A multi-surface simulation control method for longitudinal motion of a ship in waves

Abstract

The application discloses a kind of multi-surface simulation control methods of longitudinal motion of ship in wave, comprising: obtaining the physical parameter data of ship-propeller-rudder, establishing the three-dimensional physical model of ship body, propeller, rudder, tail pressure wave board and T-type hydrofoil;Each three-dimensional physical model is imported into CFD system, and CFD numerical simulation calculation domain is established, while setting ground coordinate system and each local coordinate system;The boundary condition of CFD numerical simulation calculation domain is defined, the wave-making boundary parameter is set, the single-stage control strategy of propeller speed and the cascade control strategy of stabilizer appendage are determined, and the model to be solved is obtained;According to the established CFD numerical simulation calculation domain, the model to be solved and specific control strategy, initialize flow field and carry out numerical calculation, output motion posture control result, obtain the ship motion posture change curve under multi-surface control.The application can effectively carry out comprehensive simulation control to the longitudinal motion posture of ship sailing in wave.

Description

Technical Field

[0001] This invention relates to the field of computer simulation technology, and more specifically to a multi-plane simulation control method for the longitudinal motion of a ship in waves. Background Technology

[0002] In complex marine environments, ships encountering wind and waves are prone to significant heave and pitch coupled motions, often accompanied by stall, resulting in substantial longitudinal motion. This poses a series of navigational safety risks, including those related to life, cargo, hull, and equipment. Regarding longitudinal motion control equipment, stern plates, deflectors, and hydrofoils are commonly used to enhance longitudinal stability. Research on longitudinal motion control includes both costly model testing and less expensive numerical simulation. Model testing involves creating scaled-down models to realistically reflect the effects of ship motion control. Numerical simulation, however, often uses simplified mathematical models of ship motion and control, relying on compiled programs for simulation. This approach fails to capture the detailed effects of the surrounding environment on ship motion and control, and is ill-suited to account for the nonlinearities and real-world hydrodynamic feedback in complex environments. Therefore, there is a need to develop a more realistic and effective method for simulating ship longitudinal motion control, reducing experimental costs while achieving higher accuracy and fidelity. Summary of the Invention

[0003] In view of the shortcomings of existing technologies, this invention provides a multi-plane simulation control method for the longitudinal motion of ships in waves. By considering true full viscous nonlinearity, it can effectively perform comprehensive simulation control of the longitudinal motion attitude of ships sailing in waves.

[0004] The technical means employed in this invention are as follows:

[0005] A multi-plane simulation control method for the longitudinal motion of a ship in waves includes the following steps:

[0006] S1: Obtain physical parameter data of ship-propeller-rudder, and establish a three-dimensional physical model of the hull, propeller, rudder, tail wave deflector and T-shaped hydrofoil;

[0007] S2: Import each three-dimensional physical model into the CFD system and establish a CFD numerical simulation calculation domain. The CFD numerical simulation calculation domain includes the background calculation domain, the hull motion domain, the propeller motion domain, the rudder motion domain, the tail wave deflector rotation domain, and the T-type hydrofoil rotation domain. At the same time, set up the geodetic coordinate system and each local coordinate system.

[0008] S3: Define the boundary conditions of the background computation domain, hull motion domain, propeller motion domain, rudder motion domain, tail wave deflector rotation domain and T-type hydrofoil rotation domain, set wave-making boundary parameters, determine the single-stage control strategy of propeller speed and the cascade control strategy of anti-roll appendage, and obtain the model to be solved;

[0009] S4: Based on the established CFD numerical simulation computational domain, the model to be solved, and the specific control strategy, initialize the flow field and perform numerical calculations, output the motion attitude control results, and obtain the ship motion attitude change curve under multi-wing control.

[0010] Further, S2 includes the following steps:

[0011] S201: Model the propeller, rudder, tail wave deflector and T-shaped hydrofoil separately, and integrate the other physical structures of the hull into the overall hull model;

[0012] S202: Import the individual model and the overall hull model into the CFD program, and divide the computational domain. The computational domain includes the background domain, the hull motion domain, the propeller motion domain, the rudder motion domain, the tail plate motion domain, and the T-shaped hydrofoil motion domain.

