Design method for installation position of underwater bubble generating device

Abstract

The invention relates to the field of ship engineering, in particular to a method for designing the mounting position of an underwater bubble generating device. Comprising a bubble scale determination process, a bubble rising speed determination process and a spray pipe installation distance determination process. According to the method, collaborative optimization of the bubble scale, the rising speed and the spray pipe layout is realized through multi-parameter coupling modeling. Establishing a static water bubble volume dynamic model based on liquid density, gas flow and nozzle diameter, and accurately calculating bubble diameter in combination with a transverse water flow correction factor; quantifying a bubble rising speed by adopting an empirical formula; and a nozzle interval dynamic adjustment model with the proportionality coefficient as the core is constructed, and the coverage rate is determined through displacement of bubbles in water flow, so that accurate design of the installation position is achieved. The innovation point lies in a multi-field decoupling modeling technology and a coverage rate quantification regulation and control mechanism, the limitation of the prior art is broken through, and the method is suitable for the fields of ship drag reduction, noise reduction, ocean engineering and the like.

Description

Technical Field

[0001] The present invention relates to the field of ship engineering, and in particular to a method for designing the installation position of an underwater bubble generating device. Background Art

[0002] The continuous development of new ship drag reduction technologies has driven the development of ship speed. Based on the principles of ship resistance, this paper analyzes domestic and international ship drag reduction technologies and points out that the current mainstream research directions are air drag reduction, bionic superhydrophobic drag reduction, appendage drag reduction, and step-down drag reduction.

[0003] Chinese patent publication number: CN110498006A discloses an air film drag reduction and energy-saving ship with the function of effectively forming a continuous thin layer of air film on the bottom of the ship. The design of the longitudinal air supply pipe on the bottom of the ship to supply air to the horizontal guide plate structures on the bottom of the ship can not only reduce the pipe length, but also reduce the requirement for bottom openings. It is technically suitable for the design and construction of various types of air film drag reduction and energy-saving transport ships and high-speed ships. In addition, old ships can be converted into air film drag reduction and energy-saving ships during a short dry docking period, thereby further improving the practicality of ship air film drag reduction and energy-saving technology.

[0004] It can be seen that the current bubble drag reduction technology during navigation does not effectively limit the installation positions of the nozzles on both sides of the ship, resulting in uneven bubble drag reduction capabilities and failure to achieve the purpose of effective drag reduction. Summary of the Invention

[0005] To this end, the present invention provides a method for designing the installation position of an underwater bubble generating device to overcome the problem in the prior art that drag cannot be effectively reduced.

[0006] To achieve the above-mentioned purpose, the present invention provides a method for designing the installation position of an underwater bubble generating device, comprising:

[0007] The diameter of the bubbles generated in the water is determined based on the gas flow rate and the diameter of the gas port;

[0008] Determining the rising speed of the bubbles according to the diameter of the bubbles;

[0009] determining the area of ​​the hull covered by the bubble curtain according to the rising speed of the bubbles and the traveling speed of the ship;

[0010] determining an initial installation distance of the nozzle according to the area of ​​the hull covered by the bubble curtain;

[0011] Determining the coverage rate within the initial installation distance according to the range of the bubble curtain covering the hull within the initial installation distance of the nozzle to adjust the initial nozzle installation distance;

[0012] The nozzle installation distance is the distance between two groups of bubble-generating nozzles arranged on the side of the hull.

[0013] Furthermore, the diameter of the bubbles generated in the water is determined according to the gas flow rate and the diameter of the gas port, including:

[0014] The scale of bubbles generated in water is preliminarily determined by the bubble expansion model of bubbles generated in still water, and the scale of bubbles generated in water is corrected by the influence of lateral water flow on the bubble scale.

[0015] Furthermore, the bubble expansion model for bubbles generated in still water preliminarily determines the size of bubbles generated in water, including:

[0016] The bubble size is determined by measuring the gas flow rate and the diameter of the gas port of the underwater bubble generator and calculating the bubble volume at the end of the expansion stage of the bubble in still water under ideal conditions based on several ideal underwater data.

[0017] Among them, there are several ideal underwater data, including liquid density, gas density, gravitational acceleration, resistance coefficient of bubbles moving in water, and surface tension coefficient.

