A deep-sea multiphase flow-assisted laser cleaning and welding composite device and method

Abstract

The present invention discloses a deep-sea multiphase flow-assisted laser cleaning and welding composite device and method, which aims to solve the problem that thick sediment layers on the surface of deep-sea equipment are difficult to remove and repair efficiently. The device uses seawater in the deep sea as the liquid phase, combines an abrasive ejector premixed on land with a compressed air machine, and achieves uniform mixing of three-phase fluids through a pipeline mixer to form a high-speed multiphase flow injection system. The gas phase provides power, the abrasive ejector enhances friction, and the liquid phase plays a cooling and cleaning role. The synergistic effect of the three significantly improves the cleaning efficiency and quality. This multiphase flow injection process provides ideal surface conditions for the subsequent ultrafast laser cleaning stage, ensuring that the surface before welding reaches molecular-level cleanliness, and combines laser welding technology to complete the repair of the target area. The method of the present invention is suitable for efficient cleaning and repair operations of equipment in complex deep-sea environments, and provides a new technical solution for deep-sea engineering maintenance.

Description

Technical Field

[0001] The present invention relates to underwater laser cleaning and welding technology in a deep-sea environment, and in particular to a deep-sea multiphase flow-assisted laser cleaning and welding composite device and method. Background Art

[0002] With growing global energy demand and the gradual depletion of terrestrial resources, the development and utilization of marine resources has become a focus of global attention. Oceans cover over 70% of the Earth's surface and contain abundant resources such as oil, natural gas, and minerals, making them crucial for alleviating energy crises and promoting economic development. However, the unique characteristics of the deep-sea environment present numerous challenges to resource development, particularly in the construction and maintenance of underwater projects, where underwater cleaning and welding technologies are crucial.

[0003] In deep-sea environments, especially during the daily operation and maintenance of underwater facilities such as subsea oil and gas platforms, deep-sea mineral extraction equipment, and offshore wind turbines, surface dirt, marine biofouling, and corrosion products often severely impact equipment performance and safety. Furthermore, structural damage and cracks encountered in deep-sea environments require efficient underwater welding technology for repair. Traditional underwater cleaning and welding methods suffer from low efficiency, environmental pollution, and technical difficulties. Therefore, a more efficient and environmentally friendly cleaning and welding technology is urgently needed.

[0004] Due to its high energy density, laser beams can rapidly remove material and achieve molecular-level cleanliness. As a non-contact process, laser processing does not generate mechanical stress or pollution, and has relatively little impact on the surrounding environment, effectively protecting the marine environment. However, current underwater laser cleaning technology still faces the following major challenges:

[0005] (1) The problem of thick and sticky dirt in deep-sea environment: The dirt layer on the surface of deep-sea equipment is often thick and tightly adhered. It is difficult for traditional lasers to completely remove the dirt in one go, and it often requires repeated cleaning, which is time-consuming and labor-intensive.

[0006] (2) Limitation of cleaning effect by high-pressure environment: Due to the high pressure in the deep-sea environment, although the deposits have been detached after laser cleaning, it is difficult to completely separate from the surface of the equipment, and the residual dirt affects the subsequent welding quality.

[0007] (3) Environmental pollution issues: Traditional cleaning methods mostly rely on chemical cleaning agents, which pose a risk of pollution to the marine environment.

[0008] Among the existing technologies, Chinese patent publication number CN1130705272B discloses an underwater welding device and method that achieves integrated cleaning and welding operations by utilizing dual laser heads. Chinese patent publication number CN166237341B discloses an underwater laser operation device with integrated laser cleaning functionality, integrating the cleaning and welding processes into the same joint, thereby improving work efficiency. Although both technologies integrate laser cleaning and welding functions through localized dry welding, their designs are primarily targeted at shallow water or conventional underwater environments. In deep-sea environments, equipment surfaces are often covered with thick layers of sediment, making single laser cleaning in existing technologies difficult to meet practical needs. Furthermore, while patent CN166237341B considers the obstruction to laser transmission caused by contaminant removal, its design fails to effectively address the issue of contaminants being detached from the surface but not completely removed under high-pressure conditions in the deep sea. This is because high pressure can cause sediment fragments to remain within the cleaning area, affecting the stability and quality of subsequent welding.

