An ice water pool model test method for underwater vehicle navigation under ice

Abstract

The present application relates to a kind of ice water pool model test methods of underwater submersible ice navigation, the test device used includes underwater track, motion platform, closed loop drive chain, servo drive system and test system, wherein, the test system includes force sensor and laser displacement sensor, test method includes the following steps: arrangement installs ice water pool test device simulating underwater submersible ice navigation, control the diving depth of submersible model;Preparation model ice cover: in ice water pool by cooling refrigeration, spray crystal, temperature control section preparation meets the target thickness requirement of model ice cover. Respectively using cantilever beam method measures the bending strength of model ice cover, using infinite plate method measures the elastic modulus of model ice cover, ensure that the mechanical properties of model ice cover reach target requirement;Prepare a layer of snow layer on the surface of model ice cover;Calibrate laser displacement sensor and force sensor, adjust underwater submersible model to design posture and diving depth;Test test.

Description

Technical Field

[0001] This invention belongs to the technical field of low-temperature towed ice-water pool model test, and relates to an ice-water pool model test method for simulating the underwater submersible's navigation process under ice. Background Technology

[0002] Submersibles generate gravity waves when navigating near the surface. When the surface is covered by ice, these gravity waves can cause ice sheet fracturing, a phenomenon that has attracted widespread attention from academic and engineering communities both domestically and internationally. Several scholars have conducted valuable research on this issue. Current research primarily employs theoretical analysis and model testing. Kheisin (1967) was the first to focus on ice sheet damage caused by bending gravity waves, using theoretical analysis to study the instability of a flat plate caused by eddy currents beneath the ice sheet. Kozin and Pogorelova (2008) considered the submersible as a source-sink system and simplified the ice sheet as a floating elastic plate, thus analyzing the effects of variations in the source-sink system's velocity, depth, and plate thickness on the deformation of the elastic plate. Pogorelova et al. (2017) used theoretical analysis to study the influence of the movement of slender submersibles on ice sheet deformation under different snow cover types.

[0003] The wave-making and ice-breaking process of underwater submersibles navigating under ice is comprehensively influenced by structural type, ice sheet conditions, and flow field environment. It is difficult to simultaneously reflect the complex effects of these factors and obtain accurate analytical solutions through theoretical analysis. Therefore, ice-water pool model tests have become the main method for studying this problem. A research team at Sholom State University in Russia has conducted long-term research on the wave-making and ice-breaking problem of underwater submersibles and achieved a series of research results. Zemlyak et al. (2013) studied the influence of submersible structural type on ice-breaking efficiency through theoretical analysis and model tests, conducting freshwater ice tests in a natural ice-water pool and testing three submersible models. Zemlyak et al. (2014) and Zemlyak et al. (2018) conducted a series of tests in the same outdoor ice-water pool, focusing on the shape, cross-sectional type, and protruding structure of the underwater submersible, respectively, to test the influence of structural shape on ice-wave activity. Laser displacement sensors were used in the tests to measure ice sheet deformation and observe the ice sheet fracture process. Pogorelova et al. (2019) also used an elastic polymer plate to simulate a floating ice sheet in the same natural ice water pool, and covered the plate with a layer of solid grease to simulate snow on the ice, thereby studying the effect of underwater submersible movement on the destruction process of the snow-covered ice sheet.