[0018] Furthermore, the scale of bubbles generated in water is corrected according to the influence of the lateral water flow on the scale of bubbles, including:

[0019] The size of the bubble generated in the cross-flow is determined by subtracting the reduced size of the bubble in the cross-flow from the bubble size of the bubble generated in still water;

[0020] The diameter of the bubble generated in still water is reduced in size in the transverse water flow by the product of the diameter of the bubble generated in still water and the transverse water flow correction factor, and the transverse water flow correction factor is determined by the size of the transverse water flow.

[0021] Furthermore, the method of determining the rising speed of the bubble according to the diameter of the bubble includes:

[0022] Determine the diameter of the generated bubbles,

[0023] If the bubble diameter is within the preset bubble range, the bubble rising speed under ideal conditions is determined by the set empirical formula;

[0024] If the diameter of the bubble is not within the preset bubble range, the gas flow rate or the diameter of the gas port is adjusted so that the diameter of the bubble falls within the preset bubble range.

[0025] Furthermore, the area of ​​the hull covered by the bubble curtain is determined according to the rising speed of the bubbles and the traveling speed of the ship, including:

[0026] Establishing a three-dimensional rectangular coordinate system and placing the hull model into the three-dimensional rectangular coordinate system;

[0027] Under the three-dimensional coordinates, the relative motion between the bubble and the ship is analyzed to determine the variable related to the coverage of the bubble curtain to determine the coverage of the bubble curtain;

[0028] The origin O of the three-dimensional rectangular coordinate is located at the bottom of the hull, the positive direction of the X-axis is opposite to the heading of the ship, the positive direction of the Y-axis is perpendicular to the hull, and the positive direction of the Z-axis is vertically upward.

[0029] Furthermore, the determining of the bubble curtain coverage range based on variables related to the bubble curtain coverage range includes:

[0030] The bubble rising time is confirmed by combining the bubble rising speed and the initial depth, and the displacement of the bubble in the opposite direction of navigation is determined by combining the rising time of each bubble with the navigation speed of the ship. The coverage range of the bubble curtain is determined by the displacement of the bubble with the largest initial depth in the navigation direction to determine the coverage area.

[0031] Furthermore, the method of determining the initial installation distance of the nozzle according to the area of ​​the hull covered by the bubble curtain includes:

[0032] The initial installation distance is obtained by multiplying the displacement of the bubble with the largest initial depth in the ship's sailing direction by the proportional coefficient.

[0033] Furthermore, the determining of the bubble curtain coverage map under the wave load according to the three-dimensional rectangular coordinates includes:

[0034] The port side wall of the hull compartment is unfolded onto the XOZ plane, and the trajectory of the bubble movement is marked to obtain a bubble curtain coverage range diagram under wave load to determine the bubble coverage rate of the hull within the initial installation distance range.

[0035] Furthermore, the method of determining the coverage rate within the initial installation distance according to the range of the bubble curtain covering the hull within the initial installation distance of the nozzle to adjust the initial nozzle installation distance includes:

[0036] The coverage rate of the bubble on the hull is determined by the ratio of the bubble curtain coverage area within the initial installation distance to the hull side wall area within the initial installation distance, and the initial installation distance is adjusted according to the coverage rate requirements.

[0037] Compared with the existing technology, the beneficial effect of the present invention lies in that a mathematical model is established by combining multiple parameters such as liquid density, gas flow rate, nozzle diameter, etc., the bubble size in still water is accurately calculated, and the bubble diameter is dynamically adjusted through the lateral water flow correction factor α, ensuring that the bubble curtain can still stably cover the key areas of the hull in complex flow fields, thereby improving the efficiency of drag reduction or noise reduction.

[0038] Furthermore, the preset bubble range interval of the bubbles is clearly defined, and an adjustment strategy is provided to ensure that a high-efficiency bubble curtain can be generated under different working conditions.

[0039] Furthermore, standardized procedures are adopted to avoid the waste of resources associated with traditional trial-and-error methods. By using empirical formulas and linking the drag coefficient with the Reynolds number, the rising behavior of bubbles can be quickly predicted, reducing the number of physical experiments and shortening the R&D cycle.

