Energy efficiency evaluation method for propulsion and control safety of marine main engine under wave condition

Abstract

The invention relates to an energy efficiency evaluation method for ship main engine propulsion and control safety under a wave condition, and the method comprises the following steps: S1, obtaining ship and wave parameter data, and building a ship motion MMG model; s2, the ship seakeeping module outputs ship heaving, rolling and pitching and ship surging, swaying, rolling and yawing wave resistance, wave second-order force / moment is substituted back to the MMG model, new current ship course and speed information and control propulsion performance are obtained, the moment is updated, and S2 is repeated; s3, inputting the wave second-order force / torque at multiple moments into the rapid forecasting model to obtain predicted ship motion and propulsion power requirements; and S4, comparing the predicted demand with the real-time ship power value, and adjusting the ship main engine based on a comparison result. Compared with the prior art, the method has the advantages that the corresponding speed of the ship main engine is increased under the two conditions of controlling the wave resistance, and the like.

Description

Technical Field

[0001] The invention relates to the field of ship operation, and in particular to an energy efficiency evaluation method for propulsion and maneuvering safety of a ship main engine under wave conditions. Background Art

[0002] The current proportion of fossil fuel use in the shipping industry is about 93%. Although new energy and clean energy have great potential in the shipping field, fossil fuels are still the main source of power for global shipping. Improving the energy efficiency of fossil fuels is a key way to achieve the energy conservation and emission reduction goals of the global shipping industry. In the prior art, the transmission efficiency of each power of the ship's main engine remains basically unchanged, that is, the ratio of the power received by the propeller to the machine power is usually between 0.95 and 0.98, and the ratio of effective power to received power is the propeller efficiency, and this value is between 0.60 and 0.75. This means that most of the energy loss of the ship's main engine occurs in the propeller (see the attached figure for the power transmission from the ship's main engine to the propeller). Figure 1 ), the main shortcomings include: the propeller design fails to maximize the propulsion efficiency, resulting in energy waste; the main engine's rapid response capability is insufficient, affecting the ship's operational safety in emergency situations. Summary of the invention

[0003] The purpose of the present invention is to improve the corresponding speed of the ship's main engine under the two conditions of maneuvering and seakeeping, and to provide an energy efficiency evaluation method for the propulsion and maneuvering safety of the ship's main engine under wave conditions.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] A method for evaluating energy efficiency of propulsion and maneuvering safety of a ship main engine under wave conditions, the method comprising the following steps:

[0006] S1. Obtain ship and wave parameter data, establish a ship motion MMG model, determine the initial ship's heading and speed information based on the MMG model, and use the initial ship's heading and speed information as the current ship's heading and speed information;

[0007] S2. The current ship's heading and speed information is substituted into the ship's seakeeping module, and the ship's seakeeping module outputs the ship's heave motion ξ 3 、Rolling motion 4 and pitch motion ξ 5 And the wave resistance in the ship's surge, sway, roll and pitch directions Convert wave resistance into second-order wave force / moment X acting on the hull in the directions of surge, sway, roll and pitch W ,Y W ,N W ,K W, the second-order wave force / torque is substituted back into the MMG model to obtain the new current ship's heading and speed information as well as the maneuvering and propulsion performance, update the time, and repeat S2 to obtain the second-order wave force / torque at multiple times;

[0008] S3, the second-order wave forces / torques at multiple moments are input into the rapid prediction model, and the rapid prediction model outputs the predicted ship motion and propulsion power requirements;

[0009] S4. Compare the predicted ship propulsion power demand with the real-time ship power value, and adjust the ship main engine based on the comparison result.

[0010] Furthermore, the ship seakeeping module outputs the ship heave motion ξ 3 、Rolling motion 4 and pitch motion ξ 5 And the wave resistance in the ship's surge, sway, roll and pitch directions The specific steps are:

[0011] The hull surface and free surface are discretized into surface elements by the three-dimensional Rankine surface element method, and the object surface boundary conditions, diffraction velocity potential free surface boundary conditions and radiation velocity potential free surface boundary conditions are constructed. The initial boundary value problem is solved, and the velocity potential of each surface element is obtained. After the velocity potential distribution is obtained, the pressure integration method is used to further solve the hydrodynamic characteristics of the hull, and the added mass, wave damping and wave excitation force are obtained, and the motion amplitude is obtained. The motion amplitude includes the ship heave motion ξ 3 、Rolling motion 4 and pitch motion ξ 5 , based on the motion amplitude, calculate the wave resistance in the ship's surge, sway, roll and pitch directions