[0004] In the series of model tests conducted by Sholom State University in Russia, the research team designed a test method to simulate the wave-breaking and ice-breaking process of an underwater submersible. The density of the structural model was set to be close to that of water, and a steel cable was used to pull the model underwater through a model ice sheet at a designed speed. A frame was installed at each end of the ice-water pool, with a series of pulleys guiding the steel cable, and the tension of the steel cable was adjusted by translating and adjusting the pulleys. The entire mechanism was powered by a servo motor, and the stable movement speed of the structural model could reach a maximum of 2.4 m / s. This device allows for the setting and adjustment of two key test parameters: the submersible's speed and diving depth under ice. The Russian scholars who published these results also pointed out in their series of papers that the submersible's near-ice-surface navigation is always under the influence of the Bernoulli effect of the near-wall flow field, and the flexibility of the steel cable running through the entire test area is insufficient to effectively limit the submersible's heave and sway motion. Therefore, the above-mentioned test device has deficiencies in maintaining the submersible's speed stability and navigation attitude stability. On the other hand, it is difficult to incorporate force sensors into the test device by using steel cables to tug the underwater vehicle, which is the main reason why the underwater vehicle's resistance was not measured in the tests conducted by relevant Russian agencies. Summary of the Invention

[0005] The purpose of this invention is to provide a method for simulating underwater submersible navigation in an ice-water pool. This method utilizes a submersible simulation test device centered on an underwater tracked motion platform to achieve precise adjustment and control of the submersible's speed, attitude, and diving depth without disturbing the water surface. Furthermore, a measurement system including laser displacement sensors and force sensors records ice sheet deformation and navigation resistance in real time during the submersible's navigation, enabling control of the submersible's motion parameters and measurement of key test parameters.

[0006] The technical solution is as follows:

[0007] A method for conducting ice-water pool model tests on underwater submersibles navigating under ice, the test apparatus comprising an underwater track 9, a motion platform 6, a closed-loop transmission chain 4, a servo drive system 1, and a test system, wherein...

[0008] The underwater track 9 is laid at the bottom of the ice water pool and consists of two rows of spliced ​​tracks. The splicing points are fixed by prefabricated connectors 11. The prefabricated connectors prefabricate the fixed positions of the two rows of tracks, forming a frame structure with the two rows of tracks, and are equipped with adjustment components for adjusting the height of the tracks.

[0009] The motion platform 6 is placed on the underwater track 9 via two rows of track wheels 12 at the bottom to simulate the straight-line navigation of the underwater submersible. The motion platform 6 is equipped with a height-adjustable connecting bracket 5, which is used to fix the underwater submersible model.

[0010] The closed-loop transmission chain 4, serving as the main transmission component of the motion platform, has one end connected to the front of the platform and loops around the entire underwater track and the fixed support 13 at one end of the pool wall. The other end of the transmission chain is connected to the rear of the platform. The fixed support 13 stands beside the pool wall at one end of the ice water pool, with a gear set 2 at the top and a transmission gear 10 at the bottom. The closed-loop transmission chain loops around the fixed support through the upper gear set and the lower transmission gear, transitioning from a vertical to a horizontal direction at the bottom transmission gear. The transmission chain can be adjusted to a tensioned or slack state.

[0011] The servo drive system chain 1 is connected to the gear set 2 through the power source transmission chain 3, thereby driving the closed loop transmission chain 4 to move the motion platform 6 along the underwater track 9.

[0012] The testing system includes a force sensor 8 and a laser displacement sensor 14. The force sensor 8 is fixed between the connecting bracket and the underwater submersible model and is used to measure the resistance experienced by the submersible during navigation. The laser displacement sensor is used to measure the vertical deformation of the ice sheet of the model during the test. The ice-water pool model test method includes the following steps:

[0013] (1) Set up and install an ice-water pool test device to simulate the underwater submersible's navigation under ice. The underwater track is strictly positioned and its flatness is adjusted. The diving depth of the submersible model is controlled by adjusting the height of the connecting bracket.

[0014] (2) Preparation of the model ice cap: A model ice cap meeting the target thickness requirement was prepared in an ice-water pool through cooling, spray crystallization, and temperature control. The bending strength of the model ice cap was measured using the cantilever beam method, and the elastic modulus of the model ice cap was measured using the infinite plate method to ensure that the mechanical properties of the model ice cap met the target requirements. A snow cover layer was prepared on the surface of the model ice cap;

[0015] (3) Calibrate the laser displacement sensor and force sensor: Fix the laser displacement sensor on the mobile measurement platform, place the mobile measurement platform at the predetermined observation position in the ice water pool, and adjust the underwater submersible model to the designed attitude and diving depth;

[0016] (4) Experimental testing.