[0040] Furthermore, the system innovatively decouples complex factors such as hull wave generation and current motion, retaining only the effect of X-axis displacement on coverage. This simplifies the computational complexity while ensuring engineering accuracy. Experimental verification of this simplified model shows minimal error between bubble retention time in wave fields and still water, significantly improving design reliability.

[0041] Furthermore, the nozzle spacing is dynamically adjusted through the β proportional coefficient to achieve a balance between coverage and economy. Compared with traditional uniform distribution solutions, the number of nozzles is greatly reduced, reducing manufacturing and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the coverage of the bubble curtain generated by the air jet pipes arranged vertically along the side wall of the hull in the embodiment;

[0043] Figure 2 Schematic diagram of the coverage of the bubble curtain generated by the vertical air jet pipe on the side wall of the hull in the embodiment;

[0044] Figure 3 This is an overall flow chart of the method for designing the installation position of the underwater bubble generating device in the embodiment;

[0045] Figure 4 This is a logic judgment diagram of the bubble rising speed determination process in the embodiment. DETAILED DESCRIPTION

[0046] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0047] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0048] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside", and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0049] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0050] See also Figure 1-4 As shown, Figure 1 Schematic diagram of the coverage of the bubble curtain generated by the air jet pipes arranged vertically along the side wall of the hull in the embodiment; Figure 2 Schematic diagram of the coverage of the bubble curtain generated by the vertical air jet pipe on the side wall of the hull in the embodiment; Figure 3 This is an overall flow chart of the method for designing the installation position of the underwater bubble generating device in the embodiment; Figure 4 This is a logic judgment diagram of the bubble rising speed determination process in the embodiment.

[0051] The present invention provides a method for designing the installation position of an underwater bubble generating device, comprising the following steps:

[0052] The process of determining the bubble size can determine the diameter of the bubbles generated in water based on the gas flow rate and the diameter of the gas port;

[0053] The process of determining the rising speed of bubbles can determine the rising speed of bubbles according to the diameter of the bubbles;

[0054] The process of determining the nozzle installation distance includes:

[0055] The process of determining the coverage of the bubble curtain can determine the range of the bubble covering the hull based on the rising speed of the bubble and the speed of the ship;

[0056] The bubble curtain coverage rate is determined by adjusting the preset nozzle installation distance by the proportion of the bubble range covering the hull within the preset nozzle installation distance;

[0057] The nozzle installation distance is the distance between two groups of bubble-generating nozzles arranged on the side of the hull.

[0058] Specifically, according to the classic two-stage model of bubble formation in still water, the bubble growth process in water consists of two stages: expansion and detachment. The bubble size at the end of the expansion stage in the non-jet state is essentially the same as the size after complete detachment. The bubble size at the end of the expansion stage is set as the bubble size in the bubble curtain surrounding the ship. The bubble size at the end of the expansion stage is calculated to evaluate the bubble size in the presence of transverse water flow.

[0059] At the end of the bubble expansion phase, the liquid density ρ l , gas density ρ g , gravitational acceleration g, drag coefficient C of the bubble moving in water D , gas flow Q, nozzle diameter d h , surface tension coefficient б, obtain the volume V of the bubble generated in still water to calculate the bubble diameter d;

[0060]

[0061] Among them, the resistance coefficient C of the bubble moving in water is D It is obtained by combining the Reynolds number, the liquid dynamic viscosity coefficient μ1, and the bubble center movement speed u;

[0062]

[0063] Specifically, when a ship is sailing in the water, a flow field of a certain speed will be formed around the hull. Due to the "blowing away" effect of the transverse flow, the detachment of bubbles will be greatly accelerated, so that the frequency of bubble generation will be significantly accelerated. Under the same gas volume flow rate, the detachment volume of bubbles in the transverse flow will also be correspondingly smaller than the detachment volume of bubbles in the static liquid. The data shows that under the same other conditions, the diameter of bubbles in the transverse water flow will be reduced according to the transverse water flow correction factor α (α = 10% - 40%). Therefore, under the same other conditions, the transverse water flow correction factor is determined by the size of the transverse water flow, and the diameter of the bubble generated in the static water obtained in the previous step is subtracted from the part that is reduced in the transverse water flow to obtain the diameter D and radius R of the bubble in the transverse water flow;

[0064] D=2R=(1-α)×d

[0065] The portion of the diameter of the bubble generated in still water that is reduced in the transverse water flow is the product of the diameter of the bubble generated in still water and the transverse water flow correction factor, and the transverse water flow correction factor is determined by the magnitude of the transverse water flow;

[0066] By jointly establishing multiple parameters such as liquid density, gas flow rate, and nozzle diameter, a mathematical model is established to accurately calculate the bubble size in still water. The bubble diameter is dynamically adjusted using the lateral water flow correction factor α to ensure that the bubble curtain can still stably cover key areas of the hull in complex flow fields, thereby improving drag reduction or noise reduction efficiency.