[0012] Furthermore, the wave resistance in the ship's surge, sway, roll and pitch directions is is the wave resistance is the wave resistance The directional components of surge, sway, roll and pitch, wave resistance for:

[0013]

[0014] Among them, φ I and φ d are the incident wave velocity potential and the disturbance velocity potential respectively; x and y are the ordinate and abscissa of the center of the surface element respectively, is the normal vector of the surface element; S is the area of ​​the surface element; H is the transformation matrix; ζ I and d are the incident wave height and the disturbance wave height, respectively; is the position vector; represents the wave-induced linear displacement vector; represents the angular displacement vector, the wave-induced linear displacement vector and the angular displacement vector constitute the motion amplitude, where ξ 3 represents the heave motion, ξ 4 represents the rolling motion, ξ 5 represents the pitch motion ξ 5 .

[0015] Furthermore, the motion amplitude obtained by the pressure integration method is:

[0016]

[0017] Among them, S B is the object surface mesh, is the unit incident wave velocity, the potential wave height is 1 meter, ω is the encounter frequency; n j is the normal vector in the j direction, m j is the ship mass matrix, is the diffraction velocity potential; is the radiation velocity potential, and n is the normal vector. ij ,b ij ,F i and j are respectively the ship's additional mass, wave damping, wave excitation force and motion amplitude; ρ is the seawater density.

[0018] Furthermore, the object surface boundary condition is:

[0019]

[0020] Among them, S B is the object surface mesh, is the unit incident wave velocity potential, ω is the encounter frequency; n j is the normal vector in the j direction, m j For the additional mass, is the diffraction velocity potential; is the radiation velocity potential, and n is the normal vector.

[0021] Furthermore, the free surface boundary condition of the diffraction velocity potential is:

[0022]

[0023] Where z represents the vertical coordinate of the free surface element grid, g represents the gravitational acceleration, μ represents the artificial damping coefficient on the free surface, i represents an imaginary number, and Φ represents the stack flow velocity potential. Indicates the ship speed, Φ zz Represents the second derivative of the stack flow velocity potential in the z direction.

[0024] Furthermore, the free surface boundary condition of the radiation velocity potential is:

[0025]

[0026] Where z represents the vertical coordinate of the free surface element grid, g represents the gravitational acceleration, μ represents the artificial damping coefficient on the free surface, i represents an imaginary number, and Φ represents the stack flow velocity potential. Indicates the ship speed, Φ zz Represents the second derivative of the stack flow velocity potential in the z direction.

[0027] Furthermore, the second-order wave force / moment X acting on the hull surge, sway, roll and pitch directions obtained by wave resistance conversion is W ,Y W ,N W ,K W for:

[0028]

[0029] Here, ρ is the density of seawater; g is the acceleration due to gravity; h a is the wave height; B is the ship width; L is the ship length, Wave resistance The directional components of surge, sway, roll and pitch, X W ,Y W ,N W ,K W It is the second-order wave force / moment acting on the hull in the directions of surge, sway, roll and pitch.

[0030] Furthermore, the MMG model, that is, the high-frequency model in the wave-resistant mode is:

[0031]

[0032] Where p is the rolling velocity, m is the mass of the ship, and m x and m y are the additional masses of the x-axis and y-axis, J xx and J zz are the additional moments of inertia about the x-axis and z-axis respectively. The subscripts H, R, and P represent the low-frequency hydrodynamic forces acting on the hull, rudder, and propeller respectively. P is the propeller longitudinal thrust, X W ,Y W ,N W ,K W is the second-order wave force / moment acting on the hull in the directions of surge, sway, roll and pitch, u, v, r represent the longitudinal velocity, transverse velocity and pitch velocity of the ship respectively, z G represents the vertical coordinate of the center of gravity, X H,Y H ,N H ,K H are the wave resistance coupling results at the previous moment, that is, the forces and moments acting on the hull in the directions of surge, sway, roll and pitch; X R ,Y R ,N R ,K R are the forces and moments acting on the rudder in surge, sway, roll and pitch directions respectively;

[0033] The force acting on the rudder is:

[0034]

[0035] Among them, F N is the positive pressure acting on the rudder, δ is the rudder angle, t R ,a H and x H Represents the coupling coefficient between the hull and the rudder. R and z R are the x- and z-coordinates of the rudder normal force action point, respectively;

[0036] The longitudinal thrust of the propeller is:

[0037]