[0009] Therefore, there is an urgent need to develop a deep-sea multiphase flow-assisted laser cleaning and welding composite device and method to address the aforementioned issues. "Multiphase flow" refers to a fluid composed of liquid, solid, and gas phases. The liquid phase is seawater from the deep-sea environment, providing high-kinetic energy impact as a cleaning matrix; the solid phase is premixed abrasive particles, enhancing the mechanical friction of the cleaning process; and the gas phase is compressed air, which is used to reduce fluid viscosity, enhance jet penetration, and promote the exfoliation and shedding of the deposited layer. These three phases are uniformly mixed in an optimized pipeline mixer to form a high-speed multiphase flow. This synergistic effect significantly improves the cleaning efficiency and surface treatment quality of thick deep-sea sediments, providing ideal surface conditions for the subsequent ultrafast laser fine cleaning stage. The use of natural seawater as the cleaning medium effectively avoids the use of chemical cleaning agents, reducing negative impacts on the marine environment. Furthermore, the use of ultrafast lasers allows for the removal of marine fouling without damaging the equipment coating, resulting in higher cleaning efficiency. After cleaning, laser welding can also be performed on the repaired area, effectively integrating cleaning and welding. Summary of the Invention

[0010] To achieve the above objectives, the present invention is implemented through the following technical solutions: A deep-sea multiphase flow-assisted laser cleaning and welding composite device, comprising:

[0011] A mobile shielding protection system includes a mobile drainage cover and support legs fixed to its bottom. The support legs provide guidance. An air inlet and an exhaust port are provided on the surface of the mobile drainage cover. The mobile drainage cover is connected to the external environment through the exhaust port. The exhaust port is used to discharge treated water. An exhaust valve is fixedly connected to the surface of the mobile drainage cover. The exhaust valve is connected to the interior of the mobile drainage cover through the air inlet. The exhaust valve and the air inlet are used to remove seawater from the cover to ensure the clarity and quality of the laser cleaning and welding areas. The mobile shielding protection system is used to provide a local dry operating environment and regional protection during laser cleaning and welding. Through flexible movement and precise positioning, the mobile shielding protection system includes a protective cover that can isolate seawater and impurities, ensure efficient laser cleaning, optimize environmental conditions during the welding phase, and improve welding quality and structural reliability.

[0012] A fluid power generator and a water pump, wherein the fluid power generator and the water pump are fixedly mounted on the top of the mobile drainage cover, and the fluid power generator and the water pump are connected via a pipeline, and the fluid power generator is connected to the pipeline mixer via a pipeline;

[0013] An abrasive ejector and a compressed air machine, wherein the abrasive ejector is connected to the bottom of the compressed air machine, and the air outlet of the compressed air machine is connected to the pipeline mixer;

[0014] The multiphase flow supply system is used to combine the high-speed seawater generated by the fluid power generator, the onshore premixed abrasive ejector and the compressed air machine to form a multiphase flow, and achieve uniform mixing of the three phases through the pipeline mixer;

[0015] A laser cleaning and welding system includes a laser fixedly mounted in the middle of the inner cavity of a mobile drainage hood, penetrating the hood and extending to the top. A high-speed jet system is mounted on the outer surface of the laser. The high-speed jet system includes a water jet and a baffle assembly. The water jet is used to spray high-pressure water to remove dirt from the equipment surface. The baffle assembly is used to block splashed sediment during the cleaning process and protect the laser head and other equipment. A pipeline mixer is fixedly connected to the upper surface of the water jet. The pipeline mixer generates turbulence and shear force through internal spiral blades to promote mixing of gas, liquid, and solid three-phase fluids. The laser emits a laser beam and works in conjunction with the water jet to perform underwater laser cleaning operations.

[0016] Underwater cameras, which are fixedly installed at the four corners of the inner cavity of the mobile drainage cover and are connected to computer signals. The underwater cameras collect images of the cleaning and welding areas in real time and feed the data back to the computer for operators to monitor the cleaning and welding quality in real time;

[0017] The control system includes a controller connected to the fluid power generator, laser, mobile drainage shield, and pump via cables. As the system's core control unit, the controller provides unified control of these components. The controller controls water flow, laser output, and the operation of the drainage shield according to preset programs. The control system coordinates the operation of the multiphase flow supply system, high-speed multiphase flow injection system, laser cleaning and welding system, and mobile shielding protection system, providing multi-mode parameter control and real-time monitoring capabilities.