[0017] Furthermore, during the testing, the underwater submersible model's speed was set according to the experimental conditions, and the underwater tracked motion platform was activated. During the test, the data acquisition system collected real-time data on ice surface deformation and model resistance. High-definition video recording equipment was also used to record ice surface deformation and damage phenomena.

[0018] The essential features of this invention are: ① The testing method can ensure accurate and stable speed, attitude, and diving depth of the underwater vehicle while navigating under ice without disturbing the ice surface. ② The testing system includes a force sensor and a laser displacement sensor, which can simultaneously measure the underwater vehicle's resistance and the ice sheet deformation of the model. ③ The testing method is highly adaptable and low-cost, and can be applied to various ice-water pool laboratories. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of an ice-water pool test device for simulating underwater submersible navigation under ice, according to the present invention.

[0020] Figure 2 This is a schematic diagram of the connection between the underwater tracked motion platform and the closed-loop transmission chain of the present invention.

[0021] Figure 3 This is a schematic diagram of the closed-loop transmission chain of the present invention changing direction at one end of the pool wall via a transmission gear.

[0022] The following are the labels in the diagram: 1. Servo drive system; 2. Gear set; 3. Power source transmission chain; 4. Closed-loop transmission chain; 5. Connecting bracket; 6. Underwater tracked motion platform; 7. Underwater submersible model; 8. Force sensor; 9. Underwater track; 10. Transmission gear; 11. Prefabricated connector; 12. Track wheel; 13. Fixed bracket; 14. Laser displacement sensor. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the embodiments.

[0024] (1) First, set up and install an ice-water pool test device to simulate the navigation of an underwater submersible near the ice surface.

[0025] The ice-water pool test device for simulating underwater submersible navigation near the ice surface of the present invention consists of several parts, including an underwater track 9, a motion platform 6, a closed-loop transmission chain 4, and a servo drive system 1, as detailed below:

[0026] Underwater Rail 9. Two rows of underwater rails 9 are laid and installed at the bottom of the ice water pool. The rails are made of rectangular tubing for easy leveling and connection. To ensure the stability of the underwater vehicle's movement speed, the surfaces of the two rows of underwater rails 9 must be flat, with straightness and vertical errors within ±2mm along their entire length. To facilitate adjustment of the position of the two rows of rails, prefabricated connectors 11 can be used to fix them at the joints of every two rails and in the middle of the rails. The connectors prefabricate the fixing positions of the two rows of rails, thus ensuring that the height of the rail surface, straightness, and spacing between the two rows of rails strictly meet the design requirements. At the same time, the prefabricated connectors can form a frame structure with the two rows of rails, increasing the stability of the underwater rails. The fixing bolts on the connectors can also serve as rail height adjustment devices. The spacing between the prefabricated connectors on the underwater rails should not exceed 1m. On the other hand, to avoid damaging the waterproof layer at the bottom of the pool, the underwater rails can be stabilized and fixed with counterweights (not shown in the figure).

[0027] In this embodiment, each row of tracks uses four rectangular tubes, each 6m long, for a total track length of 24m. Prefabricated connectors 11 are installed at 1m intervals along the tracks and secured to them with bolts on both sides. The straightness and upper surface height error of the two rows of tracks are adjusted by using bolt fixing positions and shims, and controlled within ±2mm. A 50kg counterweight is placed on each connector between the two rows of tracks to stabilize the underwater track.

