Installation and design method of underwater bubble generating device based on full coverage of cabin section

Abstract

The invention relates to the technical field of underwater ship engineering, in particular to an installation and design method of an underwater bubble generating device based on full coverage of a cabin section, and discloses the installation and design method of the underwater bubble generating device based on full coverage of the cabin section. Comprising the following steps: determining a bubble volume at the end moment of a bubble expansion stage based on a classical two-stage model for generating bubbles in still water; the radius of bubbles generated in the transverse water flow is determined based on the reduction proportion of the bubble volume in the transverse flow and the bubble volume at the end moment of the bubble expansion stage in the still water; the rising speed of the bubbles in the water is determined based on an instantaneous steady-state rising speed model of the large bubbles in the water; the rising time of the bubbles in the water is determined based on the rising speed of the bubbles in the water; establishing a rectangular coordinate system on the ship body based on a space coordinate system to determine an X axis, a Y axis and a Z axis; by utilizing the scattering and absorbing effects of the bubble curtain in water on the sound waves, the propagation energy of the sound waves in water can be greatly attenuated, so that the distance of positioning and tracking the ship by utilizing the sound waves is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater ship engineering, and in particular to an installation design method for an underwater bubble generating device based on full cabin coverage. Background Art

[0002] To date, sound waves are still the only physical signals that can propagate long distances in water. By utilizing the scattering and absorption of sound waves by the bubble curtain in the water, the propagation energy of sound waves in the water can be greatly attenuated, thereby reducing the distance for locating and tracking ships using sound waves.

[0003] However, to attenuate a ship's underwater radiated noise using an underwater bubble curtain, the bubble curtain must first provide a certain coverage area over the ship's hull. The greater the coverage area, the more effective the attenuation of the ship's underwater radiated noise. However, the coverage area of the bubble curtain over the hull is clearly affected by the motion patterns of bubbles in water. Therefore, this paper investigates the coverage area of underwater bubbles by studying the motion patterns of bubbles in water. Finally, a design method for the installation of an underwater bubble generator that fully covers the entire hull compartment is proposed.

[0004] It can be seen from this that the existing technology currently has a problem that the coverage of the bubble curtain generated in the water on the hull will be affected by the movement of the bubbles in the water, making it difficult to achieve full coverage of the cabin. Summary of the Invention

[0005] To this end, the present invention provides an installation design method for an underwater bubble generating device based on full coverage of the compartment, so as to overcome the problem in the prior art that the coverage of the bubble curtain on the hull is affected by the movement of bubbles in the water and it is difficult to achieve full coverage of the compartment.

[0006] To achieve the above objectives, the present invention provides a method for designing an installation of an underwater bubble generating device based on full compartment coverage, comprising:

[0007] The bubble volume at the end of the bubble expansion phase is determined based on the classic two-stage model of bubble formation in still water.

[0008] Determining the radius of bubbles generated in the transverse water flow based on the reduction ratio of the bubble volume in the transverse flow to the bubble volume at the end of the bubble expansion phase in still water;

[0009] Determine the rising velocity of bubbles in water based on the instantaneous steady-state rising velocity model of large bubbles in water;

[0010] Determine the rising time of the bubbles in the water based on the rising speed of the bubbles in the water;

[0011] Establishing a rectangular coordinate system on the hull based on the spatial coordinate system to determine the X axis, the Y axis and the Z axis;

[0012] Determine the displacement of the bubble generated in the water on the X-axis based on the ship's moving speed, the rising time of the bubble in the water, and the initial depth of the bubble;

[0013] Determine the single-layer coverage of the cabin section by the bubbles generated by a single fumarole based on the displacement of the bubbles generated in the water on the X-axis;

[0014] Holes are opened in the horizontal and vertical air jet pipes based on the single-layer coverage;

[0015] The horizontal air-jet pipe and the vertical air-jet pipe with holes opened are respectively installed on the side walls of the hull.

[0016] Furthermore, the classic two-stage process of bubble generation in still water includes an expansion stage and a detachment stage.

[0017] Furthermore, the reduction ratio is that when the ship is sailing in the water, a flow field of a certain speed will be formed around it, and under the same gas volume flow rate, the bubble detachment volume in the transverse flow will also be correspondingly smaller than the bubble detachment volume in the static liquid. Under the same other conditions, the bubble diameter in the transverse water flow will be reduced according to a certain ratio α (α = 10% 40%).

[0018] Furthermore, the spatial rectangular coordinate system includes an X-axis, a Y-axis and a Z-axis, the positive direction of the X-axis is opposite to the ship's heading, the positive direction of the Y-axis is perpendicular to the hull, and the positive direction of the Z-axis is vertically upward.