[0018] A water jet inlet and a water jet outlet are respectively provided at both ends of the water jet. The water jet is connected to the interior of the pipeline mixer through the water jet inlet. The multiphase fluid passing through the pipeline mixer enters the water jet from the water jet inlet and is sprayed out at the water jet outlet to form a uniform planar multiphase flow.

[0019] The baffle assembly includes a fixed cover and a baffle, sliding guide rails are fixedly installed on both sides of the inner wall of the fixed cover, and sliding grooves are opened on both sides of the baffle. The baffle is slidably connected to the surface of the sliding guide rail through the sliding grooves, and a buffer spring is fixedly connected between the end of the baffle and the inner wall of the fixed cover.

[0020] A pressure sensor is fixedly installed on the surface of the fixed cover. The pressure sensor monitors the change of the water jet pressure and drives the expansion and contraction adjustment of the baffle assembly according to the pressure change signal.

[0021] Preferably, the multiphase flow supply system comprises:

[0022] The liquid phase supply module includes a regulator and a sensor. The regulator controls the water output pressure by adjusting the speed of the regulating pump. The sensor is arranged at the outlet of the high-pressure pump to detect the water flow pressure and feed the data back to the controller to achieve closed-loop control.

[0023] The gas-solid supply module independently adjusts gas flow and solid abrasive delivery speed, enabling onshore operation and real-time optimization of gas and solid delivery conditions to achieve uniform mixing of the three-phase fluid. Precisely controlling the gas and solid flow rates ensures a uniform ratio of gas, solid, and liquid in the mixer, improving system efficiency and stability. Furthermore, the type and particle size of the solid abrasive can be flexibly adjusted to meet diverse cleaning and welding requirements, ensuring uniform cleaning results and enhancing system adaptability.

[0024] The three-phase flow mixing module uses internal spiral blades to generate turbulence and shear forces, promoting the mixing of gas, liquid, and solid phases. Turbulence disrupts the laminar flow of the fluids, increasing the contact area and improving mixing efficiency. Through continuous interaction within the mixer, the gas, liquid, and solid fluids quickly achieve uniform distribution. The mixer's design optimizes flow rate and direction, ensuring efficient and stable mixing of the three-phase fluids, providing an ideal fluid environment for deep-sea laser cleaning and welding.

[0025] The water jet nozzle is preferably designed with a rectangular cross-section. A uniform flow chamber and a flow-guiding structure distribute the high-pressure water flow to multiple parallel slits, each of which ejects a linear stream of water. These streams then form a uniform planar stream at the outlet. The nozzle's inner wall is precision-polished to reduce turbulence and enhance jet stability. Driven by high pressure, the planar stream, combined with an underwater abrasive ejector, scours surface deposits at multiple points, generating efficient friction to remove stubborn dirt. This makes it suitable for wide-area cleaning of equipment in deep-sea environments.

[0026] Preferably, the pulse width, energy and frequency of the laser are adjustable to meet the cleaning and welding requirements of different materials and dirt types.

[0027] Preferably, the drainage cover is remotely controlled by an onshore control system, and three-dimensional movement is achieved using a propulsion device. The support feet at the bottom provide guidance, and combined with camera feedback, the operator can accurately adjust the position. The negative pressure system adjusts the adsorption force, reduces friction and ensures stable attachment.

[0028] The baffle assembly's length is optimally adjusted based on the waterjet's jet pressure. Linked to a pressure sensor, the baffle automatically expands and contracts as the jet pressure changes, effectively shielding against debris while avoiding cleaning interference or loss of coverage caused by a fixed baffle position. Slide rails ensure smooth and reliable adjustment, adapting to varying jet pressures.

[0029] A deep-sea multiphase flow-assisted laser cleaning and welding composite method, applied to a deep-sea multiphase flow-assisted laser cleaning and welding composite device, comprises the following steps:

[0030] Step 1: Put the movable drainage cover into the sea and use the controller to move the drainage cover to the area to be cleaned;

[0031] Step 2: Turn on the underwater camera to observe the cleaning area and feed the image back to the computer. According to the actual situation of the equipment surface, select the appropriate pressure and abrasive jet. Start the fluid power generator and exhaust valve to make the water jet spray a planar high-speed multiphase flow to clean the sediment on the equipment surface.