[0013] S203: Establish a multi-level coordinate system, including a geodetic fixed coordinate system O-XYZ and a background domain coordinate system O B -X B Y B Z B The ship's motion coordinate system O G -X G Y G Z G Propeller rotating coordinate system O p -X p Y p Z p rudder rotation coordinate system O r -X r Y r Z r Tailplate rotating coordinate system O s -X s Y s Z s T-wing rotating coordinate system O T -X T Y T Z T ;

[0014] S204: Establish a three-degree-of-freedom motion model of the ship's longitudinal motion, including sway, heave, and pitch.

[0015] Further, S3 includes the following steps:

[0016] S301: Interpolation of computational information between the motion domain and the background domain, and between the motion domains, is achieved using overlapping grids. Specifically, this includes overlapping grid settings for the hull motion domain and the background domain, the hull domain and the propeller domain, the hull domain and the rudder domain, the hull domain and the stern plate domain, and the hull domain and the T-wing domain.

[0017] S302: Stokes fifth-order wave is used to simulate regular waves, and linear wavelet superposition is used to simulate irregular waves. The wave environment is simulated by setting corresponding wave generation parameters at the wave generation boundary of the background domain velocity inlet.

[0018] S303: Set the computational domain boundary as velocity inlet, pressure outlet, wall, and overlapping mesh, use VOF to capture the free surface, and use the k-ε or k-ω model for the turbulence model, where k is the turbulent kinetic energy, and ε and ω are the turbulence dissipation rates of the two turbulence models, respectively.

[0019] S304: The propeller speed is controlled by an automatic controller with speed as the error term, the tail wave deflector is controlled by a cascade controller with pitch angle as the target, and the T-shaped hydrofoil is controlled by a cascade controller with heave as the target, thereby achieving multi-plane control of the ship's longitudinal motion.

[0020] Further, S4 includes the following steps:

[0021] S401: Set the initial speed of the ship, initialize the rotation angle of the stern wave deflector and T-shaped hydrofoil, and initialize the wave environment;

[0022] S402: Based on the real-time fully viscous nonlinear effects of simulated waves on the ship-propeller-rudder, stern plate, and T-shaped hydrofoil, the ship's coupled motion attitude is calculated in real time using rigid body motion equations. Based on the difference between the real-time results of the ship's speed and heave attitude at each time step and the set target values, the speed and attitude controllers automatically update the propeller rotation speed and control the appendage rotation angle, thereby achieving real-time control of the ship's speed and longitudinal attitude in waves.

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

[0024] This invention provides a multi-plane simulation control method for the longitudinal motion of a ship in waves. It fully considers the actual environment of full viscous nonlinearity, the real-time effect of random waves on the hull, the precise force on the control appendages, and the real-time hydrodynamic feedback of the hull. It integrates the cascade control algorithm into the CFD numerical model to achieve direct simulation of the longitudinal motion control of a ship in waves under multiple control appendages. Attached Figure Description

[0025] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a flowchart of a multi-plane simulation control method for the longitudinal motion of a ship in waves according to the present invention.

[0027] Figure 2 This is a schematic diagram of the hull model and control appendage model in an embodiment of the present invention.

[0028] Figure 3 This is the instantaneous distribution of the free liquid surface around the ship under the multi-wing surface motion control in random waves during simulation calculations in this embodiment of the invention.

[0029] Figure 4 The curves show the changes in the ship's pitch attitude under the same random wave conditions with and without control appendages. Detailed Implementation

[0030] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0031] like Figure 1 As shown, this invention provides a multi-plane simulation control method for the longitudinal motion of a ship in waves, which mainly includes the following steps:

[0032] S1: Physical modeling. Based on data such as ship-propeller-rudder, physical models of the hull, propeller, rudder, tail spoiler, T-foil, etc., are established. Figure 2 The figure shows a modeling example of a tail spoiler and a T-shaped hydrofoil.

