Design method of integrated energy-saving propulsion for very large crude carrier

Abstract

The application discloses a VLCC integrated energy-saving propulsion design method, and relates to the ship technology field.The method is used for optimizing the bow linear and the stern linear type after determining the ship structure parameters, and the optimization is carried out with the optimal fast performance and energy-saving effect as the target.The designed bow linear type has the minimum wave-making resistance coefficient, and the designed stern linear type has the reverse curve structure of the transverse section line with the lowest received power of the whole ship.Through the optimization and improvement of the linear type and the water power energy-saving device, the energy efficiency level of the designed VLCC using the conventional fuel can be improved by more than 5% compared with the existing average level, and the EEDI can be reduced by more than 30% compared with the baseline, so that the requirement of the EEDI phase 3 is met.

Description

Technical Field

[0001] This application relates to the field of ship technology, and in particular to an integrated energy-saving propulsion design method for very large oil tankers. Background Technology

[0002] In recent years, the International Maritime Organization (IMO) has formulated a series of environmental regulations to promote energy conservation and emission reduction in ships, including the Preliminary Strategy for GHG Emission Reduction, the Energy Efficiency Design Index (EEDI) Guidelines for New Ships, and the Energy Efficiency Design Index (EEXI) Guidelines for Existing Ships. Continuing to strengthen the EEDI requirements under the existing energy efficiency framework has become an industry consensus, and EEDI has become the fastest and most effective way to address GHG emission reduction in ships.

[0003] Improving ship energy efficiency during the design phase to meet EEDI requirements while reducing fuel consumption and CO2 emissions is a primary goal for ship designers. Existing technologies for improving ship energy efficiency mainly include: hull design technology, energy-saving propulsion technology, innovative energy-saving technology, and alternative fuel technology. As EEDI requirements become increasingly stringent, the benefits of applying a single energy-saving and emission-reduction technology are extremely limited. Therefore, most ships will use one or two energy-saving and emission-reduction technologies in combination. However, this only meets the requirements of EEDI Phase 2 and cannot meet the requirements of higher phases (Phase 3 / Phase 4).

[0004] Moreover, existing research on improving ship energy efficiency mainly focuses on small and medium-sized ships, with a lack of research on energy-saving design for 300,000-ton Very Large Crude Carriers (VLCCs). Compared to small and medium-sized ships, energy-saving design for VLCCs is more difficult. Therefore, the current approach mainly focuses on optimizing the energy-saving performance of 300,000-ton VLCCs through new alternative fuels. However, most new alternative fuels are not yet ready for large-scale shipboard application due to limitations in technology maturity, fuel availability, economics, and infrastructure. Even with the use of new alternative fuels, VLCCs still fall far short of meeting the EEDI phase 3 requirements and there is a significant gap. Summary of the Invention

[0005] In response to the aforementioned problems and technical requirements, the applicant proposes an integrated energy-saving propulsion design method for ultra-large oil tankers. The technical solution of this application is as follows:

[0006] An integrated energy-saving propulsion design method for ultra-large oil tankers, comprising:

[0007] Determine the hull structure parameters;

[0008] A fully parameterized bow model was established, and the bow profile that minimizes the wave-making drag coefficient was determined based on the fully parameterized bow model.

[0009] Based on the established hull structure parameters and bow shape, a pre-established energy-saving effect prediction model is used to determine the stern shape that minimizes the power received by the entire ship. The transverse section of the stern has a concave structure to form a flow-rectifying cavity for accelerating the stern water flow. The energy-saving effect prediction model characterizes the mapping relationship between the wake field data of the bare hull and the power received by the entire ship after the installation of hydrodynamic energy-saving devices on the bare hull. The wake field data of the stern is related to the hull structure parameters, bow shape, and stern shape.

[0010] The bare hull of a very large oil tanker was designed based on the hull structure parameters, bow and stern lines, and hydrodynamic energy-saving devices were added to the bare hull to complete the design of the very large oil tanker.

[0011] Further technical solutions include the following: The integrated energy-saving propulsion design method for ultra-large oil tankers also includes:

[0012] Obtain a sample dataset, which includes several sets of sample data. Each set of sample data includes the bare hull design parameters of the sample supertanker and the total power received by the ship after the installation of hydrodynamic energy-saving devices on the bare hull. The bare hull design parameters include hull structural parameters, bow lines and stern lines.

[0013] The visco-potential coupling method was used to conduct self-propulsion numerical calculations to evaluate the design parameters of the bare hull in each set of sample data, so as to determine the wake field data of the bare hull at the stern of each set of sample data.

[0014] Using the wake field data of the bare hull of each sample data as input and the power received by the whole ship after installing the hydrodynamic energy-saving device on the bare hull as output, the convolutional neural network model is trained based on the sample dataset to establish an energy-saving effect prediction model.