[0032] Step 3: Open the exhaust valve to discharge the seawater and sediment in the cover to prevent the seawater and pollutants from affecting the transmission quality of the laser beam;

[0033] Step 4: Observe the cleaning area again through the underwater camera and feed it back to the computer. Select the appropriate laser parameters according to the surface condition of the equipment, start the laser, and output the laser beam to clean the surface of the equipment.

[0034] Step 5: After cleaning is completed, the cleaning effect is observed by an underwater camera and fed back to the computer to determine whether the cleaning is qualified and whether welding repair is needed;

[0035] Step 6: If the cleaning is unsatisfactory, high-speed water flow and laser cleaning can be performed again; if welding repair is required, laser repair can be performed.

[0036] Preferably, in step 2, an underwater camera is arranged at each of the four corners of the drain cover to ensure a comprehensive and detailed observation of the equipment surface, thereby monitoring the cleaning process in real time.

[0037] Preferably, in step 2, the high-speed water flow uses natural seawater as the cleaning medium to avoid the use of chemical cleaning agents, thereby reducing the impact on the marine environment. At the same time, the injection pressure is adjustable to meet the cleaning needs of different equipment surfaces.

[0038] The present invention provides a deep-sea multiphase flow-assisted laser cleaning and welding composite device. It has the following beneficial effects:

[0039] The present invention provides a deep-sea multiphase flow-assisted laser cleaning and welding composite device that can effectively solve the problems of thick sediment layers on the surface of deep-sea equipment and low efficiency of traditional cleaning methods. By using deep-sea seawater as the liquid phase, combining the gas phase and solid phase of solid abrasives and compressed air, and using a pipeline mixer to achieve uniform mixing of the three phases, a high-speed multiphase flow injection system is formed, which significantly improves the cleaning efficiency and quality, and provides ideal surface conditions for the laser cleaning and welding process. In addition, the use of seawater as a cleaning liquid avoids the use of chemical cleaning agents, reduces the risk of pollution and corrosion, and improves environmental protection. This technology effectively solves the problem of incomplete shedding of pollutants caused by high pressure in the deep-sea environment, ensures the quality of laser welding, improves the structural reliability of welding joints, and provides an innovative and environmentally friendly solution for the efficient cleaning and repair of deep-sea equipment. The high-speed water flow pressure sprayed by the fluid power generator provided by the present invention and the pulse width, energy and frequency of the laser are all adjustable to meet the cleaning needs of different equipment surfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic structural diagram of a deep-sea multiphase flow-assisted laser cleaning device provided by the present invention;

[0041] Figure 2 is a schematic diagram of the laser cleaning and welding unit of the present invention;

[0042] Figure 3 Schematic diagram of the internal structure of the water jet of the present invention;

[0043] Figure 4 Schematic diagram of the structure of the baffle assembly of the present invention;

[0044] Figure 5 It is a cross-sectional view of the baffle assembly structure of the present invention.

[0045] In the figure: 1. Pump; 2. Fluid power generator; 3. Underwater camera; 4. Laser; 5. Water jet; 6. Baffle assembly; 61. Fixed cover; 62. Baffle; 63. Sliding guide rail; 64. Slide; 65. Buffer spring; 66. Pressure sensor; 7. Air inlet; 8. Exhaust; 9. Mobile drainage cover; 10. Controller; 11. Computer; 12. Exhaust valve; 13. Abrasive ejector; 14. Compressed air machine; 15. Pipe mixer; 16. Water jet inlet; 17. Water jet outlet. DETAILED DESCRIPTION

[0046] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. The embodiments of the present invention are provided for purposes of illustration and description and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. The embodiments are chosen and described to better illustrate the principles of the invention and its practical application, and to enable those skilled in the art to understand the invention and design various embodiments with various modifications suitable for specific applications.

