Underwater structure vertical floating test system design method

Abstract

The invention discloses a design method of a vertical floating test system of an underwater structure. The method comprises the following steps: controlling the attitude of the underwater structure; counterweight ballast design is carried out; controlling an acoustic releaser; and indirectly measuring the movement speed in the floating process. According to the economical and effective measurement method for the unpowered underwater structure under the motion working condition, the acoustic releaser is used for controlling the separation of the weight ballast, so that the structure floats to the water surface in a stable posture by virtue of the buoyancy of the structure; the self-contained watertight depth meter is adopted to measure the depth in the floating process along with the movement of the structure so as to indirectly obtain the change of the movement speed. The invention provides a technical scheme for the measurement of a hydrodynamic noise floating body, the measurement of the target strength of a moving structure and other underwater domains.

Description

Technical Field

[0001] The invention belongs to the field of marine engineering technology, and in particular relates to a system design method for a vertical floating test of an underwater structure without a propulsion system, which is suitable for measuring the hydrodynamic noise of medium and high-speed underwater navigation bodies and the intensity of moving targets. Background Art

[0002] In the field of hydroacoustic engineering, hydrodynamic noise is crucial for a deep understanding of the acoustic characteristics of underwater vehicles. Hydrodynamic noise refers to the noise generated by the fluid dynamics when an underwater vehicle moves in the water. This noise not only comes from various sound waves generated by the interaction between the vehicle and the surrounding medium, but also includes the mechanical noise generated by the underwater vehicle itself. Therefore, eliminating mechanical noise interference to enhance the accuracy of hydrodynamic noise measurement has become a core problem that needs to be overcome in this field. In this context, floating body measurement technology has emerged as an efficient strategy.

[0003] Traditional methods for floating underwater structures mainly include the use of buoyancy devices (such as air bags), lifting equipment (such as cranes) or internal pressurization. Although the floating of structures can be achieved, there are many challenges in practical operation, such as low efficiency, high cost and safety hazards. Haddle et al. proposed the floating body measurement technology in the 1960s. This method releases the test floating body model freely from the deep water environment and uses only its own buoyancy instead of any external power device to push the floating body to float, thereby effectively eliminating the influence of mechanical noise on the measurement results. Since this method can significantly improve the accuracy of hydrodynamic noise measurement, and the floating body model can achieve a high floating speed, it is very suitable for hydrodynamic noise measurement of medium and high-speed underwater vehicles.

[0004] Many countries have built special floating body measurement test bases. For example, the Russian Krylov Central Ship Research Institute designed and built a deep-water floating body measurement base in the 1960s to measure the hydrodynamic noise of underwater vehicles. The maximum floating body rising speed can reach more than 22 meters per second. The United States has also planned a buoyancy boat test area in the submarine hydroacoustic test area of ​​Lake Bend Ore in Idaho, which is used for hydrodynamic noise measurement tests on the bow and command room hull of submarines. In contrast, there are relatively few experimental studies on the measurement of hydrodynamic noise by floating bodies in China, and China has not yet built a special floating body measurement test platform. Given the significant advantages of floating body measurement technology in hydrodynamic noise testing, the establishment of a special floating body measurement test platform is of great significance for in-depth research on the mechanism of hydrodynamic noise and reducing the hydrodynamic noise of underwater vehicles at medium and high speeds. Summary of the invention

[0005] In view of the deficiencies in the prior art and the characteristics of underwater structures that float rapidly under the action of buoyancy, the present invention proposes a design method for a vertical floating test system for underwater structures, which can achieve rapid vertical floating of underwater structures and effectively eliminate the influence of mechanical noise on the measurement results of hydrodynamic noise.

[0006] The technical solution of the present invention is as follows:

[0007] A method for designing a vertical floating test system for an underwater structure, comprising:

[0008] Attitude control of underwater structures;

[0009] Ballast design;

[0010] Acoustic release control;

[0011] Indirect measurement of movement speed during the ascent process.

[0012] The working principle of the present invention is that the underwater structure will automatically float up under the action of buoyancy, and this phenomenon enables the structure to float up quickly from the bottom of the water without the need for external thrust. In order to ensure that the underwater structure maintains the expected vertical posture during the floating process, it is necessary to pay attention to the center of buoyancy being located directly above the center of gravity when designing the structure, and each counterweight is installed and fixed inside the model in a separate positioning manner. After receiving a specific signal, the acoustic releaser will release the bottom weight. By recording the underwater depth of the structure in real time, its movement speed during the floating process can be indirectly measured, thereby designing a vertical floating test system for underwater structures.