[0038] Among them, n P is the propeller speed, D P

[0039] Furthermore, the new current heading of the ship is the integral result of the bow speed r output by the MMG model, and the new current speed information is the vector sum of the longitudinal speed and the lateral speed of the ship output by the MMG model, which is U represents the vector sum.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The present invention develops a ship resistance (second-order force / torque) calculation model in the frequency domain based on the three-dimensional Rankine panel method and the near-field pressure integration method. Combined with the high-frequency model MMG model in the seakeeping mode, the ship maneuvering motion under regular waves and irregular waves can be quickly predicted, the matching situation of the main engine propulsion power and wave resistance can be evaluated, the ship power can be adjusted in real time, and the main engine corresponding rate can be improved under the two conditions of maneuvering and seakeeping. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of power transmission from the ship's main engine to the propeller;

[0043] Figure 2There are two different linearization methods: Figure 2 (a) NK linearization; Figure 2 (b) DB linearization;

[0044] Figure 3 This is the coupling diagram of the mathematical model of the ship moving in the waves;

[0045] Figure 4 are the simulation results and test data of each parameter, where Figure 4 (a) and (b) are the amplitude and phase of the heave motion, respectively. Figure 4 (c) and (d) are the pitch motion amplitude and phase, respectively;

[0046] Figure 5 are the heave and pitch motion results and test data of the S175 container ship under Fn = 0.275 and transverse wave conditions (χ = 90°), where Figure 5 (a) and (b) are the heave and pitch motions of the S175 container ship under beam and oblique sea conditions, respectively;

[0047] Figure 6 are the heave and pitch motion results and test data of the S175 container ship under Fn = 0.275 and oblique sea conditions (χ = 150°), where Figure 6 (a) and (b) are the heave and pitch motions of the S175 container ship under beam and oblique sea conditions, respectively;

[0048] Figure 7 is the second-order force / moment on the S175 container ship under different wave conditions, where Figure 7 (a) is S175 in F n =0.20 The second-order force in the longitudinal direction under the head-on wave condition, Figure 7 (b) is the second-order force F in the longitudinal direction x In F n =0.15 (horizontal wave), Figure 7 (c) is the second-order force F in the sway direction y In F n =0.15 (horizontal wave), Figure 7 (d) is the second-order moment M in the heading direction z In F n =0.15 (horizontal wave);

[0049] Figure 8 The trajectories of the S175 container ship model when the right rudder turns 35° and the left rudder turns -35° in the regular wave of χ=90° are compared. Figure 8 (a) is the wavelength to ship length ratio λ / L = 0.7, Figure 8 (b) is the wavelength to ship length ratio λ / L = 1.0;

[0050] Fig. 9 The trajectories of the S175 container ship model when the right rudder turns 35° and the left rudder turns -35° in the regular wave of χ=90° are compared. Fig. 9 (a) is the wavelength to ship length ratio λ / L = 0.7, Fig. 9 (b) is the wavelength-to-length ratio λ / L=1.0. DETAILED DESCRIPTION

[0051] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0052] The present invention proposes an energy efficiency evaluation method for propulsion and maneuvering safety of ship main engine under wave conditions. By adopting the three-dimensional Rankine panel method, the hull surface and free surface are discretized into panels, and Rankine sources or dipoles are arranged on the panels to solve the potential flow field of the fluid, and the object surface boundary conditions, the diffraction velocity potential free surface boundary conditions and the radiation velocity potential free surface boundary conditions are comprehensively considered (two different linearization methods are shown in the attached figure). Figure 2 ), the motion amplitude is obtained according to the wave excitation force using the boundary element indirect method. The mathematical model of the ship's motion in waves can be decomposed into two parts: low-frequency (maneuvering) motion and high-frequency (wavekeeping) motion (see the attached schematic diagram of maneuvering and wavekeeping coupling Figure 3 ): Low-frequency motion is described by the MMG motion mathematical model that takes into account wave drift force / torque (to simulate the influence of waves) to calculate the ship's sway, pitch and bow motion. High-frequency motion is expressed by the three-dimensional Rankine panel method, including pitch, roll and heave motion. The results are used to solve the wave resistance of the ship using the near-field pressure integration method.