[0028] Motion Platform 6. The underwater tracked motion platform is the core component of the ice-water pool test device for simulating the near-ice surface navigation of an underwater submersible according to this invention. Two rows of track wheels 12 are installed at the bottom of the motion platform 6, allowing it to move back and forth along the underwater track, simulating the straight-line navigation of the underwater submersible. A height-adjustable connecting bracket 5 is installed on the motion platform. The connecting bracket 5 consists of two telescopic rods, front and rear, which can adjust the height of the bracket to control the immersion depth of the underwater submersible. The underwater submersible model is fixed above the connecting bracket 5, and the immersion depth of the submersible in the water is controlled by the height of the bracket. To avoid the influence of deformation of the connecting bracket on the submersible's motion attitude, the connecting bracket should have high rigidity, and it is recommended that the height of the bracket be limited to within 1.5m. By adjusting the connection position and fixing method between the connecting bracket and the underwater submersible model, the navigation attitude of the submersible model under the ice can be fixed. An underwater force sensor 8 can be arranged at the connection position between the connecting bracket and the model to measure the resistance encountered by the submersible during navigation. A counterweight (not shown in the figure) is placed on the upper surface of the motion platform to improve the stability of the model's motion. The connecting bracket 5 is also fixed thereon. The upper end of the connecting bracket is connected to the underwater submersible model 7 via a force sensor 8.

[0029] A closed-loop drive chain 4 is used to connect the underwater tracked motion platform 6, providing forward and backward traction. Compared to steel cables, the meshing transmission of the drive chain avoids the "slippage" problem of steel cables underwater, ensuring the stability of the submersible model's movement speed. The two ends of the closed-loop drive chain 4 are connected to the front and rear facades of the underwater tracked motion platform, respectively. Starting from the rear facade of the platform, the drive chain extends parallel to the underwater track 9 to the drive gear 10 near the pool wall. The drive gear then changes direction from horizontal to vertical, extending upwards until it connects to the gear set 2. Both the drive gear 10 and gear set 2 are mounted on a fixed bracket 13 close to the pool wall. The lower part of the fixed bracket 13 is connected to the underwater track 9, and the upper part is fixed to the pool wall. The gear set can move vertically up and down, thereby adjusting the tension of the drive chain. During testing, upward movement tensions the drive chain. During installation and replacement of the chain, the chain moves downwards to loosen it for easier assembly and disassembly. After passing over gear set 2, the chain extends vertically downwards into the water again, and then changes direction again via gear 10 to continue extending forward parallel to the underwater track 9. The chain passes under the underwater tracked motion platform 6 until it makes a 180° turn on gear 10 at the other end of the track, finally returning to the front facade of the motion platform 6.

[0030] The servo drive system 1 is the power source for the entire test setup. The servo motor and reducer can be mounted on the wall of the ice-water pool at one end, driving the underwater track platform forward and backward along the track via a transmission chain and gear set. During the selection of the servo drive system, the maximum speed should meet the speed requirements of the underwater submersible test, and the rated power should be able to overcome the submersible's motion resistance. Before the test, the speed of the servo drive system needs to be calibrated to determine the conversion relationship between the motor speed and the submersible's movement speed. The servo drive system 1 is mounted on a fixed bracket 13 on the pool wall at one end of the ice-water pool. It is connected to the gear set 2 via the power source transmission chain 3, thereby driving the closed-loop transmission chain 4, which in turn drives the underwater track platform 6 forward and backward along the underwater track 9.

[0031] In this embodiment, two rows of 24m long underwater tracks 9 are laid and installed at the bottom of the ice water pool. An underwater tracked motion platform 6, 0.5m long and 0.3m high, is placed on the underwater tracks. Two rows of four track wheels are installed at the bottom of the platform, allowing it to move back and forth along the tracks. A retractable connecting bracket 5 is fixed to the motion platform and connected to the underwater submersible model 7 via a force sensor 8. The underwater tracked motion platform 6 is connected to both ends of a closed-loop transmission chain 4. The transmission chain 4 is redirected by transmission gears 10 at both ends of the tracks and finally connected to a gear set 2 on a fixed bracket 13, which is fixed to one end of the ice water pool wall. The gear set 2 is then connected to a servo drive system 1 via a power source transmission chain 3 located outside the ice water pool. By setting the speed and direction of rotation of the servo motor, the reciprocating speed of the underwater platform along the length of the pool is controlled. The servo motor has a maximum speed of 3000 r / min and a rated power of 11 kW, which can drive the underwater submersible model to move underwater at a maximum speed of 2.5 m / s.