[0015] The further technical solution is that the cross section at each station of the stern of the supertanker includes the upper inflection point, the middle inflection point and the lower inflection point from top to bottom. All three inflection points are the inflection points of the curvature change of the cross section.

[0016] Determining the stern shape of a Very Large Crude Carrier (VLCC) involves determining the shape parameters of the cross section at each characteristic station of the stern, including:

[0017] The distance between the upper inflection point in the cross section and the centerline of the very large crude carrier (VLCC), the distance between the upper inflection point in the cross section and the baseline of the VLCC, and the distance between the upper inflection point in the cross section and the tangent of the cross section.

[0018] In addition, the distance between the mid-curve point in the cross section and the centerline of the very large crude carrier (VLCC), and the distance between the mid-curve point in the cross section and the baseline of the VLCC.

[0019] In addition, the distance between the lower inflection point in the cross section and the centerline of the very large crude carrier, and the distance between the lower inflection point in the cross section and the baseline of the very large crude carrier.

[0020] And the angle between the tangent of the cross section and the baseline of the very large crude carrier;

[0021] The very large crude carrier (VLCC) is divided into 20 stations from the bow to the stern vertical. The characteristic stations at the stern of the VLCC include stations 0.75, 1, 1.5, and 2, which are arranged sequentially from the stern vertical toward the bow. The line shape parameters of the cross section at different characteristic stations at the stern are different.

[0022] The further technical solution is that the determined cross-sectional parameters at the 0.75 station of the stern of the very large crude carrier include:

[0023] The mid-curve point M of the cross section at station 0.75 0.75 Distance Y1 from the centerline of the very large crude carrier 0.75 The inflection point is 0.04B to 0.05B. 0.75 Distance from the baseline of the Very Large Crude Carrier (VLCC) The inflection point is 0.56D to 0.59D. 0.75 The distance d from the tangent of the cross section at station 0.75 0.75 It is 0.48s 0.75 ~0.51s 0.75 ,

[0024] The lower inflection point L of the cross section at station 0.75 0.75 Distance Y2 from the centerline of the very large crude carrier 0.75 The value is 0.02B to 0.03B, and the lower inflection point is L. 0.75 Distance from the baseline of the Very Large Crude Carrier (VLCC) The value ranges from 0.09D to 0.11D.

[0025] The upper inflection point H of the cross section at station 0.75 0.75 Distance Y3 from the centerline of the very large crude carrier 0.75 The value is 0.52B to 0.54B, and the upper inflection point is H. 0.75 Distance from the baseline of the Very Large Crude Carrier (VLCC) The value ranges from 0.94D to 0.97D.

[0026] The angle θ between the tangent of the cross section at station 0.75 and the baseline of the Very Large Crude Carrier (VLCC). 0.75 The angle is 49° to 50°, B is the half-width of the Very Large Crude Carrier (VLCC), and D is the design draft of the VLCC.

[0027] The further technical solution is that the shape parameters of the transverse section at point 1 of the stern of the very large crude carrier include:

[0028] The distance Y1 from the mid-curve point M1 of the cross section at site 1 to the centerline of the very large crude carrier. 1 The distance from the mid-curvature point M1 to the baseline of the very large crude carrier (VLCC) is 0.08B to 0.1B. The distance d1 between the tangent of the cross section at the mid-curve point M1 and station 1 is 0.48s1 to 0.51s1, and is between 0.54D and 0.57D.

[0029] The distance from the lower concave point L1 of the cross section at site 1 to the centerline of the very large crude carrier. The distance from the lower concave point L1 to the baseline of the very large crude carrier is 0.04-0.06B. The value ranges from 0.04D to 0.06D.

[0030] The distance from the upper inflection point H1 of the cross section at site 1 to the centerline of the very large crude carrier. The distance from the upper inflection point H1 to the baseline of the very large crude carrier is 0.56-0.59B. The value is 0.92D to 0.95D.

[0031] The angle θ1 between the tangent of the cross section at station 1 and the baseline of the Very Large Crude Carrier (VLCC) is 49° to 50°. B is the half-width of the VLCC, and D is the design draft of the VLCC.

[0032] The further technical solution is that the shape parameters of the transverse section at station 1.5 of the stern of the very large crude carrier include:

[0033] 1.5 The mid-curve point M of the cross section at station 1.5 1.5 Distance Y1 from the centerline of the very large crude carrier 1.5 The value is 0.2B to 0.22B, with the mid-curvature point M. 1.5 Distance from the baseline of the Very Large Crude Carrier (VLCC) The inflection point is 0.52D to 0.56D. 1.5 The distance d from the tangent of the cross section at station 1.5 1.5 It is 0.37s 1.5 ~0.40s 1.5 ,

[0034] 1.5 The lower inflection point L of the cross section at station 1.5 1.5 Distance Y2 from the centerline of the very large crude carrier 1.5 The value is 0.1B to 0.12B, and the lower inflection point is L. 1.5 Distance from the baseline of the Very Large Crude Carrier (VLCC) The value ranges from 0.04D to 0.06D.