[0053] Substitute the desired wave resistance into the rapid prediction model to predict the demand for ship propulsion power in different sea conditions, and evaluate the energy efficiency response of the main engine power in irregular waves, so as to ensure that the main engine can provide sufficient power reserve while maintaining a stable propulsion power output when responding to sudden sea conditions. In addition, through systematic data analysis and real-time power management, the system can derive appropriate propulsion power and propeller load according to different sea conditions, so that the ship can maintain an efficient operating state in a complex environment while minimizing fuel consumption and emissions. The method of the present invention includes the following steps:

[0054] A method for evaluating energy efficiency of propulsion and maneuvering safety of a ship main engine under wave conditions, characterized in that the method comprises the following steps:

[0055] S1. Obtain ship and wave parameter data, establish a ship motion MMG model, determine the initial ship's heading and speed information based on the MMG model, and use the initial ship's heading and speed information as the current ship's heading and speed information;

[0056] S2. The current ship's heading and speed information is substituted into the ship's seakeeping module, and the ship's seakeeping module outputs the ship's heave motion ξ 3 、Rolling motion 4 and pitch motion ξ 5 And the wave resistance in the ship's surge, sway, roll and pitch directions Convert wave resistance into second-order wave force / moment X acting on the hull in the directions of surge, sway, roll and pitch W ,Y W ,N W ,K W , the second-order wave force / torque is substituted back into the MMG model to obtain the new current ship's heading (obtained by integrating the bow speed r) and speed information (u, v vector sum, ) and control propulsion performance, update the time, repeat S2 to obtain the second-order wave force / torque at multiple times;

[0057] S3, the second-order wave forces / torques at multiple moments are input into the rapid prediction model, and the rapid prediction model outputs the predicted ship motion and propulsion power requirements;

[0058] S4. Compare the predicted ship propulsion power demand with the real-time ship power value, and adjust the ship main engine based on the comparison result.

[0059] The working principle of the present invention is based on a ship resistance calculation model, which focuses on calculating the second-order forces of the ship in the waves, that is, nonlinear forces or effects. These forces are usually related to the interaction between waves and fluid dynamics and are the main factors of the resistance encountered by the ship during navigation.

[0060] Among them, the second-order force / torque theory solves:

[0061] Object surface boundary conditions: describe the interaction and restrictions between the ship and the waves.

[0062]

[0063] in, is the object surface mesh, is the incident wave velocity potential, ω is the encounter frequency; n j is the normal vector, m j For additional quality. is the diffraction velocity potential; is the radiation velocity potential.

[0064] The unit incident wave velocity potential is

[0065]

[0066] Here 0 is the unit incident wave frequency; χ is the wave angle, and the diffraction velocity potential free surface boundary condition: when the ship performs a small amplitude simple harmonic motion in still water, the radiation wave generated by the fluid around the ship acts on the hull structure. The radiation velocity potential under this action needs to satisfy the balance between the fluid acceleration caused by the wave and the fluid pressure gradient caused by gravity.

[0067]

[0068] Radiation velocity potential free surface boundary condition: refers to the conditions that the velocity potential needs to meet on the free water surface in the diffraction phenomenon generated when the wave encounters the hull during propagation.

[0069]

[0070] Substituting the boundary conditions:

[0071]

[0072] Use the boundary element indirect method: transform the well-defined problem of differential equations or partial differential equations into boundary integral equations, then obtain the numerical solution of the original problem by solving the boundary integral equations, and integrate the pressure to calculate the additional mass a ij 、Wave damping b ij , wave excitation force F i and motion response ξ j Calculation of

[0073]

[0074] Taking Wigley ship and S175 ship as examples, the motion calculation results are shown in the attached Figure 4-6 .

[0075] The mass matrix is I ij is the moment of inertia, M is the mass of the ship, Z G Represents the vertical coordinate of the center of gravity.

[0076] Calculate the motion amplitude based on the wave excitation force:

[0077]

[0078] The static restoring force matrix is:

[0079]

[0080] A W represents the waterplane area of ​​the hull, z B Represents the vertical coordinate of the center of buoyancy.

[0081] The added mass matrix is The wave damping matrix and additional mass matrix are similar and will not be described here.

[0082] They correspond to the surge, sway and heave motions of the ship respectively.

[0083]

[0084] Among them, φ I and φ d are the incident wave velocity potential and the disturbance velocity potential respectively; ζ I and d are the incident wave height and the disturbance wave height, respectively; is the position vector; represents the wave-induced linear displacement vector; Represents the angular displacement vector. Taking the S175 ship as an example, the calculation results of the second-order force and second-order moment (resistance) are shown in the attached Figure 7 .