[0013] A method for designing a vertical floating test system for an underwater structure is characterized by comprising:

[0014] S1. Establish a global coordinate system and a carrier coordinate system as a static reference and a moving reference respectively;

[0015] S2. Define the yaw angle and pitch angle of the structure in the carrier coordinate system relative to the global coordinate system;

[0016] S3. Install an acoustic releaser at the bottom of the structure and connect a weight to control the timing of buoyancy;

[0017] S4. Install a self-contained watertight depth gauge on the surface of the structure to indirectly measure the buoyancy speed of the structure;

[0018] S5. Design the ballast weight to ensure that the buoyancy center of the structure is directly above the center of gravity and increase the restoring moment;

[0019] S6. The acoustic releaser is used to control the detachment of the bottom weight to achieve the vertical floating test of the underwater structure.

[0020] Preferably, the underwater structure is regarded as a test floating model. During design, it must be ensured that the center of buoyancy is located directly above the center of gravity and the distance between the center of buoyancy and the center of gravity is increased as much as possible. This can increase the restoring torque, thereby significantly improving the anti-interference ability and stability of the structure during movement; the vertical buoyancy can be regarded as freely releasing the structure model from the bottom of the lake in a deep water environment, relying entirely on its own inherent buoyancy characteristics, and autonomously floating to the water surface without the aid of an external power propulsion device, thereby achieving accurate research and analysis of the dynamic behavior of the structure.

[0021] Preferably, the carrier coordinate system in step S1 is a coordinate system that takes the buoyancy center of the structure as its origin, and the z-axis pointing along the longitudinal axis of the structure to the head, and floats up with the structure; the global coordinate system is a stationary coordinate system that takes the buoyancy center of the structure as its origin, and the z-axis pointing vertically upwards, and does not float up with the structure.

[0022] Preferably, the acoustic releaser in step S3 is a device for automatic recovery of underwater equipment, which receives a release command from the water surface via an acoustic signal, triggers a release mechanism after verification, separates the structure from the weight, and floats to the water surface under the action of buoyancy for easy recovery.

[0023] Preferably, the self-contained watertight depth gauge in step S4 is a measuring device that can operate independently underwater and can accurately measure the underwater depth; the indirect measurement of the movement speed is achieved by recording the underwater depth of the structure at different times and calculating the change in movement speed.

[0024] Preferably, in the step S5, in order to ensure that the model remains vertical in the water, each counterweight is installed and fixed inside the model in a separate positioning manner during design.

[0025] Preferably, in the vertical floating test of the underwater structure in step S6, after the acoustic releaser releases the weight, the posture of the underwater structure is controlled to remain unchanged, that is, the yaw angle and the pitch angle are always maintained at 0°, until the structure floats to the surface.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] (1) The underwater structure's own buoyancy is used to achieve buoyancy without the need for additional propulsion devices, effectively avoiding the interference of mechanical noise and significantly improving the measurement accuracy and reliability of hydrodynamic noise and moving target intensity. Precise counterweight and buoyancy center design ensure that the structure always remains vertical during the buoyancy process, reducing measurement errors caused by tilt and improving the quality of measurement data.

[0028] (2) An acoustic releaser is used to receive signals to control the release of the bottom counterweight, which realizes the automation of the floating process and facilitates remote operation. Compared with traditional measurement methods, it improves the safety and convenience of operation and reduces equipment investment and maintenance costs. The real-time recording of the underwater depth of the structure can not only indirectly measure the floating speed, but also combine the hydrodynamic model for data analysis, providing a detailed basis for optimizing the design and performance evaluation, improving the measurement efficiency, and achieving higher economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a flow chart of the design method of the underwater structure vertical floating test system of the present invention;

[0030] Figure 2 is an example diagram of constructing the global coordinate system and the carrier coordinate system, where a is the global coordinate system and b is the carrier coordinate system;

[0031] Figure 3 It is the front view of the underwater structure design;

[0032] Figure 4 It is a design drawing of the internal counterweight of the structure model. The counterweight is precisely positioned individually and evenly distributed on the cross section.