[0035] 1.5 The upper inflection point H of the cross section at station 1.5 1.5 Distance Y3 from the centerline of the very large crude carrier 1.5 The curve is 0.65B to 0.68B, with the upper inflection point H. 1.5 Distance from the baseline of the Very Large Crude Carrier (VLCC) The value ranges from 0.88D to 0.92D.

[0036] 1.5 The angle θ between the tangent of the cross section at station 1.5 and the baseline of the very large crude carrier. 1.5 The angle is 45° to 46°, B is the half-width of the Very Large Crude Carrier (VLCC), and D is the design draft of the VLCC.

[0037] The further technical solution is that the shape parameters of the transverse section at two stations on the stern of the very large crude carrier include:

[0038] The distance Y1 from the mid-curve point M2 of the cross section at site 2 to the centerline of the very large crude carrier. 2 The distance Z1 from the mid-curvature point M2 to the baseline of the very large crude carrier is 0.3B to 0.32B. 2 The distance d2 between the tangent of the cross section at the mid-curve point M2 and station 2 is 0.25s2 to 0.28s2, and the curve is 0.5D to 0.54D.

[0039] The distance Y2 from the lower concave point L2 of the cross section at site 2 to the centerline of the very large crude carrier. 2 The distance from the lower concave point L2 to the baseline of the very large crude carrier (VLCC) is 0.16B to 0.18B. The value ranges from 0.06D to 0.08D.

[0040] The distance Y3 from the upper inflection point H2 of the cross section at site 2 to the centerline of the very large crude carrier. 2 The distance from the upper inflection point H2 to the baseline of the very large crude carrier is 0.73B to 0.76B. The value ranges from 0.86D to 0.9D.

[0041] The angle θ2 between the tangent of the cross section at station 2 and the baseline of the Very Large Crude Carrier (VLCC) is 44° to 45°. B is the half-width of the VLCC, and D is the design draft of the VLCC.

[0042] Its further technical solution involves determining the bow hull form of the very large crude carrier, including:

[0043] A fully parameterized bow model is established based on bow characteristic parameters including waterline inflow angle, waterline fullness, and bow cross-sectional area curve fullness.

[0044] The Sobol algorithm is used to generate a combination of parameters for multiple uniformly distributed bow feature parameters and the bow profile corresponding to each parameter combination.

[0045] Using CFD software based on potential flow theory, wave-making resistance was calculated for the fully parameterized bow model under each combination of bow characteristic parameters. The bow shape corresponding to the parameter combination of bow characteristic parameters that minimizes the wave-making resistance coefficient was taken as the bow shape of the very large crude carrier.

[0046] Its further technical solution involves determining the hull structure parameters of the very large crude carrier, including:

[0047] The Very Large Crude Carrier (VLCC) is defined as consisting of the bow, intake section, parallel midhull, outflow section, and stern section from bow to stern. The bow adopts a straight-arm bow design, with a V-shaped cross section above the structural waterline. The bottom of the bow extends smoothly from the structural draft to the main deck of the VLCC. The lowest point of the vertical section of the bow's mid-section is 48.8% of the VLCC's design draft, and the radius of curvature of the arc section is 1.6 meters. The length of the parallel midhull is 18.4% of the VLCC's length between perpendiculars, and the length of the outflow section is 38.3% of the VLCC's length between perpendiculars.

[0048] The further technical solution is that the length between perpendiculars of the very large crude carrier is 326.6 meters, the beam is 60 meters, the design draft is 20.5 meters, the structural draft is 21.8 meters, the billet coefficient of the bow is 0.7133, the billet coefficient of the stern is 0.8733, and the longitudinal position of the center of buoyancy is 3.8%; the very large crude carrier is a low-speed vessel with a Froude number of 0.13 and a billet coefficient of 0.8 at a speed of [missing information].

[0049] The beneficial technical effects of this application are:

[0050] This application discloses an integrated energy-saving propulsion design method for very large oil tankers. After determining the hull structural parameters, the method optimizes the bow linearity and stern lines with the goal of achieving optimal speed performance and energy saving effect. The bow line design minimizes the wave-making drag coefficient, and the stern line design features a concave cross section structure that minimizes the overall power received by the ship. By optimizing and improving the lines in conjunction with hydrodynamic energy-saving devices, the energy efficiency level of the designed very large oil tanker using conventional fuels can be increased by more than 5% compared to the existing average level, and the energy efficiency ratio (EEDI) can be reduced by more than 30% compared to the baseline, thereby meeting the requirements of EEDI phase 3. Attached Figure Description

[0051] Figure 1 This is a flowchart of an embodiment of the integrated energy-saving propulsion design method for ultra-large oil tankers.

[0052] Figure 2 It is a cross-sectional view of the stern section obtained from the design.

[0053] Figure 3 This is a schematic diagram of the cross section at 0.75 stations on the stern relative to the centerline and baseline.