[0085] The main feature of the MMG model used in the present invention is to decompose the fluid forces and moments acting on the ship into the fluid forces and moments acting on the bare hull, open water propeller and open water rudder according to the physical meaning, as well as the interference between them (the ship maneuvering turning trajectory under different working conditions is shown in the attached figure). Figure 8-9 ). This separated model handles the complex interactions between the ship, propeller, and rudder. Each hydrodynamic force has obvious physical meaning and is easy to express using the results obtained from a series of tests, as shown in the following formula:

[0086]

[0087] Where p is the rolling velocity and m is the mass of the ship. x and m y are the additional masses of the x-axis and y-axis respectively. xx and J zz are the additional moments of inertia about the x-axis and z-axis respectively. The subscripts H, R, and P represent the low-frequency hydrodynamic forces acting on the hull, rudder, and propeller respectively. Among them, the main engine model power is converted into the longitudinal force X P To express. W ,Y W ,N W ,K Wis the second-order force / moment acting on the hull.

[0088] Forces and moments acting on the hull:

[0089]

[0090] Where: R(u 0 ) is the straight-line resistance.

[0091] Forces acting on the rudder:

[0092]

[0093] Propeller thrust:

[0094]

[0095] Since the minimum main engine propulsion power is mainly provided by the propeller thrust, this system mainly focuses on the propeller thrust research, so as to evaluate the matching degree between the minimum main engine power and wave resistance.

[0096] Finally, the present invention also takes into account the impact of propeller design on the main engine power response, fuel consumption, and the ship's maneuvering safety. By optimizing the propeller's parameters such as the number of blades, speed, diameter, pitch, and disk ratio, the ship's maneuvering safety and energy efficiency are improved, while fuel consumption and emissions are reduced.

[0097] The present invention aims to solve the deficiencies in the prior art in the safety of ship maneuvering in waves and the energy efficiency evaluation, especially in the propulsion efficiency of the main engine. The main technical problems existing in the background technology include:

[0098] 1. Low propulsion efficiency: Since the propeller design parameters (such as disc ratio, diameter, and pitch) are not optimized, the energy loss is large and the propulsion efficiency is low.

[0099] 2. Insufficient response capability: The main engine’s insufficient rapid response capability makes it difficult for the ship to quickly adjust power output when facing sudden sea conditions, affecting the safety of operation.

[0100] 3. Lack of comprehensive evaluation method: The existing technology lacks a rapid prediction method that comprehensively considers the ship's maneuverability and seakeeping, especially the calculation model of ship resistance in the frequency domain is not accurate enough.

[0101] In view of the above problems, the present invention has the following core contents:

[0102] 1. Optimizing propeller design parameters: The present invention optimizes propeller design by adjusting propeller parameters such as disc ratio, diameter, and pitch to improve propulsion efficiency and reduce energy loss.

[0103] 2. Improve the rapid response capability of the main engine: The present invention improves the rapid response capability of the main engine by improving the main engine control system, ensuring that the ship can quickly adjust the power output when facing sudden sea conditions.

[0104] 3. Development of a rapid prediction method: The present invention proposes a rapid prediction method that combines ship maneuverability and wave resistance with consideration of the main engine propulsion efficiency. This method develops a ship resistance (second-order force / torque) calculation model in the frequency domain based on the three-dimensional Rankine panel method and the near-field pressure integration method.

[0105] 4. Database and real-time call: The ship resistance is calculated in advance according to the parameter changes caused by ship maneuvering and saved in the database. The ship calls the second-order force / torque in real time according to the maneuvering motion state to replace the impact of waves on the ship.

[0106] 5. Establish a unified model: Establish a unified model of ship maneuvering and seakeeping, which can quickly predict the ship maneuvering movement under regular waves and irregular waves.

[0107] 6. Evaluation and analysis: Based on the current resistance of the ship, evaluate the matching of the main engine propulsion power and wave resistance, and analyze the influence of propeller speed and parameters on the main engine propulsion power.

[0108] Compared with the prior art, the method for evaluating the propulsion power efficiency of the main engine for safe ship maneuvering in waves of the present invention has the following advantages and positive effects:

[0109] 1. Enhanced emergency response capabilities

[0110] This system can ensure that in the event of sudden sea conditions, the ship's main engine has the ability to respond quickly and adjust the output power in time to maintain the stability and safety of the ship.

[0111] 2. Optimized power reserve

[0112] The design of this system takes into account sufficient power reserve to ensure that the ship can still maintain the necessary propulsion force under extreme sea conditions, ensuring the continuity and safety of navigation.

[0113] 3. Improve energy efficiency and reduce fuel consumption

[0114] This system precisely controls the propeller design parameters and main engine power output, allowing the ship to maintain efficient operation in complex sea conditions while minimizing fuel consumption.

[0115] 4. Reduce emissions and promote environmental protection

[0116] This system significantly reduces CO2 and other greenhouse gas emissions by optimizing propulsion efficiency, complying with global requirements for environmental protection and reducing carbon footprint.

