating condition sequence progresses, the peak hydrodynamic force generally exhibits a significant trend of steadily increasing from approximately 650 kN to nearly 930 kN, with the theoretical and simulated increases showing a high degree of consistency. Looking at the relative error distribution on the right vertical axis, the error scatter points for all operating conditions are located on the negative half-axis, indicating that the theoretical predictions are relatively small. However, the absolute values ​​of the relative errors for all operating conditions are strictly less than 5%, which strongly verifies that the theoretical calculation model obtained in this invention has extremely high accuracy in predicting the peak hydrodynamic force experienced by the vehicle body before the closure of the water-entry cavity.

[0066] Combining equations (2) and (18), the hydrodynamic load loss on the vehicle body before and after cavity closure can be obtained: (19) in, The hydrodynamic load loss value of the vehicle body before and after cavity closure is used to assess the risk of cable breakage or to adjust the deployment speed threshold, providing data basis for the cable strength design and lowering speed strategy of the deployment and retrieval system. This represents the peak hydrodynamic force experienced by the vehicle body before the cavity closes. This refers to the hydrodynamic force exerted on the vehicle body after the cavity is closed.

[0067] The following uses operating condition 3 as an example to fully demonstrate the calculation process of this invention. The main input parameters for this operating condition are detailed in Table 3: Table 3:

[0068] The present invention provides a method for predicting hydrodynamic load loss during the entry of a deep-sea mining vehicle into water. Based on the specific physical scenario of a deep-sea mining vehicle entering water, this method combines cavity dynamics theory and a physical mechanism model calibrated from a large amount of computational fluid dynamics simulation data. This model solves the problem that dynamic added mass cannot be directly measured, and achieves high-precision prediction of hydrodynamic load loss of deep-sea mining vehicles under the cavity closure effect at the water entry interface. It provides a feasible technical path for cross-interface water entry dynamics analysis and has significant engineering practicality and cost advantages.

[0069] The foregoing has described specific embodiments of the present invention. In some cases, the actions or steps described in the embodiments of the present invention may be performed in a different order than that shown in the embodiments and the desired results may still be achieved. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0070] Based on the same concept, this invention also provides a hydrodynamic load loss prediction system for the deep-sea mining vehicle entering the water. It is applied to a server. For example... Figure 8As shown, the hydrodynamic load loss prediction system for a deep-sea mining vehicle entering the water includes: a simulation model construction module 101, a vehicle speed fitting module 102, a steady-state hydrodynamic calculation module 103, a transient hydrodynamic construction module 104, an added mass inversion module 105, a cavity volume fitting module 106, a dynamic peak value calculation module 107, and a load loss calculation module 108. The simulation model construction module 101 is used to obtain the geometric parameters, mass parameters and initial velocity of the deep-sea mining vehicle, and to construct the CFD simulation model of the deep-sea mining vehicle.

[0071] The vehicle speed fitting module 102 is used to extract the vertical velocity-time discrete data of the vehicle body at different times based on the CFD simulation model, and to fit it using a preset exponential decay function to obtain a fitting function that characterizes the change of vehicle speed with time.

[0072] The steady-state hydrodynamic calculation module 103 is used to calculate the steady-state total hydrodynamic force on the vehicle body after the cavity is closed, based on the preset additional mass coefficient and water resistance coefficient, combined with the vehicle body's geometric parameters and fitting function, and output the steady-state hydrodynamic value for the vehicle body in a fully submerged state.

[0073] The transient hydrodynamic construction module 104 is used to treat the vehicle body and the following fluid as a variable mass system when the vehicle body is partially submerged and the cavity is not closed. Based on the momentum theorem, the hydrodynamic force on the vehicle body is decomposed into dynamic buoyancy, pressure drag, additional mass inertial force and impact force, and a transient hydrodynamic expression is established.

[0074] The additional mass inversion module 105 is used to invert and calculate the expression of the additional mass of the car body before the cavity is closed, based on the law of conservation of momentum and the impulse balance relationship between the initial momentum and the peak momentum of the variable mass system.

[0075] The cavity volume fitting module 106 is used to construct a power-law relationship between dimensionless cavity volume and Froude number and dimensionless time based on the Logvinovich independent section principle and the inertia-dominated cavity expansion theory, and to fit it with CFD simulation data to output a dimensional expression for the volume of the vehicle body drainage cavity.

[0076] The dynamic peak calculation module 107 is used to substitute the dimensional expression into the additional mass expression to obtain the corrected additional mass, and then substitute the corrected additional mass into the transient hydrodynamic expression to calculate the hydrodynamic peak before the cavity closes.