[0067] Specifically, the diameter of the generated bubble is determined. If the bubble diameter is within a preset bubble range, the bubble's rise process is analyzed based on the instantaneous steady-state rise velocity model of large bubbles in water. During the bubble's rise, the flow field transforms into turbulence, and the bubble begins to deform, generating significant eddy resistance, the size of which is related to the bubble's shape. Therefore, for sparingly soluble gases, the rise velocity of bubbles within this radius is generally calculated using the Jamialahmadi empirical formula to calculate the bubble's rise velocity in water, V. s , used to evaluate the coverage of the bubble curtain;

[0068]

[0069] Obviously, the bubble rising speed V s =f(ρ l ,ρ g ,μ l ,σ,Q,d h ), is about the liquid density ρ l , gas density ρ g , liquid dynamic viscosity coefficient μ l , surface tension coefficient σ, gas flow rate Q and nozzle diameter d h function.

[0070] Therefore, for a specific gas, the rising speed of the bubbles generated in the corresponding liquid is simply the gas flow rate Q and the nozzle diameter d h The function that affects the bubble rising speed V s The factors are the gas flow rate Q and the nozzle diameter d of the bubble generating device h Therefore, the bubble rising speed V can be controlled by the gas flow Q and the nozzle diameter of the bubble generating device. s To determine, evaluate the coverage of the bubble curtain by the rising velocity of the bubbles;

[0071] If the bubble diameter is not within the preset bubble range, the bubble radius or the gas port diameter should be adjusted by adjusting the gas flow until the bubble radius is within the range, and then the bubble rising speed can be determined;

[0072] Among them, the preset bubble range is 0.8-7mm.

[0073] The bubble diameter is clearly defined within a preset range and an adjustment strategy is provided to ensure efficient bubble curtain generation under different operating conditions. For example, if the bubble diameter exceeds the limit, increasing the gas flow rate Q can quickly bring the diameter back to the optimized range, preventing device failure.

[0074] Standardized procedures are used to avoid the waste of resources associated with traditional trial-and-error methods. The Jamialahmadi empirical formula and the Reynolds number-related drag coefficient are used to quickly predict bubble rise behavior, reducing the number of physical experiments and shortening the R&D cycle.

[0075] Specifically, the process of determining the coverage of the bubble curtain is to establish a three-dimensional rectangular coordinate and put the hull model into the three-dimensional rectangular coordinate;

[0076] Under the three-dimensional coordinates, the relative motion between the bubble and the ship is analyzed to determine the variable related to the coverage of the bubble curtain to determine the coverage of the bubble curtain;

[0077] Among them, the three-dimensional rectangular coordinate origin O is located at the bottom of the hull, the positive direction of the X-axis is the opposite direction of the ship's heading, the positive direction of the Y-axis is the vertical direction of the hull, the positive direction of the Z-axis is vertically upward, A1 is the vertical jet pipe, A2 is the bubble movement path curve, and A3 is the underwater part of the cabin section.

[0078] After the bubble is generated, its movement in the water includes upward movement along the positive Z axis under the action of buoyancy, following movement along the positive X axis under the action of water flow, and following movement along the positive Y axis under the action of wave making by the hull.

[0079] The average rising velocity of bubbles in a wave field is consistent with the average free rising velocity in still water, and their residence time in the water is consistent with that in still water. Therefore, the waves created by the ship hull and the water current have no effect on the average rising velocity and residence time of bubbles in the water.

[0080] Factors influencing the bubble curtain's coverage of the ship include its Z- and X-axis displacements from the moment it's generated until it reaches the surface. The Y-axis displacement only affects the distance between the bubble curtain and the ship and has no effect on the coverage. The Z-axis displacement represents the depth at which the bubble is generated. Therefore, the primary factor affecting the bubble curtain's coverage is its X-axis displacement, i.e., its displacement in the direction opposite to the ship's direction of travel.