[0117] 5. Broad industry application prospects

[0118] It will bring the following positive impacts to the maritime industry:

[0119] 1) Improve ship navigation safety

[0120] This system can evaluate the ship's maneuverability in real time under different sea conditions, and provide assurance for navigation safety in extreme climates and complex waters. By optimizing propeller parameters and main engine power response, the ship's maneuverability in emergency situations can be improved, and risks during navigation can be reduced.

[0121] 2) Promote energy conservation, emission reduction and environmental protection

[0122] This system supports the increasingly stringent global carbon emission standards and significantly reduces fuel consumption and carbon dioxide emissions by rationally optimizing propeller design. It achieves dynamic adjustment of propulsion power, avoids unnecessary fuel waste, improves overall navigation energy efficiency, and provides support for the goal of achieving carbon neutrality and green shipping.

[0123] 3) Provide guidance for ship design and manufacturing

[0124] The application of this invention can provide accurate propeller parameter optimization models for ship design and manufacturing companies, helping to design more efficient and adaptable ship propulsion systems. By improving the matching efficiency of propellers and main engines, shipyards can develop more energy-saving ship products to meet the market's growing demand for energy-saving and environmentally friendly ships.

[0125] In summary, the present invention not only improves the maneuvering safety and energy efficiency of ships, but also has important significance for environmental protection and the sustainable development of the maritime industry, and meets the requirements for technological improvement and innovation in patent applications.

[0126] The technical points of the present invention are:

[0127] Real-time resistance calculation and power evaluation: The three-dimensional Rankine panel method is used to calculate the resistance of the ship in different sea conditions in real time, and dynamically evaluate the propulsion power demand of the main engine according to the change of resistance. This method can more accurately reflect the impact of sea condition changes on propulsion performance, ensuring that the ship can operate efficiently, economically and safely under various navigation conditions.

[0128] Optimal matching of sea conditions and propulsion power: The system can automatically adjust the power output of the main engine according to the current sea conditions, ensuring that the main engine provides sufficient power to cope with harsh environments but avoids excessive power output, thereby saving fuel and reducing emissions.

[0129] Main engine power guarantee and optimization: By evaluating the main engine's power reserve under different sea conditions, it is ensured that the main engine can respond quickly and provide sufficient propulsion power in emergency collision avoidance or other emergencies, while avoiding excessive energy consumption. This evaluation mechanism not only ensures the navigation safety of the ship, but also optimizes energy use and reduces operating costs.

[0130] Balance between energy efficiency and safety: The system not only focuses on the minimum propulsion power requirements, but also takes into account the safety performance of the ship, and can achieve the best balance between energy efficiency and safety under various complex offshore operating conditions. Through real-time data feedback and optimization adjustments, it ensures that the ship can reduce energy consumption as much as possible while ensuring safety.

[0131] Environmental benefits: Through real-time adjustment and optimization of ship propulsion power, fuel consumption can be minimized, thereby reducing ship exhaust emissions, which meets the current demand for environmental protection in the shipping industry.

[0132] The schematic diagram of power transmission from ship main engine to propeller is as follows Figure 1 shown.

[0133] The present invention Figure 4 In the paper, the simulation results are basically consistent with the experimental data (Journée J.Experiments and calculations on 4Wigley hull forms in head waves,May 1992[R].Delft University of Technology,1992.), which verifies the effectiveness of the calculation model in this paper.

[0134] The present invention Figure 5 In the figure, the heave and pitch motion results of the S175 container ship under Fn=0.275 and transverse wave conditions (χ=90°) are compared with the experimental data (Yasukawa H. Simulations of a ship maneuvering in waves (1st report: turning motion) [J]. Journal of The Japan Society of Naval Architects and Ocean Engineers, 2006, 4: 127-136.). Figures (a) and (b) show the heave and pitch motion of the S175 container ship under transverse and oblique wave conditions, respectively. It can be seen that the calculated results are basically consistent with the experimental data.

[0135] The present invention Figure 6In the figure, the heave and pitch motion results of the S175 container ship under Fn=0.275 and oblique wave conditions (χ=150°) are compared with the experimental data (Yasukawa H. Simulations of a ship maneuvering in waves (1st report: turning motion) [J]. Journal of The Japan Society of Naval Architects and Ocean Engineers, 2006, 4: 127-136.). Figures (a) and (b) show the heave and pitch motion of the S175 container ship under transverse and oblique wave conditions, respectively. It can be seen that the calculated results are basically consistent with the experimental data.