[0019] Furthermore, the displacement of the bubble generated in the water on the X-axis includes the displacement of the bubble along the X-axis during the period from the generation of the bubble to the rise of the bubble to the water surface.

[0020] Furthermore, the jet pipes include vertical jet pipes installed on the side walls of the compartment in a conformal arrangement in the vertical direction and horizontal jet pipes installed along the side walls of the hull in a horizontal direction close to the bottom of the hull.

[0021] Furthermore, the openings include a plurality of small air-injection holes opened on the sides of the vertical air-injection pipe and the horizontal air-injection pipe.

[0022] Furthermore, the single-layer coverage of the air bubbles on the compartment section is the range covered by the bubble curtain formed by the displacement of the air bubbles ejected from a single air jet hole in the X-axis direction.

[0023] Compared with the existing technology, the beneficial effect of the present invention lies in that, by analyzing the movement law of the bubble curtain in still water after it is generated, according to the classic two-stage model, the volume change law of the bubbles in still water is quickly determined. Through the volume change law of the bubbles in still water, the reduction ratio of the bubble volume in the cross flow and the bubble volume at the end of the bubble expansion stage in still water is used to determine the bubble radius generated in the cross flow, so that the bubble radius data is more accurate and the data error is optimized.

[0024] Furthermore, the radius of the bubbles generated in the cross flow is used to determine the rising velocity of the bubbles in the water using the instantaneous steady-state rising velocity model of large bubbles in the water, so as to more quickly determine the rising time of the bubbles in the water, thereby more accurately understanding the rising time of the bubbles in the water on the side of the compartment from the initial depth of the bubble generation to the water surface.

[0025] Furthermore, by understanding the rise time of bubbles in the water on the side of the compartment from the initial depth of bubble generation to the water surface, and given a given ship's motion speed, a schematic diagram of the coverage of the bubble curtain over the compartment can be obtained, providing a more intuitive understanding of the coverage of the bubble curtain over the compartment.

[0026] Furthermore, by obtaining the coverage of the underwater bubble curtain on the cabin, the design and installation of the jet pipes on the side walls of the cabin are more accurate, and the coverage of the bubble curtain on the cabin is more uniform, so that the bubble curtain increases the attenuation of the underwater radiation noise of the ship, thereby reducing the distance for positioning and tracking the ship using sound waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart of the installation design method of the underwater bubble generating device in the installation design method of the underwater bubble generating device based on full compartment coverage of the present invention;

[0028] Figure 2 Schematic diagram of the installation position of the vertical air jet pipe in the installation design method of the underwater bubble generating device based on full compartment coverage of the present invention;

[0029] Figure 3 This is a graph showing the rising path of the bubble curtain generated by the vertical jet pipe in the installation design method of the underwater bubble generating device based on full compartment coverage of the present invention;

[0030] Figure 4 A graph showing the rising path of the bubble curtain generated by the horizontal jet pipe in the design method for installing a submersible bubble generator based on full compartment coverage according to the present invention;

[0031] Figure 5 A graph showing the rising path of the bubble curtain generated by the vertical and horizontal jet pipes in the design method for installing a submersible bubble generator based on full compartment coverage according to the present invention;

[0032] Figure 6 Schematic diagram of the installation positions of the vertical and horizontal air jet pipes in the design method for installing an underwater bubble generating device based on full compartment coverage according to the present invention;

[0033] In the figure, 1-cabin section; 2-vertical jet pipe; A2-vertical jet pipe bubble rising path curve; 3-horizontal jet pipe; A3-horizontal jet pipe bubble rising path curve. DETAILED DESCRIPTION

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] See also Figures 1 to 2 As shown, Figure 1 A diagram showing the steps of the installation design method for the underwater bubble generating device in the installation design method for the underwater bubble generating device based on full compartment coverage of the present invention; Figure 2 This is a schematic diagram of the installation position of the vertical jet pipe in the installation design method of the underwater bubble generating device based on full compartment coverage described in the present invention.

[0039] The embodiment of the present invention provides a method for designing an installation of an underwater bubble generating device based on full compartment coverage, including:

[0040] Step S1, determining the bubble volume at the end of the bubble expansion phase based on a classic two-stage model of bubble generation in still water;

[0041] Specifically, the growth process of bubbles in water includes two stages: expansion and detachment. The bubble size at the end of the expansion stage in the non-jet state is basically the same as the size after complete detachment.