[0033] S2: Computational domain modeling. Import the various 3D models established in S1 into the CFD program to establish the background computational domain, hull motion domain, propeller motion domain, rudder motion domain, tail wave deflector rotation domain, and T-type hydrofoil rotation domain, and set the geodetic coordinate system and various local coordinate systems, etc.

[0034] Specifically, the steps include:

[0035] S201: 3D physical modeling, which separates the propeller, rudder, tail wave deflector and T-shaped hydrofoil described in S1 into a single physical model, and merges the remaining physical models into a single hull model.

[0036] S202: Computational domain modeling. Import the overall and individual models of S201 into the CFD program and divide the computational domain. The computational domain includes four parts: background domain, hull motion domain, propeller motion domain, rudder motion domain, tailplate motion domain, and T-type hydrofoil motion domain.

[0037] S203: Establish a multi-level coordinate system, including a geodetic fixed coordinate system O-XYZ and a background domain coordinate system O B -X B Y B Z B The ship's motion coordinate system O G -X G Y G Z G Propeller rotating coordinate system O p -X p Y p Z p rudder rotation coordinate system O r -X r Y r Z r Tailplate rotating coordinate system O s -X s Y s Z s T-wing rotating coordinate system O T -X T Y T Z T .

[0038] S204: Motion modeling, establishing a three-degree-of-freedom motion model of the ship's longitudinal motion, including sway, heave, and pitch.

[0039] S3: Set up the calculation model, define the boundary conditions of each calculation domain as described in S2, input the wave-generating boundary parameters, set the single-stage control strategy for propeller speed and the cascade control strategy for the anti-roll appendage, and set the solution model.

[0040] In this embodiment, the control strategy itself adopts conventional control methods in the field, and the control strategy is integrated into the software through secondary software development to achieve control. This step specifically includes:

[0041] S301: Mesh settings. Interpolation of computational information between the motion domain and the background domain, and between the motion domains, is achieved using overlapping meshes. Specifically, this includes overlapping mesh settings for the hull motion domain and the background domain, the hull domain and the propeller domain, the hull domain and the rudder domain, the hull domain and the stern plate domain, and the hull domain and the T-wing domain.

[0042] S302: Wave generation model. Regular wave simulation uses Stokes fifth-order wave, and irregular wave simulation uses the superposition of several linear wavelets. The wave environment is simulated by setting corresponding wave generation parameters at the wave generation boundary of the background domain velocity inlet.

[0043] According to the theory of linear superposition of random waves, at time t, the wave surface obtained by linear superposition at spatial location (x,y,z) can be expressed as:

[0044]

[0045] In the formula: a ij and ε ij It is the amplitude and random phase of a regular wave with the j-th directional angle at the i-th frequency; ω i and k i θ represents the angular frequency and wavenumber of the wave at the i-th frequency. j is the wave direction angle in the j-th direction; m and n are the wave circular frequency and the total number of wave directions, respectively. x, y, and t are the x-coordinate, y-coordinate, and time, respectively. All units used in the above and below formulas are in the International System of Units (SI).

[0046] The expressions for the three directional velocity components are:

[0047]

[0048] When m = n = 1, the above equation becomes a single regular wave. For the simulation of regular waves, a fifth-order Stokes wave is used, and the equation is as follows:

[0049]

[0050] In the above two equations: ω, d, k, and c represent the circular frequency, water depth, wave number, and wave speed, respectively; x, z, and t represent the x-coordinate, z-coordinate, and time, respectively; λ represents the correlation coefficient ratio; and the subscript n represents the nth order.

[0051] S303: Calculation model for boundary conditions, etc. The boundaries of each computational domain are conditions such as velocity inlet, pressure outlet, wall, and overlapping mesh. The VOF method is used to capture the free liquid surface, and the turbulence model adopts the k-ε or k-ω model.