[0136] The present invention Figure 7 In the figure, based on the S175 container ship, the second-order forces / moments on the ship under different wave conditions are shown. It can be seen that the numerical calculation results are in good agreement with the test data. Figure (a) shows the S175 under F n =0.20 The second-order force in the longitudinal direction under the head-on wave condition, DB linearization calculation results are in good agreement with the literature data and are closer to the experimental data than other results. Figure (b) Second-order force F in the longitudinal direction x In F n = 0.15 (transverse wave); (c) second-order force F in the transverse direction y In F n = 0.15 (beam wave); (d) second-order moment in the bow rolling direction M z In F n =0.15 (beam wave), the calculation results of Present results have good conformity, and for the second-order force F y and the second-order moment M z , which is basically consistent with the experimental data.

[0137] The present invention Figure 8 In the figure, the trajectories of the S175 container ship model in the regular wave of χ=90° ...

[0138] The present invention Fig. 9In the figure, the trajectories of the S175 container ship model with a right rudder of 35° and a left rudder of -35° in a regular wave of χ=90°, and the trajectories of the S175 container ship model with a left rudder of -35° in a regular wave of χ=90° are compared: (a) wavelength-to-ship length ratio λ / L=0.7; (b) wavelength-to-ship length ratio λ / L=1.0. Compared with the experimental data, it can be seen that the numerical results of the rotation trajectory under different incident waves show a drift phenomenon, and the drift direction is consistent with the wave propagation direction, which is consistent with the experimental data.

[0139] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for evaluating the energy efficiency of ship main engine propulsion and maneuvering safety under wave conditions, characterized in that: The method comprises the following steps: S1. Obtain ship and wave parameter data, establish a ship motion MMG model, determine the initial ship's heading and speed information based on the MMG model, and use the initial ship's heading and speed information as the current ship's heading and speed information; S2. The current heading and speed information of the ship is substituted into the ship seakeeping module, which outputs the ship's heave motion ξ3, roll motion ξ4 and pitch motion ξ5 as well as the wave resistance in the ship's pitch, sway, roll and bow directions. Convert wave resistance into second-order wave force / moment X acting on the hull in the directions of surge, sway, roll and pitch W ,Y W ,N W ,K W , the second-order wave force / torque is substituted back into the MMG model to obtain the new current ship's heading and speed information as well as the maneuvering and propulsion performance, update the time, and repeat S2 to obtain the second-order wave force / torque at multiple times; S3, the second-order wave forces / torques at multiple moments are input into the rapid prediction model, and the rapid prediction model outputs the predicted ship motion and propulsion power requirements; S4. Compare the predicted ship propulsion power demand with the real-time ship power value, and adjust the ship main engine based on the comparison result.

2. The energy efficiency evaluation method for propulsion and maneuvering safety of a ship main engine under wave conditions according to claim 1 is characterized in that: The ship seakeeping module outputs the ship's heave motion ξ3, roll motion ξ4 and pitch motion ξ5 as well as the wave resistance in the ship's pitch, sway, roll and bow directions. The specific steps are: The hull surface and free surface are discretized into surface elements through the three-dimensional Rankine surface element method, and the object surface boundary conditions, diffraction velocity potential free surface boundary conditions and radiation velocity potential free surface boundary conditions are constructed. The initial boundary value problem is solved, and the velocity potential of each surface element is obtained. After the velocity potential distribution is obtained, the pressure integration method is used to further solve the hydrodynamic characteristics of the hull, and the added mass, wave damping and wave excitation force are obtained, and the motion amplitude is obtained. The motion amplitude includes the ship's heave motion ξ3, roll motion ξ4 and pitch motion ξ5. The wave resistance of the ship in the longitudinal, sway, roll and bow directions is calculated based on the motion amplitude.

3. The energy efficiency evaluation method for propulsion and maneuvering safety of a ship main engine under wave conditions according to claim 2 is characterized in that: Wave resistance in the ship's surge, sway, roll and pitch directions is the wave resistance is the wave resistance The directional components of surge, sway, roll and pitch, wave resistance for: Among them, φ I and φ d are the incident wave velocity potential and the disturbance velocity potential respectively; x and y are the ordinate and abscissa of the center of the surface element respectively, is the normal vector of the surface element; S is the area of ​​the surface element; H is the transformation matrix; ζ I and d are the incident wave height and the disturbance wave height, respectively; is the position vector; represents the wave-induced linear displacement vector; Represents the angular displacement vector, the wave-induced linear displacement vector and the angular displacement vector constitute the motion amplitude, where ξ3 represents the heave motion, ξ4 represents the roll motion, and ξ5 represents the pitch motion ξ5.