[0033] Figure 5 It is a depth-time curve graph measured by a self-contained watertight depth gauge and a velocity-time curve graph obtained by fitting calculation. DETAILED DESCRIPTION

[0034] The invention scheme of the present invention will be described completely and clearly below in conjunction with the embodiments and drawings, but this should not limit the protection scope of the present invention.

[0035] See also Figure 1 , Figure 1 It is a flow chart of the design method of the underwater structure vertical floating test system of the present invention, such as Figure 1 As shown, a design method for a vertical floating test system for an underwater structure includes the following contents:

[0036] S1. Coordinate system construction: This embodiment adopts a dual coordinate system strategy to enhance the accuracy of the experiment and the convenience of analysis. Specifically, a global coordinate system (such as Figure 2 The coordinate system is fixed to the earth, with the vertical upward direction as z o The stationary coordinate system of the axis does not move with the structure. At the same time, a carrier coordinate system is established. This coordinate system is fixedly connected to the underwater structure, with its origin set at the buoyancy center of the structure and a moving coordinate system with the z-axis pointing to the head direction along the longitudinal axis of the structure, which moves with the underwater structure.

[0037] S2. Definition of structure attitude angle: The origin of the global coordinate system O 0 It is translated until it coincides with the origin of the carrier coordinate system (i.e., the buoyancy center of the underwater structure); the angular position relationship of the carrier coordinate system relative to the global coordinate system is expressed by the yaw angle and the pitch angle.

[0038] S3. Overall system design: The vertical floating test system of the underwater structure designed by the present invention (such as Figure 3 The structure is designed to ensure vertical stability underwater, with the center of buoyancy at the top and the center of gravity at the bottom. Buoyancy tanks are strategically placed on the top of the structure, and counterweights are fixed to the bottom to achieve stability and balance. The bottom of the structure is precisely connected to the acoustic releaser, and the lower end is firmly tied to a weight, forming a stable and responsive system component.

[0039] S4. System local design: including the structure's counterweight ballast and acoustic releaser. The counterweight is precisely positioned individually, firmly installed and fixed inside the structure, and evenly distributed on the cross section (such as Figure 4 The acoustic releaser, located at the bottom of the structure, is equipped with a highly sensitive signal receiving system that can accurately receive acoustic instructions from the water surface. After a rigorous verification procedure, it immediately triggers the release mechanism, prompting the structure to quickly separate from the heavy block at the bottom. Subsequently, driven by buoyancy, the structure is able to maintain a vertical posture and float to the water surface smoothly and quickly, demonstrating efficient and reliable operating characteristics.

[0040] Surfacing speed monitoring: The outer surface of the structure is equipped with a self-contained watertight depth gauge to directly and in real time capture the depth information of the structure. By performing fine fitting calculations on the collected depth data, the surfacing speed of the structure can be indirectly calculated, thus providing a solid foundation for subsequent data analysis and performance evaluation.

[0041] During the design, it is necessary to ensure that the center of buoyancy is directly above the center of gravity, and the distance between the center of buoyancy and the center of gravity is increased as much as possible. This can increase the restoring moment, thereby significantly improving the anti-interference ability and stability of the structure.

[0042] The vertical buoyancy can be regarded as the free release of the structure model from the bottom of the lake in a deep-water environment. It completely relies on its inherent buoyancy characteristics and floats to the water surface autonomously without the help of the thrust of an external power device, thereby realizing the precise study and analysis of the dynamic behavior of the structure.

[0043] The acoustic releaser is a device used for automatic recovery of underwater equipment. It receives release instructions from the water surface through acoustic signals, triggers the release mechanism after verification, separates the structure from the weight, and floats to the water surface under the action of buoyancy for easy recovery.

[0044] The self-contained watertight depth gauge is a measuring device that can operate independently underwater and can accurately measure the underwater depth; the indirect measurement of movement speed is to calculate and obtain the change in movement speed by recording the underwater depth of the structure at different times.

[0045] In the underwater structure vertical floating test, after the acoustic releaser releases the weight, the posture of the underwater structure is controlled to remain unchanged, that is, the yaw angle and the pitch angle are always kept at 0° until the structure floats to the surface.

[0046] Example

[0047] The following is an embodiment of the design of the underwater structure vertical floating test system based on the present invention.

[0048] In this embodiment, the underwater structure is designed based on the Benchmark submarine scale model. Figure 3 The total length of the structure is 6.27 meters, the draft position is designed to be 1.407 meters from the top of the structure, and the center of buoyancy is set at 2.431 meters below the draft position. In addition, four large tail fins are added to the end of the structure to more effectively keep the structure in a vertical position during the floating process.