[0054] Figure 4 This is the stern profile diagram obtained from the design.

[0055] Figure 5 This is a schematic diagram of the bare hull structure of the designed supertanker.

[0056] Figure 6 This is a three-dimensional structural diagram of the bow of the designed supertanker. Detailed Implementation

[0057] The specific embodiments of this application will be further described below with reference to the accompanying drawings.

[0058] This application discloses an integrated energy-saving propulsion design method for very large crude carriers (VLCCs). This method is used to design 300,000-ton VLCCs, such as common VLCCs, and the resulting VLCCs do not require the use of new alternative fuels; they can meet EEDI phase 3 requirements using only conventional fuels. The design method includes the following steps; please refer to [reference needed]. Figure 1 The flowchart shown below:

[0059] Step 1: Determine the hull structure parameters.

[0060] The hull structure of the Very Large Crude Carrier (VLCC) designed in this application comprises, from bow to stern, a bow section, a parallel midhull, a flow-out section, and a stern. Specifically, the bow adopts a straight-arm bow design, with a V-shaped cross section above the structural waterline. The bottom of the bow smoothly extends from the structural draft to the main deck of the VLCC. The lowest point of the vertical section of the bow's mid-section is 48.8% of the design draft of the VLCC, and the radius of curvature of the arc section is 1.6 meters. The length of the parallel midhull is 18.4% of the VLCC's length between perpendiculars, and the length of the flow-out section is 38.3% of the VLCC's length between perpendiculars.

[0061] The hull structure parameters of a Very Large Crude Carrier (VLCC) include: length between perpendiculars of 326.6 meters, beam of 60 meters, design draft of 20.5 meters, and structural draft of 21.8 meters. The billet coefficient is 0.7133 at the bow, 0.8733 at the stern, and the longitudinal position of the center of buoyancy is 3.8%. The VLCC is a low-speed vessel with a Froude number of 0.13 and a billet coefficient of 0.8 at its operating speed. The design waterline and structural waterline employ an approach angle adapted to a Froude number of 0.13 at the operating speed to reduce wave-making drag.

[0062] After determining the hull structure parameters, the bow and stern lines were optimized with the goal of achieving optimal speed performance and energy saving. For ease of description, the line design will be represented by the transverse section lines (commonly referred to as station lines) at the ship's stations. The very large crude carrier designed in this application is divided into 20 stations from the bow to the stern vertical line. The station number is larger closer to the bow and smaller closer to the stern. The ship's station lines are divided according to the standard 20-station structure, which will not be elaborated in this embodiment.

[0063] Step 2: Establish a fully parameterized bow model, and based on this model, determine the bow profile that minimizes the wave-making drag coefficient. This includes:

[0064] (1) Establish a fully parametric bow model based on bow characteristic parameters including waterline inflow angle, waterline fullness, and bow cross-sectional area curve fullness. This step can be completed using the parametric modeling software Friendship. In practical applications, the bow characteristic parameters include the waterline inflow angle between stations 19 and 20, the waterline fullness between stations 16 and 18, and the bow cross-sectional area curve.

[0065] (2) Generate a combination of multiple uniformly distributed bow feature parameters and the bow profile corresponding to each parameter combination using the Sobol algorithm. The complete bow profile corresponding to each parameter combination is pre-configured.

[0066] (3) Using CFD software based on potential flow theory, wave-making resistance is calculated for the fully parameterized bow model under the parameter combination of each bow characteristic parameter. The bow shape corresponding to the parameter combination of the bow characteristic parameters that minimizes the wave-making resistance coefficient is taken as the bow shape of the supertanker.

[0067] This bow shape can effectively reduce the height of wave crests and troughs at the bow, and can also effectively improve wave-making midships to reduce wave-making drag.

[0068] Step 3: Based on the determined hull structure parameters and bow hull shape, the stern hull shape that minimizes the overall power received by the ship is determined using a pre-established energy-saving effect prediction model. In the designed stern hull shape, the transverse section of the stern has a reverse-curved structure to form a flow-rectifying cavity for accelerating the stern water flow.

[0069] The energy-saving effect prediction model used in this step needs to be pre-trained based on a convolutional neural network model. This model represents the mapping relationship between the wake field data at the stern of the bare hull and the total power received by the ship after the installation of hydrodynamic energy-saving devices. The wake field data is related to the design parameters of the bare hull, including hull structural parameters, bow hull shape, and stern hull shape. Therefore, this method also includes a pre-training model process, comprising the following steps:

[0070] (1) Obtain the sample dataset, which includes several sets of sample data. Each set of sample data includes the bare hull design parameters of the sample ultra-large oil tanker and the total power received by the sample ultra-large oil tanker after the bare hull is equipped with hydrodynamic energy-saving devices.