[0032] (2) Preparation of the model ice cap. The model ice cap was prepared in an ice-water tank using processes such as spray crystal induction and temperature control. Since the ice cap damage caused by the underwater vehicle is mainly due to bending gravity waves within the ice, the ice cap exhibits typical elasto-brittle mechanical characteristics. Therefore, during the preparation of the model ice cap, it is also necessary to control the spray crystal induction and temperature control techniques to ensure that the model ice cap also exhibits elasto-brittle mechanical behavior. Following the model ice cap preparation process, a model ice cap meeting the target thickness requirements was prepared through cooling, spray crystal induction, and temperature control. The bending strength of the model ice cap was measured using the cantilever beam method, and the elastic modulus was measured using the infinite plate method to ensure that the mechanical properties of the model ice cap met the target requirements. Finally, a snow layer was prepared on the surface of the model ice cap to facilitate crack observation. The specific methods are as follows:

[0033] When the indoor temperature drops to -22°C, spray crystallization begins. Water at approximately 30°C is sprayed onto the surface of the ice pool using an industrial spray gun at about 20 atmospheres of pressure. The micro-atomized water droplets sprayed into the air above the ice pool rapidly absorb cold as they fall, forming tiny ice crystals that settle evenly on the surface. Because the surface of the water in the pool is already at freezing point, the falling micro-ice crystals do not melt, thus controlling the ice crystal lattice size and inducing ice growth. As the air continues to cool, the ice crystals grow continuously from top to bottom. The purpose of spray crystallization is to control the ice crystal lattice size. The entire spray crystallization process is conducted with the refrigeration unit shut off and the air supply stopped to avoid disturbing the water surface and causing breakage and unevenness in the ice crystal nuclei. Once a stable connection is initially formed between the ice crystal nuclei, the cooling process resumes. Cooling continues until the ice cap grows to the predetermined thickness, at which point the system is shut down, and the experiment begins.

[0034] Because the model ice sheet has high light transmittance, ice surface cracks caused by wave-making by underwater vehicles are not obvious in some cases. To improve the visibility of ice surface cracks, an additional layer of snow about 0.4 mm thick can be prepared on the model ice surface before the experiment begins. The experiment can then begin immediately after preparation, serving only as a tracer for ice surface cracks without affecting the physical and mechanical properties of the model ice sheet.

[0035] (3) Design, calibrate, and install the test system.

[0036] During underwater vehicle near-ice surface navigation tests, the physical parameters requiring special attention are navigation resistance and ice sheet deformation. The testing system is designed to address these two physical quantities and consists of several force sensors and laser displacement sensors. The force sensors are positioned at the connection point between the rigid support frame and the submersible model. These sensors should be able to operate normally within a temperature range of -20℃ to 80℃, possess a waterproof rating of IP68 or higher, and be set with a sampling frequency of 100Hz or higher.

[0037] To accurately measure the vertical deformation of the model ice sheet during the experiment, two high-precision, non-contact laser displacement sensors were used. The sensor measurement accuracy was at least 0.02 mm, and the sampling frequency was set to 100 Hz or higher. To facilitate the installation and movement of the laser displacement sensors, a movable measurement platform (not shown in the figure) spanning the surface of the ice water pool was installed, and the laser displacement sensor 14 was fixed on the movable measurement platform.

[0038] Calibrate the laser displacement sensor and force sensor, fix the laser displacement sensor 14 to the mobile measurement platform, and place the mobile measurement platform at the predetermined observation position in the ice-water pool. Adjust the underwater submersible model to the designed attitude and diving depth.