[0049] The test process of this embodiment is as follows:

[0050] 1. Install an acoustic releaser at the bottom of the underwater structure. Connect several 20 kg weights to the lower end of the releaser, so that the structure sinks to the bottom of the lake under the action of gravity.

[0051] 2. An acoustic signal is sent from the shore, and the acoustic releaser receives the release command from the water surface. After verification, the release mechanism is triggered to separate the structure from the weight.

[0052] 3. Under the action of buoyancy, the structure is able to maintain a vertical posture and float to the water surface smoothly and quickly.

[0053] 4. The depth-time curve is obtained by measuring the self-contained watertight depth gauge, and the speed-time curve is obtained by fitting calculation. The results are as follows: Figure 5 As shown in the figure, the vertical floating test of underwater structures is realized, and the movement speed of the structures during the floating process can be indirectly and accurately calculated.

[0054] The present invention achieves autonomous floating by utilizing the underwater structure's own buoyancy, avoiding the mechanical noise interference of traditional power devices, significantly improving the accuracy and feasibility of measuring hydrodynamic noise and moving target strength, and through precise counterweight and buoyancy center design, ensuring that the structure maintains an ideal vertical state throughout the floating process, greatly reducing the error effect of tilt on the measurement results, thereby greatly improving data quality. Furthermore, the present invention introduces an acoustic releaser that can remotely receive signals and accurately control the release of the bottom counterweight, achieving full automation of the floating process, and greatly enhancing the safety and convenience of operation. This design simplifies the cumbersome operating procedures in traditional measurement methods and greatly reduces equipment costs and maintenance costs. The present invention has opened up a new path for the optimal design and performance evaluation of structures, significantly improving measurement efficiency and economic benefits, and demonstrating the dual value of the present invention in technological innovation and practical application.

Claims

1. A method for designing a vertical floating test system for an underwater structure, characterized in that: include: S1. Establish a global coordinate system and a carrier coordinate system as a static reference and a moving reference respectively; S2. Define the yaw angle and pitch angle of the structure in the carrier coordinate system relative to the global coordinate system; S3. Install an acoustic releaser at the bottom of the structure and connect a weight to control the timing of buoyancy; S4. Install a self-contained watertight depth gauge on the surface of the structure to indirectly measure the buoyancy speed of the structure; S5. Design the ballast weight to ensure that the buoyancy center of the structure is directly above the center of gravity and increase the restoring moment; S6. The acoustic releaser is used to control the detachment of the bottom weight to achieve the vertical floating test of the underwater structure.

2. The method for designing a vertical floating test system for an underwater structure according to claim 1, characterized in that: The buoyancy center of the structure is located directly above the center of gravity, and the distance between the buoyancy center and the center of gravity is increased as much as possible.

3. The method for designing a vertical floating test system for an underwater structure according to claim 1, characterized in that: In step S1, the carrier coordinate system is a coordinate system that takes the buoyancy center of the structure as its origin, and the z-axis is along the longitudinal axis of the structure pointing to the head, and floats up with the structure; the global coordinate system is a stationary coordinate system that takes the buoyancy center of the structure as its origin, and the z-axis is vertically upward, and does not float up with the structure.

4. The method for designing a vertical floating test system for an underwater structure according to claim 1, characterized in that: The acoustic releaser in step S3 is a device for automatic recovery or controlled movement of underwater equipment, which receives a release command from the water surface through an acoustic signal, and triggers a release mechanism after verification to separate the structure from the weight.

5. The method for designing a vertical floating test system for an underwater structure according to claim 1, characterized in that: In step S4, the self-contained watertight depth gauge can operate independently underwater to measure the underwater depth, and calculate the buoyancy speed of the structure by recording the underwater depth data of the structure at different times.

6. The method for designing a vertical floating test system for an underwater structure according to claim 1, characterized in that: In step S5, the ballast is positioned separately and fixed inside the structure to ensure that the structure remains vertical in the water.

7. The method for designing a vertical floating test system for an underwater structure according to claim 1, characterized in that: In the vertical floating test of the underwater structure in step S6, after the acoustic releaser releases the weight, the posture of the underwater structure is controlled to remain unchanged, that is, the yaw angle and the pitch angle are always kept at 0° until the structure floats to the surface.

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