[0042] The bubble volume at the end of the bubble expansion phase is expressed by the following formula:

[0043]

[0044] Where V is the bubble volume, ρ l is the liquid density, ρ g is the gas density, g is the acceleration due to gravity, C D is the resistance coefficient of the bubble moving in water, Q is the gas flow rate, d h is the nozzle diameter, and σ is the surface tension coefficient.

[0045] in,

[0046]

[0047] Where d is the bubble diameter, Re is the Reynolds number, μ l is the dynamic viscosity coefficient of the liquid, and u is the velocity of the bubble center, that is, the radius change rate during the bubble generation stage.

[0048] Step S2, determining the radius of bubbles generated in the transverse water flow based on the reduction ratio of the bubble volume in the transverse flow to the bubble volume in still water at the end of the bubble expansion phase;

[0049] Specifically, when a ship is navigating through water, a flow field of a certain velocity forms around the hull. The "blowing" effect of the crossflow greatly accelerates the detachment of bubbles, significantly increasing the frequency of bubble generation. At the same gas volume flow rate, the volume of bubbles detaching in crossflow is correspondingly smaller than that in static liquid. Data shows that, under the same conditions, the diameter of bubbles in crossflow decreases by a certain ratio α (α = 10% - 40%).

[0050] Therefore, the bubble diameter in the horizontal water flow is expressed as,

[0051] D=2R=(1-α)d (6)

[0052] Where R is the bubble radius in the horizontal water flow.

[0053] By combining equations (1)-(6), we can get the bubble radius R in the horizontal water flow.

[0054] Step S3, determining the rising speed of the bubbles in the water based on the instantaneous steady-state rising speed model of large bubbles in the water;

[0055] The rising speed is related to the bubble radius and liquid properties. The bubble radius can be calculated according to formulas (1)-(6). According to formula (7), the rising speed of the bubble can be calculated by substituting the bubble radius and the relevant property parameters of seawater or fresh water.

[0056] Specifically, when the bubble radius is within the range of 0.8 to 7 mm, the flow field during the bubble's rise transforms into turbulence, and the bubble begins to deform. This generates significant eddy resistance, the magnitude of which is related to the bubble shape. Therefore, for sparingly soluble gases, the Jamialahmadi empirical formula is generally used to calculate the rising velocity of bubbles with a radius within this range.

[0057]

[0058] Combining equations (1)-(7), we can calculate the rising velocity v of the bubble in water. s .

[0059] Step S4, determining the rising time of the bubbles in the water based on the rising speed of the bubbles in the water;

[0060] Specifically, the bubble rise time is calculated using the formula,

[0061]

[0062] Where t is the bubble rising time and h is the initial bubble depth.

[0063] See also Figures 3 to 5 As shown, Figure 3 Schematic diagram of the coverage of the bubble curtain generated by the vertical jet pipe in the underwater bubble generating device installation design method based on full compartment coverage of the present invention; Figure 4 Schematic diagram of the coverage of the bubble curtain generated by the horizontal jet pipe in the installation design method of the underwater bubble generating device based on full compartment coverage of the present invention; Figure 5 This is a schematic diagram of the coverage range of the bubble curtain generated by the vertical jet pipe and the horizontal jet pipe in the installation design method of the underwater bubble generating device based on full compartment coverage of the present invention.

[0064] Step S5, establishing a rectangular coordinate system on the hull based on the spatial rectangular coordinate system to determine the X axis, Y axis and Z axis;

[0065] Specifically, the coordinate origin O is located at the bottom of the hull, the positive direction of the X-axis is opposite to the ship's heading, the positive direction of the Y-axis is perpendicular to the hull, and the positive direction of the Z-axis is vertically upward.

[0066] Step S6, determining the displacement of the bubble generated in the water on the X-axis based on the moving speed of the ship, the rising time of the bubble in the water, and the initial depth of the bubble;

[0067] Specifically, assuming that the ship is sailing in a straight line at a constant speed vc, the displacement of the bubble in the water in the X-axis direction is

[0068] S x =v c gt (9)

[0069] Where S x is the displacement of the bubble in the direction of the ship's length, v c is the ship's speed, and t is the bubble's rising time.

[0070] By combining equations (7)-(9), we can calculate the maximum coverage of the bubble generated by a single jet pipe in the direction of the ship's length.

[0071] Step S8, determining a single-layer coverage of the cabin section by the bubbles generated by a single blast hole based on the displacement of the bubbles generated in the water on the X-axis;

[0072] Specifically, when h is the initial depth of the deepest bubble, S x The bubbles generated at the very bottom of the hull remain in the water the longest and have the greatest displacement along the water flow. Therefore, the displacement of the bubbles at the very bottom along the X-axis is the maximum coverage of the bubble curtain generated by a single jet pipe along the length of the ship.