4. The energy efficiency evaluation method for propulsion and maneuvering safety of a ship main engine under wave conditions according to claim 3 is characterized in that: The motion amplitude obtained by the pressure integration method is: Among them, S B is the object surface mesh, is the unit incident wave velocity, the potential wave height is 1 meter, ω is the encounter frequency; n j is the normal vector in the j direction, m j is the ship mass matrix, is the diffraction velocity potential; is the radiation velocity potential, n is the normal vector, a ij ,b ij ,F i and j are respectively the ship's additional mass, wave damping, wave excitation force and motion amplitude; ρ is the seawater density.

5. The energy efficiency evaluation method for propulsion and maneuvering safety of a ship main engine under wave conditions according to claim 4 is characterized in that: The object surface boundary condition is: Among them, S B is the object surface mesh, is the unit incident wave velocity potential, ω is the encounter frequency; n j is the normal vector in the j direction, m j For the additional mass, is the diffraction velocity potential; is the radiation velocity potential, and n is the normal vector.

6. The energy efficiency evaluation method for propulsion and maneuvering safety of a ship main engine under wave conditions according to claim 5 is characterized in that: The free surface boundary condition of the diffraction velocity potential is: Where z represents the vertical coordinate of the free surface element grid, g represents the gravitational acceleration, μ represents the artificial damping coefficient on the free surface, i represents an imaginary number, and Φ represents the stack flow velocity potential. Indicates the ship speed, Φ zz Represents the second derivative of the stack flow velocity potential in the z direction.

7. The energy efficiency evaluation method for propulsion and maneuvering safety of a ship main engine under wave conditions according to claim 6 is characterized in that: The free surface boundary condition of the radiation velocity potential is: Where z represents the vertical coordinate of the free surface element grid, g represents the gravitational acceleration, μ represents the artificial damping coefficient on the free surface, i represents an imaginary number, and Φ represents the stack flow velocity potential. Indicates the ship speed, Φ zz Represents the second derivative of the stack flow velocity potential in the z direction.

8. The energy efficiency evaluation method for propulsion and maneuvering safety of a ship main engine under wave conditions according to claim 7 is characterized in that: The second-order wave force / moment X acting on the hull in the directions of surge, sway, roll and pitch obtained by converting wave resistance W ,Y W ,N W ,K W for: Here, ρ is the density of seawater; g is the acceleration due to gravity; h a is the wave height; B is the ship width; L is the ship length, Wave resistance The directional components of surge, sway, roll and pitch, X W ,Y W ,N W ,K W It is the second-order wave force / moment acting on the hull in the directions of surge, sway, roll and pitch.

9. The energy efficiency evaluation method for propulsion and maneuvering safety of a ship main engine under wave conditions according to claim 2 is characterized in that: The MMG model, that is, the high-frequency model in the wave-resistant mode is: Where p is the rolling velocity, m is the mass of the ship, and m x and m y are the additional masses of the x-axis and y-axis, J xx and J zz are the additional moments of inertia about the x-axis and z-axis respectively. The subscripts H, R, and P represent the low-frequency hydrodynamic forces acting on the hull, rudder, and propeller respectively. P is the propeller longitudinal thrust, X W ,Y W ,N W ,K W is the second-order wave force / moment acting on the hull in the directions of surge, sway, roll and pitch, u, v, r represent the longitudinal velocity, transverse velocity and pitch velocity of the ship respectively, z G represents the vertical coordinate of the center of gravity, X H ,Y H ,N H ,K H are the wave resistance coupling results at the previous moment, that is, the forces and moments acting on the hull in the directions of surge, sway, roll and pitch; X R ,Y R ,N R ,K R are the forces and moments acting on the rudder in surge, sway, roll and pitch directions respectively; The force acting on the rudder is: Among them, F N is the positive pressure acting on the rudder, δ is the rudder angle, t R ,a H and x H represents the coupling coefficient between the hull and the rudder, x R and z R are the x- and z-coordinates of the rudder normal force action point, respectively; The longitudinal thrust of the propeller is: Among them, n P is the propeller speed, D P is the propeller diameter, K T is the thrust coefficient, t P is the propeller thrust derating coefficient, and ρ is the seawater density.

10. The energy efficiency evaluation method for propulsion and maneuvering safety of a ship main engine under wave conditions according to claim 9, characterized in that: The new current heading of the ship is the integral result of the bow speed r output by the MMG model, and the new current speed information is the vector sum of the longitudinal speed and the lateral speed of the ship output by the MMG model, which is U represents the vector sum.

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