[0047] The first embodiment, as Figure 1 As shown, the present invention provides a technical solution: a deep-sea multiphase flow-assisted laser cleaning and welding composite device, comprising:

[0048] The mobile drain cover 9 and the support legs fixed to its bottom provide guidance. The surface of the mobile drain cover 9 is provided with an air inlet 7 and an exhaust port 8. The mobile drain cover 9 is connected to the external environment through the exhaust port 8. The exhaust port 8 is used to discharge the treated water. The surface of the mobile drain cover 9 is fixedly connected to an exhaust valve 12. The exhaust valve 12 is connected to the interior of the mobile drain cover 9 through the air inlet 7 and is used to remove seawater from the cover to ensure the clarity and quality of the laser cleaning and welding areas.

[0049] Laser 4 is fixedly mounted in the middle of the inner cavity of the mobile drainage hood 9. Laser 4 penetrates the mobile drainage hood 9 and extends to its top. A water jet 5 and a baffle assembly 6 are mounted on the outer surface of the laser 4, sequentially from top to bottom. The water jet 5 is used to spray high-pressure water to remove dirt from the equipment surface. The baffle assembly 6 is used to block splashing sediment during the cleaning process, protecting the laser head and other equipment. A pipeline mixer 15 is fixedly connected to the upper surface of the water jet 5. The pipeline mixer 15 generates turbulence and shear force through its internal spiral blades, promoting the mixing of the three-phase fluid of gas, liquid, and solid. Laser 4 emits a laser beam, which works in conjunction with the water jet 5 to perform underwater laser cleaning operations.

[0050] The fluid power generator 2 and the pump 1 are both fixedly mounted on top of the mobile drainage cover 9 and connected to the pump 1 via a pipe. The fluid power generator 2 and the pump 1 work together to absorb seawater and pressurize it for injection. The fluid power generator 2 is connected to the pipeline mixer 15 via a pipe.

[0051] An abrasive ejector 13 and a compressed air machine 14 are connected to the bottom of the abrasive ejector 13. The abrasive ejector 13 is driven by airflow to perform abrasive ejection-assisted cleaning. The air outlet of the compressed air machine 14 is connected to a pipeline mixer 15, which is used to mix the airflow with seawater and abrasive to form a multiphase flow to improve the cleaning effect.

[0052] Underwater cameras 3 are fixedly mounted at the four corners of the inner cavity of the mobile drainage cover 9. The underwater cameras 3 are connected to the computer 11 for signal transmission. The underwater cameras 3 collect images of the cleaning and welding areas in real time and feed the data back to the computer 11 for the operator to monitor the cleaning and welding quality in real time.

[0053] Controller 10, controller 10 is connected to the fluid power generator 2, laser 4, mobile drainage cover 9 and pump 1 through connecting lines. Controller 10 serves as the core control unit of the system and performs unified control of these components. Controller 10 controls water flow, laser output, and operation of the drainage cover according to a preset program.

[0054] The second embodiment, based on the first embodiment, see Figures 2 to 3 As shown, a water jet inlet 16 and a water jet outlet 17 are respectively provided at both ends of the water jet 5, and the water jet 5 is connected to the interior of the pipeline mixer 15 through the water jet inlet 16;

[0055] The water jet nozzle 5 is designed with a rectangular cross-section. A uniform multiphase fluid, passing through a pipeline mixer 15, enters the top water jet inlet 16. A uniform flow chamber and diversion structure distribute the high-pressure water flow to multiple parallel slits, each of which ejects linear streams of water. These streams then form a uniform planar stream upon exiting the water jet outlet 17. The nozzle's inner wall is precision-polished to reduce turbulence and enhance jet stability. Driven by high pressure, the planar water flow, combined with abrasives, scours surface deposits at multiple points, generating friction to remove stubborn dirt.

[0056] The third embodiment, based on the first and second embodiments, see Figures 2 to 5 As shown, the baffle assembly 6 includes a fixed cover 61 and a baffle 62. Sliding guide rails 63 are fixedly installed on both sides of the inner wall of the fixed cover 61. Slide grooves 64 are opened on both sides of the baffle 62. The baffle 62 is slidably connected to the surface of the sliding guide rails 63 through the slide grooves 64. A buffer spring 65 is fixedly connected between the end of the baffle 62 and the inner wall of the fixed cover 61.

[0057] A pressure sensor 66 is fixedly mounted on the surface of the fixed cover 61. The pressure sensor 66 monitors the change in the jet pressure of the water jet 5 and drives the expansion and contraction adjustment of the baffle 62 according to the pressure change signal.