[0077] The load loss calculation module 108 is used to combine the peak hydrodynamic value and the steady-state hydrodynamic value to calculate the predicted value of hydrodynamic load loss. The predicted value of hydrodynamic load loss is used to evaluate the tension surge of the cable when it is laid at the moment the cavity closes and to provide data basis for the dynamic control of cable tension.

[0078] For ease of description, the above system is described by dividing it into various modules based on their functions. Of course, in implementing the embodiments of the present invention, the functions of each module can be implemented in one or more software and / or hardware.

[0079] The system described above is applied to the corresponding method in the foregoing embodiments and has the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0080] Based on the same inventive concept, embodiments of the present invention also provide an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the method described in any of the above embodiments.

[0081] This invention provides a non-volatile computer storage medium storing at least one executable instruction that can execute the method described in any of the above embodiments.

[0082] Figure 9 This embodiment illustrates a more specific hardware structure of an electronic device, which may include a processor 501, a memory 502, an input / output interface 503, a communication interface 504, and a bus 505. The processor 501, memory 502, input / output interface 503, and communication interface 504 are interconnected internally via the bus 505.

[0083] The processor 501 can be implemented using a general-purpose CPU (Central Processing Unit), microprocessor, application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of the present invention.

[0084] The memory 502 can be implemented in the form of ROM (Read Only Memory), RAM (Random Access Memory), static storage device, dynamic storage device, etc. The memory 502 can store the operating system and other application programs. When the technical solution provided by the method embodiment of the present invention is implemented by software or firmware, the relevant program code is stored in the memory 502 and is called and executed by the processor 501.

[0085] Input / output interface 503 is used to connect input / output modules to realize information input and output. Input / output modules can be configured as components in the device (not shown in the figure) or externally connected to the device to provide corresponding functions. Input devices may include keyboards, mice, touch screens, microphones, various sensors, etc., and output devices may include displays, speakers, vibrators, indicator lights, etc.

[0086] Communication interface 504 is used to connect a communication module (not shown in the figure) to enable communication between this device and other devices. The communication module can communicate via wired means (such as USB, Ethernet cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.).

[0087] Bus 505 includes a pathway for transmitting information between various components of the device (e.g., processor 501, memory 502, input / output interface 503, and communication interface 504).

[0088] It should be noted that although the above-described device only shows the processor 501, memory 502, input / output interface 503, communication interface 504, and bus 505, in specific implementations, the device may also include other components necessary for normal operation. Furthermore, those skilled in the art will understand that the above-described device may only include the components necessary for implementing the embodiments of the present invention, and does not necessarily include all the components shown in the figures.

[0089] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of this application as described above, which are not provided in detail for the sake of brevity.

[0090] This application is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the embodiments of this invention. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this invention should be included within the protection scope of this application.

Claims

1. A method for predicting hydrodynamic load loss during the entry of a deep-sea mining vehicle into water, characterized in that, Includes the following steps: Obtain the geometric parameters, mass parameters, and initial water entry velocity of the deep-sea mining vehicle, and construct a CFD simulation model of the deep-sea mining vehicle; Based on the CFD simulation model, the vertical velocity-time discrete data of the vehicle body at different times are extracted, and the data are fitted using a preset exponential decay function to obtain a fitting function characterizing the change of vehicle body velocity with time. For a vehicle body that is completely submerged, based on the preset additional mass coefficient and water resistance coefficient, combined with the vehicle body's geometric parameters and the fitting function, the steady-state total hydrodynamic force on the vehicle body after the cavity is closed is calculated, and the steady-state hydrodynamic force value is output. For a vehicle body partially submerged and with the cavity not closed, the vehicle body and the following fluid are considered as a variable mass system. Based on the momentum theorem, the hydrodynamic force on the vehicle body is decomposed into dynamic buoyancy, pressure drag, additional mass inertial force and impact force, and a transient hydrodynamic expression is established. Based on the law of conservation of momentum, the expression for the additional mass of the vehicle body before the cavity is closed is obtained by inverse calculation using the impulse balance relationship between the initial momentum and the peak momentum of the variable mass system. Based on the Logvinovich independent section principle and the inertia-dominated cavity expansion theory, a power-law relationship between dimensionless cavity volume and Froude number and dimensionless time is constructed, and then fitted with CFD simulation data to output a dimensional expression for the volume of the vehicle body drainage cavity. Substitute the dimensional expression into the additional mass expression to obtain the corrected additional mass. Substitute the corrected additional mass into the transient hydrodynamic expression to calculate the peak hydrodynamic force before the cavity closes. By combining the peak hydrodynamic value and the steady-state hydrodynamic value, the predicted value of hydrodynamic load loss is calculated. The predicted value of hydrodynamic load loss is used to evaluate the magnitude of the tension surge when the cable is laid at the moment the cavity closes, and to provide data basis for dynamic control of cable tension.