[0081] The bubble rising time is confirmed by combining the bubble rising speed and the initial depth, and the displacement of the bubble in the opposite direction of navigation is determined by combining the rising time of each bubble with the navigation speed of the ship. The coverage range of the bubble curtain is determined by the displacement of the bubble with the largest initial depth in the navigation direction to determine the coverage area.

[0082] Assuming uniform straight-line navigation, the displacement Sx of each bubble generated in the water in the X-axis direction is determined by the ship's navigation speed vc, the bubble's rising time t, and the bubble's initial depth h.

[0083]

[0084] S x =v c t

[0085] When the initial bubble depth h is the deepest, the maximum displacement S of the bubble generated by a single jet pipe in the direction of the ship's length can be obtained: xmax , which is used to calculate the coverage of the bubble curtain on the hull.

[0086] This innovative approach decouples complex factors such as hull wave generation and current motion, retaining only the effect of X-axis displacement on coverage. This simplifies computational complexity while ensuring engineering accuracy. Experimental verification of this simplified model shows minimal error between bubble retention time in wave fields and still water, significantly improving design reliability.

[0087] Specifically, if the jet system is designed based on the maximum coverage of a single jet tube along the length of the ship, the bubble curtain generated by the system will only cover 50% of the hull sidewall. Therefore, to maximize the bubble curtain's coverage of the hull, it is necessary to increase the number of jet tubes at a certain distance within the maximum coverage of a single jet tube to increase the bubble curtain's coverage area.

[0088] The confirmation process of the initial installation distance is as follows: assuming that a second nozzle is added at a distance from the first nozzle, the initial nozzle installation distance is L = βS xmax , where β is the proportional coefficient and the value range of β is (0<β<1).

[0089] Specifically, the bubble curtain coverage rate is determined by unfolding the port sidewall of the hull compartment onto the XOZ plane, marking the initial and final positions of the bubbles generated by each nozzle on the XOZ plane, and connecting the initial position of each generated bubble with the final position of the corresponding bubble. A bubble curtain coverage range diagram under wave load is drawn to determine the bubble curtain coverage rate of the hull within the distance between adjacent nozzles.

[0090] When the distance between adjacent nozzles is L, the coverage rate of the bubble curtain on the ship is S, which is the coverage area of ​​the bubble curtain within the range of the ship length L. f and the hull sidewall area S c The ratio of

[0091]

[0092] Obviously, for a specific speed, the coverage rate P of the bubble curtain on the hull is a decreasing function of β, that is, the smaller the β value, the greater the corresponding bubble curtain coverage rate on the hull, and the larger the β value, the more Pengguan are arranged and the greater the system energy consumption. The relationship between the bubble coverage rate and the system energy consumption can be balanced by adjusting β.

[0093] After determining the gas flow rate Q and nozzle diameter d of the bubble generator h In this case, the spacing between the two jet pipes is determined according to the requirement of the bubble curtain covering the hull with a length of L, and the appropriate installation position of the bubble generating device is designed and determined.

[0094] Dynamically adjust the nozzle spacing through the β-proportional coefficient to achieve a balance between coverage and economy. Compared with traditional uniform distribution solutions, the number of nozzles is greatly reduced, reducing manufacturing and maintenance costs.

[0095] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

[0096] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for designing the installation position of an underwater bubble generating device, characterized in that: include, The diameter of the bubbles generated in the water is determined based on the gas flow rate and the diameter of the gas port; Determining the rising speed of the bubbles according to the diameter of the bubbles; determining the area of ​​the hull covered by the bubble curtain according to the rising speed of the bubbles and the traveling speed of the ship; determining an initial installation distance of the nozzle according to the area of ​​the hull covered by the bubble curtain; Determining the coverage rate within the initial installation distance according to the range of the bubble curtain covering the hull within the initial installation distance of the nozzle to adjust the initial nozzle installation distance; The nozzle installation distance is the distance between two groups of bubble-generating nozzles arranged on the side of the hull.

2. The method for designing the installation position of the underwater bubble generating device according to claim 1, characterized in that: The method of determining the diameter of bubbles generated in water according to the gas flow rate and the diameter of the gas port includes: The scale of bubbles generated in water is preliminarily determined by the bubble expansion model of bubbles generated in still water, and the scale of bubbles generated in water is corrected by the influence of lateral water flow on the bubble scale.