[0058] The length of the baffle assembly 6 is automatically adjusted based on the jet pressure of the water jet 5. A pressure sensor 66 monitors changes in the jet pressure of the water jet 5 in real time and drives the baffle assembly 6 to extend and retract based on the pressure change signal. A sliding guide 63 ensures that the baffle assembly 6 moves smoothly along its trajectory during adjustment, preventing it from getting stuck or deflecting, thereby ensuring that it always remains in an effective shielding position.

[0059] During use, the operator drops the mobile drainage cover 9 into the sea and uses the controller 10 to move the mobile drainage cover to the area to be cleaned. The operator then activates the underwater camera 3 to observe the cleaning area and feeds the image back to the computer 11. The operator selects the appropriate pressure and abrasive according to the actual conditions of the equipment surface, activates the fluid power generator 2 and the compressed air machine 14, and causes the water jet 5 to spray a planar high-speed multiphase flow to clean the sediment on the equipment surface.

[0060] At this time, the exhaust valve 12 is opened to discharge the seawater and sediment in the cover to prevent the seawater and pollutants from affecting the transmission quality of the laser beam. The cleaning area is observed again through the underwater camera 3 and the feedback is fed to the computer 11. The appropriate laser parameters are selected according to the surface condition of the equipment, and the laser 4 is started to output the laser beam to clean the surface of the equipment.

[0061] After cleaning is completed, the cleaning effect is observed by the underwater camera 3 and fed back to the computer 11 to determine whether the cleaning is qualified and whether welding repair is needed. If the cleaning is unqualified, high-speed water flow and laser cleaning can be performed again; if welding repair is required, laser repair can be performed.

[0062] A method for operating a deep-sea multiphase flow-assisted laser cleaning and welding composite device comprises the following steps:

[0063] Step 1: Put the mobile drainage cover 9 into the sea and use the controller 10 to move the drainage cover to the area to be cleaned;

[0064] Step 2: The underwater camera 3 is turned on to observe the cleaning area and feed the image back to the computer 11. The appropriate pressure and abrasive are selected according to the actual situation of the equipment surface. The fluid power generator 2 and the compressed air machine 14 are started to make the water jet 5 spray a planar high-speed multiphase flow to clean the sediment on the equipment surface.

[0065] Step 3: Open the exhaust valve 12 to discharge the seawater and sediment in the cover to prevent the seawater and pollutants from affecting the transmission quality of the laser beam;

[0066] Step 4: The cleaning area is observed again by the underwater camera 3 and fed back to the computer 11. Appropriate laser parameters are selected according to the surface condition of the equipment, and the laser 4 is started to output a laser beam to clean the surface of the equipment;

[0067] Step 5: After the cleaning is completed, the cleaning effect is observed by the underwater camera 3 and fed back to the computer 11 to determine whether the cleaning is qualified and whether welding repair is required;

[0068] Step 6: If the cleaning is unsatisfactory, high-speed water flow and laser cleaning can be performed again; if welding repair is required, laser repair can be performed.

[0069] Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field and related fields without making creative efforts should fall within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described and explained in the present invention shall be implemented in accordance with conventional means in the field unless otherwise specified or limited.