[0073] See also Figure 6 As shown, Figure 6 This is a schematic diagram of the installation positions of the vertical jet pipe and the horizontal jet pipe in the installation design method of the underwater bubble generating device based on full compartment coverage described in the present invention.

[0074] Step S9, opening holes in the horizontal air injection pipe and the vertical air injection pipe based on the single-layer coverage;

[0075] Specifically, the installation of the underwater bubble generating device should adopt an installation arrangement that combines a vertical jet pipe arranged conformally along the vertical direction of the hull side wall with a horizontal jet pipe arranged horizontally along the hull side wall.

[0076] Among them, a number of jet holes are opened on the vertical jet pipe and the horizontal jet pipe to address the problem that bubbles generated in the water at different water flow velocities and different ship speeds do not fully cover the cabin section.

[0077] Step S10: installing the horizontal air injection pipe and the vertical air injection pipe with holes opened on the side walls of the hull respectively.

[0078] Specifically, vertical jet pipes are conformally arranged along the vertical direction of the hull side walls on both sides of the hull compartment, and horizontal jet pipes are arranged along the horizontal direction of the hull side walls close to the bottom of the hull. The same underwater bubble generating device is installed on the other side wall (starboard side) of the compartment.

[0079] 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.

[0080] 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 and installing an underwater bubble generating device based on full compartment coverage, characterized in that: include: The bubble volume at the end of the bubble expansion phase is determined based on the classic two-stage model of bubble formation in still water. Determining the radius of bubbles generated in the transverse water flow based on the reduction ratio of the bubble volume in the transverse flow to the bubble volume at the end of the bubble expansion phase in still water; Determine the rising velocity of bubbles in water based on the instantaneous steady-state rising velocity model of large bubbles in water; Determine the rising time of the bubbles in the water based on the rising speed of the bubbles in the water; Establishing a rectangular coordinate system on the hull based on the spatial coordinate system to determine the X axis, the Y axis and the Z axis; Determine the displacement of the bubble generated in the water on the X-axis based on the ship's moving speed, the rising time of the bubble in the water, and the initial depth of the bubble; Determining a single-layer coverage of the cabin section by the bubbles generated by a single fumarole based on the displacement of the bubbles generated in the water on the X-axis; Holes are opened in the horizontal and vertical air jet pipes based on the single-layer coverage; The horizontal air-jet pipe and the vertical air-jet pipe with holes opened are respectively installed on the side walls of the hull.

2. The design method for installing a water bubble generator based on full compartment coverage according to claim 1 is characterized in that: The classic two-stage process of bubble generation in still water includes an expansion stage and a detachment stage.

3. The design method for installing a water bubble generator based on full compartment coverage according to claim 1 is characterized in that: The reduction ratio is that when the ship is sailing in the water, a flow field of a certain speed will be formed around it. Under the same gas volume flow rate, the bubble detachment volume in the transverse flow will also be correspondingly smaller than the bubble detachment volume in the static liquid. Under the same other conditions, the bubble diameter in the transverse water flow will be reduced according to a certain ratio α (α = 10% 40%).

4. The design method for installing a water bubble generator based on full compartment coverage according to claim 1 is characterized in that: The spatial rectangular coordinate system includes an X-axis, a Y-axis, and a Z-axis. The positive direction of the X-axis is opposite to the ship's heading, the positive direction of the Y-axis is perpendicular to the ship, and the positive direction of the Z-axis is vertically upward.

5. The design method for installing a submerged bubble generator based on full compartment coverage according to claim 1 is characterized in that: The displacement of the bubble generated in the water on the X-axis includes the displacement of the bubble along the X-axis during the period from the generation of the bubble to the rise of the bubble to the water surface.

6. The design method for installing a submerged bubble generator based on full compartment coverage according to claim 1 is characterized in that: The jet pipes include vertical jet pipes installed on the side wall of the cabin in a conformal arrangement in the vertical direction and horizontal jet pipes installed along the side wall of the hull in a horizontal direction close to the bottom of the hull.

7. The design method for installing a submerged bubble generator based on full compartment coverage according to claim 1 is characterized in that: The openings include a plurality of air-injection holes formed on the sides of the vertical air-injection pipe and the horizontal air-injection pipe.

8. The design method for installing a submerged bubble generator based on full compartment coverage according to claim 7 is characterized in that: The single-layer coverage of the air bubbles on the compartment section is the range covered by the bubble curtain formed by the displacement of the air bubbles ejected from a single air jet hole in the X-axis direction.

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