[0071] (2) The visco-potential coupling method was used to conduct self-propulsion numerical calculations to evaluate the design parameters of the bare hull in each set of sample data, so as to determine the wake field data of the bare hull at the stern of each set of sample data. The determined wake field data includes the axial velocity, radial velocity and tangential velocity at the propeller disk position.

[0072] (3) Using the wake field data of the bare hull of each sample data set as input and the power received by the whole ship after installing the hydrodynamic energy-saving device on the bare hull as output, the convolutional neural network model is trained based on the sample dataset to obtain the energy-saving effect prediction model. According to this energy-saving effect prediction model, the power received by the whole ship can be quickly predicted from the wake field data of the stern obtained by calculating the resistance of different ship types.

[0073] Then, under each set of stern lines, by combining the already determined hull structural parameters and bow lines, the visco-potential coupling method can be applied to conduct self-propulsion numerical calculations and evaluations to determine the corresponding wake field data of the bare hull. This data is then input into the established energy-saving effect prediction model to obtain the overall ship power received for that set of stern lines. By adjusting the bow lines and repeating the above process, the stern line that minimizes the overall ship power received can be determined.

[0074] Because the curvature of the transverse sections from 0.75 to 2 stations in the stern varies significantly, the changes in their shape characteristics have a substantial impact on the surface pressure distribution at the stern, the flow characteristics in the propeller and hydrodynamic energy-saving device areas, and consequently, significantly affect the hull drag performance, propeller propulsion performance, and the energy-saving effect of the hydrodynamic energy-saving device. Therefore, in this step, the determined stern shape includes the shape parameters of the transverse sections at the characteristic stations from 0.75 to 2 stations in the stern. In one embodiment, the characteristic stations in the stern of this very large crude carrier include stations 0.75, 1, 1.5, and 2, arranged sequentially from the stern vertical towards the bow.

[0075] The transverse section at each station of the stern of the Very Large Crude Carrier (VLCC) in this application includes, from top to bottom, an upper inflection point, a middle inflection point, and a lower inflection point, all three inflection points being inflection points of curvature change in the transverse section. Determining the stern profile of the VLCC involves determining the profile parameters of the transverse section at each characteristic station of the stern, including: the distance between the upper inflection point and the VLCC's centerline; the distance between the upper inflection point and the VLCC's baseline; and the distance between the upper inflection point and the tangent of the transverse section; as well as the distance between the middle inflection point and the VLCC's centerline, and the distance between the middle inflection point and the VLCC's baseline; and the distance between the lower inflection point and the VLCC's centerline, and the distance between the lower inflection point and the VLCC's baseline; and the angle between the tangent of the transverse section and the VLCC's baseline. The obtained cross-sectional line type parameters differ at different feature stations on the stern. Specifically, the cross-sectional line type parameters at the four determined feature stations are described below:

[0076] (1) The determined cross-sectional parameters of the stern section at the 0.75 station of the very large crude carrier include, please refer to... Figure 3 The diagram shown is as follows:

[0077] The mid-curve point M of the cross section at station 0.75 0.75 Distance Y1 from the centerline of the very large crude carrier 0.75 The inflection point is 0.04B to 0.05B. 0.75 Distance Z1 from the baseline of the Very Large Crude Carrier (VLCC) 0.75 The inflection point is 0.56D to 0.59D. 0.75 The distance d from the tangent of the cross section at station 0.75 0.75 It is 0.48s 0.75 ~0.51s 0.75 ,

[0078] The lower inflection point L of the cross section at station 0.75 0.75 Distance Y2 from the centerline of the very large crude carrier 0.75 The value is 0.02B to 0.03B, and the lower inflection point is L. 0.75 Distance from the baseline of the Very Large Crude Carrier (VLCC) The value ranges from 0.09D to 0.11D.

[0079] The upper inflection point H of the cross section at station 0.75 0.75 Distance Y3 from the centerline of the very large crude carrier 0.75 The value is 0.52B to 0.54B, and the upper inflection point is H. 0.75 Distance from the baseline of the Very Large Crude Carrier (VLCC) The value ranges from 0.94D to 0.97D.

[0080] The angle θ between the tangent of the cross section at station 0.75 and the baseline of the Very Large Crude Carrier (VLCC). 0.75 The angle is 49° to 50°, B is the half-width of the Very Large Crude Carrier (VLCC), and D is the design draft of the VLCC.

[0081] (2) The shape parameters of the transverse section at station 1 of the stern of the determined very large crude carrier include:

[0082] The distance Y1 from the mid-curve point M1 of the cross section at site 1 to the centerline of the very large crude carrier. 1 The distance from the mid-curvature point M1 to the baseline of the very large crude carrier (VLCC) is 0.08B to 0.1B. The distance d1 between the tangent of the cross section at the mid-curve point M1 and station 1 is 0.48s1 to 0.51s1, and is between 0.54D and 0.57D.

[0083] The distance Y2 from the lower concave point L1 of the cross section at site 1 to the centerline of the very large crude carrier. 1 The distance from the lower concave point L1 to the baseline of the very large crude carrier is 0.04-0.06B. The value ranges from 0.04D to 0.06D.