Claims

1. A deep-sea multiphase flow-assisted laser cleaning and welding composite device, characterized in that: include: A mobile shielding protection system, comprising a mobile drainage cover (9) and supporting legs fixed to the bottom thereof, an air inlet (7) and an exhaust port (8) being provided on the surface of the mobile drainage cover (9), and the mobile drainage cover (9) being connected to the external environment via the exhaust port (8); A laser cleaning and welding system, the laser cleaning and welding system comprising a laser (4), the laser (4) being fixedly mounted in the middle of an inner cavity of a movable drainage cover (9), the laser (4) penetrating the movable drainage cover (9) and extending to the top thereof, a water jet (5) and a baffle assembly (6) being mounted on the outer surface of the laser (4) in sequence from top to bottom, and a pipeline mixer (15) being fixedly connected to the upper surface of the water jet (5); A fluid power generator (2) and a water pump (1), wherein the fluid power generator (2) and the water pump (1) are both fixedly mounted on the top of the mobile drainage cover (9), and the fluid power generator (2) and the water pump (1) are connected via a pipeline, and the fluid power generator (2) is connected to a pipeline mixer (15) via a pipeline; an abrasive ejector (13) and an air compressor (14), wherein the abrasive ejector (13) is connected to the bottom of the air compressor (14), and the air outlet of the air compressor (14) is connected to the pipeline mixer (15); An underwater camera (3), the underwater camera (3) being fixedly mounted at the four corners of the inner cavity of the mobile drainage cover (9), and the underwater camera (3) being connected to the computer (11) via a signal; A control system, the control system comprising a controller (10), the controller (10) being connected to a fluid power generator (2), a laser (4), a mobile drainage cover (9), and a water pump (1) via connecting lines; A multiphase flow supply system is used to combine the high-speed seawater generated by the fluid power generator (2), the solid-phase abrasive ejected by the abrasive ejector (13), and the gas-phase compressed air ejected by the air compressor (14) to form a multiphase flow, and to uniformly mix the three phases through the pipeline mixer (15); Among them, the multiphase flow supply system includes: A liquid supply module, comprising a regulator and a sensor. The regulator controls the water output pressure by adjusting the speed of the regulating pump. The sensor is provided at the outlet of the high-pressure pump to detect the water pressure and feed the data back to the controller. A gas-solid supply module, which is used to adjust the gas flow rate and the solid abrasive conveying speed to achieve mixing of the three-phase fluid; The three-phase flow mixing module is used to adjust the gas flow rate and the solid abrasive conveying speed, and mix the gas, liquid and solid three-phase fluids.

2. The deep-sea multiphase flow-assisted laser cleaning and welding composite device according to claim 1, characterized in that: An exhaust valve (12) is fixedly connected to the surface of the mobile drainage cover (9), and the exhaust valve (12) is connected to the interior of the mobile drainage cover (9) through the air inlet (7).

3. The deep-sea multiphase flow-assisted laser cleaning and welding composite device according to claim 2, characterized in that: A water jet inlet (16) and a water jet outlet (17) are respectively provided at both ends of the water jet (5), and the water jet (5) is connected to the interior of the pipeline mixer (15) through the water jet inlet (16).

4. The deep-sea multiphase flow-assisted laser cleaning and welding composite device according to claim 3, characterized in that: The baffle assembly (6) includes a fixed cover (61) and a baffle (62), wherein sliding guide rails (63) are fixedly installed on both sides of the inner wall of the fixed cover (61), and sliding grooves (64) are opened on both sides of the baffle (62), and the baffle (62) is slidably connected to the surface of the sliding guide rail (63) through the sliding grooves (64), and a buffer spring (65) is fixedly connected between the end of the baffle (62) and the inner wall of the fixed cover (61).

5. The deep-sea multiphase flow-assisted laser cleaning and welding composite device according to claim 4, characterized in that: A pressure sensor (66) is fixedly mounted on the surface of the fixed cover (61). The pressure sensor (66) monitors the change in the jet pressure of the water jet (5) and drives the expansion and contraction adjustment of the baffle assembly according to the pressure change signal.

6. A laser cleaning and welding method using the deep-sea multiphase flow-assisted laser cleaning and welding device according to claim 5, characterized in that: It consists of the following steps: Step 1: Put the movable drainage cover (9) into the sea and move the drainage cover to the part to be cleaned through the controller (10); Step 2: Turn on the underwater camera (3) to observe the cleaning area and feed the image back to the computer (11), select the appropriate pressure and solid abrasive according to the actual situation of the equipment surface, start the fluid power generator (2) and the compressed air machine (14), and make the water jet (5) spray the surface high-speed multiphase flow to clean the sediment on the equipment surface; Underwater cameras (3) are respectively arranged at the four corners of the drainage cover; Step 3: Open the exhaust valve (12) to discharge the seawater and sediment in the cover to prevent the seawater and pollutants from affecting the transmission quality of the laser beam; Step 4: observe the cleaning area again through the underwater camera (3) and feed back to the computer (11), select appropriate laser parameters according to the surface condition of the equipment, start the laser (4), and output the laser beam to clean the surface of the equipment; Step 5: After the cleaning is completed, the cleaning effect is observed by the underwater camera (3) and fed back to the computer (11) to determine whether the cleaning is qualified; Step 6: If the cleaning is unsatisfactory, high-speed water flow and laser cleaning can be performed again; if welding repair is required, laser repair can be performed.

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