2. The method for predicting hydrodynamic load loss during the deep-sea mining vehicle's entry into water as described in claim 1, characterized in that, The geometric parameters include the vehicle body volume and the vehicle body bottom area; the mass parameters include the added mass coefficient and the water resistance coefficient; and the steady-state hydrodynamic value is calculated as follows: ， in, For still water buoyancy, The density of water, For gravity, Let the geometric volume of the vehicle body be denoted as . The pressure drag when the vehicle body is completely submerged. The coefficient of water resistance. The area facing the water flow perpendicular to the vehicle body when it is completely submerged. , The bottom area of ​​the vehicle body. For the vehicle body The pitch angle at any moment, for The vertical velocity of the vehicle at any given moment; To add mass force, For the additional quality coefficient, for The vertical acceleration of the vehicle body at any given moment.

3. The method for predicting hydrodynamic load loss during the deep-sea mining vehicle's entry into water as described in claim 2, characterized in that, The process of decomposing the hydrodynamic forces acting on the vehicle body into dynamic buoyancy, pressure drag, additional mass inertial force, and impact force based on the momentum theorem, and establishing a transient hydrodynamic expression, including: Calculate the force exerted by the fluid reaction on the vehicle body using the momentum theorem. , ,in, The instantaneous momentum of the fluid is given. , Add mass to the vehicle body before the cavity closes. These are dynamic values ​​that change over time. The instantaneous velocity of the vehicle body in the vertical direction; Based on the force of the fluid reaction on the vehicle body Decomposition yields additional mass inertial force and the power of criticism , Additional mass inertial force The impact force is the fluid inertial reaction force that the vehicle body must overcome to accelerate the surrounding fluid. This characterizes the additional impact force generated on the vehicle body when there is a drastic change in the vehicle's added mass. The instantaneous acceleration of the vehicle body in the vertical direction. Add a rate of change of mass to the vehicle body; Based on the obtained additional mass inertial force and the power of criticism Establish the transient hydrodynamic expression: ， in, Indicates dynamic buoyancy. This refers to the volume of the vehicle body's drainage cavity. This represents the pressure differential resistance when the cavity is not closed. This represents the vertical frontal area of ​​the vehicle body when the cavity is not closed, which represents the water resistance of the vehicle body.

4. The method for predicting hydrodynamic load loss during the deep-sea mining vehicle's entry into water as described in claim 3, characterized in that, The mass parameters include the vehicle body mass. Based on the law of conservation of momentum, and utilizing the impulse balance relationship between the initial momentum and the peak momentum of the variable mass system, the additional mass expression of the vehicle body before cavity closure is calculated through inversion, including: Calculate the initial momentum of the variable mass system at the moment the vehicle body enters the water. , ,in, For vehicle body mass, The speed at which the vehicle just touches the water surface; Calculate the peak moment momentum of the variable mass system when the vertical force on the vehicle body reaches its peak during water immersion. , ,in, The velocity at the peak of the vertical force experienced by the vehicle body during its immersion in water; The external impulse of the variable mass system is calculated based on dynamic buoyancy, pressure resistance when the cavity is not closed, and the integral of gravity over time. , ,in, For dynamic buoyancy, This refers to the pressure differential resistance when the cavity is not closed. According to the external impulse The initial momentum and the peak moment momentum The inversion calculation yields the expression for the additional mass of the car body before the cavity closes: .