[0084] The distance Y3 from the upper inflection point H1 of the cross section at site 1 to the centerline of the very large crude carrier. 1 The distance from the upper inflection point H1 to the baseline of the very large crude carrier is 0.56-0.59B. The value ranges from 0.92D to 0.95D.

[0085] The angle θ1 between the tangent of the cross section at station 1 and the baseline of the Very Large Crude Carrier (VLCC) is 49° to 50°. B is the half-width of the VLCC, and D is the design draft of the VLCC.

[0086] (3) The determined cross-sectional parameters of the stern section at station 1.5 of the very large crude carrier include:

[0087] 1.5 The mid-curve point M of the cross section at station 1.5 1.5 Distance Y1 from the centerline of the very large crude carrier 1.5 The value is 0.2B to 0.22B, with the mid-curvature point M. 1.5 Distance from the baseline of the Very Large Crude Carrier (VLCC) The inflection point is 0.52D to 0.56D. 1.5 The distance d from the tangent of the cross section at station 1.5 1.5 It is 0.37s 1.5 ~0.40s 1.5 ,

[0088] 1.5 The lower inflection point L of the cross section at station 1.5 1.5 Distance Y2 from the centerline of the very large crude carrier 1.5 The value is 0.1B to 0.12B, and the lower inflection point is L. 1.5 Distance from the baseline of the Very Large Crude Carrier (VLCC) The value ranges from 0.04D to 0.06D.

[0089] 1.5 The upper inflection point H of the cross section at station 1.5 1.5 Distance Y3 from the centerline of the very large crude carrier 1.5 The curve is 0.65B to 0.68B, with the upper inflection point H. 1.5 Distance from the baseline of the Very Large Crude Carrier (VLCC) The value ranges from 0.88D to 0.92D.

[0090] 1.5 The angle θ between the tangent of the cross section at station 1.5 and the baseline of the very large crude carrier. 1.5 The angle is 45° to 46°, B is the half-width of the Very Large Crude Carrier (VLCC), and D is the design draft of the VLCC.

[0091] (4) The determined cross-sectional parameters of the stern section at two stations of the very large crude carrier include:

[0092] The distance Y1 from the mid-curve point M2 of the cross section at site 2 to the centerline of the very large crude carrier. 2 The distance Z1 from the mid-curvature point M2 to the baseline of the very large crude carrier is 0.3B to 0.32B. 2 The distance d2 between the tangent of the cross section at the mid-curve point M2 and station 2 is 0.25s2 to 0.28s2, and the curve is 0.5D to 0.54D.

[0093] The distance Y2 from the lower concave point L2 of the cross section at site 2 to the centerline of the very large crude carrier. 2 The distance from the lower concave point L2 to the baseline of the very large crude carrier (VLCC) is 0.16B to 0.18B. The value ranges from 0.06D to 0.08D.

[0094] The distance Y3 from the upper inflection point H2 of the cross section at site 2 to the centerline of the very large crude carrier. 2 The distance from the upper inflection point H2 to the baseline of the very large crude carrier is 0.73B to 0.76B. The value ranges from 0.86D to 0.9D.

[0095] The angle θ2 between the tangent of the cross section at station 2 and the baseline of the Very Large Crude Carrier (VLCC) is 44° to 45°. B is the half-width of the VLCC, and D is the design draft of the VLCC.

[0096] The resulting stern profile is shown below. Figure 4 As shown, the cross-sectional view is as follows Figure 2 As shown.

[0097] Step 4: Based on the hull structure parameters, bow and stern lines, the bare hull of the very large oil tanker is designed, and its structure is as follows: Figure 5 As shown, the structural schematic diagram of the bare hull stern is as follows: Figure 6 As shown, by adding hydrodynamic energy-saving devices to the bare hull, a very large oil tanker was designed.

[0098] Even without the addition of hydrodynamic energy-saving devices, the final designed Very Large Crude Carrier (VLCC) can reduce received power by approximately 3% compared to existing VLCCs through improvements to the bare hull structure. With the addition of hydrodynamic energy-saving devices, a large bilge vortex is created at 0.4–0.6 times the propeller diameter radius and in the 300–300° direction. The energy loss generated by this bilge vortex can be recovered by the energy-saving guide wheel within the hydrodynamic energy-saving device, reducing received power by approximately 5% compared to existing VLCCs. This represents an improvement in energy efficiency of approximately 2% compared to existing VLCCs, meeting the EEDI Phase 3 requirements.

[0099] The above descriptions are merely preferred embodiments of this application, and this application is not limited to the above embodiments. It is understood that other improvements and variations that can be directly derived or conceived by those skilled in the art without departing from the spirit and concept of this application should be considered to be included within the protection scope of this application.