[0052] In this embodiment, the K-Epsilon turbulence model is a two-equation model that can solve the transport equations for turbulent kinetic energy k and turbulent dissipation rate ε to determine the turbulent eddy viscosity.

[0053] The K-Omega turbulence model is a two-equation model that solves the transport equations for turbulent kinetic energy k and unit dissipation rate ω (i.e., the dissipation rate per unit turbulent kinetic energy (ω∝ε / k)) to determine the turbulent eddy viscosity.

[0054] S304: Speed ​​control and roll reduction appendage control model settings. Propeller speed control uses an automatic controller with speed as the error term; the tail wave deflector uses a cascade controller with pitch angle as the target; and the T-type hydrofoil uses a cascade controller with heave as the target. Specifically, the propeller speed np is set as an automatic controller with speed e as the error term.

[0055]

[0056] Where: n p It is applied to the rotational speed of ship propellers, a x It is the longitudinal acceleration of the ship, V0, V i and V N These represent the target speed of the ship, the ship's speed at iteration time step i, and the current simulation time (the simulation time step corresponds to N). T The ship's speed is given by P, I, and D. P, I, and D are the corresponding proportional, integral, and differential coefficients. t is the current calculation time, and Δt is the calculation time step.

[0057] The T-type hydrofoil cascade PID control uses an outer loop for heave position (input: set heave value; output: set heave speed) and an inner loop for speed (input: set heave speed; output: hydrofoil rotation angle). The outer loop's heave speed setpoint is v. hz Relationship with heave error e1, inner ring T-shaped hydrofoil rotation angle θ Tfoil The relationships with the heave velocity error e2 are as follows:

[0058]

[0059]

[0060] In the formula: θ Tfoil It controls the angle of the attached T-shaped hydrofoil, measured in degrees or rads, and z. h0 and z h It refers to the target sag value and the current sag value, v. hz and v h These are the target heave velocity and the current heave velocity, with e1 and e2 being the corresponding error terms. P1, P2, I1, I2, D1, and D2 are the corresponding proportional, integral, and differential coefficients.

[0061] The cascade PID control of the stern wave deflector is set with the pitch angle position as the outer loop, the input being the set pitch angle of the hull, and the output being the pitch rate of the hull. The inner loop is the velocity loop, with the input being the pitch rate of the hull and the output being the stern wave deflector rotation angle. The setpoint v for the pitch rate of the outer loop is... p Relationship with pitch error e3, inner ring tail wave plate rotation angle θ SF The relationships with the pitch angular velocity error e4 are as follows:

[0062]

[0063]

[0064] In the formula: θ SF It controls the angle of the attached tail flaps, θ0 and θ are the target pitch angle and the current pitch angle, respectively, v θp and v θ These are the target pitch angular velocity and the current pitch angular velocity, with e3 and e4 being the corresponding error terms. P3, P4, I3, I4, D3, and D4 are the corresponding proportional, integral, and differential coefficients.

[0065] S4: Numerical solution calculation. Based on the CFD computational domain established in S2 and the computational model and control strategy set in S3, the flow field is initialized and settings are executed for numerical calculation, such as... Figure 3 As shown, the output results obtain the ship's motion attitude change curve under multi-wing surface control.

[0066] S401: Initialization, set the initial speed of the ship, initialize the rotation angle of the stern wave deflector and T-shaped hydrofoil, and initialize the wave environment;