5. The method for predicting hydrodynamic load loss during the deep-sea mining vehicle's entry into water as described in claim 4, characterized in that, The geometric parameters also include the vehicle body feature dimensions. Based on the Logvinovich independent section principle and the inertia-dominated cavity expansion theory, a power-law relationship is constructed between the dimensionless cavity volume and the Froude number and dimensionless time. This relationship is then fitted using CFD simulation data to output a dimensional expression for the vehicle body drainage cavity volume, including: Based on the Logvinovich independent section principle and the inertia-driven cavity expansion theory, the parameters affecting the cavity volume evolution during water entry are dimensionless, including: constructing the Froude number. Characterizing the ratio of inertial force to gravity, constructing a dimensionless time. Characterizes the ratio of vehicle diving distance to vehicle feature dimensions, and expresses this relationship in terms of vehicle volume. Based on the volume of the vehicle body drainage cavity Dimensionless transformation ,in, These are the characteristic dimensions of the vehicle body. The initial velocity of the vehicle body upon entering the water. The time measured from the moment the vehicle body touches the water surface; Establish dimensionless cavity volume The power-law relationship is as follows: ; Using CFD simulation data of several sets of vehicles with different initial water entry velocities as calibration samples, the least squares method was used for fitting, and the empirical coefficients in the power-law relationship were obtained through calibration. , , The specific values ​​are used to obtain the volume of the vehicle body drainage cavity. Dimensional expression .

6. The method for predicting hydrodynamic load loss during the deep-sea mining vehicle's entry into water as described in claim 5, characterized in that, The preset velocity decays exponentially over time as follows: ,in, The velocity in the vertical direction of the vehicle body is [value]. The time measured from the moment the vehicle body touches the water surface; The decay exponent is used to fit and extract the function by minimizing the mean square error between the exponential decay function and the vertical velocity-time discrete data points of the CFD simulation. Substituting the dimensional expression into the additional mass expression, we obtain the corrected additional mass as follows: in, This is the moment when the vertical force on the vehicle reaches its peak during the process of the vehicle entering the water.

7. The method for predicting hydrodynamic load loss during the deep-sea mining vehicle's entry into water as described in claim 6, characterized in that, Substituting the modified additional mass into the transient hydrodynamic expression, we obtain the modified peak value of the total hydrodynamic force on the vehicle body before cavity closure. , ； The hydrodynamic load loss experienced by the vehicle body before and after the cavity is closed is as follows: ,in, This represents the hydrodynamic load loss experienced by the vehicle body before and after the cavity is closed, expressed in nanometers (N). This refers to the hydrodynamic force exerted on the vehicle body after the cavity is closed.

8. A hydrodynamic load loss prediction system for deep-sea mining vehicles during water entry, characterized in that, include: The simulation model construction module is used to obtain the geometric parameters, mass parameters and initial water entry velocity of the deep-sea mining vehicle, and to construct the CFD simulation model of the deep-sea mining vehicle. The vehicle speed fitting module is used to extract the vertical velocity-time discrete data of the vehicle body at different times based on the CFD simulation model, and to fit it using a preset exponential decay function to obtain a fitting function that characterizes the change of vehicle speed with time. The steady-state hydrodynamic calculation module is used to calculate the steady-state total hydrodynamic force on the vehicle body after the cavity is closed, based on the preset additional mass coefficient and water resistance coefficient, combined with the vehicle body's geometric parameters and the fitting function, and output the steady-state hydrodynamic force value for the vehicle body in a fully submerged state. The transient hydrodynamics construction module is used to treat the vehicle body and the following fluid as a variable mass system when the vehicle body is partially submerged and the cavity is not closed. Based on the momentum theorem, the hydrodynamic force on the vehicle body is decomposed into dynamic buoyancy, pressure drag, additional mass inertial force and impact force, and a transient hydrodynamic expression is established. The additional mass inversion module is used to invert and calculate the expression of the additional mass of the vehicle body before the cavity is closed, based on the law of conservation of momentum and the impulse balance relationship between the initial momentum and the peak momentum of the variable mass system. The cavity volume fitting module is used to construct a power-law relationship between dimensionless cavity volume and Froude number and dimensionless time based on the Logvinovich independent section principle and the inertia-dominated cavity expansion theory. It then combines CFD simulation data for fitting and outputs a dimensional expression for the volume of the vehicle body drainage cavity. The dynamic peak calculation module is used to substitute the dimensional expression into the additional mass expression to obtain the corrected additional mass, and then substitute the corrected additional mass into the transient hydrodynamic expression to calculate the hydrodynamic peak before the cavity is closed. The load loss calculation module is used to combine the peak hydrodynamic value and the steady-state hydrodynamic value to calculate the predicted value of hydrodynamic load loss. The predicted value of hydrodynamic load loss is used to evaluate the magnitude of the tension surge when the cable is laid at the moment the cavity closes and to provide data basis for dynamic control of cable tension.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the prediction method as described in any one of claims 1-7.

10. A computer storage medium, characterized in that, The storage medium stores at least one executable instruction that causes the processor to perform the prediction method as described in any one of claims 1-7.

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