Claims

1. A method for integrated energy-saving propulsion design of ultra-large oil tankers, characterized in that, The integrated energy-saving propulsion design method for ultra-large oil tankers includes: Determine the hull structure parameters; A fully parameterized bow model is established, and the bow profile that minimizes the wave-making drag coefficient is determined based on the fully parameterized bow model. Based on the established hull structure parameters and bow shape, a pre-established energy-saving effect prediction model is used to determine the stern shape that minimizes the power received by the entire ship. The transverse section of the stern has a concave structure to form a flow-rectifying cavity for accelerating the stern water flow. The energy-saving effect prediction model characterizes the mapping relationship between the wake field data of the bare hull and the power received by the entire ship after the installation of hydrodynamic energy-saving devices on the bare hull. The wake field data of the stern is related to the hull structure parameters, bow shape, and stern shape. The bare hull of the supertanker was designed according to the hull structure parameters, bow shape and stern shape, and a hydrodynamic energy-saving device was installed on the bare hull to design the supertanker. The cross-section at each station on the stern of the very large crude carrier (VLCC) includes, from top to bottom, an upper inflection point, a middle inflection point, and a lower inflection point, all three inflection points being inflection points of curvature change in the cross-section. Determining the stern profile of the VLCC includes determining the profile parameters of the cross-section at each characteristic station on the stern, including: the distance between the upper inflection point and the VLCC's centerline; the distance between the upper inflection point and the VLCC's baseline; the distance between the upper inflection point and the tangent of the cross-section; and the distance between the middle inflection point and the VLCC's centerline. The distances between the mid-curve point in the transverse section and the baseline of the very large crude carrier (VLCC); the distances between the lower-curve point in the transverse section and the centerline of the VLCC, and the distances between the lower-curve point in the transverse section and the baseline of the VLCC; and the angle between the tangent of the transverse section and the baseline of the VLCC; wherein the VLCC is divided into 20 stations from the bow to the stern vertical line, and the characteristic stations of the stern of the VLCC include stations 0.75, 1, 1.5, and 2 arranged sequentially from the stern vertical line toward the bow, and the line shape parameters of the transverse section at different characteristic stations of the stern are determined to be different.

2. The integrated energy-saving propulsion design method for ultra-large oil tankers according to claim 1, characterized in that, The integrated energy-saving propulsion design method for ultra-large oil tankers also includes: Obtain a sample dataset, which includes several sets of sample data. Each set of sample data includes the bare hull design parameters of the sample supertanker and the total power received by the ship after the installation of hydrodynamic energy-saving devices on the bare hull. The bare hull design parameters include hull structural parameters, bow lines and stern lines. The visco-potential coupling method was used to conduct self-propulsion numerical calculations to evaluate the design parameters of the bare hull in each set of sample data, so as to determine the wake field data of the bare hull at the stern of each set of sample data. Using the wake field data of the bare hull of each sample data set as input and the power received by the whole ship after installing the hydrodynamic energy-saving device on the bare hull as output, the convolutional neural network model is trained based on the sample dataset to establish the energy-saving effect prediction model.

3. The integrated energy-saving propulsion design method for ultra-large oil tankers according to claim 1, characterized in that, The determined profile parameters of the transverse section at the 0.75 station of the stern of the very large crude carrier include: The mid-curve point of the cross section at station 0.75 Distance from the centerline of the aforementioned very large oil tanker The inflection point is 0.04B~0.05B. Distance from the baseline of the aforementioned very large oil tanker The inflection point is between 0.56D and 0.59D. Distance from the tangent of the cross section at station 0.75 for , ; The lower inflection point of the cross section at station 0.75 Distance from the centerline of the aforementioned very large oil tanker The lower inflection point is 0.02B~0.03B. Distance from the baseline of the aforementioned very large oil tanker The value ranges from 0.09D to 0.11D. The upper inflection point of the cross section at station 0.75 Distance from the centerline of the aforementioned very large oil tanker 0.52B~0.54B, upper inflection point Distance from the baseline of the aforementioned very large oil tanker The value ranges from 0.94D to 0.97D. The angle between the tangent of the cross section at station 0.75 and the baseline of the very large crude carrier. The angle is 49°~50°, B is the half-width of the very large crude carrier, and D is the design draft of the very large crude carrier.

4. The integrated energy-saving propulsion design method for ultra-large oil tankers according to claim 1, characterized in that, The determined profile parameters of the cross section at point 1 of the stern of the very large crude carrier include: The mid-curve point of the cross section at station 1 Distance from the centerline of the aforementioned very large oil tanker The inflection point is 0.08B~0.1B. Distance from the baseline of the aforementioned very large oil tanker The inflection point is between 0.54D and 0.57D. Distance from the tangent of the cross section at station 1 for , ; The lower inflection point of the cross section at station 1 Distance from the centerline of the aforementioned very large oil tanker The value is 0.04-0.06B, and the lower inflection point is... Distance from the baseline of the aforementioned very large oil tanker The value ranges from 0.04D to 0.06D. The upper inflection point of the cross section at station 1 Distance from the centerline of the aforementioned very large oil tanker 0.56-0.59B, upper inflection point Distance from the baseline of the aforementioned very large oil tanker The value is 0.92D~0.95D; The angle between the tangent of the cross section at site 1 and the baseline of the very large crude carrier. The angle is 49°~50°, B is the half-width of the very large crude carrier, and D is the design draft of the very large crude carrier.