3. The method for designing the installation position of the underwater bubble generating device according to claim 2, characterized in that: The bubble expansion model for bubbles generated in still water preliminarily determines the size of bubbles generated in water, including: The bubble size is determined by measuring the gas flow rate and the diameter of the gas port of the underwater bubble generator and calculating the bubble volume at the end of the expansion stage of the bubble in still water under ideal conditions based on several ideal underwater data. Among them, there are several ideal underwater data, including liquid density, gas density, gravitational acceleration, resistance coefficient of bubbles moving in water, and surface tension coefficient.

4. The method for designing the installation position of the underwater bubble generating device according to claim 2, characterized in that: The method of correcting the size of bubbles generated in water according to the influence of the lateral water flow on the size of bubbles includes: The size of the bubble generated in the cross-flow is determined by subtracting the reduced size of the bubble in the cross-flow from the bubble size of the bubble generated in still water; The diameter of the bubble generated in still water is reduced in size in the transverse water flow by the product of the diameter of the bubble generated in still water and the transverse water flow correction factor, and the transverse water flow correction factor is determined by the size of the transverse water flow.

5. The method for designing the installation position of the underwater bubble generating device according to claim 1, characterized in that: The method of determining the rising speed of the bubble according to the diameter of the bubble includes: Determine the diameter of the generated bubbles, If the bubble diameter is within the preset bubble range, the bubble rising speed under ideal conditions is determined by the set empirical formula; If the diameter of the bubble is not within the preset bubble range, the gas flow rate or the diameter of the gas port is adjusted so that the diameter of the bubble falls within the preset bubble range.

6. The method for designing the installation position of the underwater bubble generating device according to claim 1, characterized in that: The area of ​​the hull covered by the bubble curtain is determined based on the rising speed of the bubbles and the speed of the ship, including: Establishing a three-dimensional rectangular coordinate system and placing the hull model into the three-dimensional rectangular coordinate system; Under the three-dimensional coordinates, the relative motion between the bubble and the ship is analyzed to determine the variable related to the coverage of the bubble curtain to determine the coverage of the bubble curtain; The origin O of the three-dimensional rectangular coordinate is located at the bottom of the hull, the positive direction of the X-axis is opposite to the heading of the ship, the positive direction of the Y-axis is perpendicular to the hull, and the positive direction of the Z-axis is vertically upward.

7. The method for designing the installation position of the underwater bubble generating device according to claim 6, characterized in that: The method of determining the coverage range of the bubble curtain according to variables related to the coverage range of the bubble curtain includes: The bubble rising time is confirmed by combining the bubble rising speed and the initial depth, and the displacement of the bubble in the opposite direction of navigation is determined by combining the rising time of each bubble with the navigation speed of the ship. The coverage range of the bubble curtain is determined by the displacement of the bubble with the largest initial depth in the navigation direction to determine the coverage area.

8. The method for designing the installation position of the underwater bubble generating device according to claim 7, characterized in that: The initial installation distance of the nozzle is determined according to the area of ​​the hull covered by the bubble curtain. include, The initial installation distance is obtained by multiplying the displacement of the bubble with the largest initial depth in the ship's sailing direction by the proportional coefficient.

9. The method for designing the installation position of the underwater bubble generating device according to claim 8, characterized in that: The method of determining the bubble curtain coverage range diagram under the wave load according to the three-dimensional rectangular coordinates includes: The port side wall of the hull compartment is unfolded onto the XOZ plane, and the trajectory of the bubble movement is marked to obtain a bubble curtain coverage range diagram under wave load to determine the bubble coverage rate of the hull within the initial installation distance range.

10. The method for designing the installation position of the underwater bubble generating device according to claim 9, characterized in that: The method of determining the coverage rate within the initial installation distance according to the range of the bubble curtain covering the hull within the initial installation distance of the nozzle to adjust the initial nozzle installation distance includes: The coverage rate of the bubble on the hull is determined by the ratio of the bubble curtain coverage area within the initial installation distance to the hull side wall area within the initial installation distance, and the initial installation distance is adjusted according to the coverage rate requirements.

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