[0039] (4) Test. The speed of the underwater submersible model was set according to the test conditions and the underwater tracked motion platform was started. During the test, the ice surface deformation and the model's navigation resistance were collected in real time through the data acquisition system, and the ice surface deformation and damage phenomena were recorded through high-definition video recording equipment.

Claims

1. A test method for an ice-water pool model of an underwater submersible navigating under ice, the test apparatus comprising an underwater track (9), a motion platform (6), a closed-loop transmission chain (4), a servo drive system (1), and a test system, wherein, The underwater track (9) is laid at the bottom of the ice water pool and includes two rows of spliced ​​tracks. The splice is fixed by prefabricated connectors (11). The prefabricated connectors prefabricate the fixed positions of the two rows of tracks, form a frame structure with the two rows of tracks, and are equipped with adjustment components for adjusting the height of the tracks. The motion platform (6) is placed on the underwater track (9) by two rows of track wheels (12) at the bottom to simulate the straight-line navigation of the underwater submersible. The motion platform (6) is equipped with a height-adjustable connecting bracket (5) for fixing the underwater submersible model. The closed-loop transmission chain (4) serves as the main transmission component of the motion platform. One end of the chain is connected to the front of the motion platform and wraps around the entire underwater track and the fixed support (13) at one end of the pool wall. The other end of the transmission chain is connected to the rear of the motion platform. The fixed support (13) is located next to the pool wall at one end of the ice water pool. A gear set (2) is installed at the top and a transmission gear (10) is installed at the bottom. The closed-loop transmission chain wraps around the fixed support through the gear set at the top and the transmission gear at the bottom, and then turns from vertical to horizontal at the bottom transmission gear. The transmission chain can be adjusted to be tensioned or relaxed. The servo drive system chain (1) is connected to the gear set (2) through the power source transmission chain (3), thereby driving the closed loop transmission chain (4) to drive the motion platform (6) to move along the underwater track (9); The testing system includes a force sensor (8) and a laser displacement sensor (14). The force sensor (8) is fixed between the connecting bracket and the underwater submersible model and is used to measure the resistance experienced by the submersible during navigation. The laser displacement sensor is used to measure the vertical deformation of the ice sheet of the model during the test. The ice-water pool model test method includes the following steps: (1) Set up and install an ice-water pool test device to simulate the underwater submersible's navigation under ice. The underwater track is strictly positioned and its flatness is adjusted. The diving depth of the submersible model is controlled by adjusting the height of the connecting bracket. (2) Preparation of model ice cap: The model ice cap that meets the target thickness requirement is prepared in the ice water pool through cooling, spray crystal introduction and temperature control. The bending strength of the model ice cap is measured by the cantilever beam method and the elastic modulus of the model ice cap is measured by the infinite plate method to ensure that the mechanical properties of the model ice cap meet the target requirements. A snow cover layer is prepared on the surface of the model ice cap. (3) Calibrate the laser displacement sensor and force sensor: Fix the laser displacement sensor on the mobile measurement platform, place the mobile measurement platform at the predetermined observation position in the ice water pool, and adjust the underwater submersible model to the designed attitude and diving depth; (4) Tests.

2. The ice-water pool model test method for underwater submersible navigation under ice as described in claim 1, characterized in that, The adjusting component includes a fixing bolt.

3. The ice-water pool model test method for underwater submersible navigation under ice as described in claim 1, characterized in that, During the test, the underwater submersible model's speed was set according to the test conditions, and the underwater tracked motion platform was started. During the test, the ice surface deformation and the model's navigation resistance were collected in real time through the data acquisition system.

4. The ice-water pool model test method for underwater submersible navigation under ice as described in claim 3, characterized in that, They also used high-definition video recording equipment to record the deformation and damage of the ice surface.

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