5. The integrated energy-saving propulsion design method for ultra-large oil tankers according to claim 1, characterized in that, The determined cross-sectional parameters of the stern section at station 1.5 of the very large crude carrier include: 1.5 The mid-curve point of the cross section at station 1.5 Distance from the centerline of the aforementioned very large oil tanker The inflection point is between 0.2B and 0.22B. Distance from the baseline of the aforementioned very large oil tanker The inflection point is between 0.52D and 0.56D. Distance from the tangent of the cross section at station 1.5 for , ; 1.5 The lower inflection point of the cross section at station 1.5 Distance from the centerline of the aforementioned very large oil tanker For 0.1B~0.12B, the lower inflection point Distance from the baseline of the aforementioned very large oil tanker The value ranges from 0.04D to 0.06D. 1.5 The upper inflection point of the cross section at station 1.5 Distance from the centerline of the aforementioned very large oil tanker 0.65B~0.68B, upper inflection point Distance from the baseline of the aforementioned very large oil tanker The value ranges from 0.88D to 0.92D. 1.5 The angle between the tangent of the cross section at the site and the baseline of the very large crude carrier. The angle is 45°~46°, B is the half-width of the very large crude carrier, and D is the design draft of the very large crude carrier.

6. The integrated energy-saving propulsion design method for ultra-large oil tankers according to claim 1, characterized in that, The determined cross-sectional parameters of the stern section at two stations of the very large crude carrier include: The mid-curve point of the cross section at station 2 Distance from the centerline of the aforementioned very large oil tanker The inflection point is between 0.3B and 0.32B. Distance from the baseline of the aforementioned very large oil tanker The inflection point is between 0.5D and 0.54D. Distance from the tangent of the cross section at station 2 for , ; The lower inflection point of the cross section at station 2 Distance from the centerline of the aforementioned very large oil tanker The inflection point is 0.16B~0.18B. Distance from the baseline of the aforementioned very large oil tanker The value ranges from 0.06D to 0.08D. The upper inflection point of the cross section at station 2 Distance from the centerline of the aforementioned very large oil tanker The curve is 0.73B~0.76B, with the upper inflection point. Distance from the baseline of the aforementioned very large oil tanker The value is 0.86D~0.9D; The angle between the tangent of the cross section at site 2 and the baseline of the very large crude carrier. The angle is 44°~45°, B is the half-width of the very large crude carrier, and D is the design draft of the very large crude carrier.

7. The integrated energy-saving propulsion design method for ultra-large oil tankers according to claim 1, characterized in that, Determining the bow hull shape of the very large crude carrier includes: A fully parameterized bow model is established based on bow characteristic parameters including waterline inflow angle, waterline fullness, and bow cross-sectional area curve fullness. The Sobol algorithm is used to generate a combination of parameters for multiple uniformly distributed bow feature parameters and the bow profile corresponding to each parameter combination. Using CFD software based on potential flow theory, wave-making resistance is calculated for the fully parameterized bow model under each combination of bow characteristic parameters. The bow profile corresponding to the parameter combination of bow characteristic parameters that minimizes the wave-making resistance coefficient is taken as the bow profile of the very large crude carrier.

8. The integrated energy-saving propulsion design method for ultra-large oil tankers according to claim 1, characterized in that, The determination of the hull structure parameters of the very large crude carrier includes: The very large crude carrier (VLCC) is defined as comprising, from bow to stern, a bow section, a parallel midbody, a deflection section, and a stern. The bow adopts a straight-arm bow design, with a V-shaped cross section above the structural waterline. The bottom of the bow smoothly extends from the structural draft to the main deck of the VLCC. The lowest point of the vertical section of the bow's midsection is 48.8% of the VLCC's design draft, and the radius of curvature of the arc section is 1.6 meters. The length of the parallel midbody is 18.4% of the VLCC's length between perpendiculars, and the length of the deflection section is 38.3% of the VLCC's length between perpendiculars.

9. The integrated energy-saving propulsion design method for ultra-large oil tankers according to claim 8, characterized in that, The very large crude carrier has a length between perpendiculars of 326.6 meters, a beam of 60 meters, a design draft of 20.5 meters, and a structural draft of 21.8 meters. The billet coefficient of the very large crude carrier is 0.7133 at the bow, 0.8733 at the stern, and the longitudinal position of the center of buoyancy is 3.8%. The very large crude carrier is a low-speed vessel with a Froude number of 0.13 and a billet coefficient of 0.8 at its speed.

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