[0067] S402: Direct simulation calculation. Based on the real-time fully viscous nonlinear effects of simulated waves on the ship-propeller-rudder and control appendages, the coupled motion attitude of the hull is calculated in real time using rigid body motion equations. According to the difference between the real-time results of speed and heave / roll attitude at each time step and the set target values, the speed and attitude controllers automatically update the propeller rotation speed and control appendage rotation angle, thereby achieving real-time control of the ship's speed and longitudinal attitude in waves. The output results are compared with the ship's motion attitude change curves under the same wave conditions without control, such as... Figure 4 As shown.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-plane simulation control method for the longitudinal motion of a ship in waves, characterized in that, Includes the following steps: S1: Obtain physical parameter data of ship-propeller-rudder, and establish a three-dimensional physical model of the hull, propeller, rudder, tail wave deflector and T-shaped hydrofoil; S2: Import each three-dimensional physical model into the CFD system and establish a CFD numerical simulation calculation domain. The CFD numerical simulation calculation domain includes the background calculation domain, the hull motion domain, the propeller motion domain, the rudder motion domain, the tail wave deflector rotation domain, and the T-type hydrofoil rotation domain. At the same time, set up the geodetic coordinate system and each local coordinate system. S3: Define the boundary conditions of the background computation domain, hull motion domain, propeller motion domain, rudder motion domain, tail wave deflector rotation domain and T-type hydrofoil rotation domain, set wave-making boundary parameters, determine the single-stage control strategy of propeller speed and the cascade control strategy of anti-roll appendage, and obtain the model to be solved; S4: Based on the established CFD numerical simulation computational domain, the model to be solved, and the specific control strategy, initialize the flow field and perform numerical calculations, output the motion attitude control results, and obtain the ship motion attitude change curve under multi-wing control. S2 includes the following steps: S201: Model the propeller, rudder, tail wave deflector and T-shaped hydrofoil separately, and integrate the other physical structures of the hull into the overall hull model; S202: Import the individual model and the overall hull model into the CFD program, and divide the computational domain. The computational domain includes the background domain, the hull motion domain, the propeller motion domain, the rudder motion domain, the tail plate motion domain, and the T-shaped hydrofoil motion domain. S203: Establish a multi-level coordinate system, including a geodetic fixed coordinate system O-XYZ and a background domain coordinate system O B -X B Y B Z B The ship's motion coordinate system O G -X G Y G Z G Propeller rotating coordinate system O p -X p Y p Z p rudder rotation coordinate system O r -X r Y r Z r Tailplate rotating coordinate system O s -X s Y s Z s T-wing rotating coordinate system O T -X T Y T Z T ; S204: Establish a three-degree-of-freedom motion model for the longitudinal motion of a ship, including sway, heave, and pitch. S3 includes the following steps: S301: Interpolation of computational information between the motion domain and the background domain, and between the motion domains, is achieved using overlapping grids. Specifically, this includes overlapping grid settings for the hull motion domain and the background domain, the hull domain and the propeller domain, the hull domain and the rudder domain, the hull domain and the stern plate domain, and the hull domain and the T-wing domain. S302: Stokes fifth-order wave is used to simulate regular waves, and linear wavelet superposition is used to simulate irregular waves. The wave environment is simulated by setting corresponding wave generation parameters at the wave generation boundary of the background domain velocity inlet. S303: The computational domain boundary is set as velocity inlet, pressure outlet, wall, and overlapping mesh. VOF method is used to capture the free surface. The turbulence model uses k-ε or k-ω model, where... k It is turbulent kinetic energy. ε and ω These are the turbulence dissipation rates of the two turbulence models, respectively; S304: The propeller speed is controlled by an automatic controller with speed as the error term, the tail wave deflector is controlled by a cascade controller with pitch angle as the target, and the T-type hydrofoil is controlled by a cascade controller with heave as the target, thereby realizing multi-plane control of the longitudinal motion of the ship. S4 includes the following steps: S401: Set the initial speed of the ship, initialize the rotation angle of the stern wave deflector and T-shaped hydrofoil, and initialize the wave environment; S402: Based on the real-time fully viscous nonlinear effects of simulated waves on the ship-propeller-rudder, stern plate, and T-shaped hydrofoil, the ship's coupled motion attitude is calculated in real time using rigid body motion equations. Based on the difference between the real-time results of the ship's speed and heave attitude at each time step and the set target values, the speed and attitude controllers automatically update the propeller rotation speed and control the appendage rotation angle, thereby achieving real-time control of the ship's speed and longitudinal attitude in waves.

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